/******************************************************************************
 *
 * Project:  netCDF read/write Driver
 * Purpose:  GDAL bindings over netCDF library.
 * Author:   Frank Warmerdam, warmerdam@pobox.com
 *           Even Rouault <even.rouault at spatialys.com>
 *
 ******************************************************************************
 * Copyright (c) 2004, Frank Warmerdam
 * Copyright (c) 2007-2016, Even Rouault <even.rouault at spatialys.com>
 * Copyright (c) 2010, Kyle Shannon <kyle at pobox dot com>
 * Copyright (c) 2021, CLS
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 ****************************************************************************/

#include "cpl_port.h"

#include <cassert>
#include <cctype>
#include <cerrno>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <algorithm>
#include <limits>
#include <map>
#include <set>
#include <queue>
#include <string>
#include <tuple>
#include <utility>
#include <vector>

// Must be included after standard includes, otherwise VS2015 fails when
// including <ctime>
#include "netcdfdataset.h"
#include "netcdfsg.h"
#include "netcdfuffd.h"

#ifdef HAVE_NETCDF_MEM
#include "netcdf_mem.h"
#endif

#include "cpl_conv.h"
#include "cpl_error.h"
#include "cpl_json.h"
#include "cpl_minixml.h"
#include "cpl_multiproc.h"
#include "cpl_progress.h"
#include "cpl_time.h"
#include "gdal.h"
#include "gdal_frmts.h"
#include "ogr_core.h"
#include "ogr_srs_api.h"

#define ROTATED_POLE_VAR_NAME "rotated_pole"

// netCDF 4.8 switched to expecting filenames in UTF-8 on Windows
// But with netCDF 4.9 and https://github.com/Unidata/netcdf-c/pull/2277/,
// this is apparently back to expecting filenames in current codepage...
// Detect netCDF 4.8 with NC_ENCZARR
// Detect netCDF 4.9 with NC_NOATTCREORD
#if defined(NC_ENCZARR) && !defined(NC_NOATTCREORD)
#define NETCDF_USES_UTF8
#endif

// Internal function declarations.

static bool NCDFIsGDALVersionGTE(const char *pszVersion, int nTarget);

static void
NCDFAddGDALHistory(int fpImage, const char *pszFilename, bool bWriteGDALVersion,
                   bool bWriteGDALHistory, const char *pszOldHist,
                   const char *pszFunctionName,
                   const char *pszCFVersion = GDAL_DEFAULT_NCDF_CONVENTIONS);

static void NCDFAddHistory(int fpImage, const char *pszAddHist,
                           const char *pszOldHist);

static bool NCDFIsCfProjection(const char *pszProjection);

static std::vector<std::pair<std::string, double>>
NCDFGetProjAttribs(const OGR_SRSNode *poPROJCS, const char *pszProjection);

static CPLErr NCDFSafeStrcat(char **ppszDest, const char *pszSrc,
                             size_t *nDestSize);

// Var / attribute helper functions.
static CPLErr NCDFPutAttr(int nCdfId, int nVarId, const char *pszAttrName,
                          const char *pszValue);

// Replace this where used.
static CPLErr NCDFGet1DVar(int nCdfId, int nVarId, char **pszValue);
static CPLErr NCDFPut1DVar(int nCdfId, int nVarId, const char *pszValue);

// Replace this where used.
static char **NCDFTokenizeArray(const char *pszValue);
static void CopyMetadata(GDALDataset *poSrcDS, GDALRasterBand *poSrcBand,
                         GDALRasterBand *poDstBand, int fpImage, int CDFVarID,
                         const char *pszMatchPrefix = nullptr);

// NetCDF-4 groups helper functions.
// They all work also for NetCDF-3 files which are considered as
// NetCDF-4 file with only one group.
static CPLErr NCDFOpenSubDataset(int nCdfId, const char *pszSubdatasetName,
                                 int *pnGroupId, int *pnVarId);
static CPLErr NCDFGetVisibleDims(int nGroupId, int *pnDims, int **ppanDimIds);
static CPLErr NCDFGetSubGroups(int nGroupId, int *pnSubGroups,
                               int **ppanSubGroupIds);
static CPLErr NCDFGetGroupFullName(int nGroupId, char **ppszFullName,
                                   bool bNC3Compat = true);
static CPLErr NCDFGetVarFullName(int nGroupId, int nVarId, char **ppszFullName,
                                 bool bNC3Compat = true);
static CPLErr NCDFGetRootGroup(int nStartGroupId, int *pnRootGroupId);

static CPLErr NCDFResolveVarFullName(int nStartGroupId, const char *pszVar,
                                     char **ppszFullName,
                                     bool bMandatory = false);
static CPLErr NCDFResolveAttInt(int nStartGroupId, int nStartVarId,
                                const char *pszAtt, int *pnAtt,
                                bool bMandatory = false);
static CPLErr NCDFGetCoordAndBoundVarFullNames(int nCdfId, char ***ppapszVars);

// Uncomment this for more debug output.
// #define NCDF_DEBUG 1

CPLMutex *hNCMutex = nullptr;

// Workaround https://github.com/OSGeo/gdal/issues/6253
// Having 2 netCDF handles on the same file doesn't work in a multi-threaded
// way. Apparently having the same handle works better (this is OK since
// we have a global mutex on the netCDF library)
static std::map<std::string, int> goMapNameToNetCDFId;
static std::map<int, std::pair<std::string, int>> goMapNetCDFIdToKeyAndCount;

int GDAL_nc_open(const char *pszFilename, int nMode, int *pID)
{
    std::string osKey(pszFilename);
    osKey += "#####";
    osKey += std::to_string(nMode);
    auto oIter = goMapNameToNetCDFId.find(osKey);
    if (oIter == goMapNameToNetCDFId.end())
    {
        int ret = nc_open(pszFilename, nMode, pID);
        if (ret != NC_NOERR)
            return ret;
        goMapNameToNetCDFId[osKey] = *pID;
        goMapNetCDFIdToKeyAndCount[*pID] =
            std::pair<std::string, int>(osKey, 1);
        return ret;
    }
    else
    {
        *pID = oIter->second;
        goMapNetCDFIdToKeyAndCount[oIter->second].second++;
        return NC_NOERR;
    }
}

int GDAL_nc_close(int cdfid)
{
    int ret = NC_NOERR;
    auto oIter = goMapNetCDFIdToKeyAndCount.find(cdfid);
    if (oIter != goMapNetCDFIdToKeyAndCount.end())
    {
        if (--oIter->second.second == 0)
        {
            ret = nc_close(cdfid);
            goMapNameToNetCDFId.erase(oIter->second.first);
            goMapNetCDFIdToKeyAndCount.erase(oIter);
        }
    }
    else
    {
        // we can go here if file opened with nc_open_mem() or nc_create()
        ret = nc_close(cdfid);
    }
    return ret;
}

/************************************************************************/
/* ==================================================================== */
/*                         netCDFRasterBand                             */
/* ==================================================================== */
/************************************************************************/

class netCDFRasterBand final : public GDALPamRasterBand
{
    friend class netCDFDataset;

    nc_type nc_datatype;
    int cdfid;
    int nZId;
    int nZDim;
    int nLevel;
    int nBandXPos;
    int nBandYPos;
    int *panBandZPos;
    int *panBandZLev;
    bool m_bNoDataSet = false;
    double m_dfNoDataValue = 0;
    bool m_bNoDataSetAsInt64 = false;
    int64_t m_nNodataValueInt64 = 0;
    bool m_bNoDataSetAsUInt64 = false;
    uint64_t m_nNodataValueUInt64 = 0;
    bool bValidRangeValid = false;
    double adfValidRange[2]{0, 0};
    bool m_bHaveScale = false;
    bool m_bHaveOffset = false;
    double m_dfScale = 1;
    double m_dfOffset = 0;
    CPLString m_osUnitType{};
    bool bSignedData;
    bool bCheckLongitude;

    CPLErr CreateBandMetadata(const int *paDimIds,
                              const int *panExtraDimGroupIds,
                              const int *panExtraDimVarIds);
    template <class T>
    void CheckData(void *pImage, void *pImageNC, size_t nTmpBlockXSize,
                   size_t nTmpBlockYSize, bool bCheckIsNan = false);
    template <class T>
    void CheckDataCpx(void *pImage, void *pImageNC, size_t nTmpBlockXSize,
                      size_t nTmpBlockYSize, bool bCheckIsNan = false);
    void SetBlockSize();

    bool FetchNetcdfChunk(size_t xstart, size_t ystart, void *pImage);

    void SetNoDataValueNoUpdate(double dfNoData);
    void SetNoDataValueNoUpdate(int64_t nNoData);
    void SetNoDataValueNoUpdate(uint64_t nNoData);

    void SetOffsetNoUpdate(double dfVal);
    void SetScaleNoUpdate(double dfVal);
    void SetUnitTypeNoUpdate(const char *pszNewValue);

  protected:
    CPLXMLNode *SerializeToXML(const char *pszUnused) override;

  public:
    struct CONSTRUCTOR_OPEN
    {
    };
    struct CONSTRUCTOR_CREATE
    {
    };

    netCDFRasterBand(const CONSTRUCTOR_OPEN &, netCDFDataset *poDS,
                     int nGroupId, int nZId, int nZDim, int nLevel,
                     const int *panBandZLen, const int *panBandPos,
                     const int *paDimIds, int nBand,
                     const int *panExtraDimGroupIds,
                     const int *panExtraDimVarIds);
    netCDFRasterBand(const CONSTRUCTOR_CREATE &, netCDFDataset *poDS,
                     GDALDataType eType, int nBand, bool bSigned = true,
                     const char *pszBandName = nullptr,
                     const char *pszLongName = nullptr, int nZId = -1,
                     int nZDim = 2, int nLevel = 0,
                     const int *panBandZLev = nullptr,
                     const int *panBandZPos = nullptr,
                     const int *paDimIds = nullptr);
    virtual ~netCDFRasterBand();

    virtual double GetNoDataValue(int *) override;
    virtual int64_t GetNoDataValueAsInt64(int *pbSuccess = nullptr) override;
    virtual uint64_t GetNoDataValueAsUInt64(int *pbSuccess = nullptr) override;
    virtual CPLErr SetNoDataValue(double) override;
    virtual CPLErr SetNoDataValueAsInt64(int64_t nNoData) override;
    virtual CPLErr SetNoDataValueAsUInt64(uint64_t nNoData) override;
    // virtual CPLErr DeleteNoDataValue();
    virtual double GetOffset(int *) override;
    virtual CPLErr SetOffset(double) override;
    virtual double GetScale(int *) override;
    virtual CPLErr SetScale(double) override;
    virtual const char *GetUnitType() override;
    virtual CPLErr SetUnitType(const char *) override;
    virtual CPLErr IReadBlock(int, int, void *) override;
    virtual CPLErr IWriteBlock(int, int, void *) override;

    virtual CPLErr SetMetadataItem(const char *pszName, const char *pszValue,
                                   const char *pszDomain = "") override;
    virtual CPLErr SetMetadata(char **papszMD,
                               const char *pszDomain = "") override;
};

/************************************************************************/
/*                          netCDFRasterBand()                          */
/************************************************************************/

netCDFRasterBand::netCDFRasterBand(
    const netCDFRasterBand::CONSTRUCTOR_OPEN &, netCDFDataset *poNCDFDS,
    int nGroupId, int nZIdIn, int nZDimIn, int nLevelIn,
    const int *panBandZLevIn, const int *panBandZPosIn, const int *paDimIds,
    int nBandIn, const int *panExtraDimGroupIds, const int *panExtraDimVarIds)
    : nc_datatype(NC_NAT), cdfid(nGroupId), nZId(nZIdIn), nZDim(nZDimIn),
      nLevel(nLevelIn), nBandXPos(panBandZPosIn[0]),
      nBandYPos(nZDim == 1 ? -1 : panBandZPosIn[1]), panBandZPos(nullptr),
      panBandZLev(nullptr),
      bSignedData(true),  // Default signed, except for Byte.
      bCheckLongitude(false)
{
    poDS = poNCDFDS;
    nBand = nBandIn;

    // Take care of all other dimensions.
    if (nZDim > 2)
    {
        panBandZPos = static_cast<int *>(CPLCalloc(nZDim - 1, sizeof(int)));
        panBandZLev = static_cast<int *>(CPLCalloc(nZDim - 1, sizeof(int)));

        for (int i = 0; i < nZDim - 2; i++)
        {
            panBandZPos[i] = panBandZPosIn[i + 2];
            panBandZLev[i] = panBandZLevIn[i];
        }
    }

    nRasterXSize = poDS->GetRasterXSize();
    nRasterYSize = poDS->GetRasterYSize();
    nBlockXSize = poDS->GetRasterXSize();
    nBlockYSize = 1;

    // Get the type of the "z" variable, our target raster array.
    if (nc_inq_var(cdfid, nZId, nullptr, &nc_datatype, nullptr, nullptr,
                   nullptr) != NC_NOERR)
    {
        CPLError(CE_Failure, CPLE_AppDefined, "Error in nc_var_inq() on 'z'.");
        return;
    }

#ifdef NETCDF_HAS_NC4
    if (NCDFIsUserDefinedType(cdfid, nc_datatype))
    {
        // First enquire and check that the number of fields is 2
        size_t nfields, compoundsize;
        if (nc_inq_compound(cdfid, nc_datatype, nullptr, &compoundsize,
                            &nfields) != NC_NOERR)
        {
            CPLError(CE_Failure, CPLE_AppDefined,
                     "Error in nc_inq_compound() on 'z'.");
            return;
        }

        if (nfields != 2)
        {
            CPLError(CE_Failure, CPLE_AppDefined,
                     "Unsupported data type encountered in nc_inq_compound() "
                     "on 'z'.");
            return;
        }

        // Now check that that two types are the same in the struct.
        nc_type field_type1, field_type2;
        int field_dims1, field_dims2;
        if (nc_inq_compound_field(cdfid, nc_datatype, 0, nullptr, nullptr,
                                  &field_type1, &field_dims1,
                                  nullptr) != NC_NOERR)
        {
            CPLError(
                CE_Failure, CPLE_AppDefined,
                "Error in querying Field 1 in nc_inq_compound_field() on 'z'.");
            return;
        }

        if (nc_inq_compound_field(cdfid, nc_datatype, 0, nullptr, nullptr,
                                  &field_type2, &field_dims2,
                                  nullptr) != NC_NOERR)
        {
            CPLError(
                CE_Failure, CPLE_AppDefined,
                "Error in querying Field 2 in nc_inq_compound_field() on 'z'.");
            return;
        }

        if ((field_type1 != field_type2) || (field_dims1 != field_dims2) ||
            (field_dims1 != 0))
        {
            CPLError(CE_Failure, CPLE_AppDefined,
                     "Error in interpreting compound data type on 'z'.");
            return;
        }

        if (field_type1 == NC_SHORT)
            eDataType = GDT_CInt16;
        else if (field_type1 == NC_INT)
            eDataType = GDT_CInt32;
        else if (field_type1 == NC_FLOAT)
            eDataType = GDT_CFloat32;
        else if (field_type1 == NC_DOUBLE)
            eDataType = GDT_CFloat64;
        else
        {
            CPLError(CE_Failure, CPLE_AppDefined,
                     "Unsupported netCDF compound data type encountered.");
            return;
        }
    }
    else
#endif
    {
        if (nc_datatype == NC_BYTE)
            eDataType = GDT_Byte;
        else if (nc_datatype == NC_CHAR)
            eDataType = GDT_Byte;
        else if (nc_datatype == NC_SHORT)
            eDataType = GDT_Int16;
        else if (nc_datatype == NC_INT)
            eDataType = GDT_Int32;
        else if (nc_datatype == NC_FLOAT)
            eDataType = GDT_Float32;
        else if (nc_datatype == NC_DOUBLE)
            eDataType = GDT_Float64;
#ifdef NETCDF_HAS_NC4
        // NC_UBYTE (unsigned byte) is only available for NC4.
        else if (nc_datatype == NC_UBYTE)
            eDataType = GDT_Byte;
        else if (nc_datatype == NC_USHORT)
            eDataType = GDT_UInt16;
        else if (nc_datatype == NC_UINT)
            eDataType = GDT_UInt32;
        else if (nc_datatype == NC_INT64)
            eDataType = GDT_Int64;
        else if (nc_datatype == NC_UINT64)
            eDataType = GDT_UInt64;
#endif
        else
        {
            if (nBand == 1)
                CPLError(CE_Warning, CPLE_AppDefined,
                         "Unsupported netCDF datatype (%d), treat as Float32.",
                         static_cast<int>(nc_datatype));
            eDataType = GDT_Float32;
            nc_datatype = NC_FLOAT;
        }
    }

    // Find and set No Data for this variable.
    nc_type atttype = NC_NAT;
    size_t attlen = 0;
    const char *pszNoValueName = nullptr;

    // Find attribute name, either _FillValue or missing_value.
    int status = nc_inq_att(cdfid, nZId, _FillValue, &atttype, &attlen);
    if (status == NC_NOERR)
    {
        pszNoValueName = _FillValue;
    }
    else
    {
        status = nc_inq_att(cdfid, nZId, "missing_value", &atttype, &attlen);
        if (status == NC_NOERR)
        {
            pszNoValueName = "missing_value";
        }
    }

    // Fetch missing value.
    double dfNoData = 0.0;
    bool bGotNoData = false;
#ifdef NETCDF_HAS_NC4
    int64_t nNoDataAsInt64 = 0;
    bool bGotNoDataAsInt64 = false;
    uint64_t nNoDataAsUInt64 = 0;
    bool bGotNoDataAsUInt64 = false;
#endif
    if (status == NC_NOERR)
    {
#ifdef NETCDF_HAS_NC4
        nc_type nAttrType = NC_NAT;
        size_t nAttrLen = 0;
        status = nc_inq_att(cdfid, nZId, pszNoValueName, &nAttrType, &nAttrLen);
        if (status == NC_NOERR && nAttrLen == 1 && nAttrType == NC_INT64)
        {
            long long v;
            nc_get_att_longlong(cdfid, nZId, pszNoValueName, &v);
            bGotNoData = true;
            bGotNoDataAsInt64 = true;
            nNoDataAsInt64 = static_cast<int64_t>(v);
        }
        else if (status == NC_NOERR && nAttrLen == 1 && nAttrType == NC_UINT64)
        {
            unsigned long long v;
            nc_get_att_ulonglong(cdfid, nZId, pszNoValueName, &v);
            bGotNoData = true;
            bGotNoDataAsUInt64 = true;
            nNoDataAsUInt64 = static_cast<uint64_t>(v);
        }
        else
#endif
            if (NCDFGetAttr(cdfid, nZId, pszNoValueName, &dfNoData) == CE_None)
        {
            bGotNoData = true;
        }
    }

    // If NoData was not found, use the default value, but for non-Byte types
    // as it is not recommended:
    // https://www.unidata.ucar.edu/software/netcdf/docs/attribute_conventions.html
    nc_type vartype = NC_NAT;
    if (!bGotNoData)
    {
        nc_inq_vartype(cdfid, nZId, &vartype);
#ifdef NETCDF_HAS_NC4
        if (vartype == NC_INT64)
        {
            nNoDataAsInt64 =
                NCDFGetDefaultNoDataValueAsInt64(cdfid, nZId, bGotNoData);
            bGotNoDataAsInt64 = bGotNoData;
        }
        else if (vartype == NC_UINT64)
        {
            nNoDataAsUInt64 =
                NCDFGetDefaultNoDataValueAsUInt64(cdfid, nZId, bGotNoData);
            bGotNoDataAsUInt64 = bGotNoData;
        }
        else
#endif
            if (vartype != NC_CHAR && vartype != NC_BYTE
#ifdef NETCDF_HAS_NC4
                && vartype != NC_UBYTE
#endif
            )
        {
            dfNoData =
                NCDFGetDefaultNoDataValue(cdfid, nZId, vartype, bGotNoData);
            if (bGotNoData)
            {
                CPLDebug("GDAL_netCDF",
                         "did not get nodata value for variable #%d, using "
                         "default %f",
                         nZId, dfNoData);
            }
        }
    }

    bool bHasUnderscoreUnsignedAttr = false;
    bool bUnderscoreUnsignedAttrVal = false;
    {
        char *pszTemp = nullptr;
        if (NCDFGetAttr(cdfid, nZId, "_Unsigned", &pszTemp) == CE_None)
        {
            if (EQUAL(pszTemp, "true"))
            {
                bHasUnderscoreUnsignedAttr = true;
                bUnderscoreUnsignedAttrVal = true;
            }
            else if (EQUAL(pszTemp, "false"))
            {
                bHasUnderscoreUnsignedAttr = true;
                bUnderscoreUnsignedAttrVal = false;
            }
            CPLFree(pszTemp);
        }
    }

    // Look for valid_range or valid_min/valid_max.

    // First look for valid_range.
    if (CPLFetchBool(poNCDFDS->GetOpenOptions(), "HONOUR_VALID_RANGE", true))
    {
        char *pszValidRange = nullptr;
        if (NCDFGetAttr(cdfid, nZId, "valid_range", &pszValidRange) ==
                CE_None &&
            pszValidRange[0] == '{' &&
            pszValidRange[strlen(pszValidRange) - 1] == '}')
        {
            const std::string osValidRange =
                std::string(pszValidRange).substr(1, strlen(pszValidRange) - 2);
            const CPLStringList aosValidRange(
                CSLTokenizeString2(osValidRange.c_str(), ",", 0));
            if (aosValidRange.size() == 2 &&
                CPLGetValueType(aosValidRange[0]) != CPL_VALUE_STRING &&
                CPLGetValueType(aosValidRange[1]) != CPL_VALUE_STRING)
            {
                bValidRangeValid = true;
                adfValidRange[0] = CPLAtof(aosValidRange[0]);
                adfValidRange[1] = CPLAtof(aosValidRange[1]);
            }
        }
        CPLFree(pszValidRange);

        // If not found look for valid_min and valid_max.
        if (!bValidRangeValid)
        {
            double dfMin = 0;
            double dfMax = 0;
            if (NCDFGetAttr(cdfid, nZId, "valid_min", &dfMin) == CE_None &&
                NCDFGetAttr(cdfid, nZId, "valid_max", &dfMax) == CE_None)
            {
                adfValidRange[0] = dfMin;
                adfValidRange[1] = dfMax;
                bValidRangeValid = true;
            }
        }

        if (bValidRangeValid &&
            (adfValidRange[0] < 0 || adfValidRange[1] < 0) &&
            nc_datatype == NC_SHORT && bHasUnderscoreUnsignedAttr &&
            bUnderscoreUnsignedAttrVal)
        {
            if (adfValidRange[0] < 0)
                adfValidRange[0] += 65536;
            if (adfValidRange[1] < 0)
                adfValidRange[1] += 65536;
            if (adfValidRange[0] <= adfValidRange[1])
            {
                // Updating metadata item
                GDALPamRasterBand::SetMetadataItem(
                    "valid_range",
                    CPLSPrintf("{%d,%d}", static_cast<int>(adfValidRange[0]),
                               static_cast<int>(adfValidRange[1])));
            }
        }

        if (bValidRangeValid && adfValidRange[0] > adfValidRange[1])
        {
            CPLError(CE_Warning, CPLE_AppDefined,
                     "netCDFDataset::valid_range: min > max:\n"
                     "  min: %lf\n  max: %lf\n",
                     adfValidRange[0], adfValidRange[1]);
            bValidRangeValid = false;
            adfValidRange[0] = 0.0;
            adfValidRange[1] = 0.0;
        }
    }

    // Special For Byte Bands: check for signed/unsigned byte.
    if (nc_datatype == NC_BYTE)
    {
        // netcdf uses signed byte by default, but GDAL uses unsigned by default
        // This may cause unexpected results, but is needed for back-compat.
        if (poNCDFDS->bIsGdalFile)
            bSignedData = false;
        else
            bSignedData = true;

        // For NC4 format NC_BYTE is (normally) signed, NC_UBYTE is unsigned.
        // But in case a NC3 file was converted automatically and has hints
        // that it is unsigned, take them into account
        if (poNCDFDS->eFormat == NCDF_FORMAT_NC4)
        {
            bSignedData = true;
        }

        // If we got valid_range, test for signed/unsigned range.
        // https://docs.unidata.ucar.edu/netcdf-c/current/attribute_conventions.html
        if (bValidRangeValid)
        {
            // If we got valid_range={0,255}, treat as unsigned.
            if (adfValidRange[0] == 0 && adfValidRange[1] == 255)
            {
                bSignedData = false;
                // Reset valid_range.
                bValidRangeValid = false;
            }
            // If we got valid_range={-128,127}, treat as signed.
            else if (adfValidRange[0] == -128 && adfValidRange[1] == 127)
            {
                bSignedData = true;
                // Reset valid_range.
                bValidRangeValid = false;
            }
        }
        // Else test for _Unsigned.
        // https://docs.unidata.ucar.edu/nug/current/best_practices.html
        else
        {
            if (bHasUnderscoreUnsignedAttr)
                bSignedData = !bUnderscoreUnsignedAttrVal;
        }

        if (bSignedData)
        {
            // set PIXELTYPE=SIGNEDBYTE
            // See http://trac.osgeo.org/gdal/wiki/rfc14_imagestructure
            GDALPamRasterBand::SetMetadataItem("PIXELTYPE", "SIGNEDBYTE",
                                               "IMAGE_STRUCTURE");
        }
        else if (dfNoData < 0)
        {
            // Fix nodata value as it was stored signed.
            dfNoData += 256;
            if (pszNoValueName)
            {
                // Updating metadata item
                GDALPamRasterBand::SetMetadataItem(
                    pszNoValueName,
                    CPLSPrintf("%d", static_cast<int>(dfNoData)));
            }
        }
    }
    else if (nc_datatype == NC_SHORT)
    {
        if (bHasUnderscoreUnsignedAttr)
        {
            bSignedData = !bUnderscoreUnsignedAttrVal;
            if (!bSignedData)
                eDataType = GDT_UInt16;
        }

        // Fix nodata value as it was stored signed.
        if (!bSignedData && dfNoData < 0)
        {
            dfNoData += 65536;
            if (pszNoValueName)
            {
                // Updating metadata item
                GDALPamRasterBand::SetMetadataItem(
                    pszNoValueName,
                    CPLSPrintf("%d", static_cast<int>(dfNoData)));
            }
        }
    }

#ifdef NETCDF_HAS_NC4
    else if (nc_datatype == NC_UBYTE || nc_datatype == NC_USHORT ||
             nc_datatype == NC_UINT || nc_datatype == NC_UINT64)
    {
        bSignedData = false;
    }
#endif

    CPLDebug("GDAL_netCDF", "netcdf type=%d gdal type=%d signedByte=%d",
             nc_datatype, eDataType, static_cast<int>(bSignedData));

    if (bGotNoData)
    {
        // Set nodata value.
#ifdef NETCDF_HAS_NC4
        if (bGotNoDataAsInt64)
        {
            if (eDataType == GDT_Int64)
            {
                SetNoDataValueNoUpdate(nNoDataAsInt64);
            }
            else if (eDataType == GDT_UInt64 && nNoDataAsInt64 >= 0)
            {
                SetNoDataValueNoUpdate(static_cast<uint64_t>(nNoDataAsInt64));
            }
            else
            {
                SetNoDataValueNoUpdate(static_cast<double>(nNoDataAsInt64));
            }
        }
        else if (bGotNoDataAsUInt64)
        {
            if (eDataType == GDT_UInt64)
            {
                SetNoDataValueNoUpdate(nNoDataAsUInt64);
            }
            else if (eDataType == GDT_Int64 &&
                     nNoDataAsUInt64 <=
                         static_cast<uint64_t>(
                             std::numeric_limits<int64_t>::max()))
            {
                SetNoDataValueNoUpdate(static_cast<int64_t>(nNoDataAsUInt64));
            }
            else
            {
                SetNoDataValueNoUpdate(static_cast<double>(nNoDataAsUInt64));
            }
        }
        else
#endif
        {
#ifdef NCDF_DEBUG
            CPLDebug("GDAL_netCDF", "SetNoDataValue(%f) read", dfNoData);
#endif
            if (eDataType == GDT_Int64 &&
                dfNoData >=
                    static_cast<double>(std::numeric_limits<int64_t>::min()) &&
                dfNoData <=
                    static_cast<double>(std::numeric_limits<int64_t>::max()) &&
                dfNoData == static_cast<double>(static_cast<int64_t>(dfNoData)))
            {
                SetNoDataValueNoUpdate(static_cast<int64_t>(dfNoData));
            }
            else if (eDataType == GDT_UInt64 &&
                     dfNoData >= static_cast<double>(
                                     std::numeric_limits<uint64_t>::min()) &&
                     dfNoData <= static_cast<double>(
                                     std::numeric_limits<uint64_t>::max()) &&
                     dfNoData ==
                         static_cast<double>(static_cast<uint64_t>(dfNoData)))
            {
                SetNoDataValueNoUpdate(static_cast<uint64_t>(dfNoData));
            }
            else
            {
                SetNoDataValueNoUpdate(dfNoData);
            }
        }
    }

    // Create Band Metadata.
    CreateBandMetadata(paDimIds, panExtraDimGroupIds, panExtraDimVarIds);

    // Attempt to fetch the scale_factor and add_offset attributes for the
    // variable and set them.  If these values are not available, set
    // offset to 0 and scale to 1.
    if (nc_inq_attid(cdfid, nZId, CF_ADD_OFFSET, nullptr) == NC_NOERR)
    {
        double dfOffset = 0;
        status = nc_get_att_double(cdfid, nZId, CF_ADD_OFFSET, &dfOffset);
        CPLDebug("GDAL_netCDF", "got add_offset=%.16g, status=%d", dfOffset,
                 status);
        SetOffsetNoUpdate(dfOffset);
    }

    if (nc_inq_attid(cdfid, nZId, CF_SCALE_FACTOR, nullptr) == NC_NOERR)
    {
        double dfScale = 1;
        status = nc_get_att_double(cdfid, nZId, CF_SCALE_FACTOR, &dfScale);
        CPLDebug("GDAL_netCDF", "got scale_factor=%.16g, status=%d", dfScale,
                 status);
        SetScaleNoUpdate(dfScale);
    }

    // Should we check for longitude values > 360?
    bCheckLongitude =
        CPLTestBool(CPLGetConfigOption("GDAL_NETCDF_CENTERLONG_180", "YES")) &&
        NCDFIsVarLongitude(cdfid, nZId, nullptr);

    // Attempt to fetch the units attribute for the variable and set it.
    SetUnitTypeNoUpdate(GetMetadataItem(CF_UNITS));

    SetBlockSize();
}

void netCDFRasterBand::SetBlockSize()
{
    // Check for variable chunking (netcdf-4 only).
    // GDAL block size should be set to hdf5 chunk size.
#ifdef NETCDF_HAS_NC4
    int nTmpFormat = 0;
    int status = nc_inq_format(cdfid, &nTmpFormat);
    NetCDFFormatEnum eTmpFormat = static_cast<NetCDFFormatEnum>(nTmpFormat);
    if ((status == NC_NOERR) &&
        (eTmpFormat == NCDF_FORMAT_NC4 || eTmpFormat == NCDF_FORMAT_NC4C))
    {
        size_t chunksize[MAX_NC_DIMS] = {};
        // Check for chunksize and set it as the blocksize (optimizes read).
        status = nc_inq_var_chunking(cdfid, nZId, &nTmpFormat, chunksize);
        if ((status == NC_NOERR) && (nTmpFormat == NC_CHUNKED))
        {
            nBlockXSize = (int)chunksize[nZDim - 1];
            if (nZDim >= 2)
                nBlockYSize = (int)chunksize[nZDim - 2];
            else
                nBlockYSize = 1;
        }
    }
#endif

    // Deal with bottom-up datasets and nBlockYSize != 1.
    auto poGDS = static_cast<netCDFDataset *>(poDS);
    if (poGDS->bBottomUp && nBlockYSize != 1 && poGDS->poChunkCache == nullptr)
    {
        if (poGDS->eAccess == GA_ReadOnly)
        {
            // Try to cache 1 or 2 'rows' of netCDF chunks along the whole
            // width of the raster
            size_t nChunks =
                static_cast<size_t>(DIV_ROUND_UP(nRasterXSize, nBlockXSize));
            if ((nRasterYSize % nBlockYSize) != 0)
                nChunks *= 2;
            const size_t nChunkSize =
                static_cast<size_t>(GDALGetDataTypeSizeBytes(eDataType)) *
                nBlockXSize * nBlockYSize;
            constexpr size_t MAX_CACHE_SIZE = 100 * 1024 * 1024;
            nChunks = std::min(nChunks, MAX_CACHE_SIZE / nChunkSize);
            if (nChunks)
            {
                poGDS->poChunkCache.reset(
                    new netCDFDataset::ChunkCacheType(nChunks));
            }
        }
        else
        {
            nBlockYSize = 1;
        }
    }
}

// Constructor in create mode.
// If nZId and following variables are not passed, the band will have 2
// dimensions.
// TODO: Get metadata, missing val from band #1 if nZDim > 2.
netCDFRasterBand::netCDFRasterBand(
    const netCDFRasterBand::CONSTRUCTOR_CREATE &, netCDFDataset *poNCDFDS,
    const GDALDataType eTypeIn, int nBandIn, bool bSigned,
    const char *pszBandName, const char *pszLongName, int nZIdIn, int nZDimIn,
    int nLevelIn, const int *panBandZLevIn, const int *panBandZPosIn,
    const int *paDimIds)
    : nc_datatype(NC_NAT), cdfid(poNCDFDS->GetCDFID()), nZId(nZIdIn),
      nZDim(nZDimIn), nLevel(nLevelIn), nBandXPos(1), nBandYPos(0),
      panBandZPos(nullptr), panBandZLev(nullptr), bSignedData(bSigned),
      bCheckLongitude(false)
{
    poDS = poNCDFDS;
    nBand = nBandIn;

    nRasterXSize = poDS->GetRasterXSize();
    nRasterYSize = poDS->GetRasterYSize();
    nBlockXSize = poDS->GetRasterXSize();
    nBlockYSize = 1;

    if (poDS->GetAccess() != GA_Update)
    {
        CPLError(CE_Failure, CPLE_NotSupported,
                 "Dataset is not in update mode, "
                 "wrong netCDFRasterBand constructor");
        return;
    }

    // Take care of all other dimensions.
    if (nZDim > 2 && paDimIds != nullptr)
    {
        nBandXPos = panBandZPosIn[0];
        nBandYPos = panBandZPosIn[1];

        panBandZPos = static_cast<int *>(CPLCalloc(nZDim - 1, sizeof(int)));
        panBandZLev = static_cast<int *>(CPLCalloc(nZDim - 1, sizeof(int)));

        for (int i = 0; i < nZDim - 2; i++)
        {
            panBandZPos[i] = panBandZPosIn[i + 2];
            panBandZLev[i] = panBandZLevIn[i];
        }
    }

    // Get the type of the "z" variable, our target raster array.
    eDataType = eTypeIn;

    switch (eDataType)
    {
        case GDT_Byte:
            nc_datatype = NC_BYTE;
#ifdef NETCDF_HAS_NC4
            // NC_UBYTE (unsigned byte) is only available for NC4.
            if (!bSignedData && (poNCDFDS->eFormat == NCDF_FORMAT_NC4))
                nc_datatype = NC_UBYTE;
#endif
            break;
        case GDT_Int16:
            nc_datatype = NC_SHORT;
            break;
        case GDT_Int32:
            nc_datatype = NC_INT;
            break;
        case GDT_Float32:
            nc_datatype = NC_FLOAT;
            break;
        case GDT_Float64:
            nc_datatype = NC_DOUBLE;
            break;
#ifdef NETCDF_HAS_NC4
        case GDT_Int64:
            if (poNCDFDS->eFormat == NCDF_FORMAT_NC4)
            {
                nc_datatype = NC_INT64;
            }
            else
            {
                if (nBand == 1)
                    CPLError(
                        CE_Warning, CPLE_AppDefined,
                        "Unsupported GDAL datatype %s, treat as NC_DOUBLE.",
                        "Int64");
                nc_datatype = NC_DOUBLE;
                eDataType = GDT_Float64;
            }
            break;
        case GDT_UInt64:
            if (poNCDFDS->eFormat == NCDF_FORMAT_NC4)
            {
                nc_datatype = NC_UINT64;
            }
            else
            {
                if (nBand == 1)
                    CPLError(
                        CE_Warning, CPLE_AppDefined,
                        "Unsupported GDAL datatype %s, treat as NC_DOUBLE.",
                        "UInt64");
                nc_datatype = NC_DOUBLE;
                eDataType = GDT_Float64;
            }
            break;
        case GDT_UInt16:
            if (poNCDFDS->eFormat == NCDF_FORMAT_NC4)
            {
                nc_datatype = NC_USHORT;
                break;
            }
            CPL_FALLTHROUGH
        case GDT_UInt32:
            if (poNCDFDS->eFormat == NCDF_FORMAT_NC4)
            {
                nc_datatype = NC_UINT;
                break;
            }
            CPL_FALLTHROUGH
#endif
        default:
            if (nBand == 1)
                CPLError(CE_Warning, CPLE_AppDefined,
                         "Unsupported GDAL datatype (%d), treat as NC_FLOAT.",
                         static_cast<int>(eDataType));
            nc_datatype = NC_FLOAT;
            eDataType = GDT_Float32;
            break;
    }

    // Define the variable if necessary (if nZId == -1).
    bool bDefineVar = false;

    if (nZId == -1)
    {
        bDefineVar = true;

        // Make sure we are in define mode.
        static_cast<netCDFDataset *>(poDS)->SetDefineMode(true);

        char szTempPrivate[256 + 1];
        const char *pszTemp = nullptr;
        if (!pszBandName || EQUAL(pszBandName, ""))
        {
            snprintf(szTempPrivate, sizeof(szTempPrivate), "Band%d", nBand);
            pszTemp = szTempPrivate;
        }
        else
        {
            pszTemp = pszBandName;
        }

        int status;
        if (nZDim > 2 && paDimIds != nullptr)
        {
            status =
                nc_def_var(cdfid, pszTemp, nc_datatype, nZDim, paDimIds, &nZId);
        }
        else
        {
            int anBandDims[2] = {poNCDFDS->nYDimID, poNCDFDS->nXDimID};
            status =
                nc_def_var(cdfid, pszTemp, nc_datatype, 2, anBandDims, &nZId);
        }
        NCDF_ERR(status);
        CPLDebug("GDAL_netCDF", "nc_def_var(%d,%s,%d) id=%d", cdfid, pszTemp,
                 nc_datatype, nZId);

        if (!pszLongName || EQUAL(pszLongName, ""))
        {
            snprintf(szTempPrivate, sizeof(szTempPrivate),
                     "GDAL Band Number %d", nBand);
            pszTemp = szTempPrivate;
        }
        else
        {
            pszTemp = pszLongName;
        }
        status =
            nc_put_att_text(cdfid, nZId, CF_LNG_NAME, strlen(pszTemp), pszTemp);
        NCDF_ERR(status);

        poNCDFDS->DefVarDeflate(nZId, true);
    }

    // For Byte data add signed/unsigned info.
    if (eDataType == GDT_Byte)
    {
        if (bDefineVar)
        {
            // Only add attributes if creating variable.
            // For unsigned NC_BYTE (except NC4 format),
            // add valid_range and _Unsigned ( defined in CF-1 and NUG ).
            if (nc_datatype == NC_BYTE && poNCDFDS->eFormat != NCDF_FORMAT_NC4)
            {
                CPLDebug("GDAL_netCDF",
                         "adding valid_range attributes for Byte Band");
                short l_adfValidRange[2] = {0, 0};
                int status;
                if (bSignedData)
                {
                    l_adfValidRange[0] = -128;
                    l_adfValidRange[1] = 127;
                    status =
                        nc_put_att_text(cdfid, nZId, "_Unsigned", 5, "false");
                }
                else
                {
                    l_adfValidRange[0] = 0;
                    l_adfValidRange[1] = 255;
                    status =
                        nc_put_att_text(cdfid, nZId, "_Unsigned", 4, "true");
                }
                NCDF_ERR(status);
                status = nc_put_att_short(cdfid, nZId, "valid_range", NC_SHORT,
                                          2, l_adfValidRange);
                NCDF_ERR(status);
            }
        }
        // For unsigned byte set PIXELTYPE=SIGNEDBYTE.
        // See http://trac.osgeo.org/gdal/wiki/rfc14_imagestructure
        if (bSignedData)
            GDALPamRasterBand::SetMetadataItem("PIXELTYPE", "SIGNEDBYTE",
                                               "IMAGE_STRUCTURE");
    }

    if (nc_datatype != NC_BYTE && nc_datatype != NC_CHAR
#ifdef NETCDF_HAS_NC4
        && nc_datatype != NC_UBYTE
#endif
    )
    {
        // Set default nodata.
        bool bIgnored = false;
        double dfNoData =
            NCDFGetDefaultNoDataValue(cdfid, nZId, nc_datatype, bIgnored);
#ifdef NCDF_DEBUG
        CPLDebug("GDAL_netCDF", "SetNoDataValue(%f) default", dfNoData);
#endif
        netCDFRasterBand::SetNoDataValue(dfNoData);
    }

    SetBlockSize();
}

/************************************************************************/
/*                         ~netCDFRasterBand()                          */
/************************************************************************/

netCDFRasterBand::~netCDFRasterBand()
{
    netCDFRasterBand::FlushCache(true);
    CPLFree(panBandZPos);
    CPLFree(panBandZLev);
}

/************************************************************************/
/*                        SetMetadataItem()                             */
/************************************************************************/

CPLErr netCDFRasterBand::SetMetadataItem(const char *pszName,
                                         const char *pszValue,
                                         const char *pszDomain)
{
    if (GetAccess() == GA_Update &&
        (pszDomain == nullptr || pszDomain[0] == '\0') && pszValue != nullptr)
    {
        // Same logic as in CopyMetadata()

        const char *const papszIgnoreBand[] = {
            CF_ADD_OFFSET, CF_SCALE_FACTOR, "valid_range", "_Unsigned",
            _FillValue,    "coordinates",   nullptr};
        // Do not copy varname, stats, NETCDF_DIM_*, nodata
        // and items in papszIgnoreBand.
        if (STARTS_WITH(pszName, "NETCDF_VARNAME") ||
            STARTS_WITH(pszName, "STATISTICS_") ||
            STARTS_WITH(pszName, "NETCDF_DIM_") ||
            STARTS_WITH(pszName, "missing_value") ||
            STARTS_WITH(pszName, "_FillValue") ||
            CSLFindString(papszIgnoreBand, pszName) != -1)
        {
            // do nothing
        }
        else
        {
            cpl::down_cast<netCDFDataset *>(poDS)->SetDefineMode(true);

            if (!NCDFPutAttr(cdfid, nZId, pszName, pszValue))
                return CE_Failure;
        }
    }

    return GDALPamRasterBand::SetMetadataItem(pszName, pszValue, pszDomain);
}

/************************************************************************/
/*                          SetMetadata()                               */
/************************************************************************/

CPLErr netCDFRasterBand::SetMetadata(char **papszMD, const char *pszDomain)
{
    if (GetAccess() == GA_Update &&
        (pszDomain == nullptr || pszDomain[0] == '\0'))
    {
        // We don't handle metadata item removal for now
        for (const char *const *papszIter = papszMD; papszIter && *papszIter;
             ++papszIter)
        {
            char *pszName = nullptr;
            const char *pszValue = CPLParseNameValue(*papszIter, &pszName);
            if (pszName && pszValue)
                SetMetadataItem(pszName, pszValue);
            CPLFree(pszName);
        }
    }
    return GDALPamRasterBand::SetMetadata(papszMD, pszDomain);
}

/************************************************************************/
/*                             GetOffset()                              */
/************************************************************************/
double netCDFRasterBand::GetOffset(int *pbSuccess)
{
    if (pbSuccess != nullptr)
        *pbSuccess = static_cast<int>(m_bHaveOffset);

    return m_dfOffset;
}

/************************************************************************/
/*                             SetOffset()                              */
/************************************************************************/
CPLErr netCDFRasterBand::SetOffset(double dfNewOffset)
{
    CPLMutexHolderD(&hNCMutex);

    // Write value if in update mode.
    if (poDS->GetAccess() == GA_Update)
    {
        // Make sure we are in define mode.
        static_cast<netCDFDataset *>(poDS)->SetDefineMode(true);

        const int status = nc_put_att_double(cdfid, nZId, CF_ADD_OFFSET,
                                             NC_DOUBLE, 1, &dfNewOffset);

        NCDF_ERR(status);
        if (status == NC_NOERR)
        {
            SetOffsetNoUpdate(dfNewOffset);
            return CE_None;
        }

        return CE_Failure;
    }

    SetOffsetNoUpdate(dfNewOffset);
    return CE_None;
}

/************************************************************************/
/*                         SetOffsetNoUpdate()                          */
/************************************************************************/
void netCDFRasterBand::SetOffsetNoUpdate(double dfVal)
{
    m_dfOffset = dfVal;
    m_bHaveOffset = true;
}

/************************************************************************/
/*                              GetScale()                              */
/************************************************************************/
double netCDFRasterBand::GetScale(int *pbSuccess)
{
    if (pbSuccess != nullptr)
        *pbSuccess = static_cast<int>(m_bHaveScale);

    return m_dfScale;
}

/************************************************************************/
/*                              SetScale()                              */
/************************************************************************/
CPLErr netCDFRasterBand::SetScale(double dfNewScale)
{
    CPLMutexHolderD(&hNCMutex);

    // Write value if in update mode.
    if (poDS->GetAccess() == GA_Update)
    {
        // Make sure we are in define mode.
        static_cast<netCDFDataset *>(poDS)->SetDefineMode(true);

        const int status = nc_put_att_double(cdfid, nZId, CF_SCALE_FACTOR,
                                             NC_DOUBLE, 1, &dfNewScale);

        NCDF_ERR(status);
        if (status == NC_NOERR)
        {
            SetScaleNoUpdate(dfNewScale);
            return CE_None;
        }

        return CE_Failure;
    }

    SetScaleNoUpdate(dfNewScale);
    return CE_None;
}

/************************************************************************/
/*                         SetScaleNoUpdate()                           */
/************************************************************************/
void netCDFRasterBand::SetScaleNoUpdate(double dfVal)
{
    m_dfScale = dfVal;
    m_bHaveScale = true;
}

/************************************************************************/
/*                            GetUnitType()                             */
/************************************************************************/

const char *netCDFRasterBand::GetUnitType()

{
    if (!m_osUnitType.empty())
        return m_osUnitType;

    return GDALRasterBand::GetUnitType();
}

/************************************************************************/
/*                           SetUnitType()                              */
/************************************************************************/

CPLErr netCDFRasterBand::SetUnitType(const char *pszNewValue)

{
    CPLMutexHolderD(&hNCMutex);

    const std::string osUnitType = (pszNewValue != nullptr ? pszNewValue : "");

    if (!osUnitType.empty())
    {
        // Write value if in update mode.
        if (poDS->GetAccess() == GA_Update)
        {
            // Make sure we are in define mode.
            static_cast<netCDFDataset *>(poDS)->SetDefineMode(TRUE);

            const int status = nc_put_att_text(
                cdfid, nZId, CF_UNITS, osUnitType.size(), osUnitType.c_str());

            NCDF_ERR(status);
            if (status == NC_NOERR)
            {
                SetUnitTypeNoUpdate(pszNewValue);
                return CE_None;
            }

            return CE_Failure;
        }
    }

    SetUnitTypeNoUpdate(pszNewValue);

    return CE_None;
}

/************************************************************************/
/*                       SetUnitTypeNoUpdate()                          */
/************************************************************************/

void netCDFRasterBand::SetUnitTypeNoUpdate(const char *pszNewValue)
{
    m_osUnitType = (pszNewValue != nullptr ? pszNewValue : "");
}

/************************************************************************/
/*                           GetNoDataValue()                           */
/************************************************************************/

double netCDFRasterBand::GetNoDataValue(int *pbSuccess)

{
    if (m_bNoDataSetAsInt64)
    {
        if (pbSuccess)
            *pbSuccess = TRUE;
        return GDALGetNoDataValueCastToDouble(m_nNodataValueInt64);
    }

    if (m_bNoDataSetAsUInt64)
    {
        if (pbSuccess)
            *pbSuccess = TRUE;
        return GDALGetNoDataValueCastToDouble(m_nNodataValueUInt64);
    }

    if (m_bNoDataSet)
    {
        if (pbSuccess)
            *pbSuccess = TRUE;
        return m_dfNoDataValue;
    }

    return GDALPamRasterBand::GetNoDataValue(pbSuccess);
}

/************************************************************************/
/*                        GetNoDataValueAsInt64()                       */
/************************************************************************/

int64_t netCDFRasterBand::GetNoDataValueAsInt64(int *pbSuccess)

{
    if (m_bNoDataSetAsInt64)
    {
        if (pbSuccess)
            *pbSuccess = TRUE;

        return m_nNodataValueInt64;
    }

    return GDALPamRasterBand::GetNoDataValueAsInt64(pbSuccess);
}

/************************************************************************/
/*                        GetNoDataValueAsUInt64()                      */
/************************************************************************/

uint64_t netCDFRasterBand::GetNoDataValueAsUInt64(int *pbSuccess)

{
    if (m_bNoDataSetAsUInt64)
    {
        if (pbSuccess)
            *pbSuccess = TRUE;

        return m_nNodataValueUInt64;
    }

    return GDALPamRasterBand::GetNoDataValueAsUInt64(pbSuccess);
}

/************************************************************************/
/*                           SetNoDataValue()                           */
/************************************************************************/

CPLErr netCDFRasterBand::SetNoDataValue(double dfNoData)

{
    CPLMutexHolderD(&hNCMutex);

    // If already set to new value, don't do anything.
    if (m_bNoDataSet && CPLIsEqual(dfNoData, m_dfNoDataValue))
        return CE_None;

    // Write value if in update mode.
    if (poDS->GetAccess() == GA_Update)
    {
        // netcdf-4 does not allow to set _FillValue after leaving define mode,
        // but it is ok if variable has not been written to, so only print
        // debug. See bug #4484.
        if (m_bNoDataSet &&
            !reinterpret_cast<netCDFDataset *>(poDS)->GetDefineMode())
        {
            CPLDebug("GDAL_netCDF",
                     "Setting NoDataValue to %.18g (previously set to %.18g) "
                     "but file is no longer in define mode (id #%d, band #%d)",
                     dfNoData, m_dfNoDataValue, cdfid, nBand);
        }
#ifdef NCDF_DEBUG
        else
        {
            CPLDebug("GDAL_netCDF",
                     "Setting NoDataValue to %.18g (id #%d, band #%d)",
                     dfNoData, cdfid, nBand);
        }
#endif
        // Make sure we are in define mode.
        reinterpret_cast<netCDFDataset *>(poDS)->SetDefineMode(true);

        int status;
        if (eDataType == GDT_Byte)
        {
            if (bSignedData)
            {
                signed char cNoDataValue = static_cast<signed char>(dfNoData);
                status = nc_put_att_schar(cdfid, nZId, _FillValue, nc_datatype,
                                          1, &cNoDataValue);
            }
            else
            {
                const unsigned char ucNoDataValue =
                    static_cast<unsigned char>(dfNoData);
                status = nc_put_att_uchar(cdfid, nZId, _FillValue, nc_datatype,
                                          1, &ucNoDataValue);
            }
        }
        else if (eDataType == GDT_Int16)
        {
            short nsNoDataValue = static_cast<short>(dfNoData);
            status = nc_put_att_short(cdfid, nZId, _FillValue, nc_datatype, 1,
                                      &nsNoDataValue);
        }
        else if (eDataType == GDT_Int32)
        {
            int nNoDataValue = static_cast<int>(dfNoData);
            status = nc_put_att_int(cdfid, nZId, _FillValue, nc_datatype, 1,
                                    &nNoDataValue);
        }
        else if (eDataType == GDT_Float32)
        {
            float fNoDataValue = static_cast<float>(dfNoData);
            status = nc_put_att_float(cdfid, nZId, _FillValue, nc_datatype, 1,
                                      &fNoDataValue);
        }
#ifdef NETCDF_HAS_NC4
        else if (eDataType == GDT_UInt16 &&
                 reinterpret_cast<netCDFDataset *>(poDS)->eFormat ==
                     NCDF_FORMAT_NC4)
        {
            unsigned short usNoDataValue =
                static_cast<unsigned short>(dfNoData);
            status = nc_put_att_ushort(cdfid, nZId, _FillValue, nc_datatype, 1,
                                       &usNoDataValue);
        }
        else if (eDataType == GDT_UInt32 &&
                 reinterpret_cast<netCDFDataset *>(poDS)->eFormat ==
                     NCDF_FORMAT_NC4)
        {
            unsigned int unNoDataValue = static_cast<unsigned int>(dfNoData);
            status = nc_put_att_uint(cdfid, nZId, _FillValue, nc_datatype, 1,
                                     &unNoDataValue);
        }
#endif
        else
        {
            status = nc_put_att_double(cdfid, nZId, _FillValue, nc_datatype, 1,
                                       &dfNoData);
        }

        NCDF_ERR(status);

        // Update status if write worked.
        if (status == NC_NOERR)
        {
            SetNoDataValueNoUpdate(dfNoData);
            return CE_None;
        }

        return CE_Failure;
    }

    SetNoDataValueNoUpdate(dfNoData);
    return CE_None;
}

/************************************************************************/
/*                       SetNoDataValueNoUpdate()                       */
/************************************************************************/

void netCDFRasterBand::SetNoDataValueNoUpdate(double dfNoData)
{
    m_dfNoDataValue = dfNoData;
    m_bNoDataSet = true;
    m_bNoDataSetAsInt64 = false;
    m_bNoDataSetAsUInt64 = false;
}

/************************************************************************/
/*                        SetNoDataValueAsInt64()                       */
/************************************************************************/

CPLErr netCDFRasterBand::SetNoDataValueAsInt64(int64_t nNoData)

{
    CPLMutexHolderD(&hNCMutex);

    // If already set to new value, don't do anything.
    if (m_bNoDataSetAsInt64 && nNoData == m_nNodataValueInt64)
        return CE_None;

    // Write value if in update mode.
    if (poDS->GetAccess() == GA_Update)
    {
        // netcdf-4 does not allow to set _FillValue after leaving define mode,
        // but it is ok if variable has not been written to, so only print
        // debug. See bug #4484.
        if (m_bNoDataSetAsInt64 &&
            !reinterpret_cast<netCDFDataset *>(poDS)->GetDefineMode())
        {
            CPLDebug("GDAL_netCDF",
                     "Setting NoDataValue to " CPL_FRMT_GIB
                     " (previously set to " CPL_FRMT_GIB ") "
                     "but file is no longer in define mode (id #%d, band #%d)",
                     static_cast<GIntBig>(nNoData),
                     static_cast<GIntBig>(m_nNodataValueInt64), cdfid, nBand);
        }
#ifdef NCDF_DEBUG
        else
        {
            CPLDebug("GDAL_netCDF",
                     "Setting NoDataValue to " CPL_FRMT_GIB
                     " (id #%d, band #%d)",
                     static_cast<GIntBig>(nNoData), cdfid, nBand);
        }
#endif
        // Make sure we are in define mode.
        reinterpret_cast<netCDFDataset *>(poDS)->SetDefineMode(true);

        int status;
#ifdef NETCDF_HAS_NC4
        if (eDataType == GDT_Int64 &&
            reinterpret_cast<netCDFDataset *>(poDS)->eFormat == NCDF_FORMAT_NC4)
        {
            long long tmp = static_cast<long long>(nNoData);
            status = nc_put_att_longlong(cdfid, nZId, _FillValue, nc_datatype,
                                         1, &tmp);
        }
        else
#endif
        {
            double dfNoData = static_cast<double>(nNoData);
            status = nc_put_att_double(cdfid, nZId, _FillValue, nc_datatype, 1,
                                       &dfNoData);
        }

        NCDF_ERR(status);

        // Update status if write worked.
        if (status == NC_NOERR)
        {
            SetNoDataValueNoUpdate(nNoData);
            return CE_None;
        }

        return CE_Failure;
    }

    SetNoDataValueNoUpdate(nNoData);
    return CE_None;
}

/************************************************************************/
/*                       SetNoDataValueNoUpdate()                       */
/************************************************************************/

void netCDFRasterBand::SetNoDataValueNoUpdate(int64_t nNoData)
{
    m_nNodataValueInt64 = nNoData;
    m_bNoDataSet = false;
    m_bNoDataSetAsInt64 = true;
    m_bNoDataSetAsUInt64 = false;
}

/************************************************************************/
/*                        SetNoDataValueAsUInt64()                      */
/************************************************************************/

CPLErr netCDFRasterBand::SetNoDataValueAsUInt64(uint64_t nNoData)

{
    CPLMutexHolderD(&hNCMutex);

    // If already set to new value, don't do anything.
    if (m_bNoDataSetAsUInt64 && nNoData == m_nNodataValueUInt64)
        return CE_None;

    // Write value if in update mode.
    if (poDS->GetAccess() == GA_Update)
    {
        // netcdf-4 does not allow to set _FillValue after leaving define mode,
        // but it is ok if variable has not been written to, so only print
        // debug. See bug #4484.
        if (m_bNoDataSetAsUInt64 &&
            !reinterpret_cast<netCDFDataset *>(poDS)->GetDefineMode())
        {
            CPLDebug("GDAL_netCDF",
                     "Setting NoDataValue to " CPL_FRMT_GUIB
                     " (previously set to " CPL_FRMT_GUIB ") "
                     "but file is no longer in define mode (id #%d, band #%d)",
                     static_cast<GUIntBig>(nNoData),
                     static_cast<GUIntBig>(m_nNodataValueUInt64), cdfid, nBand);
        }
#ifdef NCDF_DEBUG
        else
        {
            CPLDebug("GDAL_netCDF",
                     "Setting NoDataValue to " CPL_FRMT_GUIB
                     " (id #%d, band #%d)",
                     static_cast<GUIntBig>(nNoData), cdfid, nBand);
        }
#endif
        // Make sure we are in define mode.
        reinterpret_cast<netCDFDataset *>(poDS)->SetDefineMode(true);

        int status;
#ifdef NETCDF_HAS_NC4
        if (eDataType == GDT_UInt64 &&
            reinterpret_cast<netCDFDataset *>(poDS)->eFormat == NCDF_FORMAT_NC4)
        {
            unsigned long long tmp = static_cast<long long>(nNoData);
            status = nc_put_att_ulonglong(cdfid, nZId, _FillValue, nc_datatype,
                                          1, &tmp);
        }
        else
#endif
        {
            double dfNoData = static_cast<double>(nNoData);
            status = nc_put_att_double(cdfid, nZId, _FillValue, nc_datatype, 1,
                                       &dfNoData);
        }

        NCDF_ERR(status);

        // Update status if write worked.
        if (status == NC_NOERR)
        {
            SetNoDataValueNoUpdate(nNoData);
            return CE_None;
        }

        return CE_Failure;
    }

    SetNoDataValueNoUpdate(nNoData);
    return CE_None;
}

/************************************************************************/
/*                       SetNoDataValueNoUpdate()                       */
/************************************************************************/

void netCDFRasterBand::SetNoDataValueNoUpdate(uint64_t nNoData)
{
    m_nNodataValueUInt64 = nNoData;
    m_bNoDataSet = false;
    m_bNoDataSetAsInt64 = false;
    m_bNoDataSetAsUInt64 = true;
}

/************************************************************************/
/*                        DeleteNoDataValue()                           */
/************************************************************************/

#ifdef notdef
CPLErr netCDFRasterBand::DeleteNoDataValue()

{
    CPLMutexHolderD(&hNCMutex);

    if (!bNoDataSet)
        return CE_None;

    // Write value if in update mode.
    if (poDS->GetAccess() == GA_Update)
    {
        // Make sure we are in define mode.
        static_cast<netCDFDataset *>(poDS)->SetDefineMode(true);

        status = nc_del_att(cdfid, nZId, _FillValue);

        NCDF_ERR(status);

        // Update status if write worked.
        if (status == NC_NOERR)
        {
            dfNoDataValue = 0.0;
            bNoDataSet = false;
            return CE_None;
        }

        return CE_Failure;
    }

    dfNoDataValue = 0.0;
    bNoDataSet = false;
    return CE_None;
}
#endif

/************************************************************************/
/*                           SerializeToXML()                           */
/************************************************************************/

CPLXMLNode *netCDFRasterBand::SerializeToXML(const char * /* pszUnused */)
{
    // Overridden from GDALPamDataset to add only band histogram
    // and statistics. See bug #4244.
    if (psPam == nullptr)
        return nullptr;

    // Setup root node and attributes.
    CPLXMLNode *psTree =
        CPLCreateXMLNode(nullptr, CXT_Element, "PAMRasterBand");

    if (GetBand() > 0)
    {
        CPLString oFmt;
        CPLSetXMLValue(psTree, "#band", oFmt.Printf("%d", GetBand()));
    }

    // Histograms.
    if (psPam->psSavedHistograms != nullptr)
        CPLAddXMLChild(psTree, CPLCloneXMLTree(psPam->psSavedHistograms));

    // Metadata (statistics only).
    GDALMultiDomainMetadata oMDMDStats;
    const char *papszMDStats[] = {"STATISTICS_MINIMUM", "STATISTICS_MAXIMUM",
                                  "STATISTICS_MEAN", "STATISTICS_STDDEV",
                                  nullptr};
    for (int i = 0; i < CSLCount(papszMDStats); i++)
    {
        if (GetMetadataItem(papszMDStats[i]) != nullptr)
            oMDMDStats.SetMetadataItem(papszMDStats[i],
                                       GetMetadataItem(papszMDStats[i]));
    }
    CPLXMLNode *psMD = oMDMDStats.Serialize();

    if (psMD != nullptr)
    {
        if (psMD->psChild == nullptr)
            CPLDestroyXMLNode(psMD);
        else
            CPLAddXMLChild(psTree, psMD);
    }

    // We don't want to return anything if we had no metadata to attach.
    if (psTree->psChild == nullptr || psTree->psChild->psNext == nullptr)
    {
        CPLDestroyXMLNode(psTree);
        psTree = nullptr;
    }

    return psTree;
}

/************************************************************************/
/*               Get1DVariableIndexedByDimension()                      */
/************************************************************************/

static int Get1DVariableIndexedByDimension(int cdfid, int nDimId,
                                           const char *pszDimName,
                                           bool bVerboseError, int *pnGroupID)
{
    *pnGroupID = -1;
    int nVarID = -1;
    // First try to find a variable whose name is identical to the dimension
    // name, and check that it is indeed indexed by this dimension
    if (NCDFResolveVar(cdfid, pszDimName, pnGroupID, &nVarID) == CE_None)
    {
        int nDimCountOfVariable = 0;
        nc_inq_varndims(*pnGroupID, nVarID, &nDimCountOfVariable);
        if (nDimCountOfVariable == 1)
        {
            int nDimIdOfVariable = -1;
            nc_inq_vardimid(*pnGroupID, nVarID, &nDimIdOfVariable);
            if (nDimIdOfVariable == nDimId)
            {
                return nVarID;
            }
        }
    }

    // Otherwise iterate over the variables to find potential candidates
    // TODO: should be modified to search also in other groups using the same
    //       logic than in NCDFResolveVar(), but maybe not needed if it's a
    //       very rare case? and I think this is not CF compliant.
    int nvars = 0;
    CPL_IGNORE_RET_VAL(nc_inq(cdfid, nullptr, &nvars, nullptr, nullptr));

    int nCountCandidateVars = 0;
    int nCandidateVarID = -1;
    for (int k = 0; k < nvars; k++)
    {
        int nDimCountOfVariable = 0;
        nc_inq_varndims(cdfid, k, &nDimCountOfVariable);
        if (nDimCountOfVariable == 1)
        {
            int nDimIdOfVariable = -1;
            nc_inq_vardimid(cdfid, k, &nDimIdOfVariable);
            if (nDimIdOfVariable == nDimId)
            {
                nCountCandidateVars++;
                nCandidateVarID = k;
            }
        }
    }
    if (nCountCandidateVars > 1)
    {
        if (bVerboseError)
        {
            CPLError(CE_Warning, CPLE_AppDefined,
                     "Several 1D variables are indexed by dimension %s",
                     pszDimName);
        }
        *pnGroupID = -1;
        return -1;
    }
    else if (nCandidateVarID < 0)
    {
        if (bVerboseError)
        {
            CPLError(CE_Warning, CPLE_AppDefined,
                     "No 1D variable is indexed by dimension %s", pszDimName);
        }
    }
    *pnGroupID = cdfid;
    return nCandidateVarID;
}

/************************************************************************/
/*                         CreateBandMetadata()                         */
/************************************************************************/

CPLErr netCDFRasterBand::CreateBandMetadata(const int *paDimIds,
                                            const int *panExtraDimGroupIds,
                                            const int *panExtraDimVarIds)

{
    netCDFDataset *l_poDS = reinterpret_cast<netCDFDataset *>(poDS);

    // Compute all dimensions from Band number and save in Metadata.
    char szVarName[NC_MAX_NAME + 1] = {};
    int status = nc_inq_varname(cdfid, nZId, szVarName);
    NCDF_ERR(status);

    int nd = 0;
    nc_inq_varndims(cdfid, nZId, &nd);
    // Compute multidimention band position.
    //
    // BandPosition = (Total - sum(PastBandLevels) - 1)/sum(remainingLevels)
    // if Data[2,3,4,x,y]
    //
    //  BandPos0 = (nBand) / (3*4)
    //  BandPos1 = (nBand - BandPos0*(3*4)) / (4)
    //  BandPos2 = (nBand - BandPos0*(3*4)) % (4)

    GDALPamRasterBand::SetMetadataItem("NETCDF_VARNAME", szVarName);
    int Sum = 1;
    if (nd == 3)
    {
        Sum *= panBandZLev[0];
    }

    // Loop over non-spatial dimensions.
    int result = 0;
    int Taken = 0;

    for (int i = 0; i < nd - 2; i++)
    {
        if (i != nd - 2 - 1)
        {
            Sum = 1;
            for (int j = i + 1; j < nd - 2; j++)
            {
                Sum *= panBandZLev[j];
            }
            result = static_cast<int>((nLevel - Taken) / Sum);
        }
        else
        {
            result = static_cast<int>((nLevel - Taken) % Sum);
        }

        snprintf(szVarName, sizeof(szVarName), "%s",
                 l_poDS->papszDimName[paDimIds[panBandZPos[i]]]);

        char szMetaName[NC_MAX_NAME + 1 + 32];
        snprintf(szMetaName, sizeof(szMetaName), "NETCDF_DIM_%s", szVarName);

        int nGroupID = panExtraDimGroupIds[i];
        int nVarID = panExtraDimVarIds[i];
        if (nVarID < 0)
        {
            GDALPamRasterBand::SetMetadataItem(szMetaName,
                                               CPLSPrintf("%d", result + 1));
        }
        else
        {
            // TODO: Make sure all the status checks make sense.

            nc_type nVarType = NC_NAT;
            /* status = */ nc_inq_vartype(nGroupID, nVarID, &nVarType);

            int nDims = 0;
            /* status = */ nc_inq_varndims(nGroupID, nVarID, &nDims);

            char szMetaTemp[256] = {};
            if (nDims == 1)
            {
                size_t count[1] = {1};
                size_t start[1] = {static_cast<size_t>(result)};

                switch (nVarType)
                {
                    case NC_BYTE:
                        // TODO: Check for signed/unsigned byte.
                        signed char cData;
                        /* status = */ nc_get_vara_schar(nGroupID, nVarID,
                                                         start, count, &cData);
                        snprintf(szMetaTemp, sizeof(szMetaTemp), "%d", cData);
                        break;
                    case NC_SHORT:
                        short sData;
                        /* status = */ nc_get_vara_short(nGroupID, nVarID,
                                                         start, count, &sData);
                        snprintf(szMetaTemp, sizeof(szMetaTemp), "%d", sData);
                        break;
                    case NC_INT:
                    {
                        int nData;
                        /* status = */ nc_get_vara_int(nGroupID, nVarID, start,
                                                       count, &nData);
                        snprintf(szMetaTemp, sizeof(szMetaTemp), "%d", nData);
                        break;
                    }
                    case NC_FLOAT:
                        float fData;
                        /* status = */ nc_get_vara_float(nGroupID, nVarID,
                                                         start, count, &fData);
                        CPLsnprintf(szMetaTemp, sizeof(szMetaTemp), "%.8g",
                                    fData);
                        break;
                    case NC_DOUBLE:
                        double dfData;
                        /* status = */ nc_get_vara_double(
                            nGroupID, nVarID, start, count, &dfData);
                        CPLsnprintf(szMetaTemp, sizeof(szMetaTemp), "%.16g",
                                    dfData);
                        break;
#ifdef NETCDF_HAS_NC4
                    case NC_UBYTE:
                        unsigned char ucData;
                        /* status = */ nc_get_vara_uchar(nGroupID, nVarID,
                                                         start, count, &ucData);
                        snprintf(szMetaTemp, sizeof(szMetaTemp), "%u", ucData);
                        break;
                    case NC_USHORT:
                        unsigned short usData;
                        /* status = */ nc_get_vara_ushort(
                            nGroupID, nVarID, start, count, &usData);
                        snprintf(szMetaTemp, sizeof(szMetaTemp), "%u", usData);
                        break;
                    case NC_UINT:
                    {
                        unsigned int unData;
                        /* status = */ nc_get_vara_uint(nGroupID, nVarID, start,
                                                        count, &unData);
                        snprintf(szMetaTemp, sizeof(szMetaTemp), "%u", unData);
                        break;
                    }
                    case NC_INT64:
                    {
                        long long nData;
                        /* status = */ nc_get_vara_longlong(
                            nGroupID, nVarID, start, count, &nData);
                        snprintf(szMetaTemp, sizeof(szMetaTemp), CPL_FRMT_GIB,
                                 nData);
                        break;
                    }
                    case NC_UINT64:
                    {
                        unsigned long long unData;
                        /* status = */ nc_get_vara_ulonglong(
                            nGroupID, nVarID, start, count, &unData);
                        snprintf(szMetaTemp, sizeof(szMetaTemp), CPL_FRMT_GUIB,
                                 unData);
                        break;
                    }
#endif
                    default:
                        CPLDebug("GDAL_netCDF", "invalid dim %s, type=%d",
                                 szMetaTemp, nVarType);
                        break;
                }
            }
            else
            {
                snprintf(szMetaTemp, sizeof(szMetaTemp), "%d", result + 1);
            }

            // Save dimension value.
            // NOTE: removed #original_units as not part of CF-1.

            GDALPamRasterBand::SetMetadataItem(szMetaName, szMetaTemp);
        }

        // Avoid int32 overflow. Perhaps something more sensible to do here ?
        if (result > 0 && Sum > INT_MAX / result)
            break;
        if (Taken > INT_MAX - result * Sum)
            break;

        Taken += result * Sum;
    }  // End loop non-spatial dimensions.

    // Get all other metadata.
    int nAtt = 0;
    nc_inq_varnatts(cdfid, nZId, &nAtt);

    for (int i = 0; i < nAtt; i++)
    {
        char szMetaName[NC_MAX_NAME + 1] = {};
        status = nc_inq_attname(cdfid, nZId, i, szMetaName);
        if (status != NC_NOERR)
            continue;

        if (GetMetadataItem(szMetaName) != nullptr)
        {
            continue;
        }

        char *pszMetaValue = nullptr;
        if (NCDFGetAttr(cdfid, nZId, szMetaName, &pszMetaValue) == CE_None)
        {
            GDALPamRasterBand::SetMetadataItem(szMetaName, pszMetaValue);
        }
        else
        {
            CPLDebug("GDAL_netCDF", "invalid Band metadata %s", szMetaName);
        }

        if (pszMetaValue)
        {
            CPLFree(pszMetaValue);
            pszMetaValue = nullptr;
        }
    }

    return CE_None;
}

/************************************************************************/
/*                             CheckData()                              */
/************************************************************************/
template <class T>
void netCDFRasterBand::CheckData(void *pImage, void *pImageNC,
                                 size_t nTmpBlockXSize, size_t nTmpBlockYSize,
                                 bool bCheckIsNan)
{
    CPLAssert(pImage != nullptr && pImageNC != nullptr);

    // If this block is not a full block (in the x axis), we need to re-arrange
    // the data this is because partial blocks are not arranged the same way in
    // netcdf and gdal.
    if (nTmpBlockXSize != static_cast<size_t>(nBlockXSize))
    {
        T *ptrWrite = static_cast<T *>(pImage);
        T *ptrRead = static_cast<T *>(pImageNC);
        for (size_t j = 0; j < nTmpBlockYSize;
             j++, ptrWrite += nBlockXSize, ptrRead += nTmpBlockXSize)
        {
            memmove(ptrWrite, ptrRead, nTmpBlockXSize * sizeof(T));
        }
    }

    // Is valid data checking needed or requested?
    if (bValidRangeValid || bCheckIsNan)
    {
        T *ptrImage = static_cast<T *>(pImage);
        for (size_t j = 0; j < nTmpBlockYSize; j++)
        {
            // k moves along the gdal block, skipping the out-of-range pixels.
            size_t k = j * nBlockXSize;
            for (size_t i = 0; i < nTmpBlockXSize; i++, k++)
            {
                // Check for nodata and nan.
                if (CPLIsEqual((double)ptrImage[k], m_dfNoDataValue))
                    continue;
                if (bCheckIsNan && CPLIsNan((double)ptrImage[k]))
                {
                    ptrImage[k] = (T)m_dfNoDataValue;
                    continue;
                }
                // Check for valid_range.
                if (bValidRangeValid)
                {
                    if (((adfValidRange[0] != m_dfNoDataValue) &&
                         (ptrImage[k] < (T)adfValidRange[0])) ||
                        ((adfValidRange[1] != m_dfNoDataValue) &&
                         (ptrImage[k] > (T)adfValidRange[1])))
                    {
                        ptrImage[k] = (T)m_dfNoDataValue;
                    }
                }
            }
        }
    }

    // If minimum longitude is > 180, subtract 360 from all.
    // If not, disable checking for further calls (check just once).
    // Only check first and last block elements since lon must be monotonic.
    const bool bIsSigned = std::numeric_limits<T>::is_signed;
    if (bCheckLongitude && bIsSigned &&
        !CPLIsEqual((double)((T *)pImage)[0], m_dfNoDataValue) &&
        !CPLIsEqual((double)((T *)pImage)[nTmpBlockXSize - 1],
                    m_dfNoDataValue) &&
        std::min(((T *)pImage)[0], ((T *)pImage)[nTmpBlockXSize - 1]) > 180.0)
    {
        T *ptrImage = static_cast<T *>(pImage);
        for (size_t j = 0; j < nTmpBlockYSize; j++)
        {
            size_t k = j * nBlockXSize;
            for (size_t i = 0; i < nTmpBlockXSize; i++, k++)
            {
                if (!CPLIsEqual((double)ptrImage[k], m_dfNoDataValue))
                    ptrImage[k] = static_cast<T>(ptrImage[k] - 360);
            }
        }
    }
    else
    {
        bCheckLongitude = false;
    }
}

/************************************************************************/
/*                             CheckDataCpx()                              */
/************************************************************************/
template <class T>
void netCDFRasterBand::CheckDataCpx(void *pImage, void *pImageNC,
                                    size_t nTmpBlockXSize,
                                    size_t nTmpBlockYSize, bool bCheckIsNan)
{
    CPLAssert(pImage != nullptr && pImageNC != nullptr);

    // If this block is not a full block (in the x axis), we need to re-arrange
    // the data this is because partial blocks are not arranged the same way in
    // netcdf and gdal.
    if (nTmpBlockXSize != static_cast<size_t>(nBlockXSize))
    {
        T *ptrWrite = static_cast<T *>(pImage);
        T *ptrRead = static_cast<T *>(pImageNC);
        for (size_t j = 0; j < nTmpBlockYSize; j++,
                    ptrWrite += (2 * nBlockXSize),
                    ptrRead += (2 * nTmpBlockXSize))
        {
            memmove(ptrWrite, ptrRead, nTmpBlockXSize * sizeof(T) * 2);
        }
    }

    // Is valid data checking needed or requested?
    if (bValidRangeValid || bCheckIsNan)
    {
        T *ptrImage = static_cast<T *>(pImage);
        for (size_t j = 0; j < nTmpBlockYSize; j++)
        {
            // k moves along the gdal block, skipping the out-of-range pixels.
            size_t k = 2 * j * nBlockXSize;
            for (size_t i = 0; i < (2 * nTmpBlockXSize); i++, k++)
            {
                // Check for nodata and nan.
                if (CPLIsEqual((double)ptrImage[k], m_dfNoDataValue))
                    continue;
                if (bCheckIsNan && CPLIsNan((double)ptrImage[k]))
                {
                    ptrImage[k] = (T)m_dfNoDataValue;
                    continue;
                }
                // Check for valid_range.
                if (bValidRangeValid)
                {
                    if (((adfValidRange[0] != m_dfNoDataValue) &&
                         (ptrImage[k] < (T)adfValidRange[0])) ||
                        ((adfValidRange[1] != m_dfNoDataValue) &&
                         (ptrImage[k] > (T)adfValidRange[1])))
                    {
                        ptrImage[k] = (T)m_dfNoDataValue;
                    }
                }
            }
        }
    }
}

/************************************************************************/
/*                         FetchNetcdfChunk()                           */
/************************************************************************/

bool netCDFRasterBand::FetchNetcdfChunk(size_t xstart, size_t ystart,
                                        void *pImage)
{
    size_t start[MAX_NC_DIMS] = {};
    size_t edge[MAX_NC_DIMS] = {};

    start[nBandXPos] = xstart;
    edge[nBandXPos] = nBlockXSize;
    if ((start[nBandXPos] + edge[nBandXPos]) > (size_t)nRasterXSize)
        edge[nBandXPos] = nRasterXSize - start[nBandXPos];
    if (nBandYPos >= 0)
    {
        start[nBandYPos] = ystart;
        edge[nBandYPos] = nBlockYSize;
        if ((start[nBandYPos] + edge[nBandYPos]) > (size_t)nRasterYSize)
            edge[nBandYPos] = nRasterYSize - start[nBandYPos];
    }
    const size_t nYChunkSize = nBandYPos < 0 ? 1 : edge[nBandYPos];

#ifdef NCDF_DEBUG
    CPLDebug("GDAL_netCDF", "start={%ld,%ld} edge={%ld,%ld} bBottomUp=%d",
             start[nBandXPos], nBandYPos < 0 ? 0 : start[nBandYPos],
             edge[nBandXPos], nYChunkSize, ((netCDFDataset *)poDS)->bBottomUp);
#endif

    int nd = 0;
    nc_inq_varndims(cdfid, nZId, &nd);
    if (nd == 3)
    {
        start[panBandZPos[0]] = nLevel;  // z
        edge[panBandZPos[0]] = 1;
    }

    // Compute multidimention band position.
    //
    // BandPosition = (Total - sum(PastBandLevels) - 1)/sum(remainingLevels)
    // if Data[2,3,4,x,y]
    //
    //  BandPos0 = (nBand) / (3*4)
    //  BandPos1 = (nBand - (3*4)) / (4)
    //  BandPos2 = (nBand - (3*4)) % (4)
    if (nd > 3)
    {
        int Sum = -1;
        int Taken = 0;
        for (int i = 0; i < nd - 2; i++)
        {
            if (i != nd - 2 - 1)
            {
                Sum = 1;
                for (int j = i + 1; j < nd - 2; j++)
                {
                    Sum *= panBandZLev[j];
                }
                start[panBandZPos[i]] = (int)((nLevel - Taken) / Sum);
                edge[panBandZPos[i]] = 1;
            }
            else
            {
                start[panBandZPos[i]] = (int)((nLevel - Taken) % Sum);
                edge[panBandZPos[i]] = 1;
            }
            Taken += static_cast<int>(start[panBandZPos[i]]) * Sum;
        }
    }

    // Make sure we are in data mode.
    static_cast<netCDFDataset *>(poDS)->SetDefineMode(false);

    // If this block is not a full block in the x axis, we need to
    // re-arrange the data because partial blocks are not arranged the
    // same way in netcdf and gdal, so we first we read the netcdf data at
    // the end of the gdal block buffer then re-arrange rows in CheckData().
    void *pImageNC = pImage;
    if (edge[nBandXPos] != static_cast<size_t>(nBlockXSize))
    {
        pImageNC =
            static_cast<GByte *>(pImage) +
            ((nBlockXSize * nBlockYSize - edge[nBandXPos] * nYChunkSize) *
             (GDALGetDataTypeSize(eDataType) / 8));
    }

    // Read data according to type.
    int status;
    if (eDataType == GDT_Byte)
    {
        if (bSignedData)
        {
            status = nc_get_vara_schar(cdfid, nZId, start, edge,
                                       static_cast<signed char *>(pImageNC));
            if (status == NC_NOERR)
                CheckData<signed char>(pImage, pImageNC, edge[nBandXPos],
                                       nYChunkSize, false);
        }
        else
        {
            status = nc_get_vara_uchar(cdfid, nZId, start, edge,
                                       static_cast<unsigned char *>(pImageNC));
            if (status == NC_NOERR)
                CheckData<unsigned char>(pImage, pImageNC, edge[nBandXPos],
                                         nYChunkSize, false);
        }
    }
    else if (nc_datatype == NC_SHORT)
    {
        status = nc_get_vara_short(cdfid, nZId, start, edge,
                                   static_cast<short *>(pImageNC));
        if (status == NC_NOERR)
        {
            if (eDataType == GDT_Int16)
            {
                CheckData<GInt16>(pImage, pImageNC, edge[nBandXPos],
                                  nYChunkSize, false);
            }
            else
            {
                CheckData<GUInt16>(pImage, pImageNC, edge[nBandXPos],
                                   nYChunkSize, false);
            }
        }
    }
    else if (eDataType == GDT_Int32)
    {
#if SIZEOF_UNSIGNED_LONG == 4
        status = nc_get_vara_long(cdfid, nZId, start, edge,
                                  static_cast<long *>(pImageNC));
        if (status == NC_NOERR)
            CheckData<long>(pImage, pImageNC, edge[nBandXPos], nYChunkSize,
                            false);
#else
        status = nc_get_vara_int(cdfid, nZId, start, edge,
                                 static_cast<int *>(pImageNC));
        if (status == NC_NOERR)
            CheckData<int>(pImage, pImageNC, edge[nBandXPos], nYChunkSize,
                           false);
#endif
    }
    else if (eDataType == GDT_Float32)
    {
        status = nc_get_vara_float(cdfid, nZId, start, edge,
                                   static_cast<float *>(pImageNC));
        if (status == NC_NOERR)
            CheckData<float>(pImage, pImageNC, edge[nBandXPos], nYChunkSize,
                             true);
    }
    else if (eDataType == GDT_Float64)
    {
        status = nc_get_vara_double(cdfid, nZId, start, edge,
                                    static_cast<double *>(pImageNC));
        if (status == NC_NOERR)
            CheckData<double>(pImage, pImageNC, edge[nBandXPos], nYChunkSize,
                              true);
    }
#ifdef NETCDF_HAS_NC4
    else if (eDataType == GDT_UInt16)
    {
        status = nc_get_vara_ushort(cdfid, nZId, start, edge,
                                    static_cast<unsigned short *>(pImageNC));
        if (status == NC_NOERR)
            CheckData<unsigned short>(pImage, pImageNC, edge[nBandXPos],
                                      nYChunkSize, false);
    }
    else if (eDataType == GDT_UInt32)
    {
        status = nc_get_vara_uint(cdfid, nZId, start, edge,
                                  static_cast<unsigned int *>(pImageNC));
        if (status == NC_NOERR)
            CheckData<unsigned int>(pImage, pImageNC, edge[nBandXPos],
                                    nYChunkSize, false);
    }
    else if (eDataType == GDT_Int64)
    {
        status = nc_get_vara_longlong(cdfid, nZId, start, edge,
                                      static_cast<long long *>(pImageNC));
        if (status == NC_NOERR)
            CheckData<std::int64_t>(pImage, pImageNC, edge[nBandXPos],
                                    nYChunkSize, false);
    }
    else if (eDataType == GDT_UInt64)
    {
        status =
            nc_get_vara_ulonglong(cdfid, nZId, start, edge,
                                  static_cast<unsigned long long *>(pImageNC));
        if (status == NC_NOERR)
            CheckData<std::uint64_t>(pImage, pImageNC, edge[nBandXPos],
                                     nYChunkSize, false);
    }
    else if (eDataType == GDT_CInt16)
    {
        status = nc_get_vara(cdfid, nZId, start, edge, pImageNC);
        if (status == NC_NOERR)
            CheckDataCpx<short>(pImage, pImageNC, edge[nBandXPos], nYChunkSize,
                                false);
    }
    else if (eDataType == GDT_CInt32)
    {
        status = nc_get_vara(cdfid, nZId, start, edge, pImageNC);
        if (status == NC_NOERR)
            CheckDataCpx<int>(pImage, pImageNC, edge[nBandXPos], nYChunkSize,
                              false);
    }
    else if (eDataType == GDT_CFloat32)
    {
        status = nc_get_vara(cdfid, nZId, start, edge, pImageNC);
        if (status == NC_NOERR)
            CheckDataCpx<float>(pImage, pImageNC, edge[nBandXPos], nYChunkSize,
                                false);
    }
    else if (eDataType == GDT_CFloat64)
    {
        status = nc_get_vara(cdfid, nZId, start, edge, pImageNC);
        if (status == NC_NOERR)
            CheckDataCpx<double>(pImage, pImageNC, edge[nBandXPos], nYChunkSize,
                                 false);
    }

#endif
    else
        status = NC_EBADTYPE;

    if (status != NC_NOERR)
    {
        CPLError(CE_Failure, CPLE_AppDefined,
                 "netCDF chunk fetch failed: #%d (%s)", status,
                 nc_strerror(status));
        return false;
    }
    return true;
}

/************************************************************************/
/*                             IReadBlock()                             */
/************************************************************************/

CPLErr netCDFRasterBand::IReadBlock(int nBlockXOff, int nBlockYOff,
                                    void *pImage)

{
    CPLMutexHolderD(&hNCMutex);

    // Locate X, Y and Z position in the array.

    size_t xstart = nBlockXOff * nBlockXSize;
    size_t ystart = 0;

    // Check y order.
    if (nBandYPos >= 0)
    {
        auto poGDS = static_cast<netCDFDataset *>(poDS);
        if (poGDS->bBottomUp)
        {
            if (nBlockYSize == 1)
            {
                ystart = nRasterYSize - 1 - nBlockYOff;
            }
            else
            {
                // in GDAL space
                ystart = nBlockYOff * nBlockYSize;
                const size_t yend =
                    std::min(ystart + nBlockYSize - 1,
                             static_cast<size_t>(nRasterYSize - 1));
                // in netCDF space
                const size_t nFirstChunkLine = nRasterYSize - 1 - yend;
                const size_t nLastChunkLine = nRasterYSize - 1 - ystart;
                const size_t nFirstChunkBlock = nFirstChunkLine / nBlockYSize;
                const size_t nLastChunkBlock = nLastChunkLine / nBlockYSize;

                const auto firstKey = netCDFDataset::ChunkKey(
                    nBlockXOff, nFirstChunkBlock, nBand);
                const auto secondKey =
                    netCDFDataset::ChunkKey(nBlockXOff, nLastChunkBlock, nBand);

                // Retrieve data from the one or 2 needed netCDF chunks
                std::shared_ptr<std::vector<GByte>> firstChunk;
                std::shared_ptr<std::vector<GByte>> secondChunk;
                if (poGDS->poChunkCache)
                {
                    poGDS->poChunkCache->tryGet(firstKey, firstChunk);
                    if (firstKey != secondKey)
                        poGDS->poChunkCache->tryGet(secondKey, secondChunk);
                }
                const size_t nChunkLineSize =
                    static_cast<size_t>(GDALGetDataTypeSizeBytes(eDataType)) *
                    nBlockXSize;
                const size_t nChunkSize = nChunkLineSize * nBlockYSize;
                if (!firstChunk)
                {
                    firstChunk.reset(new std::vector<GByte>(nChunkSize));
                    if (!FetchNetcdfChunk(xstart,
                                          nFirstChunkBlock * nBlockYSize,
                                          firstChunk.get()->data()))
                        return CE_Failure;
                    if (poGDS->poChunkCache)
                        poGDS->poChunkCache->insert(firstKey, firstChunk);
                }
                if (!secondChunk && firstKey != secondKey)
                {
                    secondChunk.reset(new std::vector<GByte>(nChunkSize));
                    if (!FetchNetcdfChunk(xstart, nLastChunkBlock * nBlockYSize,
                                          secondChunk.get()->data()))
                        return CE_Failure;
                    if (poGDS->poChunkCache)
                        poGDS->poChunkCache->insert(secondKey, secondChunk);
                }

                // Assemble netCDF chunks into GDAL block
                GByte *pabyImage = static_cast<GByte *>(pImage);
                const size_t nFirstChunkBlockLine =
                    nFirstChunkBlock * nBlockYSize;
                const size_t nLastChunkBlockLine =
                    nLastChunkBlock * nBlockYSize;
                for (size_t iLine = ystart; iLine <= yend; iLine++)
                {
                    const size_t nLineFromBottom = nRasterYSize - 1 - iLine;
                    const size_t nChunkY = nLineFromBottom / nBlockYSize;
                    if (nChunkY == nFirstChunkBlock)
                    {
                        memcpy(pabyImage + nChunkLineSize * (iLine - ystart),
                               firstChunk.get()->data() +
                                   (nLineFromBottom - nFirstChunkBlockLine) *
                                       nChunkLineSize,
                               nChunkLineSize);
                    }
                    else
                    {
                        CPLAssert(nChunkY == nLastChunkBlock);
                        assert(secondChunk);
                        memcpy(pabyImage + nChunkLineSize * (iLine - ystart),
                               secondChunk.get()->data() +
                                   (nLineFromBottom - nLastChunkBlockLine) *
                                       nChunkLineSize,
                               nChunkLineSize);
                    }
                }
                return CE_None;
            }
        }
        else
        {
            ystart = nBlockYOff * nBlockYSize;
        }
    }

    return FetchNetcdfChunk(xstart, ystart, pImage) ? CE_None : CE_Failure;
}

/************************************************************************/
/*                             IWriteBlock()                            */
/************************************************************************/

CPLErr netCDFRasterBand::IWriteBlock(CPL_UNUSED int nBlockXOff, int nBlockYOff,
                                     void *pImage)
{
    CPLMutexHolderD(&hNCMutex);

#ifdef NCDF_DEBUG
    if (nBlockYOff == 0 || (nBlockYOff == nRasterYSize - 1))
        CPLDebug("GDAL_netCDF",
                 "netCDFRasterBand::IWriteBlock( %d, %d, ...) nBand=%d",
                 nBlockXOff, nBlockYOff, nBand);
#endif

    int nd = 0;
    nc_inq_varndims(cdfid, nZId, &nd);

    // Locate X, Y and Z position in the array.

    size_t start[MAX_NC_DIMS];
    memset(start, 0, sizeof(start));
    start[nBandXPos] = nBlockXOff * nBlockXSize;

    // check y order.
    if (static_cast<netCDFDataset *>(poDS)->bBottomUp)
    {
        if (nBlockYSize == 1)
        {
            start[nBandYPos] = nRasterYSize - 1 - nBlockYOff;
        }
        else
        {
            CPLError(CE_Failure, CPLE_AppDefined,
                     "nBlockYSize = %d, only 1 supported when "
                     "writing bottom-up dataset",
                     nBlockYSize);
            return CE_Failure;
        }
    }
    else
    {
        start[nBandYPos] = nBlockYOff * nBlockYSize;  // y
    }

    size_t edge[MAX_NC_DIMS] = {};

    edge[nBandXPos] = nBlockXSize;
    if ((start[nBandXPos] + edge[nBandXPos]) > (size_t)nRasterXSize)
        edge[nBandXPos] = nRasterXSize - start[nBandXPos];
    edge[nBandYPos] = nBlockYSize;
    if ((start[nBandYPos] + edge[nBandYPos]) > (size_t)nRasterYSize)
        edge[nBandYPos] = nRasterYSize - start[nBandYPos];

    if (nd == 3)
    {
        start[panBandZPos[0]] = nLevel;  // z
        edge[panBandZPos[0]] = 1;
    }

    // Compute multidimention band position.
    //
    // BandPosition = (Total - sum(PastBandLevels) - 1)/sum(remainingLevels)
    // if Data[2,3,4,x,y]
    //
    //  BandPos0 = (nBand) / (3*4)
    //  BandPos1 = (nBand - (3*4)) / (4)
    //  BandPos2 = (nBand - (3*4)) % (4)
    if (nd > 3)
    {
        int Sum = -1;
        int Taken = 0;
        for (int i = 0; i < nd - 2; i++)
        {
            if (i != nd - 2 - 1)
            {
                Sum = 1;
                for (int j = i + 1; j < nd - 2; j++)
                {
                    Sum *= panBandZLev[j];
                }
                start[panBandZPos[i]] = (int)((nLevel - Taken) / Sum);
                edge[panBandZPos[i]] = 1;
            }
            else
            {
                start[panBandZPos[i]] = (int)((nLevel - Taken) % Sum);
                edge[panBandZPos[i]] = 1;
            }
            Taken += static_cast<int>(start[panBandZPos[i]]) * Sum;
        }
    }

    // Make sure we are in data mode.
    static_cast<netCDFDataset *>(poDS)->SetDefineMode(false);

    // Copy data according to type.
    int status = 0;
    if (eDataType == GDT_Byte)
    {
        if (bSignedData)
            status = nc_put_vara_schar(cdfid, nZId, start, edge,
                                       static_cast<signed char *>(pImage));
        else
            status = nc_put_vara_uchar(cdfid, nZId, start, edge,
                                       static_cast<unsigned char *>(pImage));
    }
    else if (nc_datatype == NC_SHORT)
    {
        status = nc_put_vara_short(cdfid, nZId, start, edge,
                                   static_cast<short *>(pImage));
    }
    else if (eDataType == GDT_Int32)
    {
        status = nc_put_vara_int(cdfid, nZId, start, edge,
                                 static_cast<int *>(pImage));
    }
    else if (eDataType == GDT_Float32)
    {
        status = nc_put_vara_float(cdfid, nZId, start, edge,
                                   static_cast<float *>(pImage));
    }
    else if (eDataType == GDT_Float64)
    {
        status = nc_put_vara_double(cdfid, nZId, start, edge,
                                    static_cast<double *>(pImage));
    }
#ifdef NETCDF_HAS_NC4
    else if (eDataType == GDT_UInt16 &&
             static_cast<netCDFDataset *>(poDS)->eFormat == NCDF_FORMAT_NC4)
    {
        status = nc_put_vara_ushort(cdfid, nZId, start, edge,
                                    static_cast<unsigned short *>(pImage));
    }
    else if (eDataType == GDT_UInt32 &&
             static_cast<netCDFDataset *>(poDS)->eFormat == NCDF_FORMAT_NC4)
    {
        status = nc_put_vara_uint(cdfid, nZId, start, edge,
                                  static_cast<unsigned int *>(pImage));
    }
    else if (eDataType == GDT_UInt64 &&
             static_cast<netCDFDataset *>(poDS)->eFormat == NCDF_FORMAT_NC4)
    {
        status =
            nc_put_vara_ulonglong(cdfid, nZId, start, edge,
                                  static_cast<unsigned long long *>(pImage));
    }
    else if (eDataType == GDT_Int64 &&
             static_cast<netCDFDataset *>(poDS)->eFormat == NCDF_FORMAT_NC4)
    {
        status = nc_put_vara_longlong(cdfid, nZId, start, edge,
                                      static_cast<long long *>(pImage));
    }
#endif
    else
    {
        CPLError(CE_Failure, CPLE_NotSupported,
                 "The NetCDF driver does not support GDAL data type %d",
                 eDataType);
        status = NC_EBADTYPE;
    }
    NCDF_ERR(status);

    if (status != NC_NOERR)
    {
        CPLError(CE_Failure, CPLE_AppDefined,
                 "netCDF scanline write failed: %s", nc_strerror(status));
        return CE_Failure;
    }

    return CE_None;
}

/************************************************************************/
/* ==================================================================== */
/*                              netCDFDataset                           */
/* ==================================================================== */
/************************************************************************/

/************************************************************************/
/*                           netCDFDataset()                            */
/************************************************************************/

netCDFDataset::netCDFDataset()
    :
// Basic dataset vars.
#ifdef ENABLE_NCDUMP
      bFileToDestroyAtClosing(false),
#endif
      cdfid(-1), nSubDatasets(0), papszSubDatasets(nullptr),
      papszMetadata(nullptr), bBottomUp(true), eFormat(NCDF_FORMAT_NONE),
      bIsGdalFile(false), bIsGdalCfFile(false), pszCFProjection(nullptr),
      pszCFCoordinates(nullptr), nCFVersion(1.6), bSGSupport(false),
      eMultipleLayerBehavior(SINGLE_LAYER), logCount(0), vcdf(cdfid),
      GeometryScribe(vcdf, this->generateLogName()),
      FieldScribe(vcdf, this->generateLogName()),
      bufManager(CPLGetUsablePhysicalRAM() / 5),

      // projection/GT.
      nXDimID(-1), nYDimID(-1), bIsProjected(false),
      bIsGeographic(false),  // Can be not projected, and also not geographic

      // State vars.
      bDefineMode(true), bAddedGridMappingRef(false),

      // Create vars.
      papszCreationOptions(nullptr), eCompress(NCDF_COMPRESS_NONE),
      nZLevel(NCDF_DEFLATE_LEVEL),
#ifdef NETCDF_HAS_NC4
      bChunking(false),
#endif
      nCreateMode(NC_CLOBBER), bSignedData(true)
{
    m_oSRS.SetAxisMappingStrategy(OAMS_TRADITIONAL_GIS_ORDER);

    // Projection/GT.
    m_adfGeoTransform[0] = 0.0;
    m_adfGeoTransform[1] = 1.0;
    m_adfGeoTransform[2] = 0.0;
    m_adfGeoTransform[3] = 0.0;
    m_adfGeoTransform[4] = 0.0;
    m_adfGeoTransform[5] = 1.0;

    // Set buffers
    bufManager.addBuffer(&(GeometryScribe.getMemBuffer()));
    bufManager.addBuffer(&(FieldScribe.getMemBuffer()));
}

/************************************************************************/
/*                           ~netCDFDataset()                           */
/************************************************************************/

netCDFDataset::~netCDFDataset()

{
    CPLMutexHolderD(&hNCMutex);

#ifdef NCDF_DEBUG
    CPLDebug("GDAL_netCDF",
             "netCDFDataset::~netCDFDataset(), cdfid=%d filename=%s", cdfid,
             osFilename.c_str());
#endif

    // Write data related to geotransform
    if (GetAccess() == GA_Update && !m_bAddedProjectionVarsData &&
        (m_bHasProjection || m_bHasGeoTransform))
    {
        // Ensure projection is written if GeoTransform OR Projection are
        // missing.
        if (!m_bAddedProjectionVarsDefs)
        {
            AddProjectionVars(true, nullptr, nullptr);
        }
        AddProjectionVars(false, nullptr, nullptr);
    }

    netCDFDataset::FlushCache(true);
    SGCommitPendingTransaction();

    for (size_t i = 0; i < apoVectorDatasets.size(); i++)
        delete apoVectorDatasets[i];

    // Make sure projection variable is written to band variable.
    if (GetAccess() == GA_Update && !bAddedGridMappingRef)
        AddGridMappingRef();

    CSLDestroy(papszMetadata);
    CSLDestroy(papszSubDatasets);
    CSLDestroy(papszCreationOptions);

    CPLFree(pszCFProjection);

    if (cdfid > 0)
    {
#ifdef NCDF_DEBUG
        CPLDebug("GDAL_netCDF", "calling nc_close( %d)", cdfid);
#endif
        int status = GDAL_nc_close(cdfid);
#ifdef ENABLE_UFFD
        NETCDF_UFFD_UNMAP(pCtx);
#endif
        NCDF_ERR(status);
    }

    if (fpVSIMEM)
        VSIFCloseL(fpVSIMEM);

#ifdef ENABLE_NCDUMP
    if (bFileToDestroyAtClosing)
        VSIUnlink(osFilename);
#endif
}

/************************************************************************/
/*                            SetDefineMode()                           */
/************************************************************************/
bool netCDFDataset::SetDefineMode(bool bNewDefineMode)
{
    // Do nothing if already in new define mode
    // or if dataset is in read-only mode or if dataset is true NC4 dataset.
    if (bDefineMode == bNewDefineMode || GetAccess() == GA_ReadOnly ||
        eFormat == NCDF_FORMAT_NC4)
        return true;

    CPLDebug("GDAL_netCDF", "SetDefineMode(%d) old=%d",
             static_cast<int>(bNewDefineMode), static_cast<int>(bDefineMode));

    bDefineMode = bNewDefineMode;

    int status;
    if (bDefineMode)
        status = nc_redef(cdfid);
    else
        status = nc_enddef(cdfid);

    NCDF_ERR(status);
    return status == NC_NOERR;
}

/************************************************************************/
/*                      GetMetadataDomainList()                         */
/************************************************************************/

char **netCDFDataset::GetMetadataDomainList()
{
    char **papszDomains = BuildMetadataDomainList(
        GDALDataset::GetMetadataDomainList(), TRUE, "SUBDATASETS", nullptr);
    for (const auto &kv : m_oMapDomainToJSon)
        papszDomains = CSLAddString(papszDomains, ("json:" + kv.first).c_str());
    return papszDomains;
}

/************************************************************************/
/*                            GetMetadata()                             */
/************************************************************************/
char **netCDFDataset::GetMetadata(const char *pszDomain)
{
    if (pszDomain != nullptr && STARTS_WITH_CI(pszDomain, "SUBDATASETS"))
        return papszSubDatasets;

    if (pszDomain != nullptr && STARTS_WITH(pszDomain, "json:"))
    {
        auto iter = m_oMapDomainToJSon.find(pszDomain + strlen("json:"));
        if (iter != m_oMapDomainToJSon.end())
            return iter->second.List();
    }

    return GDALDataset::GetMetadata(pszDomain);
}

/************************************************************************/
/*                        SetMetadataItem()                             */
/************************************************************************/

CPLErr netCDFDataset::SetMetadataItem(const char *pszName, const char *pszValue,
                                      const char *pszDomain)
{
    if (GetAccess() == GA_Update &&
        (pszDomain == nullptr || pszDomain[0] == '\0') && pszValue != nullptr)
    {
        std::string osName(pszName);

        // Same logic as in CopyMetadata()
        if (STARTS_WITH(osName.c_str(), "NC_GLOBAL#"))
            osName = osName.substr(strlen("NC_GLOBAL#"));
        else if (strchr(osName.c_str(), '#') == nullptr)
            osName = "GDAL_" + osName;

        if (STARTS_WITH(osName.c_str(), "NETCDF_DIM_") ||
            strchr(osName.c_str(), '#') != nullptr)
        {
            // do nothing
        }
        else
        {
            SetDefineMode(true);

            if (!NCDFPutAttr(cdfid, NC_GLOBAL, osName.c_str(), pszValue))
                return CE_Failure;
        }
    }

    return GDALPamDataset::SetMetadataItem(pszName, pszValue, pszDomain);
}

/************************************************************************/
/*                          SetMetadata()                               */
/************************************************************************/

CPLErr netCDFDataset::SetMetadata(char **papszMD, const char *pszDomain)
{
    if (GetAccess() == GA_Update &&
        (pszDomain == nullptr || pszDomain[0] == '\0'))
    {
        // We don't handle metadata item removal for now
        for (const char *const *papszIter = papszMD; papszIter && *papszIter;
             ++papszIter)
        {
            char *pszName = nullptr;
            const char *pszValue = CPLParseNameValue(*papszIter, &pszName);
            if (pszName && pszValue)
                SetMetadataItem(pszName, pszValue);
            CPLFree(pszName);
        }
    }
    return GDALPamDataset::SetMetadata(papszMD, pszDomain);
}

/************************************************************************/
/*                          GetSpatialRef()                             */
/************************************************************************/

const OGRSpatialReference *netCDFDataset::GetSpatialRef() const
{
    if (m_bHasProjection)
        return m_oSRS.IsEmpty() ? nullptr : &m_oSRS;

    return GDALPamDataset::GetSpatialRef();
}

/************************************************************************/
/*                           SerializeToXML()                           */
/************************************************************************/

CPLXMLNode *netCDFDataset::SerializeToXML(const char *pszUnused)

{
    // Overridden from GDALPamDataset to add only band histogram
    // and statistics. See bug #4244.

    if (psPam == nullptr)
        return nullptr;

    // Setup root node and attributes.
    CPLXMLNode *psDSTree = CPLCreateXMLNode(nullptr, CXT_Element, "PAMDataset");

    // Process bands.
    for (int iBand = 0; iBand < GetRasterCount(); iBand++)
    {
        netCDFRasterBand *poBand =
            static_cast<netCDFRasterBand *>(GetRasterBand(iBand + 1));

        if (poBand == nullptr || !(poBand->GetMOFlags() & GMO_PAM_CLASS))
            continue;

        CPLXMLNode *psBandTree = poBand->SerializeToXML(pszUnused);

        if (psBandTree != nullptr)
            CPLAddXMLChild(psDSTree, psBandTree);
    }

    // We don't want to return anything if we had no metadata to attach.
    if (psDSTree->psChild == nullptr)
    {
        CPLDestroyXMLNode(psDSTree);
        psDSTree = nullptr;
    }

    return psDSTree;
}

/************************************************************************/
/*                           FetchCopyParam()                            */
/************************************************************************/

double netCDFDataset::FetchCopyParam(const char *pszGridMappingValue,
                                     const char *pszParam, double dfDefault,
                                     bool *pbFound)

{
    char *pszTemp =
        CPLStrdup(CPLSPrintf("%s#%s", pszGridMappingValue, pszParam));
    const char *pszValue = CSLFetchNameValue(papszMetadata, pszTemp);
    CPLFree(pszTemp);

    if (pbFound)
    {
        *pbFound = (pszValue != nullptr);
    }

    if (pszValue)
    {
        return CPLAtofM(pszValue);
    }

    return dfDefault;
}

/************************************************************************/
/*                           FetchStandardParallels()                   */
/************************************************************************/

std::vector<std::string>
netCDFDataset::FetchStandardParallels(const char *pszGridMappingValue)
{
    // cf-1.0 tags
    const char *pszValue = FetchAttr(pszGridMappingValue, CF_PP_STD_PARALLEL);

    std::vector<std::string> ret;
    if (pszValue != nullptr)
    {
        CPLStringList aosValues;
        if (pszValue[0] != '{' &&
            CPLString(pszValue).Trim().find(' ') != std::string::npos)
        {
            // Some files like
            // ftp://data.knmi.nl/download/KNW-NetCDF-3D/1.0/noversion/2013/11/14/KNW-1.0_H37-ERA_NL_20131114.nc
            // do not use standard formatting for arrays, but just space
            // separated syntax
            aosValues = CSLTokenizeString2(pszValue, " ", 0);
        }
        else
        {
            aosValues = NCDFTokenizeArray(pszValue);
        }
        for (int i = 0; i < aosValues.size(); i++)
        {
            ret.push_back(aosValues[i]);
        }
    }
    // Try gdal tags.
    else
    {
        pszValue = FetchAttr(pszGridMappingValue, CF_PP_STD_PARALLEL_1);

        if (pszValue != nullptr)
            ret.push_back(pszValue);

        pszValue = FetchAttr(pszGridMappingValue, CF_PP_STD_PARALLEL_2);

        if (pszValue != nullptr)
            ret.push_back(pszValue);
    }

    return ret;
}

/************************************************************************/
/*                           FetchAttr()                                */
/************************************************************************/

const char *netCDFDataset::FetchAttr(const char *pszVarFullName,
                                     const char *pszAttr)

{
    char *pszKey = CPLStrdup(CPLSPrintf("%s#%s", pszVarFullName, pszAttr));
    const char *pszValue = CSLFetchNameValue(papszMetadata, pszKey);
    CPLFree(pszKey);
    return pszValue;
}

const char *netCDFDataset::FetchAttr(int nGroupId, int nVarId,
                                     const char *pszAttr)

{
    char *pszVarFullName = nullptr;
    NCDFGetVarFullName(nGroupId, nVarId, &pszVarFullName);
    const char *pszValue = FetchAttr(pszVarFullName, pszAttr);
    CPLFree(pszVarFullName);
    return pszValue;
}

/************************************************************************/
/*                       IsDifferenceBelow()                            */
/************************************************************************/

static bool IsDifferenceBelow(double dfA, double dfB, double dfError)
{
    const double dfAbsDiff = fabs(dfA - dfB);
    return dfAbsDiff <= dfError;
}

/************************************************************************/
/*                      SetProjectionFromVar()                          */
/************************************************************************/
void netCDFDataset::SetProjectionFromVar(int nGroupId, int nVarId,
                                         bool bReadSRSOnly,
                                         const char *pszGivenGM,
                                         std::string *returnProjStr,
                                         nccfdriver::SGeometry_Reader *sg)
{
    bool bGotGeogCS = false;
    bool bGotCfSRS = false;
    bool bGotCfWktSRS = false;
    bool bGotGdalSRS = false;
    bool bGotCfGT = false;
    bool bGotGdalGT = false;

    // These values from CF metadata.
    OGRSpatialReference oSRS;
    oSRS.SetAxisMappingStrategy(OAMS_TRADITIONAL_GIS_ORDER);
    char szDimNameX[NC_MAX_NAME + 1];
    // char szDimNameY[NC_MAX_NAME + 1];
    size_t xdim = nRasterXSize;
    size_t ydim = nRasterYSize;

    // These values from GDAL metadata.
    const char *pszWKT = nullptr;
    const char *pszGeoTransform = nullptr;

    netCDFDataset *poDS = this;  // Perhaps this should be removed for clarity.

    CPLDebug("GDAL_netCDF", "\n=====\nSetProjectionFromVar( %d, %d)", nGroupId,
             nVarId);

    // Get x/y range information.

    // Temp variables to use in SetGeoTransform() and SetProjection().
    double adfTempGeoTransform[6] = {0.0, 1.0, 0.0, 0.0, 0.0, 1.0};

    // Look for grid_mapping metadata.
    const char *pszValue = pszGivenGM;
    CPLString osTmpGridMapping;  // let is in this outer scope as pszValue may
                                 // point to it
    if (pszValue == nullptr)
    {
        pszValue = FetchAttr(nGroupId, nVarId, CF_GRD_MAPPING);
        if (pszValue && strchr(pszValue, ':') && strchr(pszValue, ' '))
        {
            // Expanded form of grid_mapping
            // e.g. "crsOSGB: x y crsWGS84: lat lon"
            // Pickup the grid_mapping whose coordinates are dimensions of the
            // variable
            CPLStringList aosTokens(CSLTokenizeString2(pszValue, " ", 0));
            if ((aosTokens.size() % 3) == 0)
            {
                for (int i = 0; i < aosTokens.size() / 3; i++)
                {
                    if (CSLFindString(poDS->papszDimName,
                                      aosTokens[3 * i + 1]) >= 0 &&
                        CSLFindString(poDS->papszDimName,
                                      aosTokens[3 * i + 2]) >= 0)
                    {
                        osTmpGridMapping = aosTokens[3 * i];
                        if (!osTmpGridMapping.empty() &&
                            osTmpGridMapping.back() == ':')
                        {
                            osTmpGridMapping.resize(osTmpGridMapping.size() -
                                                    1);
                        }
                        pszValue = osTmpGridMapping.c_str();
                        break;
                    }
                }
            }
        }
    }
    char *pszGridMappingValue = CPLStrdup(pszValue ? pszValue : "");

    if (!EQUAL(pszGridMappingValue, ""))
    {
        // Read grid_mapping metadata.
        int nProjGroupID = -1;
        int nProjVarID = -1;
        if (NCDFResolveVar(nGroupId, pszGridMappingValue, &nProjGroupID,
                           &nProjVarID) == CE_None)
        {
            poDS->ReadAttributes(nProjGroupID, nProjVarID);

            // Look for GDAL spatial_ref and GeoTransform within grid_mapping.
            CPLFree(pszGridMappingValue);
            pszGridMappingValue = nullptr;
            NCDFGetVarFullName(nProjGroupID, nProjVarID, &pszGridMappingValue);
            if (pszGridMappingValue)
            {
                CPLDebug("GDAL_netCDF", "got grid_mapping %s",
                         pszGridMappingValue);
                pszWKT = FetchAttr(pszGridMappingValue, NCDF_SPATIAL_REF);
                if (!pszWKT)
                {
                    pszWKT = FetchAttr(pszGridMappingValue, NCDF_CRS_WKT);
                }
                else
                {
                    bGotGdalSRS = true;
                    CPLDebug("GDAL_netCDF", "setting WKT from GDAL");
                }
                if (pszWKT)
                {
                    if (!bGotGdalSRS)
                    {
                        bGotCfWktSRS = true;
                        CPLDebug("GDAL_netCDF", "setting WKT from CF");
                    }
                    if (returnProjStr != nullptr)
                    {
                        (*returnProjStr) = std::string(pszWKT);
                    }
                    else
                    {
                        m_bAddedProjectionVarsDefs = true;
                        m_bAddedProjectionVarsData = true;
                        OGRSpatialReference oSRSTmp;
                        oSRSTmp.SetAxisMappingStrategy(
                            OAMS_TRADITIONAL_GIS_ORDER);
                        oSRSTmp.importFromWkt(pszWKT);
                        SetSpatialRefNoUpdate(&oSRSTmp);
                    }
                    pszGeoTransform =
                        FetchAttr(pszGridMappingValue, NCDF_GEOTRANSFORM);
                }
            }
            else
            {
                pszGridMappingValue = CPLStrdup("");
            }
        }
    }

    // Get information about the file.
    //
    // Was this file created by the GDAL netcdf driver?
    // Was this file created by the newer (CF-conformant) driver?
    //
    // 1) If GDAL netcdf metadata is set, and version >= 1.9,
    //    it was created with the new driver
    // 2) Else, if spatial_ref and GeoTransform are present in the
    //    grid_mapping variable, it was created by the old driver
    pszValue = FetchAttr("NC_GLOBAL", "GDAL");

    if (pszValue && NCDFIsGDALVersionGTE(pszValue, 1900))
    {
        bIsGdalFile = true;
        bIsGdalCfFile = true;
    }
    else if (pszWKT != nullptr && pszGeoTransform != nullptr)
    {
        bIsGdalFile = true;
        bIsGdalCfFile = false;
    }

    // Set default bottom-up default value.
    // Y axis dimension and absence of GT can modify this value.
    // Override with Config option GDAL_NETCDF_BOTTOMUP.

    // New driver is bottom-up by default.
    if ((bIsGdalFile && !bIsGdalCfFile) || bSwitchedXY)
        poDS->bBottomUp = false;
    else
        poDS->bBottomUp = true;

    CPLDebug("GDAL_netCDF",
             "bIsGdalFile=%d bIsGdalCfFile=%d bSwitchedXY=%d bBottomUp=%d",
             static_cast<int>(bIsGdalFile), static_cast<int>(bIsGdalCfFile),
             static_cast<int>(bSwitchedXY), static_cast<int>(bBottomUp));

    // Look for dimension: lon.

    memset(szDimNameX, '\0', sizeof(szDimNameX));
    // memset(szDimNameY, '\0', sizeof(szDimNameY));

    if (!bReadSRSOnly)
    {
        for (unsigned int i = 0;
             i < strlen(poDS->papszDimName[poDS->nXDimID]) && i < 3; i++)
        {
            szDimNameX[i] =
                (char)tolower((poDS->papszDimName[poDS->nXDimID])[i]);
        }
        szDimNameX[3] = '\0';
        // for( unsigned int i = 0;
        //      (i < strlen(poDS->papszDimName[poDS->nYDimID])
        //                        && i < 3 ); i++ ) {
        //    szDimNameY[i]=(char)tolower((poDS->papszDimName[poDS->nYDimID])[i]);
        // }
        // szDimNameY[3] = '\0';
    }

    // Read grid_mapping information and set projections.

    bool bRotatedPole = false;

    if (!pszWKT && !EQUAL(pszGridMappingValue, ""))
    {
        pszValue = FetchAttr(pszGridMappingValue, CF_GRD_MAPPING_NAME);

        // Some files such as
        // http://www.ecad.eu/download/ensembles/data/Grid_0.44deg_rot/tg_0.44deg_rot_v16.0.nc.gz
        // lack an explicit projection_var:grid_mapping_name attribute
        if (pszValue == nullptr &&
            FetchAttr(pszGridMappingValue, CF_PP_GRID_NORTH_POLE_LONGITUDE) !=
                nullptr)
        {
            pszValue = CF_PT_ROTATED_LATITUDE_LONGITUDE;
        }

        if (pszValue != nullptr)
        {
            // Check for datum/spheroid information.
            double dfEarthRadius = poDS->FetchCopyParam(
                pszGridMappingValue, CF_PP_EARTH_RADIUS, -1.0);

            const double dfLonPrimeMeridian = poDS->FetchCopyParam(
                pszGridMappingValue, CF_PP_LONG_PRIME_MERIDIAN, 0.0);

            const char *pszPMName =
                FetchAttr(pszGridMappingValue, CF_PRIME_MERIDIAN_NAME);

            // Should try to find PM name from its value if not Greenwich.
            if (pszPMName == nullptr && !CPLIsEqual(dfLonPrimeMeridian, 0.0))
                pszPMName = "unknown";

            double dfInverseFlattening = poDS->FetchCopyParam(
                pszGridMappingValue, CF_PP_INVERSE_FLATTENING, -1.0);

            double dfSemiMajorAxis = poDS->FetchCopyParam(
                pszGridMappingValue, CF_PP_SEMI_MAJOR_AXIS, -1.0);

            const double dfSemiMinorAxis = poDS->FetchCopyParam(
                pszGridMappingValue, CF_PP_SEMI_MINOR_AXIS, -1.0);

            // See if semi-major exists if radius doesn't.
            if (dfEarthRadius < 0.0)
                dfEarthRadius = dfSemiMajorAxis;

            // If still no radius, check old tag.
            if (dfEarthRadius < 0.0)
                dfEarthRadius = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_EARTH_RADIUS_OLD, -1.0);

            const char *pszEllipsoidName =
                FetchAttr(pszGridMappingValue, CF_REFERENCE_ELLIPSOID_NAME);

            const char *pszDatumName =
                FetchAttr(pszGridMappingValue, CF_HORIZONTAL_DATUM_NAME);

            const char *pszGeogName =
                FetchAttr(pszGridMappingValue, CF_GEOGRAPHIC_CRS_NAME);
            if (pszGeogName == nullptr)
                pszGeogName = "unknown";

            // Has radius value.
            if (dfEarthRadius > 0.0)
            {
                // Check for inv_flat tag.
                if (dfInverseFlattening < 0.0)
                {
                    // No inv_flat tag, check for semi_minor.
                    if (dfSemiMinorAxis < 0.0)
                    {
                        // No way to get inv_flat, use sphere.
                        oSRS.SetGeogCS(
                            pszGeogName, pszDatumName,
                            pszEllipsoidName ? pszEllipsoidName : "Sphere",
                            dfEarthRadius, 0.0, pszPMName, dfLonPrimeMeridian);
                        bGotGeogCS = true;
                    }
                    else
                    {
                        if (dfSemiMajorAxis < 0.0)
                            dfSemiMajorAxis = dfEarthRadius;
                        // set inv_flat using semi_minor/major
                        dfInverseFlattening = OSRCalcInvFlattening(
                            dfSemiMajorAxis, dfSemiMinorAxis);

                        oSRS.SetGeogCS(pszGeogName, pszDatumName,
                                       pszEllipsoidName ? pszEllipsoidName
                                                        : "Spheroid",
                                       dfEarthRadius, dfInverseFlattening,
                                       pszPMName, dfLonPrimeMeridian);
                        bGotGeogCS = true;
                    }
                }
                else
                {
                    oSRS.SetGeogCS(pszGeogName, pszDatumName,
                                   pszEllipsoidName ? pszEllipsoidName
                                                    : "Spheroid",
                                   dfEarthRadius, dfInverseFlattening,
                                   pszPMName, dfLonPrimeMeridian);
                    bGotGeogCS = true;
                }

                if (bGotGeogCS)
                    CPLDebug("GDAL_netCDF", "got spheroid from CF: (%f , %f)",
                             dfEarthRadius, dfInverseFlattening);
            }
            // no radius, set as wgs84 as default?
            else
            {
                // This would be too indiscriminate.  But we should set
                // it if we know the data is geographic.
                // oSRS.SetWellKnownGeogCS("WGS84");
            }

            // Transverse Mercator.
            if (EQUAL(pszValue, CF_PT_TM))
            {
                const double dfScale = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_SCALE_FACTOR_MERIDIAN, 1.0);

                const double dfCenterLon = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_LONG_CENTRAL_MERIDIAN, 0.0);

                const double dfCenterLat = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_LAT_PROJ_ORIGIN, 0.0);

                const double dfFalseEasting = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_FALSE_EASTING, 0.0);

                const double dfFalseNorthing = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_FALSE_NORTHING, 0.0);

                bGotCfSRS = true;
                oSRS.SetTM(dfCenterLat, dfCenterLon, dfScale, dfFalseEasting,
                           dfFalseNorthing);

                if (!bGotGeogCS)
                    oSRS.SetWellKnownGeogCS("WGS84");
            }

            // Albers Equal Area.
            if (EQUAL(pszValue, CF_PT_AEA))
            {
                const double dfCenterLon = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_LONG_CENTRAL_MERIDIAN, 0.0);

                const double dfFalseEasting = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_FALSE_EASTING, 0.0);

                const double dfFalseNorthing = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_FALSE_NORTHING, 0.0);

                const auto aosStdParallels =
                    FetchStandardParallels(pszGridMappingValue);

                double dfStdP1 = 0;
                double dfStdP2 = 0;
                if (aosStdParallels.size() == 1)
                {
                    // TODO CF-1 standard says it allows AEA to be encoded
                    // with only 1 standard parallel.  How should this
                    // actually map to a 2StdP OGC WKT version?
                    CPLError(CE_Warning, CPLE_NotSupported,
                             "NetCDF driver import of AEA-1SP is not tested, "
                             "using identical std. parallels.");
                    dfStdP1 = CPLAtofM(aosStdParallels[0].c_str());
                    dfStdP2 = dfStdP1;
                }
                else if (aosStdParallels.size() == 2)
                {
                    dfStdP1 = CPLAtofM(aosStdParallels[0].c_str());
                    dfStdP2 = CPLAtofM(aosStdParallels[1].c_str());
                }
                // Old default.
                else
                {
                    dfStdP1 = poDS->FetchCopyParam(pszGridMappingValue,
                                                   CF_PP_STD_PARALLEL_1, 0.0);

                    dfStdP2 = poDS->FetchCopyParam(pszGridMappingValue,
                                                   CF_PP_STD_PARALLEL_2, 0.0);
                }

                const double dfCenterLat = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_LAT_PROJ_ORIGIN, 0.0);

                bGotCfSRS = true;
                oSRS.SetACEA(dfStdP1, dfStdP2, dfCenterLat, dfCenterLon,
                             dfFalseEasting, dfFalseNorthing);

                if (!bGotGeogCS)
                    oSRS.SetWellKnownGeogCS("WGS84");
            }

            // Cylindrical Equal Area
            else if (EQUAL(pszValue, CF_PT_CEA) || EQUAL(pszValue, CF_PT_LCEA))
            {
                const auto aosStdParallels =
                    FetchStandardParallels(pszGridMappingValue);

                double dfStdP1 = 0;
                if (!aosStdParallels.empty())
                {
                    dfStdP1 = CPLAtofM(aosStdParallels[0].c_str());
                }
                else
                {
                    // TODO: Add support for 'scale_factor_at_projection_origin'
                    // variant to standard parallel.  Probably then need to calc
                    // a std parallel equivalent.
                    CPLError(
                        CE_Failure, CPLE_NotSupported,
                        "NetCDF driver does not support import of CF-1 LCEA "
                        "'scale_factor_at_projection_origin' variant yet.");
                }

                const double dfCentralMeridian = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_LONG_CENTRAL_MERIDIAN, 0.0);

                const double dfFalseEasting = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_FALSE_EASTING, 0.0);

                const double dfFalseNorthing = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_FALSE_NORTHING, 0.0);

                bGotCfSRS = true;
                oSRS.SetCEA(dfStdP1, dfCentralMeridian, dfFalseEasting,
                            dfFalseNorthing);

                if (!bGotGeogCS)
                    oSRS.SetWellKnownGeogCS("WGS84");
            }

            // lambert_azimuthal_equal_area.
            else if (EQUAL(pszValue, CF_PT_LAEA))
            {
                const double dfCenterLon = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_LON_PROJ_ORIGIN, 0.0);

                const double dfCenterLat = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_LAT_PROJ_ORIGIN, 0.0);

                const double dfFalseEasting = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_FALSE_EASTING, 0.0);

                const double dfFalseNorthing = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_FALSE_NORTHING, 0.0);

                bGotCfSRS = true;
                oSRS.SetLAEA(dfCenterLat, dfCenterLon, dfFalseEasting,
                             dfFalseNorthing);

                if (!bGotGeogCS)
                    oSRS.SetWellKnownGeogCS("WGS84");

                if (oSRS.GetAttrValue("DATUM") != nullptr &&
                    EQUAL(oSRS.GetAttrValue("DATUM"), "WGS_1984"))
                {
                    oSRS.SetProjCS("LAEA (WGS84)");
                }
            }

            // Azimuthal Equidistant.
            else if (EQUAL(pszValue, CF_PT_AE))
            {
                const double dfCenterLon = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_LON_PROJ_ORIGIN, 0.0);

                const double dfCenterLat = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_LAT_PROJ_ORIGIN, 0.0);

                const double dfFalseEasting = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_FALSE_EASTING, 0.0);

                const double dfFalseNorthing = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_FALSE_NORTHING, 0.0);

                bGotCfSRS = true;
                oSRS.SetAE(dfCenterLat, dfCenterLon, dfFalseEasting,
                           dfFalseNorthing);

                if (!bGotGeogCS)
                    oSRS.SetWellKnownGeogCS("WGS84");
            }

            // Lambert conformal conic.
            else if (EQUAL(pszValue, CF_PT_LCC))
            {
                const double dfCenterLon = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_LONG_CENTRAL_MERIDIAN, 0.0);

                const double dfCenterLat = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_LAT_PROJ_ORIGIN, 0.0);

                const double dfFalseEasting = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_FALSE_EASTING, 0.0);

                const double dfFalseNorthing = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_FALSE_NORTHING, 0.0);

                const auto aosStdParallels =
                    FetchStandardParallels(pszGridMappingValue);

                // 2SP variant.
                if (aosStdParallels.size() == 2)
                {
                    const double dfStdP1 = CPLAtofM(aosStdParallels[0].c_str());
                    const double dfStdP2 = CPLAtofM(aosStdParallels[1].c_str());
                    oSRS.SetLCC(dfStdP1, dfStdP2, dfCenterLat, dfCenterLon,
                                dfFalseEasting, dfFalseNorthing);
                }
                // 1SP variant (with standard_parallel or center lon).
                // See comments in netcdfdataset.h for this projection.
                else
                {
                    double dfScale = poDS->FetchCopyParam(
                        pszGridMappingValue, CF_PP_SCALE_FACTOR_ORIGIN, -1.0);

                    // CF definition, without scale factor.
                    if (CPLIsEqual(dfScale, -1.0))
                    {
                        double dfStdP1;
                        // With standard_parallel.
                        if (aosStdParallels.size() == 1)
                            dfStdP1 = CPLAtofM(aosStdParallels[0].c_str());
                        // With center lon instead.
                        else
                            dfStdP1 = dfCenterLat;
                        // dfStdP2 = dfStdP1;

                        // Test if we should actually compute scale factor.
                        if (!CPLIsEqual(dfStdP1, dfCenterLat))
                        {
                            CPLError(
                                CE_Warning, CPLE_NotSupported,
                                "NetCDF driver import of LCC-1SP with "
                                "standard_parallel1 != "
                                "latitude_of_projection_origin "
                                "(which forces a computation of scale_factor) "
                                "is experimental (bug #3324)");
                            // Use Snyder eq. 15-4 to compute dfScale from
                            // dfStdP1 and dfCenterLat.  Only tested for
                            // dfStdP1=dfCenterLat and (25,26), needs more data
                            // for testing.  Other option: use the 2SP variant -
                            // how to compute new standard parallels?
                            dfScale =
                                (cos(dfStdP1) * pow(tan(M_PI / 4 + dfStdP1 / 2),
                                                    sin(dfStdP1))) /
                                (cos(dfCenterLat) *
                                 pow(tan(M_PI / 4 + dfCenterLat / 2),
                                     sin(dfCenterLat)));
                        }
                        // Default is 1.0.
                        else
                        {
                            dfScale = 1.0;
                        }

                        oSRS.SetLCC1SP(dfCenterLat, dfCenterLon, dfScale,
                                       dfFalseEasting, dfFalseNorthing);
                        // Store dfStdP1 so we can output it to CF later.
                        oSRS.SetNormProjParm(SRS_PP_STANDARD_PARALLEL_1,
                                             dfStdP1);
                    }
                    // OGC/PROJ.4 definition with scale factor.
                    else
                    {
                        oSRS.SetLCC1SP(dfCenterLat, dfCenterLon, dfScale,
                                       dfFalseEasting, dfFalseNorthing);
                    }
                }

                bGotCfSRS = true;
                if (!bGotGeogCS)
                    oSRS.SetWellKnownGeogCS("WGS84");
            }

            // Is this Latitude/Longitude Grid explicitly?

            else if (EQUAL(pszValue, CF_PT_LATITUDE_LONGITUDE))
            {
                bGotCfSRS = true;
                if (!bGotGeogCS)
                    oSRS.SetWellKnownGeogCS("WGS84");
            }

            // Mercator.
            else if (EQUAL(pszValue, CF_PT_MERCATOR))
            {

                // If there is a standard_parallel, know it is Mercator 2SP.
                const auto aosStdParallels =
                    FetchStandardParallels(pszGridMappingValue);

                if (!aosStdParallels.empty())
                {
                    // CF-1 Mercator 2SP always has lat centered at equator.
                    const double dfStdP1 = CPLAtofM(aosStdParallels[0].c_str());

                    const double dfCenterLat = 0.0;

                    const double dfCenterLon = poDS->FetchCopyParam(
                        pszGridMappingValue, CF_PP_LON_PROJ_ORIGIN, 0.0);

                    const double dfFalseEasting = poDS->FetchCopyParam(
                        pszGridMappingValue, CF_PP_FALSE_EASTING, 0.0);

                    const double dfFalseNorthing = poDS->FetchCopyParam(
                        pszGridMappingValue, CF_PP_FALSE_NORTHING, 0.0);

                    oSRS.SetMercator2SP(dfStdP1, dfCenterLat, dfCenterLon,
                                        dfFalseEasting, dfFalseNorthing);
                }
                else
                {
                    const double dfCenterLon = poDS->FetchCopyParam(
                        pszGridMappingValue, CF_PP_LON_PROJ_ORIGIN, 0.0);

                    const double dfCenterLat = poDS->FetchCopyParam(
                        pszGridMappingValue, CF_PP_LAT_PROJ_ORIGIN, 0.0);

                    const double dfScale = poDS->FetchCopyParam(
                        pszGridMappingValue, CF_PP_SCALE_FACTOR_ORIGIN, 1.0);

                    const double dfFalseEasting = poDS->FetchCopyParam(
                        pszGridMappingValue, CF_PP_FALSE_EASTING, 0.0);

                    const double dfFalseNorthing = poDS->FetchCopyParam(
                        pszGridMappingValue, CF_PP_FALSE_NORTHING, 0.0);

                    oSRS.SetMercator(dfCenterLat, dfCenterLon, dfScale,
                                     dfFalseEasting, dfFalseNorthing);
                }

                bGotCfSRS = true;

                if (!bGotGeogCS)
                    oSRS.SetWellKnownGeogCS("WGS84");
            }

            // Orthographic.
            else if (EQUAL(pszValue, CF_PT_ORTHOGRAPHIC))
            {
                const double dfCenterLon = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_LON_PROJ_ORIGIN, 0.0);

                const double dfCenterLat = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_LAT_PROJ_ORIGIN, 0.0);

                const double dfFalseEasting = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_FALSE_EASTING, 0.0);

                const double dfFalseNorthing = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_FALSE_NORTHING, 0.0);

                bGotCfSRS = true;

                oSRS.SetOrthographic(dfCenterLat, dfCenterLon, dfFalseEasting,
                                     dfFalseNorthing);

                if (!bGotGeogCS)
                    oSRS.SetWellKnownGeogCS("WGS84");
            }

            // Polar Stereographic.
            else if (EQUAL(pszValue, CF_PT_POLAR_STEREO))
            {
                const auto aosStdParallels =
                    FetchStandardParallels(pszGridMappingValue);

                const double dfCenterLon = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_VERT_LONG_FROM_POLE, 0.0);

                const double dfFalseEasting = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_FALSE_EASTING, 0.0);

                const double dfFalseNorthing = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_FALSE_NORTHING, 0.0);

                // CF allows the use of standard_parallel (lat_ts) OR
                // scale_factor (k0), make sure we have standard_parallel, using
                // Snyder eq. 22-7 with k=1 and lat=standard_parallel.
                if (!aosStdParallels.empty())
                {
                    const double dfStdP1 = CPLAtofM(aosStdParallels[0].c_str());

                    // Polar Stereographic Variant B with latitude of standard
                    // parallel
                    oSRS.SetPS(dfStdP1, dfCenterLon, 1.0, dfFalseEasting,
                               dfFalseNorthing);
                }
                else
                {
                    // Fetch latitude_of_projection_origin (+90/-90).
                    double dfLatProjOrigin = poDS->FetchCopyParam(
                        pszGridMappingValue, CF_PP_LAT_PROJ_ORIGIN, 0.0);
                    if (!CPLIsEqual(dfLatProjOrigin, 90.0) &&
                        !CPLIsEqual(dfLatProjOrigin, -90.0))
                    {
                        CPLError(CE_Failure, CPLE_NotSupported,
                                 "Polar Stereographic must have a %s "
                                 "parameter equal to +90 or -90.",
                                 CF_PP_LAT_PROJ_ORIGIN);
                        dfLatProjOrigin = 90.0;
                    }

                    const double dfScale = poDS->FetchCopyParam(
                        pszGridMappingValue, CF_PP_SCALE_FACTOR_ORIGIN, 1.0);

                    // Polar Stereographic Variant A with scale factor at
                    // natural origin and latitude of origin = +/- 90
                    oSRS.SetPS(dfLatProjOrigin, dfCenterLon, dfScale,
                               dfFalseEasting, dfFalseNorthing);
                }

                bGotCfSRS = true;

                if (!bGotGeogCS)
                    oSRS.SetWellKnownGeogCS("WGS84");
            }

            // Stereographic.
            else if (EQUAL(pszValue, CF_PT_STEREO))
            {
                const double dfCenterLon = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_LON_PROJ_ORIGIN, 0.0);

                const double dfCenterLat = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_LAT_PROJ_ORIGIN, 0.0);

                const double dfScale = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_SCALE_FACTOR_ORIGIN, 1.0);

                const double dfFalseEasting = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_FALSE_EASTING, 0.0);

                const double dfFalseNorthing = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_FALSE_NORTHING, 0.0);

                bGotCfSRS = true;
                oSRS.SetStereographic(dfCenterLat, dfCenterLon, dfScale,
                                      dfFalseEasting, dfFalseNorthing);

                if (!bGotGeogCS)
                    oSRS.SetWellKnownGeogCS("WGS84");
            }

            // Geostationary.
            else if (EQUAL(pszValue, CF_PT_GEOS))
            {
                const double dfCenterLon = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_LON_PROJ_ORIGIN, 0.0);

                const double dfSatelliteHeight = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_PERSPECTIVE_POINT_HEIGHT,
                    35785831.0);

                const char *pszSweepAxisAngle = poDS->FetchAttr(
                    pszGridMappingValue, CF_PP_SWEEP_ANGLE_AXIS);

                const double dfFalseEasting = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_FALSE_EASTING, 0.0);

                const double dfFalseNorthing = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_FALSE_NORTHING, 0.0);

                bGotCfSRS = true;
                oSRS.SetGEOS(dfCenterLon, dfSatelliteHeight, dfFalseEasting,
                             dfFalseNorthing);

                if (!bGotGeogCS)
                    oSRS.SetWellKnownGeogCS("WGS84");

                if (pszSweepAxisAngle != nullptr &&
                    EQUAL(pszSweepAxisAngle, "x"))
                {
                    char *pszProj4 = nullptr;
                    oSRS.exportToProj4(&pszProj4);
                    CPLString osProj4 = pszProj4;
                    osProj4 += " +sweep=x";
                    oSRS.SetExtension(oSRS.GetRoot()->GetValue(), "PROJ4",
                                      osProj4);
                    CPLFree(pszProj4);
                }
            }

            else if (EQUAL(pszValue, CF_PT_ROTATED_LATITUDE_LONGITUDE))
            {
                const double dfGridNorthPoleLong = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_GRID_NORTH_POLE_LONGITUDE, 0.0);
                const double dfGridNorthPoleLat = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_GRID_NORTH_POLE_LATITUDE, 0.0);
                const double dfNorthPoleGridLong = poDS->FetchCopyParam(
                    pszGridMappingValue, CF_PP_NORTH_POLE_GRID_LONGITUDE, 0.0);

                oSRS.SetDerivedGeogCRSWithPoleRotationNetCDFCFConvention(
                    "Rotated_pole", dfGridNorthPoleLat, dfGridNorthPoleLong,
                    dfNorthPoleGridLong);
                bRotatedPole = true;
            }

            if (oSRS.IsProjected())
            {
                const char *pszProjectedCRSName =
                    FetchAttr(pszGridMappingValue, CF_PROJECTED_CRS_NAME);
                if (pszProjectedCRSName)
                    oSRS.SetProjCS(pszProjectedCRSName);
            }

            // Is this Latitude/Longitude Grid, default?
        }
        else if (EQUAL(szDimNameX, NCDF_DIMNAME_LON))
        {
            oSRS.SetWellKnownGeogCS("WGS84");
        }
        else
        {
            // This would be too indiscriminate.  But we should set
            // it if we know the data is geographic.
            // oSRS.SetWellKnownGeogCS("WGS84");
        }
    }
    else
    {
        // Dataset from https://github.com/OSGeo/gdal/issues/4075 has a "crs"
        // attribute hold on the variable of interest that contains a PROJ.4
        // string
        pszValue = FetchAttr(nGroupId, nVarId, "crs");
        if (pszValue &&
            (strstr(pszValue, "+proj=") != nullptr ||
             strstr(pszValue, "GEOGCS") != nullptr ||
             strstr(pszValue, "PROJCS") != nullptr ||
             strstr(pszValue, "EPSG:") != nullptr) &&
            oSRS.SetFromUserInput(pszValue) == OGRERR_NONE)
        {
            bGotCfSRS = true;
        }
    }
    // Read projection coordinates.

    int nGroupDimXID = -1;
    int nVarDimXID = -1;
    int nGroupDimYID = -1;
    int nVarDimYID = -1;
    if (sg != nullptr)
    {
        nGroupDimXID = sg->get_ncID();
        nGroupDimYID = sg->get_ncID();
        nVarDimXID = sg->getNodeCoordVars()[0];
        nVarDimYID = sg->getNodeCoordVars()[1];
    }

    if (!bReadSRSOnly)
    {
        NCDFResolveVar(nGroupId, poDS->papszDimName[nXDimID], &nGroupDimXID,
                       &nVarDimXID);
        NCDFResolveVar(nGroupId, poDS->papszDimName[nYDimID], &nGroupDimYID,
                       &nVarDimYID);
        // TODO: if above resolving fails we should also search for coordinate
        // variables without same name than dimension using the same resolving
        // logic. This should handle for example NASA Ocean Color L2 products.

        const bool bIgnoreXYAxisNameChecks =
            CPLTestBool(CSLFetchNameValueDef(
                papszOpenOptions, "IGNORE_XY_AXIS_NAME_CHECKS",
                CPLGetConfigOption("GDAL_NETCDF_IGNORE_XY_AXIS_NAME_CHECKS",
                                   "NO"))) ||
            // Dataset from https://github.com/OSGeo/gdal/issues/4075 has a res
            // and transform attributes
            (FetchAttr(nGroupId, nVarId, "res") != nullptr &&
             FetchAttr(nGroupId, nVarId, "transform") != nullptr) ||
            FetchAttr(nGroupId, NC_GLOBAL, "GMT_version") != nullptr;

        // Check that they are 1D or 2D variables
        if (nVarDimXID >= 0)
        {
            int ndims = -1;
            nc_inq_varndims(nGroupId, nVarDimXID, &ndims);
            if (ndims == 0 || ndims > 2)
                nVarDimXID = -1;
            else if (!bIgnoreXYAxisNameChecks)
            {
                if (!NCDFIsVarLongitude(nGroupId, nVarDimXID, nullptr) &&
                    !NCDFIsVarProjectionX(nGroupId, nVarDimXID, nullptr) &&
                    // In case of inversion of X/Y
                    !NCDFIsVarLatitude(nGroupId, nVarDimXID, nullptr) &&
                    !NCDFIsVarProjectionY(nGroupId, nVarDimXID, nullptr))
                {
                    char szVarNameX[NC_MAX_NAME + 1];
                    CPL_IGNORE_RET_VAL(
                        nc_inq_varname(nGroupId, nVarDimXID, szVarNameX));
                    if (!(ndims == 1 &&
                          (EQUAL(szVarNameX, CF_LONGITUDE_STD_NAME) ||
                           EQUAL(szVarNameX, CF_LONGITUDE_VAR_NAME))))
                    {
                        CPLDebug(
                            "netCDF",
                            "Georeferencing ignored due to non-specific "
                            "enough X axis name. "
                            "Set GDAL_NETCDF_IGNORE_XY_AXIS_NAME_CHECKS=YES "
                            "as configuration option to bypass this check");
                        nVarDimXID = -1;
                    }
                }
            }
        }

        if (nVarDimYID >= 0)
        {
            int ndims = -1;
            nc_inq_varndims(nGroupId, nVarDimYID, &ndims);
            if (ndims == 0 || ndims > 2)
                nVarDimYID = -1;
            else if (!bIgnoreXYAxisNameChecks)
            {
                if (!NCDFIsVarLatitude(nGroupId, nVarDimYID, nullptr) &&
                    !NCDFIsVarProjectionY(nGroupId, nVarDimYID, nullptr) &&
                    // In case of inversion of X/Y
                    !NCDFIsVarLongitude(nGroupId, nVarDimYID, nullptr) &&
                    !NCDFIsVarProjectionX(nGroupId, nVarDimYID, nullptr))
                {
                    char szVarNameY[NC_MAX_NAME + 1];
                    CPL_IGNORE_RET_VAL(
                        nc_inq_varname(nGroupId, nVarDimYID, szVarNameY));
                    if (!(ndims == 1 &&
                          (EQUAL(szVarNameY, CF_LATITUDE_STD_NAME) ||
                           EQUAL(szVarNameY, CF_LATITUDE_VAR_NAME))))
                    {
                        CPLDebug(
                            "netCDF",
                            "Georeferencing ignored due to non-specific "
                            "enough Y axis name. "
                            "Set GDAL_NETCDF_IGNORE_XY_AXIS_NAME_CHECKS=YES "
                            "as configuration option to bypass this check");
                        nVarDimYID = -1;
                    }
                }
            }
        }

        if ((nVarDimXID >= 0 && xdim == 1) || (nVarDimXID >= 0 && ydim == 1))
        {
            CPLError(CE_Warning, CPLE_AppDefined,
                     "1-pixel width/height files not supported, "
                     "xdim: %ld ydim: %ld",
                     static_cast<long>(xdim), static_cast<long>(ydim));
            nVarDimXID = -1;
            nVarDimYID = -1;
        }
    }

    // Set Projection from CF.
    if ((bGotGeogCS || bGotCfSRS))
    {
        if ((nVarDimXID != -1) && (nVarDimYID != -1) && xdim > 0 && ydim > 0)
        {
            // Set SRS Units.

            // Check units for x and y.
            if (oSRS.IsProjected())
            {
                const char *pszUnitsX =
                    FetchAttr(nGroupDimXID, nVarDimXID, "units");
                const char *pszUnitsY =
                    FetchAttr(nGroupDimYID, nVarDimYID, "units");

                const char *pszUnits = nullptr;

                // TODO: What to do if units are not equal in X and Y.
                if ((pszUnitsX != nullptr) && (pszUnitsY != nullptr) &&
                    EQUAL(pszUnitsX, pszUnitsY))
                    pszUnits = pszUnitsX;

                // Add units to PROJCS.
                if (pszUnits != nullptr && !EQUAL(pszUnits, ""))
                {
                    CPLDebug("GDAL_netCDF", "units=%s", pszUnits);
                    if (EQUAL(pszUnits, "m"))
                    {
                        oSRS.SetLinearUnits("metre", 1.0);
                        oSRS.SetAuthority("PROJCS|UNIT", "EPSG", 9001);
                    }
                    else if (EQUAL(pszUnits, "km"))
                    {
                        oSRS.SetLinearUnits("kilometre", 1000.0);
                        oSRS.SetAuthority("PROJCS|UNIT", "EPSG", 9036);
                    }
                    else if (EQUAL(pszUnits, "US_survey_foot") ||
                             EQUAL(pszUnits, "US_survey_feet"))
                    {
                        oSRS.SetLinearUnits("US survey foot",
                                            CPLAtof(SRS_UL_US_FOOT_CONV));
                        oSRS.SetAuthority("PROJCS|UNIT", "EPSG", 9003);
                    }
                    // TODO: Check for other values.
                    // else
                    //     oSRS.SetLinearUnits(pszUnits, 1.0);
                }
            }
            else if (oSRS.IsGeographic() && !bRotatedPole)
            {
                oSRS.SetAngularUnits(CF_UNITS_D, CPLAtof(SRS_UA_DEGREE_CONV));
                oSRS.SetAuthority("GEOGCS|UNIT", "EPSG", 9122);
            }
        }

        // Set projection.
        char *pszTempProjection = nullptr;
        oSRS.exportToWkt(&pszTempProjection);
        if (pszTempProjection)
        {
            CPLDebug("GDAL_netCDF", "setting WKT from CF");
            if (returnProjStr != nullptr)
            {
                (*returnProjStr) = std::string(pszTempProjection);
            }
            else
            {
                m_bAddedProjectionVarsDefs = true;
                m_bAddedProjectionVarsData = true;
                SetSpatialRefNoUpdate(&oSRS);
            }
        }
        CPLFree(pszTempProjection);
    }

    if (!bReadSRSOnly && (nVarDimXID != -1) && (nVarDimYID != -1) && xdim > 0 &&
        ydim > 0)
    {
        double *pdfXCoord =
            static_cast<double *>(CPLCalloc(xdim, sizeof(double)));
        double *pdfYCoord =
            static_cast<double *>(CPLCalloc(ydim, sizeof(double)));

        size_t start[2] = {0, 0};
        size_t edge[2] = {xdim, 0};
        int status = nc_get_vara_double(nGroupDimXID, nVarDimXID, start, edge,
                                        pdfXCoord);
        NCDF_ERR(status);

        edge[0] = ydim;
        status = nc_get_vara_double(nGroupDimYID, nVarDimYID, start, edge,
                                    pdfYCoord);
        NCDF_ERR(status);

        nc_type nc_var_dimx_datatype = NC_NAT;
        status =
            nc_inq_vartype(nGroupDimXID, nVarDimXID, &nc_var_dimx_datatype);
        NCDF_ERR(status);

        nc_type nc_var_dimy_datatype = NC_NAT;
        status =
            nc_inq_vartype(nGroupDimYID, nVarDimYID, &nc_var_dimy_datatype);
        NCDF_ERR(status);

        if (!poDS->bSwitchedXY)
        {
            // Convert ]180,540] longitude values to ]-180,0].
            if (NCDFIsVarLongitude(nGroupDimXID, nVarDimXID, nullptr) &&
                CPLTestBool(
                    CPLGetConfigOption("GDAL_NETCDF_CENTERLONG_180", "YES")))
            {
                // If minimum longitude is > 180, subtract 360 from all.
                // Add a check on the maximum X value too, since
                // NCDFIsVarLongitude() is not very specific by default (see
                // https://github.com/OSGeo/gdal/issues/1440)
                if (std::min(pdfXCoord[0], pdfXCoord[xdim - 1]) > 180.0 &&
                    std::max(pdfXCoord[0], pdfXCoord[xdim - 1]) <= 540)
                {
                    CPLDebug(
                        "GDAL_netCDF",
                        "Offsetting longitudes from ]180,540] to ]-180,180]. "
                        "Can be disabled with GDAL_NETCDF_CENTERLONG_180=NO");
                    for (size_t i = 0; i < xdim; i++)
                        pdfXCoord[i] -= 360;
                }
            }
        }

        // Is pixel spacing uniform across the map?

        // Check Longitude.

        bool bLonSpacingOK = false;
        if (xdim == 2)
        {
            bLonSpacingOK = true;
        }
        else
        {
            bool bWestIsLeft = (pdfXCoord[0] < pdfXCoord[xdim - 1]);

            // fix longitudes if longitudes should increase from
            // west to east, but west > east
            if (NCDFIsVarLongitude(nGroupDimXID, nVarDimXID, nullptr) &&
                !bWestIsLeft)
            {
                size_t ndecreases = 0;

                // there is lon wrap if longitudes increase
                // with one single decrease
                for (size_t i = 1; i < xdim; i++)
                {
                    if (pdfXCoord[i] < pdfXCoord[i - 1])
                        ndecreases++;
                }

                if (ndecreases == 1)
                {
                    CPLDebug("GDAL_netCDF", "longitude wrap detected");
                    for (size_t i = 0; i < xdim; i++)
                    {
                        if (pdfXCoord[i] > pdfXCoord[xdim - 1])
                            pdfXCoord[i] -= 360;
                    }
                }
            }

            const double dfSpacingBegin = pdfXCoord[1] - pdfXCoord[0];
            const double dfSpacingMiddle =
                pdfXCoord[xdim / 2 + 1] - pdfXCoord[xdim / 2];
            const double dfSpacingLast =
                pdfXCoord[xdim - 1] - pdfXCoord[xdim - 2];

            CPLDebug("GDAL_netCDF",
                     "xdim: %ld dfSpacingBegin: %f dfSpacingMiddle: %f "
                     "dfSpacingLast: %f",
                     static_cast<long>(xdim), dfSpacingBegin, dfSpacingMiddle,
                     dfSpacingLast);
#ifdef NCDF_DEBUG
            CPLDebug("GDAL_netCDF", "xcoords: %f %f %f %f %f %f", pdfXCoord[0],
                     pdfXCoord[1], pdfXCoord[xdim / 2],
                     pdfXCoord[(xdim / 2) + 1], pdfXCoord[xdim - 2],
                     pdfXCoord[xdim - 1]);
#endif

            // ftp://ftp.cdc.noaa.gov/Datasets/NARR/Dailies/monolevel/vwnd.10m.2015.nc
            // requires a 0.02% tolerance, so let's settle for 0.05%

            // For float variables, increase to 0.2% (as seen in
            // https://github.com/OSGeo/gdal/issues/3663)
            const double dfEpsRel =
                nc_var_dimx_datatype == NC_FLOAT ? 0.002 : 0.0005;

            const double dfEps =
                dfEpsRel *
                std::max(fabs(dfSpacingBegin),
                         std::max(fabs(dfSpacingMiddle), fabs(dfSpacingLast)));
            if (IsDifferenceBelow(dfSpacingBegin, dfSpacingLast, dfEps) &&
                IsDifferenceBelow(dfSpacingBegin, dfSpacingMiddle, dfEps) &&
                IsDifferenceBelow(dfSpacingMiddle, dfSpacingLast, dfEps))
            {
                bLonSpacingOK = true;
            }
            else if (CPLTestBool(CPLGetConfigOption(
                         "GDAL_NETCDF_IGNORE_EQUALLY_SPACED_XY_CHECK", "NO")))
            {
                bLonSpacingOK = true;
                CPLDebug(
                    "GDAL_netCDF",
                    "Longitude/X is not equally spaced, but will be considered "
                    "as such because of "
                    "GDAL_NETCDF_IGNORE_EQUALLY_SPACED_XY_CHECK");
            }
        }

        if (bLonSpacingOK == false)
        {
            CPLDebug(
                "GDAL_netCDF", "%s",
                "Longitude/X is not equally spaced (with a 0.05% tolerance). "
                "You may set the "
                "GDAL_NETCDF_IGNORE_EQUALLY_SPACED_XY_CHECK configuration "
                "option to YES to ignore this check");
        }

        // Check Latitude.
        bool bLatSpacingOK = false;

        if (ydim == 2)
        {
            bLatSpacingOK = true;
        }
        else
        {
            const double dfSpacingBegin = pdfYCoord[1] - pdfYCoord[0];
            const double dfSpacingMiddle =
                pdfYCoord[ydim / 2 + 1] - pdfYCoord[ydim / 2];

            const double dfSpacingLast =
                pdfYCoord[ydim - 1] - pdfYCoord[ydim - 2];

            CPLDebug("GDAL_netCDF",
                     "ydim: %ld dfSpacingBegin: %f dfSpacingMiddle: %f "
                     "dfSpacingLast: %f",
                     (long)ydim, dfSpacingBegin, dfSpacingMiddle,
                     dfSpacingLast);
#ifdef NCDF_DEBUG
            CPLDebug("GDAL_netCDF", "ycoords: %f %f %f %f %f %f", pdfYCoord[0],
                     pdfYCoord[1], pdfYCoord[ydim / 2],
                     pdfYCoord[(ydim / 2) + 1], pdfYCoord[ydim - 2],
                     pdfYCoord[ydim - 1]);
#endif

            const double dfEpsRel =
                nc_var_dimy_datatype == NC_FLOAT ? 0.002 : 0.0005;

            const double dfEps =
                dfEpsRel *
                std::max(fabs(dfSpacingBegin),
                         std::max(fabs(dfSpacingMiddle), fabs(dfSpacingLast)));
            if (IsDifferenceBelow(dfSpacingBegin, dfSpacingLast, dfEps) &&
                IsDifferenceBelow(dfSpacingBegin, dfSpacingMiddle, dfEps) &&
                IsDifferenceBelow(dfSpacingMiddle, dfSpacingLast, dfEps))
            {
                bLatSpacingOK = true;
            }
            else if (CPLTestBool(CPLGetConfigOption(
                         "GDAL_NETCDF_IGNORE_EQUALLY_SPACED_XY_CHECK", "NO")))
            {
                bLatSpacingOK = true;
                CPLDebug(
                    "GDAL_netCDF",
                    "Latitude/Y is not equally spaced, but will be considered "
                    "as such because of "
                    "GDAL_NETCDF_IGNORE_EQUALLY_SPACED_XY_CHECK");
            }
            else if (!oSRS.IsProjected() &&
                     fabs(dfSpacingBegin - dfSpacingLast) <= 0.1 &&
                     fabs(dfSpacingBegin - dfSpacingMiddle) <= 0.1 &&
                     fabs(dfSpacingMiddle - dfSpacingLast) <= 0.1)
            {
                bLatSpacingOK = true;
                CPLError(CE_Warning, CPLE_AppDefined,
                         "Latitude grid not spaced evenly.  "
                         "Setting projection for grid spacing is "
                         "within 0.1 degrees threshold.");

                CPLDebug("GDAL_netCDF",
                         "Latitude grid not spaced evenly, but within 0.1 "
                         "degree threshold (probably a Gaussian grid).  "
                         "Saving original latitude values in Y_VALUES "
                         "geolocation metadata");
                Set1DGeolocation(nGroupDimYID, nVarDimYID, "Y");
            }

            if (bLatSpacingOK == false)
            {
                CPLDebug(
                    "GDAL_netCDF", "%s",
                    "Latitude/Y is not equally spaced (with a 0.05% "
                    "tolerance). "
                    "You may set the "
                    "GDAL_NETCDF_IGNORE_EQUALLY_SPACED_XY_CHECK configuration "
                    "option to YES to ignore this check");
            }
        }

        if (bLonSpacingOK && bLatSpacingOK)
        {
            // We have gridded data so we can set the Georeferencing info.

            // Enable GeoTransform.

            // In the following "actual_range" and "node_offset"
            // are attributes used by netCDF files created by GMT.
            // If we find them we know how to proceed. Else, use
            // the original algorithm.
            bGotCfGT = true;

            int node_offset = 0;
            NCDFResolveAttInt(nGroupId, NC_GLOBAL, "node_offset", &node_offset);

            double adfActualRange[2] = {0.0, 0.0};
            double xMinMax[2] = {0.0, 0.0};
            double yMinMax[2] = {0.0, 0.0};

            if (!nc_get_att_double(nGroupDimXID, nVarDimXID, "actual_range",
                                   adfActualRange))
            {
                xMinMax[0] = adfActualRange[0];
                xMinMax[1] = adfActualRange[1];

                // Present xMinMax[] in the same order as padfXCoord
                if ((xMinMax[0] - xMinMax[1]) *
                        (pdfXCoord[0] - pdfXCoord[xdim - 1]) <
                    0)
                {
                    std::swap(xMinMax[0], xMinMax[1]);
                }
            }
            else
            {
                xMinMax[0] = pdfXCoord[0];
                xMinMax[1] = pdfXCoord[xdim - 1];
                node_offset = 0;
            }

            if (!nc_get_att_double(nGroupDimYID, nVarDimYID, "actual_range",
                                   adfActualRange))
            {
                yMinMax[0] = adfActualRange[0];
                yMinMax[1] = adfActualRange[1];

                // Present yMinMax[] in the same order as pdfYCoord
                if ((yMinMax[0] - yMinMax[1]) *
                        (pdfYCoord[0] - pdfYCoord[ydim - 1]) <
                    0)
                {
                    std::swap(yMinMax[0], yMinMax[1]);
                }
            }
            else
            {
                yMinMax[0] = pdfYCoord[0];
                yMinMax[1] = pdfYCoord[ydim - 1];
                node_offset = 0;
            }

            double dfCoordOffset = 0.0;
            double dfCoordScale = 1.0;
            if (!nc_get_att_double(nGroupId, nVarDimXID, CF_ADD_OFFSET,
                                   &dfCoordOffset) &&
                !nc_get_att_double(nGroupId, nVarDimXID, CF_SCALE_FACTOR,
                                   &dfCoordScale))
            {
                xMinMax[0] = dfCoordOffset + xMinMax[0] * dfCoordScale;
                xMinMax[1] = dfCoordOffset + xMinMax[1] * dfCoordScale;
            }

            if (!nc_get_att_double(nGroupId, nVarDimYID, CF_ADD_OFFSET,
                                   &dfCoordOffset) &&
                !nc_get_att_double(nGroupId, nVarDimYID, CF_SCALE_FACTOR,
                                   &dfCoordScale))
            {
                yMinMax[0] = dfCoordOffset + yMinMax[0] * dfCoordScale;
                yMinMax[1] = dfCoordOffset + yMinMax[1] * dfCoordScale;
            }

            // Check for reverse order of y-coordinate.
            if (!bSwitchedXY)
            {
                poDS->bBottomUp = (yMinMax[0] <= yMinMax[1]);
                CPLDebug("GDAL_netCDF", "set bBottomUp = %d from Y axis",
                         static_cast<int>(poDS->bBottomUp));
                if (!poDS->bBottomUp)
                {
                    std::swap(yMinMax[0], yMinMax[1]);
                }
            }

            // Geostationary satellites can specify units in (micro)radians
            // So we check if they do, and if so convert to linear units
            // (meters)
            const char *pszProjName = oSRS.GetAttrValue("PROJECTION");
            if (pszProjName != nullptr)
            {
                if (EQUAL(pszProjName, SRS_PT_GEOSTATIONARY_SATELLITE))
                {
                    double satelliteHeight =
                        oSRS.GetProjParm(SRS_PP_SATELLITE_HEIGHT, 1.0);
                    size_t nAttlen = 0;
                    char szUnits[NC_MAX_NAME + 1];
                    szUnits[0] = '\0';
                    nc_type nAttype = NC_NAT;
                    nc_inq_att(nGroupId, nVarDimXID, "units", &nAttype,
                               &nAttlen);
                    if (nAttlen < sizeof(szUnits) &&
                        nc_get_att_text(nGroupId, nVarDimXID, "units",
                                        szUnits) == NC_NOERR)
                    {
                        szUnits[nAttlen] = '\0';
                        if (EQUAL(szUnits, "microradian"))
                        {
                            xMinMax[0] =
                                xMinMax[0] * satelliteHeight * 0.000001;
                            xMinMax[1] =
                                xMinMax[1] * satelliteHeight * 0.000001;
                        }
                        else if (EQUAL(szUnits, "rad") ||
                                 EQUAL(szUnits, "radian"))
                        {
                            xMinMax[0] = xMinMax[0] * satelliteHeight;
                            xMinMax[1] = xMinMax[1] * satelliteHeight;
                        }
                    }
                    szUnits[0] = '\0';
                    nc_inq_att(nGroupId, nVarDimYID, "units", &nAttype,
                               &nAttlen);
                    if (nAttlen < sizeof(szUnits) &&
                        nc_get_att_text(nGroupId, nVarDimYID, "units",
                                        szUnits) == NC_NOERR)
                    {
                        szUnits[nAttlen] = '\0';
                        if (EQUAL(szUnits, "microradian"))
                        {
                            yMinMax[0] =
                                yMinMax[0] * satelliteHeight * 0.000001;
                            yMinMax[1] =
                                yMinMax[1] * satelliteHeight * 0.000001;
                        }
                        else if (EQUAL(szUnits, "rad") ||
                                 EQUAL(szUnits, "radian"))
                        {
                            yMinMax[0] = yMinMax[0] * satelliteHeight;
                            yMinMax[1] = yMinMax[1] * satelliteHeight;
                        }
                    }
                }
            }

            adfTempGeoTransform[0] = xMinMax[0];
            adfTempGeoTransform[1] = (xMinMax[1] - xMinMax[0]) /
                                     (poDS->nRasterXSize + (node_offset - 1));
            adfTempGeoTransform[2] = 0;
            if (bSwitchedXY)
            {
                adfTempGeoTransform[3] = yMinMax[0];
                adfTempGeoTransform[4] = 0;
                adfTempGeoTransform[5] =
                    (yMinMax[1] - yMinMax[0]) /
                    (poDS->nRasterYSize + (node_offset - 1));
            }
            else
            {
                adfTempGeoTransform[3] = yMinMax[1];
                adfTempGeoTransform[4] = 0;
                adfTempGeoTransform[5] =
                    (yMinMax[0] - yMinMax[1]) /
                    (poDS->nRasterYSize + (node_offset - 1));
            }

            // Compute the center of the pixel.
            if (!node_offset)
            {
                // Otherwise its already the pixel center.
                adfTempGeoTransform[0] -= (adfTempGeoTransform[1] / 2);
                adfTempGeoTransform[3] -= (adfTempGeoTransform[5] / 2);
            }
        }

        CPLFree(pdfXCoord);
        CPLFree(pdfYCoord);
    }  // end if(has dims)

    // Process custom GeoTransform GDAL value.
    if (!EQUAL(pszGridMappingValue, "") && !bGotCfGT)
    {
        // TODO: Read the GT values and detect for conflict with CF.
        // This could resolve the GT precision loss issue.

        if (pszGeoTransform != nullptr)
        {
            char **papszGeoTransform =
                CSLTokenizeString2(pszGeoTransform, " ", CSLT_HONOURSTRINGS);
            if (CSLCount(papszGeoTransform) == 6)
            {
                bGotGdalGT = true;
                for (int i = 0; i < 6; i++)
                    adfTempGeoTransform[i] = CPLAtof(papszGeoTransform[i]);
            }
            CSLDestroy(papszGeoTransform);
        }
        else
        {
            // Look for corner array values.
            // CPLDebug("GDAL_netCDF",
            //           "looking for geotransform corners");
            bool bGotNN = false;
            double dfNN = FetchCopyParam(pszGridMappingValue,
                                         "Northernmost_Northing", 0, &bGotNN);

            bool bGotSN = false;
            double dfSN = FetchCopyParam(pszGridMappingValue,
                                         "Southernmost_Northing", 0, &bGotSN);

            bool bGotEE = false;
            double dfEE = FetchCopyParam(pszGridMappingValue,
                                         "Easternmost_Easting", 0, &bGotEE);

            bool bGotWE = false;
            double dfWE = FetchCopyParam(pszGridMappingValue,
                                         "Westernmost_Easting", 0, &bGotWE);

            // Only set the GeoTransform if we got all the values.
            if (bGotNN && bGotSN && bGotEE && bGotWE)
            {
                bGotGdalGT = true;

                adfTempGeoTransform[0] = dfWE;
                adfTempGeoTransform[1] =
                    (dfEE - dfWE) / (poDS->GetRasterXSize() - 1);
                adfTempGeoTransform[2] = 0.0;
                adfTempGeoTransform[3] = dfNN;
                adfTempGeoTransform[4] = 0.0;
                adfTempGeoTransform[5] =
                    (dfSN - dfNN) / (poDS->GetRasterYSize() - 1);
                // Compute the center of the pixel.
                adfTempGeoTransform[0] = dfWE - (adfTempGeoTransform[1] / 2);
                adfTempGeoTransform[3] = dfNN - (adfTempGeoTransform[5] / 2);
            }
        }  // (pszGeoTransform != NULL)

        if (bGotGdalSRS && !bGotGdalGT)
            CPLDebug("GDAL_netCDF", "Got SRS but no geotransform from GDAL!");
    }

    if (!pszWKT && !bGotCfSRS)
    {
        // Some netCDF files have a srid attribute (#6613) like
        // urn:ogc:def:crs:EPSG::6931
        const char *pszSRID = FetchAttr(pszGridMappingValue, "srid");
        if (pszSRID != nullptr)
        {
            oSRS.Clear();
            if (oSRS.SetFromUserInput(
                    pszSRID,
                    OGRSpatialReference::
                        SET_FROM_USER_INPUT_LIMITATIONS_get()) == OGRERR_NONE)
            {
                char *pszWKTExport = nullptr;
                CPLDebug("GDAL_netCDF", "Got SRS from %s", pszSRID);
                oSRS.exportToWkt(&pszWKTExport);
                if (returnProjStr != nullptr)
                {
                    (*returnProjStr) = std::string(pszWKTExport);
                }
                else
                {
                    m_bAddedProjectionVarsDefs = true;
                    m_bAddedProjectionVarsData = true;
                    SetSpatialRefNoUpdate(&oSRS);
                }
                CPLFree(pszWKTExport);
            }
        }
    }

    CPLFree(pszGridMappingValue);

    if (bReadSRSOnly)
        return;

    // Process geolocation arrays from CF "coordinates" attribute.
    std::string osGeolocXName, osGeolocYName;
    if (ProcessCFGeolocation(nGroupId, nVarId, osGeolocXName, osGeolocYName))
    {
        bool bCanCancelGT = true;
        if ((nVarDimXID != -1) && (nVarDimYID != -1))
        {
            char szVarNameX[NC_MAX_NAME + 1];
            CPL_IGNORE_RET_VAL(
                nc_inq_varname(nGroupId, nVarDimXID, szVarNameX));
            char szVarNameY[NC_MAX_NAME + 1];
            CPL_IGNORE_RET_VAL(
                nc_inq_varname(nGroupId, nVarDimYID, szVarNameY));
            bCanCancelGT =
                !(osGeolocXName == szVarNameX && osGeolocYName == szVarNameY);
        }
        if (bCanCancelGT && !m_oSRS.IsGeographic() && !m_oSRS.IsProjected() &&
            !bSwitchedXY)
        {
            bGotCfGT = false;
        }
    }

    // Set GeoTransform if we got a complete one - after projection has been set
    if (bGotCfGT || bGotGdalGT)
    {
        m_bAddedProjectionVarsDefs = true;
        m_bAddedProjectionVarsData = true;
        SetGeoTransformNoUpdate(adfTempGeoTransform);
    }

    // Debugging reports.
    CPLDebug("GDAL_netCDF",
             "bGotGeogCS=%d bGotCfSRS=%d bGotCfGT=%d bGotCfWktSRS=%d "
             "bGotGdalSRS=%d bGotGdalGT=%d",
             static_cast<int>(bGotGeogCS), static_cast<int>(bGotCfSRS),
             static_cast<int>(bGotCfGT), static_cast<int>(bGotCfWktSRS),
             static_cast<int>(bGotGdalSRS), static_cast<int>(bGotGdalGT));

    if (!bGotCfGT && !bGotGdalGT)
        CPLDebug("GDAL_netCDF", "did not get geotransform from CF nor GDAL!");

    if (!bGotGeogCS && !bGotCfSRS && !bGotGdalSRS && !bGotCfGT && !bGotCfWktSRS)
        CPLDebug("GDAL_netCDF", "did not get projection from CF nor GDAL!");

        // Search for Well-known GeogCS if got only CF WKT
        // Disabled for now, as a named datum also include control points
        // (see mailing list and bug#4281
        // For example, WGS84 vs. GDA94 (EPSG:3577) - AEA in netcdf_cf.py

        // Disabled for now, but could be set in a config option.
#if 0
    bool bLookForWellKnownGCS = false;  // This could be a Config Option.

    if( bLookForWellKnownGCS && bGotCfSRS && !bGotGdalSRS )
    {
        // ET - Could use a more exhaustive method by scanning all EPSG codes in
        // data/gcs.csv as proposed by Even in the gdal-dev mailing list "help
        // for comparing two WKT".
        // This code could be contributed to a new function.
        // OGRSpatialReference * OGRSpatialReference::FindMatchingGeogCS(
        //     const OGRSpatialReference *poOther) */
        CPLDebug("GDAL_netCDF", "Searching for Well-known GeogCS");
        const char *pszWKGCSList[] = { "WGS84", "WGS72", "NAD27", "NAD83" };
        char *pszWKGCS = NULL;
        oSRS.exportToPrettyWkt(&pszWKGCS);
        for( size_t i = 0; i < sizeof(pszWKGCSList) / 8; i++ )
        {
            pszWKGCS = CPLStrdup(pszWKGCSList[i]);
            OGRSpatialReference oSRSTmp;
            oSRSTmp.SetWellKnownGeogCS(pszWKGCSList[i]);
            // Set datum to unknown, bug #4281.
            if( oSRSTmp.GetAttrNode("DATUM" ) )
                oSRSTmp.GetAttrNode("DATUM")->GetChild(0)->SetValue("unknown");
            // Could use OGRSpatialReference::StripCTParms(), but let's keep
            // TOWGS84.
            oSRSTmp.GetRoot()->StripNodes("AXIS");
            oSRSTmp.GetRoot()->StripNodes("AUTHORITY");
            oSRSTmp.GetRoot()->StripNodes("EXTENSION");

            oSRSTmp.exportToPrettyWkt(&pszWKGCS);
            if( oSRS.IsSameGeogCS(&oSRSTmp) )
            {
                oSRS.SetWellKnownGeogCS(pszWKGCSList[i]);
                oSRS.exportToWkt(&(pszTempProjection));
                SetProjection(pszTempProjection);
                CPLFree(pszTempProjection);
            }
        }
    }
#endif
}

void netCDFDataset::SetProjectionFromVar(int nGroupId, int nVarId,
                                         bool bReadSRSOnly)
{
    SetProjectionFromVar(nGroupId, nVarId, bReadSRSOnly, nullptr, nullptr,
                         nullptr);
}

int netCDFDataset::ProcessCFGeolocation(int nGroupId, int nVarId,
                                        std::string &osGeolocXNameOut,
                                        std::string &osGeolocYNameOut)
{
    bool bAddGeoloc = false;
    char *pszTemp = nullptr;

    if (NCDFGetAttr(nGroupId, nVarId, "coordinates", &pszTemp) == CE_None)
    {
        // Get X and Y geolocation names from coordinates attribute.
        char **papszTokens = CSLTokenizeString2(pszTemp, " ", 0);
        if (CSLCount(papszTokens) >= 2)
        {
            char szGeolocXName[NC_MAX_NAME + 1];
            char szGeolocYName[NC_MAX_NAME + 1];
            szGeolocXName[0] = '\0';
            szGeolocYName[0] = '\0';

            // Test that each variable is longitude/latitude.
            for (int i = 0; i < CSLCount(papszTokens); i++)
            {
                if (NCDFIsVarLongitude(nGroupId, -1, papszTokens[i]))
                {
                    int nOtherGroupId = -1;
                    int nOtherVarId = -1;
                    // Check that the variable actually exists
                    // Needed on Sentinel-3 products
                    if (NCDFResolveVar(nGroupId, papszTokens[i], &nOtherGroupId,
                                       &nOtherVarId) == CE_None)
                    {
                        snprintf(szGeolocXName, sizeof(szGeolocXName), "%s",
                                 papszTokens[i]);
                    }
                }
                else if (NCDFIsVarLatitude(nGroupId, -1, papszTokens[i]))
                {
                    int nOtherGroupId = -1;
                    int nOtherVarId = -1;
                    // Check that the variable actually exists
                    // Needed on Sentinel-3 products
                    if (NCDFResolveVar(nGroupId, papszTokens[i], &nOtherGroupId,
                                       &nOtherVarId) == CE_None)
                    {
                        snprintf(szGeolocYName, sizeof(szGeolocYName), "%s",
                                 papszTokens[i]);
                    }
                }
            }
            // Add GEOLOCATION metadata.
            if (!EQUAL(szGeolocXName, "") && !EQUAL(szGeolocYName, ""))
            {
                osGeolocXNameOut = szGeolocXName;
                osGeolocYNameOut = szGeolocYName;

                char *pszGeolocXFullName = nullptr;
                char *pszGeolocYFullName = nullptr;
                if (NCDFResolveVarFullName(nGroupId, szGeolocXName,
                                           &pszGeolocXFullName) == CE_None &&
                    NCDFResolveVarFullName(nGroupId, szGeolocYName,
                                           &pszGeolocYFullName) == CE_None)
                {
                    if (bSwitchedXY)
                    {
                        std::swap(pszGeolocXFullName, pszGeolocYFullName);
                        GDALPamDataset::SetMetadataItem("SWAP_XY", "YES",
                                                        "GEOLOCATION");
                    }

                    bAddGeoloc = true;
                    CPLDebug("GDAL_netCDF",
                             "using variables %s and %s for GEOLOCATION",
                             pszGeolocXFullName, pszGeolocYFullName);

                    GDALPamDataset::SetMetadataItem(
                        "SRS", SRS_WKT_WGS84_LAT_LONG, "GEOLOCATION");

                    CPLString osTMP;
                    osTMP.Printf("NETCDF:\"%s\":%s", osFilename.c_str(),
                                 pszGeolocXFullName);

                    GDALPamDataset::SetMetadataItem("X_DATASET", osTMP,
                                                    "GEOLOCATION");
                    GDALPamDataset::SetMetadataItem("X_BAND", "1",
                                                    "GEOLOCATION");
                    osTMP.Printf("NETCDF:\"%s\":%s", osFilename.c_str(),
                                 pszGeolocYFullName);

                    GDALPamDataset::SetMetadataItem("Y_DATASET", osTMP,
                                                    "GEOLOCATION");
                    GDALPamDataset::SetMetadataItem("Y_BAND", "1",
                                                    "GEOLOCATION");

                    GDALPamDataset::SetMetadataItem("PIXEL_OFFSET", "0",
                                                    "GEOLOCATION");
                    GDALPamDataset::SetMetadataItem("PIXEL_STEP", "1",
                                                    "GEOLOCATION");

                    GDALPamDataset::SetMetadataItem("LINE_OFFSET", "0",
                                                    "GEOLOCATION");
                    GDALPamDataset::SetMetadataItem("LINE_STEP", "1",
                                                    "GEOLOCATION");

                    GDALPamDataset::SetMetadataItem("GEOREFERENCING_CONVENTION",
                                                    "PIXEL_CENTER",
                                                    "GEOLOCATION");
                }
                else
                {
                    CPLDebug("GDAL_netCDF",
                             "cannot resolve location of "
                             "lat/lon variables specified by the coordinates "
                             "attribute [%s]",
                             pszTemp);
                }
                CPLFree(pszGeolocXFullName);
                CPLFree(pszGeolocYFullName);
            }
            else
            {
                CPLDebug("GDAL_netCDF",
                         "coordinates attribute [%s] is unsupported", pszTemp);
            }
        }
        else
        {
            CPLDebug("GDAL_netCDF",
                     "coordinates attribute [%s] with %d element(s) is "
                     "unsupported",
                     pszTemp, CSLCount(papszTokens));
        }
        if (papszTokens)
            CSLDestroy(papszTokens);
    }

    CPLFree(pszTemp);

    return bAddGeoloc;
}

CPLErr netCDFDataset::Set1DGeolocation(int nGroupId, int nVarId,
                                       const char *szDimName)
{
    // Get values.
    char *pszVarValues = nullptr;
    CPLErr eErr = NCDFGet1DVar(nGroupId, nVarId, &pszVarValues);
    if (eErr != CE_None)
        return eErr;

    // Write metadata.
    char szTemp[NC_MAX_NAME + 1 + 32] = {};
    snprintf(szTemp, sizeof(szTemp), "%s_VALUES", szDimName);
    GDALPamDataset::SetMetadataItem(szTemp, pszVarValues, "GEOLOCATION2");

    CPLFree(pszVarValues);

    return CE_None;
}

double *netCDFDataset::Get1DGeolocation(CPL_UNUSED const char *szDimName,
                                        int &nVarLen)
{
    nVarLen = 0;

    // Get Y_VALUES as tokens.
    char **papszValues =
        NCDFTokenizeArray(GetMetadataItem("Y_VALUES", "GEOLOCATION2"));
    if (papszValues == nullptr)
        return nullptr;

    // Initialize and fill array.
    nVarLen = CSLCount(papszValues);
    double *pdfVarValues =
        static_cast<double *>(CPLCalloc(nVarLen, sizeof(double)));

    for (int i = 0, j = 0; i < nVarLen; i++)
    {
        if (!bBottomUp)
            j = nVarLen - 1 - i;
        else
            j = i;  // Invert latitude values.
        char *pszTemp = nullptr;
        pdfVarValues[j] = CPLStrtod(papszValues[i], &pszTemp);
    }
    CSLDestroy(papszValues);

    return pdfVarValues;
}

/************************************************************************/
/*                        SetSpatialRefNoUpdate()                       */
/************************************************************************/

void netCDFDataset::SetSpatialRefNoUpdate(const OGRSpatialReference *poSRS)
{
    m_oSRS.Clear();
    if (poSRS)
        m_oSRS = *poSRS;
    m_bHasProjection = true;
}

/************************************************************************/
/*                          SetSpatialRef()                             */
/************************************************************************/

CPLErr netCDFDataset::SetSpatialRef(const OGRSpatialReference *poSRS)
{
    CPLMutexHolderD(&hNCMutex);

    if (GetAccess() != GA_Update || m_bHasProjection)
    {
        CPLError(CE_Failure, CPLE_AppDefined,
                 "netCDFDataset::_SetProjection() should only be called once "
                 "in update mode!");
        return CE_Failure;
    }

    if (m_bHasGeoTransform)
    {
        SetSpatialRefNoUpdate(poSRS);

        // For NC4/NC4C, writing both projection variables and data,
        // followed by redefining nodata value, cancels the projection
        // info from the Band variable, so for now only write the
        // variable definitions, and write data at the end.
        // See https://trac.osgeo.org/gdal/ticket/7245
        return AddProjectionVars(true, nullptr, nullptr);
    }

    SetSpatialRefNoUpdate(poSRS);

    return CE_None;
}

/************************************************************************/
/*                     SetGeoTransformNoUpdate()                        */
/************************************************************************/

void netCDFDataset::SetGeoTransformNoUpdate(double *padfTransform)
{
    memcpy(m_adfGeoTransform, padfTransform, sizeof(double) * 6);
    m_bHasGeoTransform = true;
}

/************************************************************************/
/*                          SetGeoTransform()                           */
/************************************************************************/

CPLErr netCDFDataset::SetGeoTransform(double *padfTransform)
{
    CPLMutexHolderD(&hNCMutex);

    if (GetAccess() != GA_Update || m_bHasGeoTransform)
    {
        CPLError(CE_Failure, CPLE_AppDefined,
                 "netCDFDataset::SetGeoTransform() should only be called once "
                 "in update mode!");
        return CE_Failure;
    }

    CPLDebug("GDAL_netCDF", "SetGeoTransform(%f,%f,%f,%f,%f,%f)",
             padfTransform[0], padfTransform[1], padfTransform[2],
             padfTransform[3], padfTransform[4], padfTransform[5]);

    if (m_bHasProjection)
    {
        SetGeoTransformNoUpdate(padfTransform);

        // For NC4/NC4C, writing both projection variables and data,
        // followed by redefining nodata value, cancels the projection
        // info from the Band variable, so for now only write the
        // variable definitions, and write data at the end.
        // See https://trac.osgeo.org/gdal/ticket/7245
        return AddProjectionVars(true, nullptr, nullptr);
    }

    SetGeoTransformNoUpdate(padfTransform);
    return CE_None;
}

/************************************************************************/
/*                         NCDFWriteSRSVariable()                       */
/************************************************************************/

int NCDFWriteSRSVariable(int cdfid, const OGRSpatialReference *poSRS,
                         char **ppszCFProjection, bool bWriteGDALTags,
                         const std::string &srsVarName)
{
    char *pszCFProjection = nullptr;
    bool bWriteWkt = true;

    struct Value
    {
        std::string key{};
        std::string valueStr{};
        size_t doubleCount = 0;
        double doubles[2] = {0, 0};
    };

    std::vector<Value> oParams;

    const auto addParamString = [&oParams](const char *key, const char *value)
    {
        Value v;
        v.key = key;
        v.valueStr = value;
        oParams.push_back(v);
    };

    const auto addParamDouble = [&oParams](const char *key, double value)
    {
        Value v;
        v.key = key;
        v.doubleCount = 1;
        v.doubles[0] = value;
        oParams.push_back(v);
    };

    const auto addParam2Double =
        [&oParams](const char *key, double value1, double value2)
    {
        Value v;
        v.key = key;
        v.doubleCount = 2;
        v.doubles[0] = value1;
        v.doubles[1] = value2;
        oParams.push_back(v);
    };

    *ppszCFProjection = nullptr;

    if (poSRS->IsProjected())
    {
        // Write CF-1.5 compliant Projected attributes.

        const OGR_SRSNode *poPROJCS = poSRS->GetAttrNode("PROJCS");
        if (poPROJCS == nullptr)
            return -1;
        const char *pszProjName = poSRS->GetAttrValue("PROJECTION");
        if (pszProjName == nullptr)
            return -1;

        // Basic Projection info (grid_mapping and datum).
        for (int i = 0; poNetcdfSRS_PT[i].WKT_SRS != nullptr; i++)
        {
            if (EQUAL(poNetcdfSRS_PT[i].WKT_SRS, pszProjName))
            {
                CPLDebug("GDAL_netCDF",
                         "GDAL PROJECTION = %s , NCDF PROJECTION = %s",
                         poNetcdfSRS_PT[i].WKT_SRS, poNetcdfSRS_PT[i].CF_SRS);
                pszCFProjection = CPLStrdup(poNetcdfSRS_PT[i].CF_SRS);
                CPLDebug("GDAL_netCDF", "nc_def_var(%d,%s,%d)", cdfid,
                         poNetcdfSRS_PT[i].CF_SRS, NC_CHAR);
                break;
            }
        }
        if (pszCFProjection == nullptr)
            return -1;

        addParamString(CF_GRD_MAPPING_NAME, pszCFProjection);

        // Various projection attributes.
        // PDS: keep in sync with SetProjection function
        auto oOutList = NCDFGetProjAttribs(poPROJCS, pszProjName);

        /* Write all the values that were found */
        double dfStdP[2] = {0, 0};
        bool bFoundStdP1 = false;
        bool bFoundStdP2 = false;
        for (const auto &it : oOutList)
        {
            const char *pszParamVal = it.first.c_str();
            double dfValue = it.second;
            /* Handle the STD_PARALLEL attrib */
            if (EQUAL(pszParamVal, CF_PP_STD_PARALLEL_1))
            {
                bFoundStdP1 = true;
                dfStdP[0] = dfValue;
            }
            else if (EQUAL(pszParamVal, CF_PP_STD_PARALLEL_2))
            {
                bFoundStdP2 = true;
                dfStdP[1] = dfValue;
            }
            else
            {
                addParamDouble(pszParamVal, dfValue);
            }
        }
        /* Now write the STD_PARALLEL attrib */
        if (bFoundStdP1)
        {
            /* one value  */
            if (!bFoundStdP2)
            {
                addParamDouble(CF_PP_STD_PARALLEL, dfStdP[0]);
            }
            else
            {
                // Two values.
                addParam2Double(CF_PP_STD_PARALLEL, dfStdP[0], dfStdP[1]);
            }
        }

        if (EQUAL(pszProjName, SRS_PT_GEOSTATIONARY_SATELLITE))
        {
            const char *pszPredefProj4 = poSRS->GetExtension(
                poSRS->GetRoot()->GetValue(), "PROJ4", nullptr);
            const char *pszSweepAxisAngle = (pszPredefProj4 != nullptr &&
                                             strstr(pszPredefProj4, "+sweep=x"))
                                                ? "x"
                                                : "y";
            addParamString(CF_PP_SWEEP_ANGLE_AXIS, pszSweepAxisAngle);
        }
    }
    else if (poSRS->IsDerivedGeographic())
    {
        const OGR_SRSNode *poConversion =
            poSRS->GetAttrNode("DERIVINGCONVERSION");
        if (poConversion == nullptr)
            return -1;
        const char *pszMethod = poSRS->GetAttrValue("METHOD");
        if (pszMethod == nullptr)
            return -1;

        std::map<std::string, double> oValMap;
        for (int iChild = 0; iChild < poConversion->GetChildCount(); iChild++)
        {
            const OGR_SRSNode *poNode = poConversion->GetChild(iChild);
            if (!EQUAL(poNode->GetValue(), "PARAMETER") ||
                poNode->GetChildCount() <= 2)
                continue;
            const char *pszParamStr = poNode->GetChild(0)->GetValue();
            const char *pszParamVal = poNode->GetChild(1)->GetValue();
            oValMap[pszParamStr] = CPLAtof(pszParamVal);
        }

        if (EQUAL(pszMethod, "PROJ ob_tran o_proj=longlat"))
        {
            // Not enough interoperable to be written as WKT
            bWriteWkt = false;

            const double dfLon0 = oValMap["lon_0"];
            const double dfLonp = oValMap["o_lon_p"];
            const double dfLatp = oValMap["o_lat_p"];

            pszCFProjection = CPLStrdup(ROTATED_POLE_VAR_NAME);
            addParamString(CF_GRD_MAPPING_NAME,
                           CF_PT_ROTATED_LATITUDE_LONGITUDE);
            addParamDouble(CF_PP_GRID_NORTH_POLE_LONGITUDE, dfLon0 - 180);
            addParamDouble(CF_PP_GRID_NORTH_POLE_LATITUDE, dfLatp);
            addParamDouble(CF_PP_NORTH_POLE_GRID_LONGITUDE, dfLonp);
        }
        else if (EQUAL(pszMethod, "Pole rotation (netCDF CF convention)"))
        {
            // Not enough interoperable to be written as WKT
            bWriteWkt = false;

            const double dfGridNorthPoleLat =
                oValMap["Grid north pole latitude (netCDF CF convention)"];
            const double dfGridNorthPoleLong =
                oValMap["Grid north pole longitude (netCDF CF convention)"];
            const double dfNorthPoleGridLong =
                oValMap["North pole grid longitude (netCDF CF convention)"];

            pszCFProjection = CPLStrdup(ROTATED_POLE_VAR_NAME);
            addParamString(CF_GRD_MAPPING_NAME,
                           CF_PT_ROTATED_LATITUDE_LONGITUDE);
            addParamDouble(CF_PP_GRID_NORTH_POLE_LONGITUDE,
                           dfGridNorthPoleLong);
            addParamDouble(CF_PP_GRID_NORTH_POLE_LATITUDE, dfGridNorthPoleLat);
            addParamDouble(CF_PP_NORTH_POLE_GRID_LONGITUDE,
                           dfNorthPoleGridLong);
        }
        else if (EQUAL(pszMethod, "Pole rotation (GRIB convention)"))
        {
            // Not enough interoperable to be written as WKT
            bWriteWkt = false;

            const double dfLatSouthernPole =
                oValMap["Latitude of the southern pole (GRIB convention)"];
            const double dfLonSouthernPole =
                oValMap["Longitude of the southern pole (GRIB convention)"];
            const double dfAxisRotation =
                oValMap["Axis rotation (GRIB convention)"];

            const double dfLon0 = dfLonSouthernPole;
            const double dfLonp = dfAxisRotation == 0 ? 0 : -dfAxisRotation;
            const double dfLatp =
                dfLatSouthernPole == 0 ? 0 : -dfLatSouthernPole;

            pszCFProjection = CPLStrdup(ROTATED_POLE_VAR_NAME);
            addParamString(CF_GRD_MAPPING_NAME,
                           CF_PT_ROTATED_LATITUDE_LONGITUDE);
            addParamDouble(CF_PP_GRID_NORTH_POLE_LONGITUDE, dfLon0 - 180);
            addParamDouble(CF_PP_GRID_NORTH_POLE_LATITUDE, dfLatp);
            addParamDouble(CF_PP_NORTH_POLE_GRID_LONGITUDE, dfLonp);
        }
        else
        {
            CPLError(CE_Failure, CPLE_NotSupported,
                     "Unsupported method for DerivedGeographicCRS: %s",
                     pszMethod);
            return -1;
        }
    }
    else
    {
        // Write CF-1.5 compliant Geographics attributes.
        // Note: WKT information will not be preserved (e.g. WGS84).
        pszCFProjection = CPLStrdup("crs");
        addParamString(CF_GRD_MAPPING_NAME, CF_PT_LATITUDE_LONGITUDE);
    }

    addParamString(CF_LNG_NAME, "CRS definition");

    // Write CF-1.5 compliant common attributes.

    // DATUM information.
    addParamDouble(CF_PP_LONG_PRIME_MERIDIAN, poSRS->GetPrimeMeridian());
    addParamDouble(CF_PP_SEMI_MAJOR_AXIS, poSRS->GetSemiMajor());
    addParamDouble(CF_PP_INVERSE_FLATTENING, poSRS->GetInvFlattening());

    if (bWriteWkt)
    {
        char *pszSpatialRef = nullptr;
        poSRS->exportToWkt(&pszSpatialRef);
        if (pszSpatialRef && pszSpatialRef[0])
        {
            if (bWriteGDALTags)
            {
                // SPATIAL_REF is deprecated. Will be removed in GDAL 4.
                addParamString(NCDF_SPATIAL_REF, pszSpatialRef);
            }
            addParamString(NCDF_CRS_WKT, pszSpatialRef);
        }
        CPLFree(pszSpatialRef);
    }

    int NCDFVarID;
    std::map<std::string, size_t> oMapAttNameToIdx;
    std::string varNameRadix(pszCFProjection);
    int nCounter = 2;
    while (true)
    {
        NCDFVarID = -1;
        nc_inq_varid(cdfid, pszCFProjection, &NCDFVarID);
        if (NCDFVarID < 0)
            break;
        if (oMapAttNameToIdx.empty())
        {
            for (size_t i = 0; i < oParams.size(); ++i)
            {
                oMapAttNameToIdx[oParams[i].key] = i;
            }
        }
        int nbAttr = 0;
        NCDF_ERR(nc_inq_varnatts(cdfid, NCDFVarID, &nbAttr));
        bool bSame = nbAttr == static_cast<int>(oParams.size());
        for (int i = 0; bSame && (i < nbAttr); i++)
        {
            char szAttrName[NC_MAX_NAME + 1];
            szAttrName[0] = 0;
            NCDF_ERR(nc_inq_attname(cdfid, NCDFVarID, i, szAttrName));
            auto oIter = oMapAttNameToIdx.find(szAttrName);
            if (oIter == oMapAttNameToIdx.end())
            {
                bSame = false;
                break;
            }
            const auto &oParam(oParams[oIter->second]);

            nc_type atttype = NC_NAT;
            size_t attlen = 0;
            NCDF_ERR(
                nc_inq_att(cdfid, NCDFVarID, szAttrName, &atttype, &attlen));
            if (atttype != NC_CHAR && atttype != NC_DOUBLE)
            {
                bSame = false;
                break;
            }
            if (atttype == NC_CHAR)
            {
                if (oParam.doubleCount != 0)
                {
                    bSame = false;
                    break;
                }
                std::string val;
                val.resize(attlen);
                nc_get_att_text(cdfid, NCDFVarID, szAttrName, &val[0]);
                if (val != oParam.valueStr)
                {
                    bSame = false;
                    break;
                }
            }
            else
            {
                if (oParam.doubleCount != attlen)
                {
                    bSame = false;
                    break;
                }
                double vals[2];
                nc_get_att_double(cdfid, NCDFVarID, szAttrName, vals);
                if (vals[0] != oParam.doubles[0] ||
                    (attlen == 2 && vals[1] != oParam.doubles[1]))
                {
                    bSame = false;
                    break;
                }
            }
        }
        if (bSame)
        {
            *ppszCFProjection = pszCFProjection;
            return NCDFVarID;
        }
        CPLFree(pszCFProjection);
        pszCFProjection =
            CPLStrdup(CPLSPrintf("%s_%d", varNameRadix.c_str(), nCounter));
        nCounter++;
    }

    *ppszCFProjection = pszCFProjection;

    const char *pszVarName;

    if (srsVarName != "")
    {
        pszVarName = srsVarName.c_str();
    }
    else
    {
        pszVarName = pszCFProjection;
    }

    int status = nc_def_var(cdfid, pszVarName, NC_CHAR, 0, nullptr, &NCDFVarID);
    NCDF_ERR(status);
    for (const auto &it : oParams)
    {
        if (it.doubleCount == 0)
        {
            status = nc_put_att_text(cdfid, NCDFVarID, it.key.c_str(),
                                     it.valueStr.size(), it.valueStr.c_str());
        }
        else
        {
            status = nc_put_att_double(cdfid, NCDFVarID, it.key.c_str(),
                                       NC_DOUBLE, it.doubleCount, it.doubles);
        }
        NCDF_ERR(status);
    }

    return NCDFVarID;
}

/************************************************************************/
/*                   NCDFWriteLonLatVarsAttributes()                    */
/************************************************************************/

void NCDFWriteLonLatVarsAttributes(nccfdriver::netCDFVID &vcdf, int nVarLonID,
                                   int nVarLatID)
{

    try
    {
        vcdf.nc_put_vatt_text(nVarLatID, CF_STD_NAME, CF_LATITUDE_STD_NAME);
        vcdf.nc_put_vatt_text(nVarLatID, CF_LNG_NAME, CF_LATITUDE_LNG_NAME);
        vcdf.nc_put_vatt_text(nVarLatID, CF_UNITS, CF_DEGREES_NORTH);
        vcdf.nc_put_vatt_text(nVarLonID, CF_STD_NAME, CF_LONGITUDE_STD_NAME);
        vcdf.nc_put_vatt_text(nVarLonID, CF_LNG_NAME, CF_LONGITUDE_LNG_NAME);
        vcdf.nc_put_vatt_text(nVarLonID, CF_UNITS, CF_DEGREES_EAST);
    }
    catch (nccfdriver::SG_Exception &e)
    {
        CPLError(CE_Failure, CPLE_FileIO, "%s", e.get_err_msg());
    }
}

/************************************************************************/
/*                   NCDFWriteRLonRLatVarsAttributes()                    */
/************************************************************************/

void NCDFWriteRLonRLatVarsAttributes(nccfdriver::netCDFVID &vcdf,
                                     int nVarRLonID, int nVarRLatID)
{
    try
    {
        vcdf.nc_put_vatt_text(nVarRLatID, CF_STD_NAME, "grid_latitude");
        vcdf.nc_put_vatt_text(nVarRLatID, CF_LNG_NAME,
                              "latitude in rotated pole grid");
        vcdf.nc_put_vatt_text(nVarRLatID, CF_UNITS, "degrees");
        vcdf.nc_put_vatt_text(nVarRLatID, CF_AXIS, "Y");

        vcdf.nc_put_vatt_text(nVarRLonID, CF_STD_NAME, "grid_longitude");
        vcdf.nc_put_vatt_text(nVarRLonID, CF_LNG_NAME,
                              "longitude in rotated pole grid");
        vcdf.nc_put_vatt_text(nVarRLonID, CF_UNITS, "degrees");
        vcdf.nc_put_vatt_text(nVarRLonID, CF_AXIS, "X");
    }
    catch (nccfdriver::SG_Exception &e)
    {
        CPLError(CE_Failure, CPLE_FileIO, "%s", e.get_err_msg());
    }
}

/************************************************************************/
/*                        NCDFGetProjectedCFUnit()                      */
/************************************************************************/

const char *NCDFGetProjectedCFUnit(const OGRSpatialReference *poSRS)
{
    const char *pszUnits = nullptr;
    const char *pszUnitsToWrite = "";

    const double dfUnits = poSRS->GetLinearUnits(&pszUnits);
    if (fabs(dfUnits - 1.0) < 1e-15 || pszUnits == nullptr ||
        EQUAL(pszUnits, "m") || EQUAL(pszUnits, "metre"))
    {
        pszUnitsToWrite = "m";
    }
    else if (fabs(dfUnits - 1000.0) < 1e-15)
    {
        pszUnitsToWrite = "km";
    }
    else if (fabs(dfUnits - CPLAtof(SRS_UL_US_FOOT_CONV)) < 1e-15 ||
             EQUAL(pszUnits, SRS_UL_US_FOOT) ||
             EQUAL(pszUnits, "US survey foot"))
    {
        pszUnitsToWrite = "US_survey_foot";
    }

    return pszUnitsToWrite;
}

/************************************************************************/
/*                     NCDFWriteXYVarsAttributes()                      */
/************************************************************************/

void NCDFWriteXYVarsAttributes(nccfdriver::netCDFVID &vcdf, int nVarXID,
                               int nVarYID, OGRSpatialReference *poSRS)
{
    const char *pszUnitsToWrite = NCDFGetProjectedCFUnit(poSRS);

    try
    {
        vcdf.nc_put_vatt_text(nVarXID, CF_STD_NAME, CF_PROJ_X_COORD);
        vcdf.nc_put_vatt_text(nVarXID, CF_LNG_NAME, CF_PROJ_X_COORD_LONG_NAME);
        vcdf.nc_put_vatt_text(nVarXID, CF_UNITS, pszUnitsToWrite);
        vcdf.nc_put_vatt_text(nVarYID, CF_STD_NAME, CF_PROJ_Y_COORD);
        vcdf.nc_put_vatt_text(nVarYID, CF_LNG_NAME, CF_PROJ_Y_COORD_LONG_NAME);
        vcdf.nc_put_vatt_text(nVarYID, CF_UNITS, pszUnitsToWrite);
    }
    catch (nccfdriver::SG_Exception &e)
    {
        CPLError(CE_Failure, CPLE_FileIO, "%s", e.get_err_msg());
    }
}

/************************************************************************/
/*                          AddProjectionVars()                         */
/************************************************************************/

CPLErr netCDFDataset::AddProjectionVars(bool bDefsOnly,
                                        GDALProgressFunc pfnProgress,
                                        void *pProgressData)
{
    if (nCFVersion >= 1.8)
        return CE_None;  // do nothing

    bool bWriteGridMapping = false;
    bool bWriteLonLat = false;
    bool bHasGeoloc = false;
    bool bWriteGDALTags = false;
    bool bWriteGeoTransform = false;

    // For GEOLOCATION information.
    GDALDatasetH hDS_X = nullptr;
    GDALRasterBandH hBand_X = nullptr;
    GDALDatasetH hDS_Y = nullptr;
    GDALRasterBandH hBand_Y = nullptr;

    OGRSpatialReference oSRS(m_oSRS);
    if (!m_oSRS.IsEmpty())
    {
        if (oSRS.IsProjected())
            bIsProjected = true;
        else if (oSRS.IsGeographic())
            bIsGeographic = true;
    }

    if (bDefsOnly)
    {
        char *pszProjection = nullptr;
        m_oSRS.exportToWkt(&pszProjection);
        CPLDebug("GDAL_netCDF",
                 "SetProjection, WKT now = [%s]\nprojected: %d geographic: %d",
                 pszProjection ? pszProjection : "(null)",
                 static_cast<int>(bIsProjected),
                 static_cast<int>(bIsGeographic));
        CPLFree(pszProjection);

        if (!m_bHasGeoTransform)
            CPLDebug("GDAL_netCDF",
                     "netCDFDataset::AddProjectionVars() called, "
                     "but GeoTransform has not yet been defined!");

        if (!m_bHasProjection)
            CPLDebug("GDAL_netCDF",
                     "netCDFDataset::AddProjectionVars() called, "
                     "but Projection has not yet been defined!");
    }

    // Check GEOLOCATION information.
    char **papszGeolocationInfo = netCDFDataset::GetMetadata("GEOLOCATION");
    if (papszGeolocationInfo != nullptr)
    {
        // Look for geolocation datasets.
        const char *pszDSName =
            CSLFetchNameValue(papszGeolocationInfo, "X_DATASET");
        if (pszDSName != nullptr)
            hDS_X = GDALOpenShared(pszDSName, GA_ReadOnly);
        pszDSName = CSLFetchNameValue(papszGeolocationInfo, "Y_DATASET");
        if (pszDSName != nullptr)
            hDS_Y = GDALOpenShared(pszDSName, GA_ReadOnly);

        if (hDS_X != nullptr && hDS_Y != nullptr)
        {
            int nBand = std::max(1, atoi(CSLFetchNameValueDef(
                                        papszGeolocationInfo, "X_BAND", "0")));
            hBand_X = GDALGetRasterBand(hDS_X, nBand);
            nBand = std::max(1, atoi(CSLFetchNameValueDef(papszGeolocationInfo,
                                                          "Y_BAND", "0")));
            hBand_Y = GDALGetRasterBand(hDS_Y, nBand);

            // If geoloc bands are found, do basic validation based on their
            // dimensions.
            if (hBand_X != nullptr && hBand_Y != nullptr)
            {
                int nXSize_XBand = GDALGetRasterXSize(hDS_X);
                int nYSize_XBand = GDALGetRasterYSize(hDS_X);
                int nXSize_YBand = GDALGetRasterXSize(hDS_Y);
                int nYSize_YBand = GDALGetRasterYSize(hDS_Y);

                // TODO 1D geolocation arrays not implemented.
                if (nYSize_XBand == 1 && nYSize_YBand == 1)
                {
                    bHasGeoloc = false;
                    CPLDebug("GDAL_netCDF",
                             "1D GEOLOCATION arrays not supported yet");
                }
                // 2D bands must have same sizes as the raster bands.
                else if (nXSize_XBand != nRasterXSize ||
                         nYSize_XBand != nRasterYSize ||
                         nXSize_YBand != nRasterXSize ||
                         nYSize_YBand != nRasterYSize)
                {
                    bHasGeoloc = false;
                    CPLDebug("GDAL_netCDF",
                             "GEOLOCATION array sizes (%dx%d %dx%d) differ "
                             "from raster (%dx%d), not supported",
                             nXSize_XBand, nYSize_XBand, nXSize_YBand,
                             nYSize_YBand, nRasterXSize, nRasterYSize);
                }
                else
                {
                    bHasGeoloc = true;
                    CPLDebug("GDAL_netCDF",
                             "dataset has GEOLOCATION information, will try to "
                             "write it");
                }
            }
        }
    }

    // Process projection options.
    if (bIsProjected)
    {
        bool bIsCfProjection =
            NCDFIsCfProjection(oSRS.GetAttrValue("PROJECTION"));
        bWriteGridMapping = true;
        bWriteGDALTags = CPL_TO_BOOL(
            CSLFetchBoolean(papszCreationOptions, "WRITE_GDAL_TAGS", TRUE));
        // Force WRITE_GDAL_TAGS if is not a CF projection.
        if (!bWriteGDALTags && !bIsCfProjection)
            bWriteGDALTags = true;
        if (bWriteGDALTags)
            bWriteGeoTransform = true;

        // Write lon/lat: default is NO, except if has geolocation.
        // With IF_NEEDED: write if has geoloc or is not CF projection.
        const char *pszValue =
            CSLFetchNameValue(papszCreationOptions, "WRITE_LONLAT");
        if (pszValue)
        {
            if (EQUAL(pszValue, "IF_NEEDED"))
            {
                bWriteLonLat = bHasGeoloc || !bIsCfProjection;
            }
            else
            {
                bWriteLonLat = CPLTestBool(pszValue);
            }
        }
        else
        {
            bWriteLonLat = bHasGeoloc;
        }

        // Save value of pszCFCoordinates for later.
        if (bWriteLonLat)
        {
            pszCFCoordinates = NCDF_LONLAT;
        }
    }
    else
    {
        // Files without a Datum will not have a grid_mapping variable and
        // geographic information.
        bWriteGridMapping = bIsGeographic;

        if (bHasGeoloc)
        {
            bWriteLonLat = true;
        }
        else
        {
            bWriteGDALTags = CPL_TO_BOOL(CSLFetchBoolean(
                papszCreationOptions, "WRITE_GDAL_TAGS", bWriteGridMapping));
            if (bWriteGDALTags)
                bWriteGeoTransform = true;

            const char *pszValue = CSLFetchNameValueDef(papszCreationOptions,
                                                        "WRITE_LONLAT", "YES");
            if (EQUAL(pszValue, "IF_NEEDED"))
                bWriteLonLat = true;
            else
                bWriteLonLat = CPLTestBool(pszValue);
            //  Don't write lon/lat if no source geotransform.
            if (!m_bHasGeoTransform)
                bWriteLonLat = false;
            // If we don't write lon/lat, set dimnames to X/Y and write gdal
            // tags.
            if (!bWriteLonLat)
            {
                CPLError(CE_Warning, CPLE_AppDefined,
                         "creating geographic file without lon/lat values!");
                if (m_bHasGeoTransform)
                {
                    bWriteGDALTags = true;  // Not desirable if no geotransform.
                    bWriteGeoTransform = true;
                }
            }
        }
    }

    // Make sure we write grid_mapping if we need to write GDAL tags.
    if (bWriteGDALTags)
        bWriteGridMapping = true;

    // bottom-up value: new driver is bottom-up by default.
    // Override with WRITE_BOTTOMUP.
    bBottomUp = CPL_TO_BOOL(
        CSLFetchBoolean(papszCreationOptions, "WRITE_BOTTOMUP", TRUE));

    if (bDefsOnly)
    {
        CPLDebug(
            "GDAL_netCDF",
            "bIsProjected=%d bIsGeographic=%d bWriteGridMapping=%d "
            "bWriteGDALTags=%d bWriteLonLat=%d bBottomUp=%d bHasGeoloc=%d",
            static_cast<int>(bIsProjected), static_cast<int>(bIsGeographic),
            static_cast<int>(bWriteGridMapping),
            static_cast<int>(bWriteGDALTags), static_cast<int>(bWriteLonLat),
            static_cast<int>(bBottomUp), static_cast<int>(bHasGeoloc));
    }

    // Exit if nothing to do.
    if (!bIsProjected && !bWriteLonLat)
        return CE_None;

    // Define dimension names.

    if (bDefsOnly)
    {
        int nVarLonID = -1;
        int nVarLatID = -1;
        int nVarXID = -1;
        int nVarYID = -1;

        m_bAddedProjectionVarsDefs = true;

        // Make sure we are in define mode.
        SetDefineMode(true);

        // Write projection attributes.
        if (bWriteGridMapping)
        {
            const int NCDFVarID = NCDFWriteSRSVariable(
                cdfid, &oSRS, &pszCFProjection, bWriteGDALTags);
            if (NCDFVarID < 0)
                return CE_Failure;

            // Optional GDAL custom projection tags.
            if (bWriteGDALTags)
            {
                CPLString osGeoTransform;
                for (int i = 0; i < 6; i++)
                {
                    osGeoTransform +=
                        CPLSPrintf("%.16g ", m_adfGeoTransform[i]);
                }
                CPLDebug("GDAL_netCDF", "szGeoTransform = %s",
                         osGeoTransform.c_str());

                // if( strlen(pszProj4Defn) > 0 ) {
                //     nc_put_att_text(cdfid, NCDFVarID, "proj4",
                //                      strlen(pszProj4Defn), pszProj4Defn);
                // }

                // For now, write the geotransform for back-compat or else
                // the old (1.8.1) driver overrides the CF geotransform with
                // empty values from dfNN, dfSN, dfEE, dfWE;

                // TODO: fix this in 1.8 branch, and then remove this here.
                if (bWriteGeoTransform && m_bHasGeoTransform)
                {
                    {
                        const int status = nc_put_att_text(
                            cdfid, NCDFVarID, NCDF_GEOTRANSFORM,
                            osGeoTransform.size(), osGeoTransform.c_str());
                        NCDF_ERR(status);
                    }
                }
            }

            // Write projection variable to band variable.
            // Need to call later if there are no bands.
            AddGridMappingRef();
        }  // end if( bWriteGridMapping )

        // Write CF Projection vars.

        const bool bIsRotatedPole =
            pszCFProjection != nullptr &&
            EQUAL(pszCFProjection, ROTATED_POLE_VAR_NAME);
        if (bIsRotatedPole)
        {
            // Rename dims to rlat/rlon.
            papszDimName
                .Clear();  // If we add other dims one day, this has to change
            papszDimName.AddString(NCDF_DIMNAME_RLAT);
            papszDimName.AddString(NCDF_DIMNAME_RLON);

            int status = nc_rename_dim(cdfid, nYDimID, NCDF_DIMNAME_RLAT);
            NCDF_ERR(status);
            status = nc_rename_dim(cdfid, nXDimID, NCDF_DIMNAME_RLON);
            NCDF_ERR(status);
        }
        // Rename dimensions if lon/lat.
        else if (!bIsProjected && !bHasGeoloc)
        {
            // Rename dims to lat/lon.
            papszDimName
                .Clear();  // If we add other dims one day, this has to change
            papszDimName.AddString(NCDF_DIMNAME_LAT);
            papszDimName.AddString(NCDF_DIMNAME_LON);

            int status = nc_rename_dim(cdfid, nYDimID, NCDF_DIMNAME_LAT);
            NCDF_ERR(status);
            status = nc_rename_dim(cdfid, nXDimID, NCDF_DIMNAME_LON);
            NCDF_ERR(status);
        }

        // Write X/Y attributes.
        else /* if( bIsProjected || bHasGeoloc ) */
        {
            // X
            int anXDims[1];
            anXDims[0] = nXDimID;
            CPLDebug("GDAL_netCDF", "nc_def_var(%d,%s,%d)", cdfid,
                     CF_PROJ_X_VAR_NAME, NC_DOUBLE);
            int status = nc_def_var(cdfid, CF_PROJ_X_VAR_NAME, NC_DOUBLE, 1,
                                    anXDims, &nVarXID);
            NCDF_ERR(status);

            // Y
            int anYDims[1];
            anYDims[0] = nYDimID;
            CPLDebug("GDAL_netCDF", "nc_def_var(%d,%s,%d)", cdfid,
                     CF_PROJ_Y_VAR_NAME, NC_DOUBLE);
            status = nc_def_var(cdfid, CF_PROJ_Y_VAR_NAME, NC_DOUBLE, 1,
                                anYDims, &nVarYID);
            NCDF_ERR(status);

            if (bIsProjected)
            {
                NCDFWriteXYVarsAttributes(this->vcdf, nVarXID, nVarYID, &oSRS);
            }
            else
            {
                CPLAssert(bHasGeoloc);
                try
                {
                    vcdf.nc_put_vatt_text(nVarXID, CF_AXIS, CF_SG_X_AXIS);
                    vcdf.nc_put_vatt_text(nVarXID, CF_LNG_NAME,
                                          "x-coordinate in Cartesian system");
                    vcdf.nc_put_vatt_text(nVarXID, CF_UNITS, "m");
                    vcdf.nc_put_vatt_text(nVarYID, CF_AXIS, CF_SG_Y_AXIS);
                    vcdf.nc_put_vatt_text(nVarYID, CF_LNG_NAME,
                                          "y-coordinate in Cartesian system");
                    vcdf.nc_put_vatt_text(nVarYID, CF_UNITS, "m");

                    pszCFCoordinates = NCDF_LONLAT;
                }
                catch (nccfdriver::SG_Exception &e)
                {
                    CPLError(CE_Failure, CPLE_FileIO, "%s", e.get_err_msg());
                    return CE_Failure;
                }
            }
        }

        // Write lat/lon attributes if needed.
        if (bWriteLonLat)
        {
            int *panLatDims = nullptr;
            int *panLonDims = nullptr;
            int nLatDims = -1;
            int nLonDims = -1;

            // Get information.
            if (bHasGeoloc)
            {
                // Geoloc
                nLatDims = 2;
                panLatDims =
                    static_cast<int *>(CPLCalloc(nLatDims, sizeof(int)));
                panLatDims[0] = nYDimID;
                panLatDims[1] = nXDimID;
                nLonDims = 2;
                panLonDims =
                    static_cast<int *>(CPLCalloc(nLonDims, sizeof(int)));
                panLonDims[0] = nYDimID;
                panLonDims[1] = nXDimID;
            }
            else if (bIsProjected)
            {
                // Projected
                nLatDims = 2;
                panLatDims =
                    static_cast<int *>(CPLCalloc(nLatDims, sizeof(int)));
                panLatDims[0] = nYDimID;
                panLatDims[1] = nXDimID;
                nLonDims = 2;
                panLonDims =
                    static_cast<int *>(CPLCalloc(nLonDims, sizeof(int)));
                panLonDims[0] = nYDimID;
                panLonDims[1] = nXDimID;
            }
            else
            {
                // Geographic
                nLatDims = 1;
                panLatDims =
                    static_cast<int *>(CPLCalloc(nLatDims, sizeof(int)));
                panLatDims[0] = nYDimID;
                nLonDims = 1;
                panLonDims =
                    static_cast<int *>(CPLCalloc(nLonDims, sizeof(int)));
                panLonDims[0] = nXDimID;
            }

            nc_type eLonLatType = NC_NAT;
            if (bIsProjected)
            {
                eLonLatType = NC_FLOAT;
                const char *pszValue = CSLFetchNameValueDef(
                    papszCreationOptions, "TYPE_LONLAT", "FLOAT");
                if (EQUAL(pszValue, "DOUBLE"))
                    eLonLatType = NC_DOUBLE;
            }
            else
            {
                eLonLatType = NC_DOUBLE;
                const char *pszValue = CSLFetchNameValueDef(
                    papszCreationOptions, "TYPE_LONLAT", "DOUBLE");
                if (EQUAL(pszValue, "FLOAT"))
                    eLonLatType = NC_FLOAT;
            }

            // Def vars and attributes.
            {
                const char *pszVarName =
                    bIsRotatedPole ? NCDF_DIMNAME_RLAT : CF_LATITUDE_VAR_NAME;
                int status = nc_def_var(cdfid, pszVarName, eLonLatType,
                                        nLatDims, panLatDims, &nVarLatID);
                CPLDebug("GDAL_netCDF", "nc_def_var(%d,%s,%d,%d,-,-) got id %d",
                         cdfid, pszVarName, eLonLatType, nLatDims, nVarLatID);
                NCDF_ERR(status);
                DefVarDeflate(nVarLatID, false);  // Don't set chunking.
            }

            {
                const char *pszVarName =
                    bIsRotatedPole ? NCDF_DIMNAME_RLON : CF_LONGITUDE_VAR_NAME;
                int status = nc_def_var(cdfid, pszVarName, eLonLatType,
                                        nLonDims, panLonDims, &nVarLonID);
                CPLDebug("GDAL_netCDF", "nc_def_var(%d,%s,%d,%d,-,-) got id %d",
                         cdfid, pszVarName, eLonLatType, nLatDims, nVarLonID);
                NCDF_ERR(status);
                DefVarDeflate(nVarLonID, false);  // Don't set chunking.
            }

            if (bIsRotatedPole)
                NCDFWriteRLonRLatVarsAttributes(this->vcdf, nVarLonID,
                                                nVarLatID);
            else
                NCDFWriteLonLatVarsAttributes(this->vcdf, nVarLonID, nVarLatID);

            CPLFree(panLatDims);
            CPLFree(panLonDims);
        }
    }

    if (!bDefsOnly)
    {
        m_bAddedProjectionVarsData = true;

        int nVarXID = -1;
        int nVarYID = -1;

        nc_inq_varid(cdfid, CF_PROJ_X_VAR_NAME, &nVarXID);
        nc_inq_varid(cdfid, CF_PROJ_Y_VAR_NAME, &nVarYID);

        int nVarLonID = -1;
        int nVarLatID = -1;

        const bool bIsRotatedPole =
            pszCFProjection != nullptr &&
            EQUAL(pszCFProjection, ROTATED_POLE_VAR_NAME);
        nc_inq_varid(cdfid,
                     bIsRotatedPole ? NCDF_DIMNAME_RLON : CF_LONGITUDE_VAR_NAME,
                     &nVarLonID);
        nc_inq_varid(cdfid,
                     bIsRotatedPole ? NCDF_DIMNAME_RLAT : CF_LATITUDE_VAR_NAME,
                     &nVarLatID);

        // Get projection values.

        double *padLonVal = nullptr;
        double *padLatVal = nullptr;

        if (bIsProjected)
        {
            OGRSpatialReference *poLatLonSRS = nullptr;
            OGRCoordinateTransformation *poTransform = nullptr;

            size_t startX[1];
            size_t countX[1];
            size_t startY[1];
            size_t countY[1];

            CPLDebug("GDAL_netCDF", "Getting (X,Y) values");

            double *padXVal =
                static_cast<double *>(CPLMalloc(nRasterXSize * sizeof(double)));
            double *padYVal =
                static_cast<double *>(CPLMalloc(nRasterYSize * sizeof(double)));

            // Get Y values.
            const double dfY0 = (!bBottomUp) ? m_adfGeoTransform[3] :
                                             // Invert latitude values.
                                    m_adfGeoTransform[3] +
                                        (m_adfGeoTransform[5] * nRasterYSize);
            const double dfDY = m_adfGeoTransform[5];

            for (int j = 0; j < nRasterYSize; j++)
            {
                // The data point is centered inside the pixel.
                if (!bBottomUp)
                    padYVal[j] = dfY0 + (j + 0.5) * dfDY;
                else  // Invert latitude values.
                    padYVal[j] = dfY0 - (j + 0.5) * dfDY;
            }
            startX[0] = 0;
            countX[0] = nRasterXSize;

            // Get X values.
            const double dfX0 = m_adfGeoTransform[0];
            const double dfDX = m_adfGeoTransform[1];

            for (int i = 0; i < nRasterXSize; i++)
            {
                // The data point is centered inside the pixel.
                padXVal[i] = dfX0 + (i + 0.5) * dfDX;
            }
            startY[0] = 0;
            countY[0] = nRasterYSize;

            // Write X/Y values.

            // Make sure we are in data mode.
            SetDefineMode(false);

            CPLDebug("GDAL_netCDF", "Writing X values");
            int status =
                nc_put_vara_double(cdfid, nVarXID, startX, countX, padXVal);
            NCDF_ERR(status);

            CPLDebug("GDAL_netCDF", "Writing Y values");
            status =
                nc_put_vara_double(cdfid, nVarYID, startY, countY, padYVal);
            NCDF_ERR(status);

            if (pfnProgress)
                pfnProgress(0.20, nullptr, pProgressData);

            // Write lon/lat arrays (CF coordinates) if requested.

            // Get OGR transform if GEOLOCATION is not available.
            if (bWriteLonLat && !bHasGeoloc)
            {
                poLatLonSRS = m_oSRS.CloneGeogCS();
                if (poLatLonSRS != nullptr)
                {
                    poLatLonSRS->SetAxisMappingStrategy(
                        OAMS_TRADITIONAL_GIS_ORDER);
                    poTransform =
                        OGRCreateCoordinateTransformation(&m_oSRS, poLatLonSRS);
                }
                // If no OGR transform, then don't write CF lon/lat.
                if (poTransform == nullptr)
                {
                    CPLError(CE_Failure, CPLE_AppDefined,
                             "Unable to get Coordinate Transform");
                    bWriteLonLat = false;
                }
            }

            if (bWriteLonLat)
            {
                if (!bHasGeoloc)
                    CPLDebug("GDAL_netCDF", "Transforming (X,Y)->(lon,lat)");
                else
                    CPLDebug("GDAL_netCDF",
                             "Writing (lon,lat) from GEOLOCATION arrays");

                bool bOK = true;
                double dfProgress = 0.2;

                size_t start[] = {0, 0};
                size_t count[] = {1, (size_t)nRasterXSize};
                padLatVal = static_cast<double *>(
                    CPLMalloc(nRasterXSize * sizeof(double)));
                padLonVal = static_cast<double *>(
                    CPLMalloc(nRasterXSize * sizeof(double)));

                for (int j = 0; j < nRasterYSize && bOK && status == NC_NOERR;
                     j++)
                {
                    start[0] = j;

                    // Get values from geotransform.
                    if (!bHasGeoloc)
                    {
                        // Fill values to transform.
                        for (int i = 0; i < nRasterXSize; i++)
                        {
                            padLatVal[i] = padYVal[j];
                            padLonVal[i] = padXVal[i];
                        }

                        // Do the transform.
                        bOK = CPL_TO_BOOL(poTransform->Transform(
                            nRasterXSize, padLonVal, padLatVal, nullptr));
                        if (!bOK)
                        {
                            CPLError(CE_Failure, CPLE_AppDefined,
                                     "Unable to Transform (X,Y) to (lon,lat).");
                        }
                    }
                    // Get values from geoloc arrays.
                    else
                    {
                        CPLErr eErr = GDALRasterIO(
                            hBand_Y, GF_Read, 0, j, nRasterXSize, 1, padLatVal,
                            nRasterXSize, 1, GDT_Float64, 0, 0);
                        if (eErr == CE_None)
                        {
                            eErr = GDALRasterIO(
                                hBand_X, GF_Read, 0, j, nRasterXSize, 1,
                                padLonVal, nRasterXSize, 1, GDT_Float64, 0, 0);
                        }

                        if (eErr == CE_None)
                        {
                            bOK = true;
                        }
                        else
                        {
                            bOK = false;
                            CPLError(CE_Failure, CPLE_AppDefined,
                                     "Unable to get scanline %d", j);
                        }
                    }

                    // Write data.
                    if (bOK)
                    {
                        status = nc_put_vara_double(cdfid, nVarLatID, start,
                                                    count, padLatVal);
                        NCDF_ERR(status);
                        status = nc_put_vara_double(cdfid, nVarLonID, start,
                                                    count, padLonVal);
                        NCDF_ERR(status);
                    }

                    if (pfnProgress && (nRasterYSize / 10) > 0 &&
                        (j % (nRasterYSize / 10) == 0))
                    {
                        dfProgress += 0.08;
                        pfnProgress(dfProgress, nullptr, pProgressData);
                    }
                }
            }

            if (poLatLonSRS != nullptr)
                delete poLatLonSRS;
            if (poTransform != nullptr)
                delete poTransform;

            CPLFree(padXVal);
            CPLFree(padYVal);
        }  // Projected

        // If not projected/geographic and has geoloc
        else if (!bIsGeographic && bHasGeoloc)
        {
            // Use
            // https://cfconventions.org/Data/cf-conventions/cf-conventions-1.9/cf-conventions.html#_two_dimensional_latitude_longitude_coordinate_variables

            bool bOK = true;
            double dfProgress = 0.2;

            // Make sure we are in data mode.
            SetDefineMode(false);

            size_t startX[1];
            size_t countX[1];
            size_t startY[1];
            size_t countY[1];
            startX[0] = 0;
            countX[0] = nRasterXSize;

            startY[0] = 0;
            countY[0] = nRasterYSize;

            std::vector<double> adfXVal(nRasterXSize);
            for (int i = 0; i < nRasterXSize; i++)
                adfXVal[i] = i;

            std::vector<double> adfYVal(nRasterYSize);
            for (int i = 0; i < nRasterYSize; i++)
                adfYVal[i] = bBottomUp ? nRasterYSize - 1 - i : i;

            CPLDebug("GDAL_netCDF", "Writing X values");
            int status = nc_put_vara_double(cdfid, nVarXID, startX, countX,
                                            adfXVal.data());
            NCDF_ERR(status);

            CPLDebug("GDAL_netCDF", "Writing Y values");
            status = nc_put_vara_double(cdfid, nVarYID, startY, countY,
                                        adfYVal.data());
            NCDF_ERR(status);

            if (pfnProgress)
                pfnProgress(0.20, nullptr, pProgressData);

            size_t start[] = {0, 0};
            size_t count[] = {1, (size_t)nRasterXSize};
            padLatVal =
                static_cast<double *>(CPLMalloc(nRasterXSize * sizeof(double)));
            padLonVal =
                static_cast<double *>(CPLMalloc(nRasterXSize * sizeof(double)));

            for (int j = 0; j < nRasterYSize && bOK && status == NC_NOERR; j++)
            {
                start[0] = j;

                CPLErr eErr = GDALRasterIO(hBand_Y, GF_Read, 0,
                                           bBottomUp ? nRasterYSize - 1 - j : j,
                                           nRasterXSize, 1, padLatVal,
                                           nRasterXSize, 1, GDT_Float64, 0, 0);
                if (eErr == CE_None)
                {
                    eErr = GDALRasterIO(hBand_X, GF_Read, 0,
                                        bBottomUp ? nRasterYSize - 1 - j : j,
                                        nRasterXSize, 1, padLonVal,
                                        nRasterXSize, 1, GDT_Float64, 0, 0);
                }

                if (eErr == CE_None)
                {
                    bOK = true;
                }
                else
                {
                    bOK = false;
                    CPLError(CE_Failure, CPLE_AppDefined,
                             "Unable to get scanline %d", j);
                }

                // Write data.
                if (bOK)
                {
                    status = nc_put_vara_double(cdfid, nVarLatID, start, count,
                                                padLatVal);
                    NCDF_ERR(status);
                    status = nc_put_vara_double(cdfid, nVarLonID, start, count,
                                                padLonVal);
                    NCDF_ERR(status);
                }

                if (pfnProgress && (nRasterYSize / 10) > 0 &&
                    (j % (nRasterYSize / 10) == 0))
                {
                    dfProgress += 0.08;
                    pfnProgress(dfProgress, nullptr, pProgressData);
                }
            }
        }

        // If not projected, assume geographic to catch grids without Datum.
        else if (bWriteLonLat)
        {
            // Get latitude values.
            const double dfY0 = (!bBottomUp) ? m_adfGeoTransform[3] :
                                             // Invert latitude values.
                                    m_adfGeoTransform[3] +
                                        (m_adfGeoTransform[5] * nRasterYSize);
            const double dfDY = m_adfGeoTransform[5];

            // Override lat values with the ones in GEOLOCATION/Y_VALUES.
            if (netCDFDataset::GetMetadataItem("Y_VALUES", "GEOLOCATION") !=
                nullptr)
            {
                int nTemp = 0;
                padLatVal = Get1DGeolocation("Y_VALUES", nTemp);
                // Make sure we got the correct amount, if not fallback to GT */
                // could add test fabs(fabs(padLatVal[0]) - fabs(dfY0)) <= 0.1))
                if (nTemp == nRasterYSize)
                {
                    CPLDebug(
                        "GDAL_netCDF",
                        "Using Y_VALUES geolocation metadata for lat values");
                }
                else
                {
                    CPLDebug("GDAL_netCDF",
                             "Got %d elements from Y_VALUES geolocation "
                             "metadata, need %d",
                             nTemp, nRasterYSize);
                    if (padLatVal)
                    {
                        CPLFree(padLatVal);
                        padLatVal = nullptr;
                    }
                }
            }

            if (padLatVal == nullptr)
            {
                padLatVal = static_cast<double *>(
                    CPLMalloc(nRasterYSize * sizeof(double)));
                for (int i = 0; i < nRasterYSize; i++)
                {
                    // The data point is centered inside the pixel.
                    if (!bBottomUp)
                        padLatVal[i] = dfY0 + (i + 0.5) * dfDY;
                    else  // Invert latitude values.
                        padLatVal[i] = dfY0 - (i + 0.5) * dfDY;
                }
            }

            size_t startLat[1] = {0};
            size_t countLat[1] = {static_cast<size_t>(nRasterYSize)};

            // Get longitude values.
            const double dfX0 = m_adfGeoTransform[0];
            const double dfDX = m_adfGeoTransform[1];

            padLonVal =
                static_cast<double *>(CPLMalloc(nRasterXSize * sizeof(double)));
            for (int i = 0; i < nRasterXSize; i++)
            {
                // The data point is centered inside the pixel.
                padLonVal[i] = dfX0 + (i + 0.5) * dfDX;
            }

            size_t startLon[1] = {0};
            size_t countLon[1] = {static_cast<size_t>(nRasterXSize)};

            // Write latitude and longitude values.

            // Make sure we are in data mode.
            SetDefineMode(false);

            // Write values.
            CPLDebug("GDAL_netCDF", "Writing lat values");

            int status = nc_put_vara_double(cdfid, nVarLatID, startLat,
                                            countLat, padLatVal);
            NCDF_ERR(status);

            CPLDebug("GDAL_netCDF", "Writing lon values");
            status = nc_put_vara_double(cdfid, nVarLonID, startLon, countLon,
                                        padLonVal);
            NCDF_ERR(status);

        }  // Not projected.

        CPLFree(padLatVal);
        CPLFree(padLonVal);

        if (pfnProgress)
            pfnProgress(1.00, nullptr, pProgressData);
    }

    if (hDS_X != nullptr)
    {
        GDALClose(hDS_X);
    }
    if (hDS_Y != nullptr)
    {
        GDALClose(hDS_Y);
    }

    return CE_None;
}

// Write Projection variable to band variable.
// Moved from AddProjectionVars() for cases when bands are added after
// projection.
void netCDFDataset::AddGridMappingRef()
{
    bool bOldDefineMode = bDefineMode;

    if ((GetAccess() == GA_Update) && (nBands >= 1) && (GetRasterBand(1)) &&
        ((pszCFCoordinates != nullptr && !EQUAL(pszCFCoordinates, "")) ||
         (pszCFProjection != nullptr && !EQUAL(pszCFProjection, ""))))
    {
        bAddedGridMappingRef = true;

        // Make sure we are in define mode.
        SetDefineMode(true);

        for (int i = 1; i <= nBands; i++)
        {
            const int nVarId =
                static_cast<netCDFRasterBand *>(GetRasterBand(i))->nZId;

            if (pszCFProjection != nullptr && !EQUAL(pszCFProjection, ""))
            {
                int status =
                    nc_put_att_text(cdfid, nVarId, CF_GRD_MAPPING,
                                    strlen(pszCFProjection), pszCFProjection);
                NCDF_ERR(status);
            }
            if (pszCFCoordinates != nullptr && !EQUAL(pszCFCoordinates, ""))
            {
                int status =
                    nc_put_att_text(cdfid, nVarId, CF_COORDINATES,
                                    strlen(pszCFCoordinates), pszCFCoordinates);
                NCDF_ERR(status);
            }
        }

        // Go back to previous define mode.
        SetDefineMode(bOldDefineMode);
    }
}

/************************************************************************/
/*                          GetGeoTransform()                           */
/************************************************************************/

CPLErr netCDFDataset::GetGeoTransform(double *padfTransform)

{
    memcpy(padfTransform, m_adfGeoTransform, sizeof(double) * 6);
    if (m_bHasGeoTransform)
        return CE_None;

    return GDALPamDataset::GetGeoTransform(padfTransform);
}

/************************************************************************/
/*                                rint()                                */
/************************************************************************/

double netCDFDataset::rint(double dfX)
{
    return std::round(dfX);
}

/************************************************************************/
/*                          NCDFReadIsoMetadata()                       */
/************************************************************************/

#ifdef NETCDF_HAS_NC4

static void NCDFReadMetadataAsJson(int cdfid, CPLJSONObject &obj)
{
    int nbAttr = 0;
    NCDF_ERR(nc_inq_varnatts(cdfid, NC_GLOBAL, &nbAttr));

    std::map<std::string, CPLJSONArray> oMapNameToArray;
    for (int l = 0; l < nbAttr; l++)
    {
        char szAttrName[NC_MAX_NAME + 1];
        szAttrName[0] = 0;
        NCDF_ERR(nc_inq_attname(cdfid, NC_GLOBAL, l, szAttrName));

        char *pszMetaValue = nullptr;
        if (NCDFGetAttr(cdfid, NC_GLOBAL, szAttrName, &pszMetaValue) == CE_None)
        {
            nc_type nAttrType = NC_NAT;
            size_t nAttrLen = 0;

            NCDF_ERR(nc_inq_att(cdfid, NC_GLOBAL, szAttrName, &nAttrType,
                                &nAttrLen));

            std::string osAttrName(szAttrName);
            const auto sharpPos = osAttrName.find('#');
            if (sharpPos == std::string::npos)
            {
                if (nAttrType == NC_DOUBLE || nAttrType == NC_FLOAT)
                    obj.Add(osAttrName, CPLAtof(pszMetaValue));
                else
                    obj.Add(osAttrName, pszMetaValue);
            }
            else
            {
                osAttrName.resize(sharpPos);
                auto iter = oMapNameToArray.find(osAttrName);
                if (iter == oMapNameToArray.end())
                {
                    CPLJSONArray array;
                    obj.Add(osAttrName, array);
                    oMapNameToArray[osAttrName] = array;
                    array.Add(pszMetaValue);
                }
                else
                {
                    iter->second.Add(pszMetaValue);
                }
            }
            CPLFree(pszMetaValue);
            pszMetaValue = nullptr;
        }
    }

    int nSubGroups = 0;
    int *panSubGroupIds = nullptr;
    NCDFGetSubGroups(cdfid, &nSubGroups, &panSubGroupIds);
    oMapNameToArray.clear();
    for (int i = 0; i < nSubGroups; i++)
    {
        CPLJSONObject subObj;
        NCDFReadMetadataAsJson(panSubGroupIds[i], subObj);

        std::string osGroupName;
        osGroupName.resize(NC_MAX_NAME);
        NCDF_ERR(nc_inq_grpname(panSubGroupIds[i], &osGroupName[0]));
        osGroupName.resize(strlen(osGroupName.data()));
        const auto sharpPos = osGroupName.find('#');
        if (sharpPos == std::string::npos)
        {
            obj.Add(osGroupName, subObj);
        }
        else
        {
            osGroupName.resize(sharpPos);
            auto iter = oMapNameToArray.find(osGroupName);
            if (iter == oMapNameToArray.end())
            {
                CPLJSONArray array;
                obj.Add(osGroupName, array);
                oMapNameToArray[osGroupName] = array;
                array.Add(subObj);
            }
            else
            {
                iter->second.Add(subObj);
            }
        }
    }
    CPLFree(panSubGroupIds);
}

std::string NCDFReadMetadataAsJson(int cdfid)
{
    CPLJSONDocument oDoc;
    CPLJSONObject oRoot = oDoc.GetRoot();
    NCDFReadMetadataAsJson(cdfid, oRoot);
    return oDoc.SaveAsString();
}

#endif

/************************************************************************/
/*                        ReadAttributes()                              */
/************************************************************************/
CPLErr netCDFDataset::ReadAttributes(int cdfidIn, int var)

{
    char *pszVarFullName = nullptr;
    ERR_RET(NCDFGetVarFullName(cdfidIn, var, &pszVarFullName));
#ifdef NETCDF_HAS_NC4
    // For metadata in Sentinel 5
    if (STARTS_WITH(pszVarFullName, "/METADATA/"))
    {
        for (const char *key :
             {"ISO_METADATA", "ESA_METADATA", "EOP_METADATA", "QA_STATISTICS",
              "GRANULE_DESCRIPTION", "ALGORITHM_SETTINGS"})
        {
            if (var == NC_GLOBAL &&
                strcmp(pszVarFullName,
                       CPLSPrintf("/METADATA/%s/NC_GLOBAL", key)) == 0)
            {
                CPLFree(pszVarFullName);
                CPLStringList aosList;
                aosList.AddString(CPLString(NCDFReadMetadataAsJson(cdfidIn))
                                      .replaceAll("\\/", '/'));
                m_oMapDomainToJSon[key] = std::move(aosList);
                return CE_None;
            }
        }
    }
    if (STARTS_WITH(pszVarFullName, "/PRODUCT/SUPPORT_DATA/"))
    {
        CPLFree(pszVarFullName);
        CPLStringList aosList;
        aosList.AddString(
            CPLString(NCDFReadMetadataAsJson(cdfidIn)).replaceAll("\\/", '/'));
        m_oMapDomainToJSon["SUPPORT_DATA"] = std::move(aosList);
        return CE_None;
    }
#endif

    size_t nMetaNameSize =
        sizeof(char) * (strlen(pszVarFullName) + 1 + NC_MAX_NAME + 1);
    char *pszMetaName = static_cast<char *>(CPLMalloc(nMetaNameSize));

    int nbAttr = 0;
    NCDF_ERR(nc_inq_varnatts(cdfidIn, var, &nbAttr));

    for (int l = 0; l < nbAttr; l++)
    {
        char szAttrName[NC_MAX_NAME + 1];
        szAttrName[0] = 0;
        NCDF_ERR(nc_inq_attname(cdfidIn, var, l, szAttrName));
        snprintf(pszMetaName, nMetaNameSize, "%s#%s", pszVarFullName,
                 szAttrName);

        char *pszMetaTemp = nullptr;
        if (NCDFGetAttr(cdfidIn, var, szAttrName, &pszMetaTemp) == CE_None)
        {
            papszMetadata =
                CSLSetNameValue(papszMetadata, pszMetaName, pszMetaTemp);
            CPLFree(pszMetaTemp);
            pszMetaTemp = nullptr;
        }
        else
        {
            CPLDebug("GDAL_netCDF", "invalid metadata %s", pszMetaName);
        }
    }

    CPLFree(pszVarFullName);
    CPLFree(pszMetaName);

    if (var == NC_GLOBAL)
    {
        // Recurse on sub-groups.
        int nSubGroups = 0;
        int *panSubGroupIds = nullptr;
        NCDFGetSubGroups(cdfidIn, &nSubGroups, &panSubGroupIds);
        for (int i = 0; i < nSubGroups; i++)
        {
            ReadAttributes(panSubGroupIds[i], var);
        }
        CPLFree(panSubGroupIds);
    }

    return CE_None;
}

/************************************************************************/
/*                netCDFDataset::CreateSubDatasetList()                 */
/************************************************************************/
void netCDFDataset::CreateSubDatasetList(int nGroupId)
{
    char szVarStdName[NC_MAX_NAME + 1];
    int *ponDimIds = nullptr;
    nc_type nAttype;
    size_t nAttlen;

    netCDFDataset *poDS = this;

    int nVarCount;
    nc_inq_nvars(nGroupId, &nVarCount);

    for (int nVar = 0; nVar < nVarCount; nVar++)
    {

        int nDims;
        nc_inq_varndims(nGroupId, nVar, &nDims);

        if (nDims >= 2)
        {
            ponDimIds = static_cast<int *>(CPLCalloc(nDims, sizeof(int)));
            nc_inq_vardimid(nGroupId, nVar, ponDimIds);

            // Create Sub dataset list.
            CPLString osDim;
            for (int i = 0; i < nDims; i++)
            {
                size_t nDimLen;
                nc_inq_dimlen(nGroupId, ponDimIds[i], &nDimLen);
                osDim += CPLSPrintf("%dx", (int)nDimLen);
            }
            CPLFree(ponDimIds);

            nc_type nVarType;
            nc_inq_vartype(nGroupId, nVar, &nVarType);
            // Get rid of the last "x" character.
            osDim.resize(osDim.size() - 1);
            const char *pszType = "";
            switch (nVarType)
            {
                case NC_BYTE:
                    pszType = "8-bit integer";
                    break;
                case NC_CHAR:
                    pszType = "8-bit character";
                    break;
                case NC_SHORT:
                    pszType = "16-bit integer";
                    break;
                case NC_INT:
                    pszType = "32-bit integer";
                    break;
                case NC_FLOAT:
                    pszType = "32-bit floating-point";
                    break;
                case NC_DOUBLE:
                    pszType = "64-bit floating-point";
                    break;
#ifdef NETCDF_HAS_NC4
                case NC_UBYTE:
                    pszType = "8-bit unsigned integer";
                    break;
                case NC_USHORT:
                    pszType = "16-bit unsigned integer";
                    break;
                case NC_UINT:
                    pszType = "32-bit unsigned integer";
                    break;
                case NC_INT64:
                    pszType = "64-bit integer";
                    break;
                case NC_UINT64:
                    pszType = "64-bit unsigned integer";
                    break;
#endif
                default:
                    break;
            }

            char *pszName = nullptr;
            if (NCDFGetVarFullName(nGroupId, nVar, &pszName) != CE_None)
                continue;

            nSubDatasets++;

            nAttlen = 0;
            nc_inq_att(nGroupId, nVar, CF_STD_NAME, &nAttype, &nAttlen);
            if (nAttlen < sizeof(szVarStdName) &&
                nc_get_att_text(nGroupId, nVar, CF_STD_NAME, szVarStdName) ==
                    NC_NOERR)
            {
                szVarStdName[nAttlen] = '\0';
            }
            else
            {
                snprintf(szVarStdName, sizeof(szVarStdName), "%s", pszName);
            }

            char szTemp[NC_MAX_NAME + 1];
            snprintf(szTemp, sizeof(szTemp), "SUBDATASET_%d_NAME",
                     nSubDatasets);

            poDS->papszSubDatasets =
                CSLSetNameValue(poDS->papszSubDatasets, szTemp,
                                CPLSPrintf("NETCDF:\"%s\":%s",
                                           poDS->osFilename.c_str(), pszName));
            CPLFree(pszName);

            snprintf(szTemp, sizeof(szTemp), "SUBDATASET_%d_DESC",
                     nSubDatasets);

            poDS->papszSubDatasets =
                CSLSetNameValue(poDS->papszSubDatasets, szTemp,
                                CPLSPrintf("[%s] %s (%s)", osDim.c_str(),
                                           szVarStdName, pszType));
        }
    }

    // Recurse on sub groups.
    int nSubGroups = 0;
    int *panSubGroupIds = nullptr;
    NCDFGetSubGroups(nGroupId, &nSubGroups, &panSubGroupIds);
    for (int i = 0; i < nSubGroups; i++)
    {
        CreateSubDatasetList(panSubGroupIds[i]);
    }
    CPLFree(panSubGroupIds);
}

/************************************************************************/
/*                              IdentifyFormat()                      */
/************************************************************************/

NetCDFFormatEnum netCDFDataset::IdentifyFormat(GDALOpenInfo *poOpenInfo,
                                               bool bCheckExt)
{
    // Does this appear to be a netcdf file? If so, which format?
    // http://www.unidata.ucar.edu/software/netcdf/docs/faq.html#fv1_5

    if (STARTS_WITH_CI(poOpenInfo->pszFilename, "NETCDF:"))
        return NCDF_FORMAT_UNKNOWN;
    if (poOpenInfo->nHeaderBytes < 4)
        return NCDF_FORMAT_NONE;
    const char *pszHeader =
        reinterpret_cast<const char *>(poOpenInfo->pabyHeader);

#ifdef ENABLE_NCDUMP
    if (poOpenInfo->fpL != nullptr && STARTS_WITH(pszHeader, "netcdf ") &&
        strstr(pszHeader, "dimensions:") && strstr(pszHeader, "variables:"))
    {
#ifdef NETCDF_HAS_NC4
        if (strstr(pszHeader, "// NC4C"))
            return NCDF_FORMAT_NC4C;
        else if (strstr(pszHeader, "// NC4"))
            return NCDF_FORMAT_NC4;
        else
#endif  // NETCDF_HAS_NC4
            return NCDF_FORMAT_NC;
    }
#endif  // ENABLE_NCDUMP

#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
    // We don't necessarily want to catch bugs in libnetcdf ...
    if (CPLGetConfigOption("DISABLE_OPEN_REAL_NETCDF_FILES", nullptr))
    {
        return NCDF_FORMAT_NONE;
    }
#endif

    constexpr char achHDF5Signature[] = "\211HDF\r\n\032\n";

    if (STARTS_WITH_CI(pszHeader, "CDF\001"))
    {
        // In case the netCDF driver is registered before the GMT driver,
        // avoid opening GMT files.
        if (GDALGetDriverByName("GMT") != nullptr)
        {
            bool bFoundZ = false;
            bool bFoundDimension = false;
            for (int i = 0; i < poOpenInfo->nHeaderBytes - 11; i++)
            {
                if (poOpenInfo->pabyHeader[i] == 1 &&
                    poOpenInfo->pabyHeader[i + 1] == 'z' &&
                    poOpenInfo->pabyHeader[i + 2] == 0)
                    bFoundZ = true;
                else if (poOpenInfo->pabyHeader[i] == 9 &&
                         memcmp((const char *)poOpenInfo->pabyHeader + i + 1,
                                "dimension", 9) == 0 &&
                         poOpenInfo->pabyHeader[i + 10] == 0)
                    bFoundDimension = true;
            }
            if (bFoundZ && bFoundDimension)
                return NCDF_FORMAT_UNKNOWN;
        }

        return NCDF_FORMAT_NC;
    }
    else if (STARTS_WITH_CI(pszHeader, "CDF\002"))
    {
        return NCDF_FORMAT_NC2;
    }
    else if (STARTS_WITH_CI(pszHeader, achHDF5Signature) ||
             (poOpenInfo->nHeaderBytes > 512 + 8 &&
              memcmp(pszHeader + 512, achHDF5Signature, 8) == 0))
    {
        // Requires netCDF-4/HDF5 support in libnetcdf (not just libnetcdf-v4).
        // If HDF5 is not supported in GDAL, this driver will try to open the
        // file Else, make sure this driver does not try to open HDF5 files If
        // user really wants to open with this driver, use NETCDF:file.h5
        // format.  This check should be relaxed, but there is no clear way to
        // make a difference.

        // Check for HDF5 support in GDAL.
#ifdef HAVE_HDF5
        if (bCheckExt)
        {
            // Check by default.
            const char *pszExtension = CPLGetExtension(poOpenInfo->pszFilename);
            if (!(EQUAL(pszExtension, "nc") || EQUAL(pszExtension, "cdf") ||
                  EQUAL(pszExtension, "nc2") || EQUAL(pszExtension, "nc4") ||
                  EQUAL(pszExtension, "nc3") || EQUAL(pszExtension, "grd") ||
                  EQUAL(pszExtension, "gmac")))
            {
                if (GDALGetDriverByName("HDF5") != nullptr)
                {
                    return NCDF_FORMAT_HDF5;
                }
            }
        }
#endif

        // Check for netcdf-4 support in libnetcdf.
#ifdef NETCDF_HAS_NC4
        return NCDF_FORMAT_NC4;
#else
        return NCDF_FORMAT_HDF5;
#endif
    }
    else if (STARTS_WITH_CI(pszHeader, "\016\003\023\001"))
    {
        // Requires HDF4 support in libnetcdf, but if HF4 is supported by GDAL
        // don't try to open.
        // If user really wants to open with this driver, use NETCDF:file.hdf
        // syntax.

        // Check for HDF4 support in GDAL.
#ifdef HAVE_HDF4
        if (bCheckExt && GDALGetDriverByName("HDF4") != nullptr)
        {
            // Check by default.
            // Always treat as HDF4 file.
            return NCDF_FORMAT_HDF4;
        }
#endif

        // Check for HDF4 support in libnetcdf.
#ifdef NETCDF_HAS_HDF4
        return NCDF_FORMAT_NC4;
#else
        return NCDF_FORMAT_HDF4;
#endif
    }

    // The HDF5 signature of netCDF 4 files can be at offsets 512, 1024, 2048,
    // etc.
    const char *pszExtension = CPLGetExtension(poOpenInfo->pszFilename);
    if (poOpenInfo->fpL != nullptr &&
        (!bCheckExt || EQUAL(pszExtension, "nc") ||
         EQUAL(pszExtension, "cdf") || EQUAL(pszExtension, "nc4")))
    {
        vsi_l_offset nOffset = 512;
        for (int i = 0; i < 64; i++)
        {
            GByte abyBuf[8];
            if (VSIFSeekL(poOpenInfo->fpL, nOffset, SEEK_SET) != 0 ||
                VSIFReadL(abyBuf, 1, 8, poOpenInfo->fpL) != 8)
            {
                break;
            }
            if (memcmp(abyBuf, achHDF5Signature, 8) == 0)
            {
#ifdef NETCDF_HAS_NC4
                return NCDF_FORMAT_NC4;
#else
                return NCDF_FORMAT_HDF5;
#endif
            }
            nOffset *= 2;
        }
    }

    return NCDF_FORMAT_NONE;
}

/************************************************************************/
/*                            TestCapability()                          */
/************************************************************************/

int netCDFDataset::TestCapability(const char *pszCap)
{
    if (EQUAL(pszCap, ODsCCreateLayer))
    {
        return eAccess == GA_Update && nBands == 0 &&
               (eMultipleLayerBehavior != SINGLE_LAYER ||
                this->GetLayerCount() == 0 || bSGSupport);
    }
    else if (EQUAL(pszCap, ODsCZGeometries))
        return true;

    return false;
}

/************************************************************************/
/*                            GetLayer()                                */
/************************************************************************/

OGRLayer *netCDFDataset::GetLayer(int nIdx)
{
    if (nIdx < 0 || nIdx >= this->GetLayerCount())
        return nullptr;
    return papoLayers[nIdx].get();
}

/************************************************************************/
/*                            ICreateLayer()                            */
/************************************************************************/

OGRLayer *netCDFDataset::ICreateLayer(const char *pszName,
                                      OGRSpatialReference *poSpatialRef,
                                      OGRwkbGeometryType eGType,
                                      char **papszOptions)
{
    int nLayerCDFId = cdfid;
    if (!TestCapability(ODsCCreateLayer))
        return nullptr;

    CPLString osNetCDFLayerName(pszName);
    const netCDFWriterConfigLayer *poLayerConfig = nullptr;
    if (oWriterConfig.m_bIsValid)
    {
        std::map<CPLString, netCDFWriterConfigLayer>::const_iterator
            oLayerIter = oWriterConfig.m_oLayers.find(pszName);
        if (oLayerIter != oWriterConfig.m_oLayers.end())
        {
            poLayerConfig = &(oLayerIter->second);
            osNetCDFLayerName = poLayerConfig->m_osNetCDFName;
        }
    }

    netCDFDataset *poLayerDataset = nullptr;
    if (eMultipleLayerBehavior == SEPARATE_FILES)
    {
        char **papszDatasetOptions = nullptr;
        papszDatasetOptions = CSLSetNameValue(
            papszDatasetOptions, "CONFIG_FILE",
            CSLFetchNameValue(papszCreationOptions, "CONFIG_FILE"));
        papszDatasetOptions =
            CSLSetNameValue(papszDatasetOptions, "FORMAT",
                            CSLFetchNameValue(papszCreationOptions, "FORMAT"));
        papszDatasetOptions = CSLSetNameValue(
            papszDatasetOptions, "WRITE_GDAL_TAGS",
            CSLFetchNameValue(papszCreationOptions, "WRITE_GDAL_TAGS"));
        CPLString osLayerFilename(
            CPLFormFilename(osFilename, osNetCDFLayerName, "nc"));
        CPLAcquireMutex(hNCMutex, 1000.0);
        poLayerDataset =
            CreateLL(osLayerFilename, 0, 0, 0, papszDatasetOptions);
        CPLReleaseMutex(hNCMutex);
        CSLDestroy(papszDatasetOptions);
        if (poLayerDataset == nullptr)
            return nullptr;

        nLayerCDFId = poLayerDataset->cdfid;
        NCDFAddGDALHistory(nLayerCDFId, osLayerFilename, bWriteGDALVersion,
                           bWriteGDALHistory, "", "Create",
                           NCDF_CONVENTIONS_CF_V1_6);
    }
#ifdef NETCDF_HAS_NC4
    else if (eMultipleLayerBehavior == SEPARATE_GROUPS)
    {
        SetDefineMode(true);

        nLayerCDFId = -1;
        int status = nc_def_grp(cdfid, osNetCDFLayerName, &nLayerCDFId);
        NCDF_ERR(status);
        if (status != NC_NOERR)
            return nullptr;

        NCDFAddGDALHistory(nLayerCDFId, osFilename, bWriteGDALVersion,
                           bWriteGDALHistory, "", "Create",
                           NCDF_CONVENTIONS_CF_V1_6);
    }
#endif

    // Make a clone to workaround a bug in released MapServer versions
    // that destroys the passed SRS instead of releasing it .
    OGRSpatialReference *poSRS = poSpatialRef;
    if (poSRS != nullptr)
    {
        poSRS = poSRS->Clone();
        poSRS->SetAxisMappingStrategy(OAMS_TRADITIONAL_GIS_ORDER);
    }
    std::shared_ptr<netCDFLayer> poLayer(
        new netCDFLayer(poLayerDataset ? poLayerDataset : this, nLayerCDFId,
                        osNetCDFLayerName, eGType, poSRS));
    if (poSRS != nullptr)
        poSRS->Release();

    // Fetch layer creation options coming from config file
    char **papszNewOptions = CSLDuplicate(papszOptions);
    if (oWriterConfig.m_bIsValid)
    {
        std::map<CPLString, CPLString>::const_iterator oIter;
        for (oIter = oWriterConfig.m_oLayerCreationOptions.begin();
             oIter != oWriterConfig.m_oLayerCreationOptions.end(); ++oIter)
        {
            papszNewOptions =
                CSLSetNameValue(papszNewOptions, oIter->first, oIter->second);
        }
        if (poLayerConfig != nullptr)
        {
            for (oIter = poLayerConfig->m_oLayerCreationOptions.begin();
                 oIter != poLayerConfig->m_oLayerCreationOptions.end(); ++oIter)
            {
                papszNewOptions = CSLSetNameValue(papszNewOptions, oIter->first,
                                                  oIter->second);
            }
        }
    }

    const bool bRet = poLayer->Create(papszNewOptions, poLayerConfig);
    CSLDestroy(papszNewOptions);

    if (!bRet)
    {
        return nullptr;
    }

    if (poLayerDataset != nullptr)
        apoVectorDatasets.push_back(poLayerDataset);

    papoLayers.push_back(poLayer);
    return poLayer.get();
}

/************************************************************************/
/*                           CloneAttributes()                          */
/************************************************************************/

bool netCDFDataset::CloneAttributes(int old_cdfid, int new_cdfid, int nSrcVarId,
                                    int nDstVarId)
{
    int nAttCount = -1;
    int status = nc_inq_varnatts(old_cdfid, nSrcVarId, &nAttCount);
    NCDF_ERR(status);

    for (int i = 0; i < nAttCount; i++)
    {
        char szName[NC_MAX_NAME + 1];
        szName[0] = 0;
        status = nc_inq_attname(old_cdfid, nSrcVarId, i, szName);
        NCDF_ERR(status);

        status =
            nc_copy_att(old_cdfid, nSrcVarId, szName, new_cdfid, nDstVarId);
        NCDF_ERR(status);
        if (status != NC_NOERR)
            return false;
    }

    return true;
}

/************************************************************************/
/*                          CloneVariableContent()                      */
/************************************************************************/

bool netCDFDataset::CloneVariableContent(int old_cdfid, int new_cdfid,
                                         int nSrcVarId, int nDstVarId)
{
    int nVarDimCount = -1;
    int status = nc_inq_varndims(old_cdfid, nSrcVarId, &nVarDimCount);
    NCDF_ERR(status);
    int anDimIds[] = {-1, 1};
    status = nc_inq_vardimid(old_cdfid, nSrcVarId, anDimIds);
    NCDF_ERR(status);
    nc_type nc_datatype = NC_NAT;
    status = nc_inq_vartype(old_cdfid, nSrcVarId, &nc_datatype);
    NCDF_ERR(status);
    size_t nTypeSize = 0;
    switch (nc_datatype)
    {
        case NC_BYTE:
        case NC_CHAR:
            nTypeSize = 1;
            break;
        case NC_SHORT:
            nTypeSize = 2;
            break;
        case NC_INT:
            nTypeSize = 4;
            break;
        case NC_FLOAT:
            nTypeSize = 4;
            break;
        case NC_DOUBLE:
            nTypeSize = 8;
            break;
#ifdef NETCDF_HAS_NC4
        case NC_UBYTE:
            nTypeSize = 1;
            break;
        case NC_USHORT:
            nTypeSize = 2;
            break;
        case NC_UINT:
            nTypeSize = 4;
            break;
        case NC_INT64:
        case NC_UINT64:
            nTypeSize = 8;
            break;
        case NC_STRING:
            nTypeSize = sizeof(char *);
            break;
#endif
        default:
        {
            CPLError(CE_Failure, CPLE_NotSupported, "Unsupported data type: %d",
                     nc_datatype);
            return false;
        }
    }

    size_t nElems = 1;
    size_t anStart[NC_MAX_DIMS];
    size_t anCount[NC_MAX_DIMS];
    size_t nRecords = 1;
    for (int i = 0; i < nVarDimCount; i++)
    {
        anStart[i] = 0;
        if (i == 0)
        {
            anCount[i] = 1;
            status = nc_inq_dimlen(old_cdfid, anDimIds[i], &nRecords);
            NCDF_ERR(status);
        }
        else
        {
            anCount[i] = 0;
            status = nc_inq_dimlen(old_cdfid, anDimIds[i], &anCount[i]);
            NCDF_ERR(status);
            nElems *= anCount[i];
        }
    }

    /* Workaround in some cases a netCDF bug:
     * https://github.com/Unidata/netcdf-c/pull/1442 */
    if (nRecords > 0 && nRecords < 10 * 1000 * 1000 / (nElems * nTypeSize))
    {
        nElems *= nRecords;
        anCount[0] = nRecords;
        nRecords = 1;
    }

    void *pBuffer = VSI_MALLOC2_VERBOSE(nElems, nTypeSize);
    if (pBuffer == nullptr)
        return false;

    for (size_t iRecord = 0; iRecord < nRecords; iRecord++)
    {
        anStart[0] = iRecord;

        switch (nc_datatype)
        {
            case NC_BYTE:
                status =
                    nc_get_vara_schar(old_cdfid, nSrcVarId, anStart, anCount,
                                      static_cast<signed char *>(pBuffer));
                if (!status)
                    status = nc_put_vara_schar(
                        new_cdfid, nDstVarId, anStart, anCount,
                        static_cast<signed char *>(pBuffer));
                break;
            case NC_CHAR:
                status =
                    nc_get_vara_text(old_cdfid, nSrcVarId, anStart, anCount,
                                     static_cast<char *>(pBuffer));
                if (!status)
                    status =
                        nc_put_vara_text(new_cdfid, nDstVarId, anStart, anCount,
                                         static_cast<char *>(pBuffer));
                break;
            case NC_SHORT:
                status =
                    nc_get_vara_short(old_cdfid, nSrcVarId, anStart, anCount,
                                      static_cast<short *>(pBuffer));
                if (!status)
                    status = nc_put_vara_short(new_cdfid, nDstVarId, anStart,
                                               anCount,
                                               static_cast<short *>(pBuffer));
                break;
            case NC_INT:
                status = nc_get_vara_int(old_cdfid, nSrcVarId, anStart, anCount,
                                         static_cast<int *>(pBuffer));
                if (!status)
                    status =
                        nc_put_vara_int(new_cdfid, nDstVarId, anStart, anCount,
                                        static_cast<int *>(pBuffer));
                break;
            case NC_FLOAT:
                status =
                    nc_get_vara_float(old_cdfid, nSrcVarId, anStart, anCount,
                                      static_cast<float *>(pBuffer));
                if (!status)
                    status = nc_put_vara_float(new_cdfid, nDstVarId, anStart,
                                               anCount,
                                               static_cast<float *>(pBuffer));
                break;
            case NC_DOUBLE:
                status =
                    nc_get_vara_double(old_cdfid, nSrcVarId, anStart, anCount,
                                       static_cast<double *>(pBuffer));
                if (!status)
                    status = nc_put_vara_double(new_cdfid, nDstVarId, anStart,
                                                anCount,
                                                static_cast<double *>(pBuffer));
                break;
#ifdef NETCDF_HAS_NC4
            case NC_STRING:
                status =
                    nc_get_vara_string(old_cdfid, nSrcVarId, anStart, anCount,
                                       static_cast<char **>(pBuffer));
                if (!status)
                {
                    status = nc_put_vara_string(
                        new_cdfid, nDstVarId, anStart, anCount,
                        static_cast<const char **>(pBuffer));
                    nc_free_string(nElems, static_cast<char **>(pBuffer));
                }
                break;

            case NC_UBYTE:
                status =
                    nc_get_vara_uchar(old_cdfid, nSrcVarId, anStart, anCount,
                                      static_cast<unsigned char *>(pBuffer));
                if (!status)
                    status = nc_put_vara_uchar(
                        new_cdfid, nDstVarId, anStart, anCount,
                        static_cast<unsigned char *>(pBuffer));
                break;
            case NC_USHORT:
                status =
                    nc_get_vara_ushort(old_cdfid, nSrcVarId, anStart, anCount,
                                       static_cast<unsigned short *>(pBuffer));
                if (!status)
                    status = nc_put_vara_ushort(
                        new_cdfid, nDstVarId, anStart, anCount,
                        static_cast<unsigned short *>(pBuffer));
                break;
            case NC_UINT:
                status =
                    nc_get_vara_uint(old_cdfid, nSrcVarId, anStart, anCount,
                                     static_cast<unsigned int *>(pBuffer));
                if (!status)
                    status =
                        nc_put_vara_uint(new_cdfid, nDstVarId, anStart, anCount,
                                         static_cast<unsigned int *>(pBuffer));
                break;
            case NC_INT64:
                status =
                    nc_get_vara_longlong(old_cdfid, nSrcVarId, anStart, anCount,
                                         static_cast<long long *>(pBuffer));
                if (!status)
                    status = nc_put_vara_longlong(
                        new_cdfid, nDstVarId, anStart, anCount,
                        static_cast<long long *>(pBuffer));
                break;
            case NC_UINT64:
                status = nc_get_vara_ulonglong(
                    old_cdfid, nSrcVarId, anStart, anCount,
                    static_cast<unsigned long long *>(pBuffer));
                if (!status)
                    status = nc_put_vara_ulonglong(
                        new_cdfid, nDstVarId, anStart, anCount,
                        static_cast<unsigned long long *>(pBuffer));
                break;
#endif
            default:
                status = NC_EBADTYPE;
        }

        NCDF_ERR(status);
        if (status != NC_NOERR)
        {
            VSIFree(pBuffer);
            return false;
        }
    }

    VSIFree(pBuffer);
    return true;
}

/************************************************************************/
/*                         NCDFIsUnlimitedDim()                         */
/************************************************************************/

bool NCDFIsUnlimitedDim(bool
#ifdef NETCDF_HAS_NC4
                            bIsNC4
#endif
                        ,
                        int cdfid, int nDimId)
{
#ifdef NETCDF_HAS_NC4
    if (bIsNC4)
    {
        int nUnlimitedDims = 0;
        nc_inq_unlimdims(cdfid, &nUnlimitedDims, nullptr);
        bool bFound = false;
        if (nUnlimitedDims)
        {
            int *panUnlimitedDimIds =
                static_cast<int *>(CPLMalloc(sizeof(int) * nUnlimitedDims));
            nc_inq_unlimdims(cdfid, nullptr, panUnlimitedDimIds);
            for (int i = 0; i < nUnlimitedDims; i++)
            {
                if (panUnlimitedDimIds[i] == nDimId)
                {
                    bFound = true;
                    break;
                }
            }
            CPLFree(panUnlimitedDimIds);
        }
        return bFound;
    }
    else
#endif
    {
        int nUnlimitedDimId = -1;
        nc_inq(cdfid, nullptr, nullptr, nullptr, &nUnlimitedDimId);
        return nDimId == nUnlimitedDimId;
    }
}

/************************************************************************/
/*                              CloneGrp()                              */
/************************************************************************/

bool netCDFDataset::CloneGrp(int nOldGrpId, int nNewGrpId, bool bIsNC4,
                             int nLayerId, int nDimIdToGrow, size_t nNewSize)
{
    // Clone dimensions
    int nDimCount = -1;
    int status = nc_inq_ndims(nOldGrpId, &nDimCount);
    NCDF_ERR(status);
    int *panDimIds = static_cast<int *>(CPLMalloc(sizeof(int) * nDimCount));
    int nUnlimiDimID = -1;
    status = nc_inq_unlimdim(nOldGrpId, &nUnlimiDimID);
    NCDF_ERR(status);
#ifdef NETCDF_HAS_NC4
    if (bIsNC4)
    {
        // In NC4, the dimension ids of a group are not necessarily in
        // [0,nDimCount-1] range
        int nDimCount2 = -1;
        status = nc_inq_dimids(nOldGrpId, &nDimCount2, panDimIds, FALSE);
        NCDF_ERR(status);
        CPLAssert(nDimCount == nDimCount2);
    }
    else
#endif
    {
        for (int i = 0; i < nDimCount; i++)
            panDimIds[i] = i;
    }
    for (int i = 0; i < nDimCount; i++)
    {
        char szDimName[NC_MAX_NAME + 1];
        szDimName[0] = 0;
        size_t nLen = 0;
        const int nDimId = panDimIds[i];
        status = nc_inq_dim(nOldGrpId, nDimId, szDimName, &nLen);
        NCDF_ERR(status);
        if (NCDFIsUnlimitedDim(bIsNC4, nOldGrpId, nDimId))
            nLen = NC_UNLIMITED;
        else if (nDimId == nDimIdToGrow && nOldGrpId == nLayerId)
            nLen = nNewSize;
        int nNewDimId = -1;
        status = nc_def_dim(nNewGrpId, szDimName, nLen, &nNewDimId);
        NCDF_ERR(status);
        CPLAssert(nDimId == nNewDimId);
        if (status != NC_NOERR)
        {
            CPLFree(panDimIds);
            return false;
        }
    }
    CPLFree(panDimIds);

    // Clone main attributes
    if (!CloneAttributes(nOldGrpId, nNewGrpId, NC_GLOBAL, NC_GLOBAL))
    {
        return false;
    }

    // Clone variable definitions
    int nVarCount = -1;
    status = nc_inq_nvars(nOldGrpId, &nVarCount);
    NCDF_ERR(status);

    for (int i = 0; i < nVarCount; i++)
    {
        char szVarName[NC_MAX_NAME + 1];
        szVarName[0] = 0;
        status = nc_inq_varname(nOldGrpId, i, szVarName);
        NCDF_ERR(status);
        nc_type nc_datatype = NC_NAT;
        status = nc_inq_vartype(nOldGrpId, i, &nc_datatype);
        NCDF_ERR(status);
        int nVarDimCount = -1;
        status = nc_inq_varndims(nOldGrpId, i, &nVarDimCount);
        NCDF_ERR(status);
        int anDimIds[NC_MAX_DIMS];
        status = nc_inq_vardimid(nOldGrpId, i, anDimIds);
        NCDF_ERR(status);
        int nNewVarId = -1;
        status = nc_def_var(nNewGrpId, szVarName, nc_datatype, nVarDimCount,
                            anDimIds, &nNewVarId);
        NCDF_ERR(status);
        CPLAssert(i == nNewVarId);
        if (status != NC_NOERR)
        {
            return false;
        }

        if (!CloneAttributes(nOldGrpId, nNewGrpId, i, i))
        {
            return false;
        }
    }

    status = nc_enddef(nNewGrpId);
    NCDF_ERR(status);
    if (status != NC_NOERR)
    {
        return false;
    }

    // Clone variable content
    for (int i = 0; i < nVarCount; i++)
    {
        if (!CloneVariableContent(nOldGrpId, nNewGrpId, i, i))
        {
            return false;
        }
    }

    return true;
}

/************************************************************************/
/*                              GrowDim()                               */
/************************************************************************/

bool netCDFDataset::GrowDim(int nLayerId, int nDimIdToGrow, size_t nNewSize)
{
    int nCreationMode;
    // Set nCreationMode based on eFormat.
    switch (eFormat)
    {
#ifdef NETCDF_HAS_NC2
        case NCDF_FORMAT_NC2:
            nCreationMode = NC_CLOBBER | NC_64BIT_OFFSET;
            break;
#endif
#ifdef NETCDF_HAS_NC4
        case NCDF_FORMAT_NC4:
            nCreationMode = NC_CLOBBER | NC_NETCDF4;
            break;
        case NCDF_FORMAT_NC4C:
            nCreationMode = NC_CLOBBER | NC_NETCDF4 | NC_CLASSIC_MODEL;
            break;
#endif
        case NCDF_FORMAT_NC:
        default:
            nCreationMode = NC_CLOBBER;
            break;
    }

    int new_cdfid = -1;
    CPLString osTmpFilename(osFilename + ".tmp");
    CPLString osFilenameForNCCreate(osTmpFilename);
#if defined(WIN32) && !defined(NETCDF_USES_UTF8)
    if (CPLTestBool(CPLGetConfigOption("GDAL_FILENAME_IS_UTF8", "YES")))
    {
        char *pszTemp =
            CPLRecode(osFilenameForNCCreate, CPL_ENC_UTF8, "CP_ACP");
        osFilenameForNCCreate = pszTemp;
        CPLFree(pszTemp);
    }
#endif
    int status = nc_create(osFilenameForNCCreate, nCreationMode, &new_cdfid);
    NCDF_ERR(status);
    if (status != NC_NOERR)
        return false;

    if (!CloneGrp(cdfid, new_cdfid, eFormat == NCDF_FORMAT_NC4, nLayerId,
                  nDimIdToGrow, nNewSize))
    {
        GDAL_nc_close(new_cdfid);
        return false;
    }

#ifdef NETCDF_HAS_NC4
    int nGroupCount = 0;
    std::vector<CPLString> oListGrpName;
    if (eFormat == NCDF_FORMAT_NC4 &&
        nc_inq_grps(cdfid, &nGroupCount, nullptr) == NC_NOERR &&
        nGroupCount > 0)
    {
        int *panGroupIds =
            static_cast<int *>(CPLMalloc(sizeof(int) * nGroupCount));
        status = nc_inq_grps(cdfid, nullptr, panGroupIds);
        NCDF_ERR(status);
        for (int i = 0; i < nGroupCount; i++)
        {
            char szGroupName[NC_MAX_NAME + 1];
            szGroupName[0] = 0;
            nc_inq_grpname(panGroupIds[i], szGroupName);
            int nNewGrpId = -1;
            status = nc_def_grp(new_cdfid, szGroupName, &nNewGrpId);
            NCDF_ERR(status);
            if (status != NC_NOERR)
            {
                CPLFree(panGroupIds);
                GDAL_nc_close(new_cdfid);
                return false;
            }
            if (!CloneGrp(panGroupIds[i], nNewGrpId, eFormat == NCDF_FORMAT_NC4,
                          nLayerId, nDimIdToGrow, nNewSize))
            {
                CPLFree(panGroupIds);
                GDAL_nc_close(new_cdfid);
                return false;
            }
        }
        CPLFree(panGroupIds);

        for (int i = 0; i < this->GetLayerCount(); i++)
        {
            auto poLayer = dynamic_cast<netCDFLayer *>(papoLayers[i].get());
            if (poLayer)
            {
                char szGroupName[NC_MAX_NAME + 1];
                szGroupName[0] = 0;
                status = nc_inq_grpname(poLayer->GetCDFID(), szGroupName);
                NCDF_ERR(status);
                oListGrpName.push_back(szGroupName);
            }
        }
    }
#endif

    GDAL_nc_close(cdfid);
    cdfid = -1;
    GDAL_nc_close(new_cdfid);

    CPLString osOriFilename(osFilename + ".ori");
    if (VSIRename(osFilename, osOriFilename) != 0 ||
        VSIRename(osTmpFilename, osFilename) != 0)
    {
        CPLError(CE_Failure, CPLE_FileIO, "Renaming of files failed");
        return false;
    }
    VSIUnlink(osOriFilename);

    CPLString osFilenameForNCOpen(osFilename);
#if defined(WIN32) && !defined(NETCDF_USES_UTF8)
    if (CPLTestBool(CPLGetConfigOption("GDAL_FILENAME_IS_UTF8", "YES")))
    {
        char *pszTemp = CPLRecode(osFilenameForNCOpen, CPL_ENC_UTF8, "CP_ACP");
        osFilenameForNCOpen = pszTemp;
        CPLFree(pszTemp);
    }
#endif
    status = GDAL_nc_open(osFilenameForNCOpen, NC_WRITE, &cdfid);
    NCDF_ERR(status);
    if (status != NC_NOERR)
        return false;
    bDefineMode = false;

#ifdef NETCDF_HAS_NC4
    if (!oListGrpName.empty())
    {
        for (int i = 0; i < this->GetLayerCount(); i++)
        {
            auto poLayer = dynamic_cast<netCDFLayer *>(papoLayers[i].get());
            if (poLayer)
            {
                int nNewLayerCDFID = -1;
                status = nc_inq_ncid(cdfid, oListGrpName[i].c_str(),
                                     &nNewLayerCDFID);
                NCDF_ERR(status);
                poLayer->SetCDFID(nNewLayerCDFID);
            }
        }
    }
    else
#endif
    {
        for (int i = 0; i < this->GetLayerCount(); i++)
        {
            auto poLayer = dynamic_cast<netCDFLayer *>(papoLayers[i].get());
            if (poLayer)
                poLayer->SetCDFID(cdfid);
        }
    }

    return true;
}

/************************************************************************/
/*                              Identify()                              */
/************************************************************************/

int netCDFDataset::Identify(GDALOpenInfo *poOpenInfo)

{
    if (STARTS_WITH_CI(poOpenInfo->pszFilename, "NETCDF:"))
    {
        return TRUE;
    }
    const NetCDFFormatEnum eTmpFormat = IdentifyFormat(poOpenInfo,
                                                       /* bCheckExt = */ true);
    if (NCDF_FORMAT_NC == eTmpFormat || NCDF_FORMAT_NC2 == eTmpFormat ||
        NCDF_FORMAT_NC4 == eTmpFormat || NCDF_FORMAT_NC4C == eTmpFormat)
        return TRUE;

    return FALSE;
}

#ifdef ENABLE_NCDUMP

/************************************************************************/
/*                      netCDFDatasetCreateTempFile()                   */
/************************************************************************/

/* Create a netCDF file from a text dump (format of ncdump) */
/* Mostly to easy fuzzing of the driver, while still generating valid */
/* netCDF files. */
/* Note: not all data types are supported ! */
bool netCDFDatasetCreateTempFile(NetCDFFormatEnum eFormat,
                                 const char *pszTmpFilename, VSILFILE *fpSrc)
{
    CPL_IGNORE_RET_VAL(eFormat);
    int nCreateMode = NC_CLOBBER;
#ifdef NETCDF_HAS_NC4
    if (eFormat == NCDF_FORMAT_NC4)
        nCreateMode |= NC_NETCDF4;
    else if (eFormat == NCDF_FORMAT_NC4C)
        nCreateMode |= NC_NETCDF4 | NC_CLASSIC_MODEL;
#endif
    int nCdfId = -1;
    int status = nc_create(pszTmpFilename, nCreateMode, &nCdfId);
    if (status != NC_NOERR)
    {
        return false;
    }
    VSIFSeekL(fpSrc, 0, SEEK_SET);
    const char *pszLine;
    constexpr int SECTION_NONE = 0;
    constexpr int SECTION_DIMENSIONS = 1;
    constexpr int SECTION_VARIABLES = 2;
    constexpr int SECTION_DATA = 3;
    int nActiveSection = SECTION_NONE;
    std::map<CPLString, int> oMapDimToId;
    std::map<int, int> oMapDimIdToDimLen;
    std::map<CPLString, int> oMapVarToId;
    std::map<int, std::vector<int>> oMapVarIdToVectorOfDimId;
    std::map<int, int> oMapVarIdToType;
    std::set<CPLString> oSetAttrDefined;
    oMapVarToId[""] = -1;
    size_t nTotalVarSize = 0;
    while ((pszLine = CPLReadLineL(fpSrc)) != nullptr)
    {
        if (STARTS_WITH(pszLine, "dimensions:") &&
            nActiveSection == SECTION_NONE)
        {
            nActiveSection = SECTION_DIMENSIONS;
        }
        else if (STARTS_WITH(pszLine, "variables:") &&
                 nActiveSection == SECTION_DIMENSIONS)
        {
            nActiveSection = SECTION_VARIABLES;
        }
        else if (STARTS_WITH(pszLine, "data:") &&
                 nActiveSection == SECTION_VARIABLES)
        {
            nActiveSection = SECTION_DATA;
            status = nc_enddef(nCdfId);
            if (status != NC_NOERR)
            {
                CPLDebug("netCDF", "nc_enddef() failed: %s",
                         nc_strerror(status));
            }
        }
        else if (nActiveSection == SECTION_DIMENSIONS)
        {
            char **papszTokens = CSLTokenizeString2(pszLine, " \t=;", 0);
            if (CSLCount(papszTokens) == 2)
            {
                const char *pszDimName = papszTokens[0];
                bool bValidName = true;
                if (STARTS_WITH(pszDimName, "_nc4_non_coord_"))
                {
                    // This is an internal netcdf prefix. Using it may
                    // cause memory leaks.
                    bValidName = false;
                }
                if (!bValidName)
                {
                    CPLDebug("netCDF",
                             "nc_def_dim(%s) failed: invalid name found",
                             pszDimName);
                    CSLDestroy(papszTokens);
                    continue;
                }

                const bool bIsASCII =
                    CPLIsASCII(pszDimName, static_cast<size_t>(-1));
                if (!bIsASCII)
                {
                    // Workaround https://github.com/Unidata/netcdf-c/pull/450
                    CPLDebug("netCDF",
                             "nc_def_dim(%s) failed: rejected because "
                             "of non-ASCII characters",
                             pszDimName);
                    CSLDestroy(papszTokens);
                    continue;
                }
                int nDimSize = EQUAL(papszTokens[1], "UNLIMITED")
                                   ? NC_UNLIMITED
                                   : atoi(papszTokens[1]);
                if (nDimSize >= 1000)
                    nDimSize = 1000;  // to avoid very long processing
                if (nDimSize >= 0)
                {
                    int nDimId = -1;
                    status = nc_def_dim(nCdfId, pszDimName, nDimSize, &nDimId);
                    if (status != NC_NOERR)
                    {
                        CPLDebug("netCDF", "nc_def_dim(%s, %d) failed: %s",
                                 pszDimName, nDimSize, nc_strerror(status));
                    }
                    else
                    {
#ifdef DEBUG_VERBOSE
                        CPLDebug("netCDF", "nc_def_dim(%s, %d) (%s) succeeded",
                                 pszDimName, nDimSize, pszLine);
#endif
                        oMapDimToId[pszDimName] = nDimId;
                        oMapDimIdToDimLen[nDimId] = nDimSize;
                    }
                }
            }
            CSLDestroy(papszTokens);
        }
        else if (nActiveSection == SECTION_VARIABLES)
        {
            while (*pszLine == ' ' || *pszLine == '\t')
                pszLine++;
            const char *pszColumn = strchr(pszLine, ':');
            const char *pszEqual = strchr(pszLine, '=');
            if (pszColumn == nullptr)
            {
                char **papszTokens = CSLTokenizeString2(pszLine, " \t=(),;", 0);
                if (CSLCount(papszTokens) >= 2)
                {
                    const char *pszVarName = papszTokens[1];
                    bool bValidName = true;
                    if (STARTS_WITH(pszVarName, "_nc4_non_coord_"))
                    {
                        // This is an internal netcdf prefix. Using it may
                        // cause memory leaks.
                        bValidName = false;
                    }
                    for (int i = 0; pszVarName[i]; i++)
                    {
                        if (!((pszVarName[i] >= 'a' && pszVarName[i] <= 'z') ||
                              (pszVarName[i] >= 'A' && pszVarName[i] <= 'Z') ||
                              (pszVarName[i] >= '0' && pszVarName[i] <= '9') ||
                              pszVarName[i] == '_'))
                        {
                            bValidName = false;
                        }
                    }
                    if (!bValidName)
                    {
                        CPLDebug(
                            "netCDF",
                            "nc_def_var(%s) failed: illegal character found",
                            pszVarName);
                        CSLDestroy(papszTokens);
                        continue;
                    }
                    if (oMapVarToId.find(pszVarName) != oMapVarToId.end())
                    {
                        CPLDebug("netCDF",
                                 "nc_def_var(%s) failed: already defined",
                                 pszVarName);
                        CSLDestroy(papszTokens);
                        continue;
                    }
                    const char *pszVarType = papszTokens[0];
                    int nc_datatype = NC_BYTE;
                    size_t nDataTypeSize = 1;
                    if (EQUAL(pszVarType, "char"))
                    {
                        nc_datatype = NC_CHAR;
                        nDataTypeSize = 1;
                    }
                    else if (EQUAL(pszVarType, "byte"))
                    {
                        nc_datatype = NC_BYTE;
                        nDataTypeSize = 1;
                    }
                    else if (EQUAL(pszVarType, "short"))
                    {
                        nc_datatype = NC_SHORT;
                        nDataTypeSize = 2;
                    }
                    else if (EQUAL(pszVarType, "int"))
                    {
                        nc_datatype = NC_INT;
                        nDataTypeSize = 4;
                    }
                    else if (EQUAL(pszVarType, "float"))
                    {
                        nc_datatype = NC_FLOAT;
                        nDataTypeSize = 4;
                    }
                    else if (EQUAL(pszVarType, "double"))
                    {
                        nc_datatype = NC_DOUBLE;
                        nDataTypeSize = 8;
                    }
#ifdef NETCDF_HAS_NC4
                    else if (EQUAL(pszVarType, "ubyte"))
                    {
                        nc_datatype = NC_UBYTE;
                        nDataTypeSize = 1;
                    }
                    else if (EQUAL(pszVarType, "ushort"))
                    {
                        nc_datatype = NC_USHORT;
                        nDataTypeSize = 2;
                    }
                    else if (EQUAL(pszVarType, "uint"))
                    {
                        nc_datatype = NC_UINT;
                        nDataTypeSize = 4;
                    }
                    else if (EQUAL(pszVarType, "int64"))
                    {
                        nc_datatype = NC_INT64;
                        nDataTypeSize = 8;
                    }
                    else if (EQUAL(pszVarType, "uint64"))
                    {
                        nc_datatype = NC_UINT64;
                        nDataTypeSize = 8;
                    }
#endif

                    int nDims = CSLCount(papszTokens) - 2;
                    if (nDims >= 32)
                    {
                        // The number of dimensions in a netCDFv4 file is
                        // limited by #define H5S_MAX_RANK    32
                        // but libnetcdf doesn't check that...
                        CPLDebug("netCDF",
                                 "nc_def_var(%s) failed: too many dimensions",
                                 pszVarName);
                        CSLDestroy(papszTokens);
                        continue;
                    }
                    std::vector<int> aoDimIds;
                    bool bFailed = false;
                    size_t nSize = 1;
                    for (int i = 0; i < nDims; i++)
                    {
                        const char *pszDimName = papszTokens[2 + i];
                        if (oMapDimToId.find(pszDimName) == oMapDimToId.end())
                        {
                            bFailed = true;
                            break;
                        }
                        const int nDimId = oMapDimToId[pszDimName];
                        aoDimIds.push_back(nDimId);

                        const size_t nDimSize = oMapDimIdToDimLen[nDimId];
                        if (nDimSize != 0)
                        {
                            if (nSize >
                                std::numeric_limits<size_t>::max() / nDimSize)
                            {
                                bFailed = true;
                                break;
                            }
                            else
                            {
                                nSize *= nDimSize;
                            }
                        }
                    }
                    if (bFailed)
                    {
                        CPLDebug("netCDF",
                                 "nc_def_var(%s) failed: unknown dimension(s)",
                                 pszVarName);
                        CSLDestroy(papszTokens);
                        continue;
                    }
                    if (nSize > 100U * 1024 * 1024 / nDataTypeSize)
                    {
                        CPLDebug("netCDF",
                                 "nc_def_var(%s) failed: too large data",
                                 pszVarName);
                        CSLDestroy(papszTokens);
                        continue;
                    }
                    if (nTotalVarSize >
                            std::numeric_limits<size_t>::max() - nSize ||
                        nTotalVarSize + nSize > 100 * 1024 * 1024)
                    {
                        CPLDebug("netCDF",
                                 "nc_def_var(%s) failed: too large data",
                                 pszVarName);
                        CSLDestroy(papszTokens);
                        continue;
                    }
                    nTotalVarSize += nSize;

                    int nVarId = -1;
                    status =
                        nc_def_var(nCdfId, pszVarName, nc_datatype, nDims,
                                   (nDims) ? &aoDimIds[0] : nullptr, &nVarId);
                    if (status != NC_NOERR)
                    {
                        CPLDebug("netCDF", "nc_def_var(%s) failed: %s",
                                 pszVarName, nc_strerror(status));
                    }
                    else
                    {
#ifdef DEBUG_VERBOSE
                        CPLDebug("netCDF", "nc_def_var(%s) (%s) succeeded",
                                 pszVarName, pszLine);
#endif
                        oMapVarToId[pszVarName] = nVarId;
                        oMapVarIdToType[nVarId] = nc_datatype;
                        oMapVarIdToVectorOfDimId[nVarId] = aoDimIds;
                    }
                }
                CSLDestroy(papszTokens);
            }
            else if (pszEqual != nullptr && pszEqual - pszColumn > 0)
            {
                CPLString osVarName(pszLine, pszColumn - pszLine);
                CPLString osAttrName(pszColumn + 1, pszEqual - pszColumn - 1);
                osAttrName.Trim();
                if (oMapVarToId.find(osVarName) == oMapVarToId.end())
                {
                    CPLDebug("netCDF",
                             "nc_put_att(%s:%s) failed: "
                             "no corresponding variable",
                             osVarName.c_str(), osAttrName.c_str());
                    continue;
                }
                bool bValidName = true;
                for (size_t i = 0; i < osAttrName.size(); i++)
                {
                    if (!((osAttrName[i] >= 'a' && osAttrName[i] <= 'z') ||
                          (osAttrName[i] >= 'A' && osAttrName[i] <= 'Z') ||
                          (osAttrName[i] >= '0' && osAttrName[i] <= '9') ||
                          osAttrName[i] == '_'))
                    {
                        bValidName = false;
                    }
                }
                if (!bValidName)
                {
                    CPLDebug(
                        "netCDF",
                        "nc_put_att(%s:%s) failed: illegal character found",
                        osVarName.c_str(), osAttrName.c_str());
                    continue;
                }
                if (oSetAttrDefined.find(osVarName + ":" + osAttrName) !=
                    oSetAttrDefined.end())
                {
                    CPLDebug("netCDF",
                             "nc_put_att(%s:%s) failed: already defined",
                             osVarName.c_str(), osAttrName.c_str());
                    continue;
                }

                const int nVarId = oMapVarToId[osVarName];
                const char *pszValue = pszEqual + 1;
                while (*pszValue == ' ')
                    pszValue++;

                status = NC_EBADTYPE;
                if (*pszValue == '"')
                {
                    // For _FillValue, the attribute type should match
                    // the variable type. Leaks memory with NC4 otherwise
                    if (osAttrName == "_FillValue")
                    {
                        CPLDebug("netCDF", "nc_put_att_(%s:%s) failed: %s",
                                 osVarName.c_str(), osAttrName.c_str(),
                                 nc_strerror(status));
                        continue;
                    }

                    // Unquote and unescape string value
                    CPLString osVal(pszValue + 1);
                    while (!osVal.empty())
                    {
                        if (osVal.back() == ';' || osVal.back() == ' ')
                        {
                            osVal.resize(osVal.size() - 1);
                        }
                        else if (osVal.back() == '"')
                        {
                            osVal.resize(osVal.size() - 1);
                            break;
                        }
                        else
                        {
                            break;
                        }
                    }
                    osVal.replaceAll("\\\"", '"');
                    status = nc_put_att_text(nCdfId, nVarId, osAttrName,
                                             osVal.size(), osVal.c_str());
                }
                else
                {
                    CPLString osVal(pszValue);
                    while (!osVal.empty())
                    {
                        if (osVal.back() == ';' || osVal.back() == ' ')
                        {
                            osVal.resize(osVal.size() - 1);
                        }
                        else
                        {
                            break;
                        }
                    }
                    int nc_datatype = -1;
                    if (!osVal.empty() && osVal.back() == 'b')
                    {
                        nc_datatype = NC_BYTE;
                        osVal.resize(osVal.size() - 1);
                    }
                    else if (!osVal.empty() && osVal.back() == 's')
                    {
                        nc_datatype = NC_SHORT;
                        osVal.resize(osVal.size() - 1);
                    }
                    if (CPLGetValueType(osVal) == CPL_VALUE_INTEGER)
                    {
                        if (nc_datatype < 0)
                            nc_datatype = NC_INT;
                    }
                    else if (CPLGetValueType(osVal) == CPL_VALUE_REAL)
                    {
                        nc_datatype = NC_DOUBLE;
                    }
                    else
                    {
                        nc_datatype = -1;
                    }

                    // For _FillValue, check that the attribute type matches
                    // the variable type. Leaks memory with NC4 otherwise
                    if (osAttrName == "_FillValue")
                    {
                        if (nVarId < 0 ||
                            nc_datatype != oMapVarIdToType[nVarId])
                        {
                            nc_datatype = -1;
                        }
                    }

                    if (nc_datatype == NC_BYTE)
                    {
                        signed char chVal =
                            static_cast<signed char>(atoi(osVal));
                        status = nc_put_att_schar(nCdfId, nVarId, osAttrName,
                                                  NC_BYTE, 1, &chVal);
                    }
                    else if (nc_datatype == NC_SHORT)
                    {
                        short nVal = static_cast<short>(atoi(osVal));
                        status = nc_put_att_short(nCdfId, nVarId, osAttrName,
                                                  NC_SHORT, 1, &nVal);
                    }
                    else if (nc_datatype == NC_INT)
                    {
                        int nVal = static_cast<int>(atoi(osVal));
                        status = nc_put_att_int(nCdfId, nVarId, osAttrName,
                                                NC_INT, 1, &nVal);
                    }
                    else if (nc_datatype == NC_DOUBLE)
                    {
                        double dfVal = CPLAtof(osVal);
                        status = nc_put_att_double(nCdfId, nVarId, osAttrName,
                                                   NC_DOUBLE, 1, &dfVal);
                    }
                }
                if (status != NC_NOERR)
                {
                    CPLDebug("netCDF", "nc_put_att_(%s:%s) failed: %s",
                             osVarName.c_str(), osAttrName.c_str(),
                             nc_strerror(status));
                }
                else
                {
                    oSetAttrDefined.insert(osVarName + ":" + osAttrName);
#ifdef DEBUG_VERBOSE
                    CPLDebug("netCDF", "nc_put_att_(%s:%s) (%s) succeeded",
                             osVarName.c_str(), osAttrName.c_str(), pszLine);
#endif
                }
            }
        }
        else if (nActiveSection == SECTION_DATA)
        {
            while (*pszLine == ' ' || *pszLine == '\t')
                pszLine++;
            const char *pszEqual = strchr(pszLine, '=');
            if (pszEqual)
            {
                CPLString osVarName(pszLine, pszEqual - pszLine);
                osVarName.Trim();
                if (oMapVarToId.find(osVarName) == oMapVarToId.end())
                    continue;
                const int nVarId = oMapVarToId[osVarName];
                CPLString osAccVal(pszEqual + 1);
                osAccVal.Trim();
                while (osAccVal.empty() || osAccVal.back() != ';')
                {
                    pszLine = CPLReadLineL(fpSrc);
                    if (pszLine == nullptr)
                        break;
                    CPLString osVal(pszLine);
                    osVal.Trim();
                    osAccVal += osVal;
                }
                if (pszLine == nullptr)
                    break;
                osAccVal.resize(osAccVal.size() - 1);

                const std::vector<int> aoDimIds =
                    oMapVarIdToVectorOfDimId[nVarId];
                size_t nSize = 1;
                std::vector<size_t> aoStart, aoEdge;
                aoStart.resize(aoDimIds.size());
                aoEdge.resize(aoDimIds.size());
                for (size_t i = 0; i < aoDimIds.size(); ++i)
                {
                    const size_t nDimSize = oMapDimIdToDimLen[aoDimIds[i]];
                    if (nDimSize != 0 &&
                        nSize > std::numeric_limits<size_t>::max() / nDimSize)
                    {
                        nSize = 0;
                    }
                    else
                    {
                        nSize *= nDimSize;
                    }
                    aoStart[i] = 0;
                    aoEdge[i] = nDimSize;
                }

                status = NC_EBADTYPE;
                if (nSize == 0)
                {
                    // Might happen with a unlimited dimension
                }
                else if (oMapVarIdToType[nVarId] == NC_DOUBLE)
                {
                    if (!aoStart.empty())
                    {
                        char **papszTokens =
                            CSLTokenizeString2(osAccVal, " ,;", 0);
                        size_t nTokens = CSLCount(papszTokens);
                        if (nTokens >= nSize)
                        {
                            double *padfVals = static_cast<double *>(
                                VSI_CALLOC_VERBOSE(nSize, sizeof(double)));
                            if (padfVals)
                            {
                                for (size_t i = 0; i < nSize; i++)
                                {
                                    padfVals[i] = CPLAtof(papszTokens[i]);
                                }
                                status = nc_put_vara_double(
                                    nCdfId, nVarId, &aoStart[0], &aoEdge[0],
                                    padfVals);
                                VSIFree(padfVals);
                            }
                        }
                        CSLDestroy(papszTokens);
                    }
                }
                else if (oMapVarIdToType[nVarId] == NC_BYTE)
                {
                    if (!aoStart.empty())
                    {
                        char **papszTokens =
                            CSLTokenizeString2(osAccVal, " ,;", 0);
                        size_t nTokens = CSLCount(papszTokens);
                        if (nTokens >= nSize)
                        {
                            signed char *panVals = static_cast<signed char *>(
                                VSI_CALLOC_VERBOSE(nSize, sizeof(signed char)));
                            if (panVals)
                            {
                                for (size_t i = 0; i < nSize; i++)
                                {
                                    panVals[i] = static_cast<signed char>(
                                        atoi(papszTokens[i]));
                                }
                                status = nc_put_vara_schar(nCdfId, nVarId,
                                                           &aoStart[0],
                                                           &aoEdge[0], panVals);
                                VSIFree(panVals);
                            }
                        }
                        CSLDestroy(papszTokens);
                    }
                }
                else if (oMapVarIdToType[nVarId] == NC_CHAR)
                {
                    if (aoStart.size() == 2)
                    {
                        std::vector<CPLString> aoStrings;
                        bool bInString = false;
                        CPLString osCurString;
                        for (size_t i = 0; i < osAccVal.size();)
                        {
                            if (!bInString)
                            {
                                if (osAccVal[i] == '"')
                                {
                                    bInString = true;
                                    osCurString.clear();
                                }
                                i++;
                            }
                            else if (osAccVal[i] == '\\' &&
                                     i + 1 < osAccVal.size() &&
                                     osAccVal[i + 1] == '"')
                            {
                                osCurString += '"';
                                i += 2;
                            }
                            else if (osAccVal[i] == '"')
                            {
                                aoStrings.push_back(osCurString);
                                osCurString.clear();
                                bInString = false;
                                i++;
                            }
                            else
                            {
                                osCurString += osAccVal[i];
                                i++;
                            }
                        }
                        const size_t nRecords = oMapDimIdToDimLen[aoDimIds[0]];
                        const size_t nWidth = oMapDimIdToDimLen[aoDimIds[1]];
                        size_t nIters = aoStrings.size();
                        if (nIters > nRecords)
                            nIters = nRecords;
                        for (size_t i = 0; i < nIters; i++)
                        {
                            size_t anIndex[2];
                            anIndex[0] = i;
                            anIndex[1] = 0;
                            size_t anCount[2];
                            anCount[0] = 1;
                            anCount[1] = aoStrings[i].size();
                            if (anCount[1] > nWidth)
                                anCount[1] = nWidth;
                            status =
                                nc_put_vara_text(nCdfId, nVarId, anIndex,
                                                 anCount, aoStrings[i].c_str());
                            if (status != NC_NOERR)
                                break;
                        }
                    }
                }
                if (status != NC_NOERR)
                {
                    CPLDebug("netCDF", "nc_put_var_(%s) failed: %s",
                             osVarName.c_str(), nc_strerror(status));
                }
            }
        }
    }

    GDAL_nc_close(nCdfId);
    return true;
}

#endif  // ENABLE_NCDUMP

/************************************************************************/
/*                                Open()                                */
/************************************************************************/

GDALDataset *netCDFDataset::Open(GDALOpenInfo *poOpenInfo)

{
#ifdef NCDF_DEBUG
    CPLDebug("GDAL_netCDF", "\n=====\nOpen(), filename=[%s]",
             poOpenInfo->pszFilename);
#endif

    // Does this appear to be a netcdf file?
    NetCDFFormatEnum eTmpFormat = NCDF_FORMAT_NONE;
    if (!STARTS_WITH_CI(poOpenInfo->pszFilename, "NETCDF:"))
    {
        eTmpFormat = IdentifyFormat(poOpenInfo, /* bCheckExt = */ true);
#ifdef NCDF_DEBUG
        CPLDebug("GDAL_netCDF", "identified format %d", eTmpFormat);
#endif
        // Note: not calling Identify() directly, because we want the file type.
        // Only support NCDF_FORMAT* formats.
        if (!(NCDF_FORMAT_NC == eTmpFormat || NCDF_FORMAT_NC2 == eTmpFormat ||
              NCDF_FORMAT_NC4 == eTmpFormat || NCDF_FORMAT_NC4C == eTmpFormat))
            return nullptr;
    }
    else
    {
#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
        // We don't necessarily want to catch bugs in libnetcdf ...
        if (CPLGetConfigOption("DISABLE_OPEN_REAL_NETCDF_FILES", nullptr))
        {
            return nullptr;
        }
#endif
    }

#ifdef NETCDF_HAS_NC4
    if (poOpenInfo->nOpenFlags & GDAL_OF_MULTIDIM_RASTER)
    {
        return OpenMultiDim(poOpenInfo);
    }
#endif

    CPLMutexHolderD(&hNCMutex);

    CPLReleaseMutex(hNCMutex);  // Release mutex otherwise we'll deadlock with
                                // GDALDataset own mutex.
    netCDFDataset *poDS = new netCDFDataset();
    poDS->papszOpenOptions = CSLDuplicate(poOpenInfo->papszOpenOptions);
    CPLAcquireMutex(hNCMutex, 1000.0);

    poDS->SetDescription(poOpenInfo->pszFilename);

    // Check if filename start with NETCDF: tag.
    bool bTreatAsSubdataset = false;
    CPLString osSubdatasetName;

#ifdef ENABLE_NCDUMP
    const char *pszHeader =
        reinterpret_cast<const char *>(poOpenInfo->pabyHeader);
    if (poOpenInfo->fpL != nullptr && STARTS_WITH(pszHeader, "netcdf ") &&
        strstr(pszHeader, "dimensions:") && strstr(pszHeader, "variables:"))
    {
        // By default create a temporary file that will be destroyed,
        // unless NETCDF_TMP_FILE is defined. Can be useful to see which
        // netCDF file has been generated from a potential fuzzed input.
        poDS->osFilename = CPLGetConfigOption("NETCDF_TMP_FILE", "");
        if (poDS->osFilename.empty())
        {
            poDS->bFileToDestroyAtClosing = true;
            poDS->osFilename = CPLGenerateTempFilename("netcdf_tmp");
        }
        if (!netCDFDatasetCreateTempFile(eTmpFormat, poDS->osFilename,
                                         poOpenInfo->fpL))
        {
            CPLReleaseMutex(hNCMutex);  // Release mutex otherwise we'll
                                        // deadlock with GDALDataset own mutex.
            delete poDS;
            CPLAcquireMutex(hNCMutex, 1000.0);
            return nullptr;
        }
        bTreatAsSubdataset = false;
        poDS->eFormat = eTmpFormat;
    }
    else
#endif

        if (STARTS_WITH_CI(poOpenInfo->pszFilename, "NETCDF:"))
    {
        char **papszName =
            CSLTokenizeString2(poOpenInfo->pszFilename, ":",
                               CSLT_HONOURSTRINGS | CSLT_PRESERVEESCAPES);

        if (CSLCount(papszName) >= 3 &&
            ((strlen(papszName[1]) == 1 && /* D:\\bla */
              (papszName[2][0] == '/' || papszName[2][0] == '\\')) ||
             EQUAL(papszName[1], "http") || EQUAL(papszName[1], "https") ||
             EQUAL(papszName[1], "/vsicurl/http") ||
             EQUAL(papszName[1], "/vsicurl/https") ||
             EQUAL(papszName[1], "/vsicurl_streaming/http") ||
             EQUAL(papszName[1], "/vsicurl_streaming/https")))
        {
            const int nCountBefore = CSLCount(papszName);
            CPLString osTmp = papszName[1];
            osTmp += ':';
            osTmp += papszName[2];
            CPLFree(papszName[1]);
            CPLFree(papszName[2]);
            papszName[1] = CPLStrdup(osTmp);
            memmove(papszName + 2, papszName + 3,
                    (nCountBefore - 2) * sizeof(char *));
        }

        if (CSLCount(papszName) == 3)
        {
            poDS->osFilename = papszName[1];
            osSubdatasetName = papszName[2];
            bTreatAsSubdataset = true;
            CSLDestroy(papszName);
        }
        else if (CSLCount(papszName) == 2)
        {
            poDS->osFilename = papszName[1];
            osSubdatasetName = "";
            bTreatAsSubdataset = false;
            CSLDestroy(papszName);
        }
        else
        {
            CSLDestroy(papszName);
            CPLReleaseMutex(hNCMutex);  // Release mutex otherwise we'll
                                        // deadlock with GDALDataset own mutex.
            delete poDS;
            CPLAcquireMutex(hNCMutex, 1000.0);
            CPLError(CE_Failure, CPLE_AppDefined,
                     "Failed to parse NETCDF: prefix string into expected 2, 3 "
                     "or 4 fields.");
            return nullptr;
        }

        if (!STARTS_WITH(poDS->osFilename, "http://") &&
            !STARTS_WITH(poDS->osFilename, "https://"))
        {
            // Identify Format from real file, with bCheckExt=FALSE.
            GDALOpenInfo *poOpenInfo2 =
                new GDALOpenInfo(poDS->osFilename.c_str(), GA_ReadOnly);
            poDS->eFormat =
                IdentifyFormat(poOpenInfo2, /* bCheckExt = */ false);
            delete poOpenInfo2;
            if (NCDF_FORMAT_NONE == poDS->eFormat ||
                NCDF_FORMAT_UNKNOWN == poDS->eFormat)
            {
                CPLReleaseMutex(hNCMutex);  // Release mutex otherwise we'll
                    // deadlock with GDALDataset own mutex.
                delete poDS;
                CPLAcquireMutex(hNCMutex, 1000.0);
                return nullptr;
            }
        }
    }
    else
    {
        poDS->osFilename = poOpenInfo->pszFilename;
        bTreatAsSubdataset = false;
        poDS->eFormat = eTmpFormat;
    }

    // Try opening the dataset.
#if defined(NCDF_DEBUG) && defined(ENABLE_UFFD)
    CPLDebug("GDAL_netCDF", "calling nc_open_mem(%s)",
             poDS->osFilename.c_str());
#elif defined(NCDF_DEBUG) && !defined(ENABLE_UFFD)
    CPLDebug("GDAL_netCDF", "calling nc_open(%s)", poDS->osFilename.c_str());
#endif
    int cdfid = -1;
    const int nMode = ((poOpenInfo->nOpenFlags & GDAL_OF_UPDATE) != 0)
                          ? NC_WRITE
                          : NC_NOWRITE;
    CPLString osFilenameForNCOpen(poDS->osFilename);
#if defined(WIN32) && !defined(NETCDF_USES_UTF8)
    if (CPLTestBool(CPLGetConfigOption("GDAL_FILENAME_IS_UTF8", "YES")))
    {
        char *pszTemp = CPLRecode(osFilenameForNCOpen, CPL_ENC_UTF8, "CP_ACP");
        osFilenameForNCOpen = pszTemp;
        CPLFree(pszTemp);
    }
#endif
    int status2 = -1;

#ifdef ENABLE_UFFD
    cpl_uffd_context *pCtx = nullptr;
#endif

#ifdef HAVE_NETCDF_MEM
    if (STARTS_WITH(osFilenameForNCOpen, "/vsimem/") &&
        poOpenInfo->eAccess == GA_ReadOnly)
    {
        vsi_l_offset nLength = 0;
        poDS->fpVSIMEM = VSIFOpenL(osFilenameForNCOpen, "rb");
        if (poDS->fpVSIMEM)
        {
            // We assume that the file will not be modified. If it is, then
            // pabyBuffer might become invalid.
            GByte *pabyBuffer =
                VSIGetMemFileBuffer(osFilenameForNCOpen, &nLength, false);
            if (pabyBuffer)
            {
                status2 = nc_open_mem(CPLGetFilename(osFilenameForNCOpen),
                                      nMode, static_cast<size_t>(nLength),
                                      pabyBuffer, &cdfid);
            }
        }
    }
    else
#endif
    {
#ifdef ENABLE_UFFD
        bool bVsiFile = !strncmp(osFilenameForNCOpen, "/vsi", strlen("/vsi"));
        bool bReadOnly = (poOpenInfo->eAccess == GA_ReadOnly);
        void *pVma = nullptr;
        uint64_t nVmaSize = 0;

        if (bVsiFile && bReadOnly && CPLIsUserFaultMappingSupported())
            pCtx = CPLCreateUserFaultMapping(osFilenameForNCOpen, &pVma,
                                             &nVmaSize);
        if (pCtx != nullptr && pVma != nullptr && nVmaSize > 0)
        {
            // netCDF code, at least for netCDF 4.7.0, is confused by filenames
            // like /vsicurl/http[s]://example.com/foo.nc, so just pass the
            // final part
            status2 = nc_open_mem(CPLGetFilename(osFilenameForNCOpen), nMode,
                                  static_cast<size_t>(nVmaSize), pVma, &cdfid);
        }
        else
            status2 = GDAL_nc_open(osFilenameForNCOpen, nMode, &cdfid);
#else
        status2 = GDAL_nc_open(osFilenameForNCOpen, nMode, &cdfid);
#endif
    }
    if (status2 != NC_NOERR)
    {
#ifdef NCDF_DEBUG
        CPLDebug("GDAL_netCDF", "error opening");
#endif
        CPLReleaseMutex(hNCMutex);  // Release mutex otherwise we'll deadlock
                                    // with GDALDataset own mutex.
        delete poDS;
        CPLAcquireMutex(hNCMutex, 1000.0);
        return nullptr;
    }
#ifdef NCDF_DEBUG
    CPLDebug("GDAL_netCDF", "got cdfid=%d", cdfid);
#endif

#if defined(ENABLE_NCDUMP) && !defined(WIN32)
    // Try to destroy the temporary file right now on Unix
    if (poDS->bFileToDestroyAtClosing)
    {
        if (VSIUnlink(poDS->osFilename) == 0)
        {
            poDS->bFileToDestroyAtClosing = false;
        }
    }
#endif

    // Is this a real netCDF file?
    int ndims;
    int ngatts;
    int nvars;
    int unlimdimid;
    int status = nc_inq(cdfid, &ndims, &nvars, &ngatts, &unlimdimid);
    if (status != NC_NOERR)
    {
        CPLReleaseMutex(hNCMutex);  // Release mutex otherwise we'll deadlock
                                    // with GDALDataset own mutex.
        delete poDS;
        CPLAcquireMutex(hNCMutex, 1000.0);
        return nullptr;
    }

    // Get file type from netcdf.
    int nTmpFormat = NCDF_FORMAT_NONE;
    status = nc_inq_format(cdfid, &nTmpFormat);
    if (status != NC_NOERR)
    {
        NCDF_ERR(status);
    }
    else
    {
        CPLDebug("GDAL_netCDF",
                 "driver detected file type=%d, libnetcdf detected type=%d",
                 poDS->eFormat, nTmpFormat);
        if (static_cast<NetCDFFormatEnum>(nTmpFormat) != poDS->eFormat)
        {
            // Warn if file detection conflicts with that from libnetcdf
            // except for NC4C, which we have no way of detecting initially.
            if (nTmpFormat != NCDF_FORMAT_NC4C &&
                !STARTS_WITH(poDS->osFilename, "http://") &&
                !STARTS_WITH(poDS->osFilename, "https://"))
            {
                CPLError(CE_Warning, CPLE_AppDefined,
                         "NetCDF driver detected file type=%d, but libnetcdf "
                         "detected type=%d",
                         poDS->eFormat, nTmpFormat);
            }
            CPLDebug("GDAL_netCDF", "setting file type to %d, was %d",
                     nTmpFormat, poDS->eFormat);
            poDS->eFormat = static_cast<NetCDFFormatEnum>(nTmpFormat);
        }
    }

    // Does the request variable exist?
    if (bTreatAsSubdataset)
    {
        int dummy;
        if (NCDFOpenSubDataset(cdfid, osSubdatasetName.c_str(), &dummy,
                               &dummy) != CE_None)
        {
            CPLError(CE_Warning, CPLE_AppDefined,
                     "%s is a netCDF file, but %s is not a variable.",
                     poOpenInfo->pszFilename, osSubdatasetName.c_str());

            GDAL_nc_close(cdfid);
#ifdef ENABLE_UFFD
            NETCDF_UFFD_UNMAP(pCtx);
#endif
            CPLReleaseMutex(hNCMutex);  // Release mutex otherwise we'll
                                        // deadlock with GDALDataset own mutex.
            delete poDS;
            CPLAcquireMutex(hNCMutex, 1000.0);
            return nullptr;
        }
    }

    // Figure out whether or not the listed dataset has support for simple
    // geometries (CF-1.8)
    poDS->nCFVersion = nccfdriver::getCFVersion(cdfid);
    if (poDS->nCFVersion >= 1.8)
    {
        poDS->bSGSupport = true;
        poDS->DetectAndFillSGLayers(cdfid);
        poDS->vcdf.enableFullVirtualMode();
    }
    else
    {
        poDS->bSGSupport = false;
    }

    char szConventions[NC_MAX_NAME + 1];
    szConventions[0] = '\0';
    nc_type nAttype = NC_NAT;
    size_t nAttlen = 0;
    nc_inq_att(cdfid, NC_GLOBAL, "Conventions", &nAttype, &nAttlen);
    if (nAttlen >= sizeof(szConventions) ||
        nc_get_att_text(cdfid, NC_GLOBAL, "Conventions", szConventions) !=
            NC_NOERR)
    {
        CPLDebug("GDAL_netCDF", "No UNIDATA NC_GLOBAL:Conventions attribute");
        // Note that 'Conventions' is always capital 'C' in CF spec.
    }
    else
    {
        szConventions[nAttlen] = '\0';
    }

    // Create band information objects.
    CPLDebug("GDAL_netCDF", "var_count = %d", nvars);

    // Create a corresponding GDALDataset.
    // Create Netcdf Subdataset if filename as NETCDF tag.
    poDS->cdfid = cdfid;
#ifdef ENABLE_UFFD
    poDS->pCtx = pCtx;
#endif
    poDS->eAccess = poOpenInfo->eAccess;
    poDS->bDefineMode = false;

    poDS->ReadAttributes(cdfid, NC_GLOBAL);

    // Identify coordinate and boundary variables that we should
    // ignore as Raster Bands.
    char **papszIgnoreVars = nullptr;
    NCDFGetCoordAndBoundVarFullNames(cdfid, &papszIgnoreVars);
    // Filter variables to keep only valid 2+D raster bands and vector fields.
    int nRasterVars = 0;
    int nIgnoredVars = 0;
    int nGroupID = -1;
    int nVarID = -1;

    std::map<std::array<int, 3>, std::vector<std::pair<int, int>>>
        oMap2DDimsToGroupAndVar;
#ifdef NETCDF_HAS_NC4
    if ((poOpenInfo->nOpenFlags & GDAL_OF_VECTOR) != 0 &&
        STARTS_WITH(CSLFetchNameValueDef(poDS->papszMetadata,
                                         "NC_GLOBAL#mission_name", ""),
                    "Sentinel 3") &&
        EQUAL(CSLFetchNameValueDef(poDS->papszMetadata,
                                   "NC_GLOBAL#altimeter_sensor_name", ""),
              "SRAL") &&
        EQUAL(CSLFetchNameValueDef(poDS->papszMetadata,
                                   "NC_GLOBAL#radiometer_sensor_name", ""),
              "MWR"))
    {
        if (poDS->eAccess == GA_Update)
        {
            CPLReleaseMutex(hNCMutex);  // Release mutex otherwise we'll
                                        // deadlock with GDALDataset own mutex.
            delete poDS;
            return nullptr;
        }
        poDS->ProcessSentinel3_SRAL_MWR();
    }
    else
#endif
    {
        poDS->FilterVars(cdfid, (poOpenInfo->nOpenFlags & GDAL_OF_RASTER) != 0,
                         (poOpenInfo->nOpenFlags & GDAL_OF_VECTOR) != 0,
                         papszIgnoreVars, &nRasterVars, &nGroupID, &nVarID,
                         &nIgnoredVars, oMap2DDimsToGroupAndVar);
    }
    CSLDestroy(papszIgnoreVars);

    // Case where there is no raster variable
    if (nRasterVars == 0 && !bTreatAsSubdataset)
    {
        poDS->GDALPamDataset::SetMetadata(poDS->papszMetadata);
        CPLReleaseMutex(hNCMutex);  // Release mutex otherwise we'll deadlock
                                    // with GDALDataset own mutex.
        poDS->TryLoadXML();
        // If the dataset has been opened in raster mode only, exit
        if ((poOpenInfo->nOpenFlags & GDAL_OF_RASTER) != 0 &&
            (poOpenInfo->nOpenFlags & GDAL_OF_VECTOR) == 0)
        {
            delete poDS;
            poDS = nullptr;
        }
        // Otherwise if the dataset is opened in vector mode, that there is
        // no vector layer and we are in read-only, exit too.
        else if (poDS->GetLayerCount() == 0 &&
                 (poOpenInfo->nOpenFlags & GDAL_OF_VECTOR) != 0 &&
                 poOpenInfo->eAccess == GA_ReadOnly)
        {
            delete poDS;
            poDS = nullptr;
        }
        CPLAcquireMutex(hNCMutex, 1000.0);
        return poDS;
    }

    // We have more than one variable with 2 dimensions in the
    // file, then treat this as a subdataset container dataset.
    bool bSeveralVariablesAsBands = false;
    if ((nRasterVars > 1) && !bTreatAsSubdataset)
    {
        if (CPLFetchBool(poOpenInfo->papszOpenOptions, "VARIABLES_AS_BANDS",
                         false) &&
            oMap2DDimsToGroupAndVar.size() == 1)
        {
            std::tie(nGroupID, nVarID) =
                oMap2DDimsToGroupAndVar.begin()->second.front();
            bSeveralVariablesAsBands = true;
        }
        else
        {
            poDS->CreateSubDatasetList(cdfid);
            poDS->GDALPamDataset::SetMetadata(poDS->papszMetadata);
            CPLReleaseMutex(hNCMutex);  // Release mutex otherwise we'll
                                        // deadlock with GDALDataset own mutex.
            poDS->TryLoadXML();
            CPLAcquireMutex(hNCMutex, 1000.0);
            return poDS;
        }
    }

    // If we are not treating things as a subdataset, then capture
    // the name of the single available variable as the subdataset.
    if (!bTreatAsSubdataset)
    {
        char *pszVarName = nullptr;
        NCDF_ERR(NCDFGetVarFullName(nGroupID, nVarID, &pszVarName));
        osSubdatasetName = (pszVarName != nullptr ? pszVarName : "");
        CPLFree(pszVarName);
    }

    // We have ignored at least one variable, so we should report them
    // as subdatasets for reference.
    if (nIgnoredVars > 0 && !bTreatAsSubdataset)
    {
        CPLDebug("GDAL_netCDF",
                 "As %d variables were ignored, creating subdataset list "
                 "for reference. Variable #%d [%s] is the main variable",
                 nIgnoredVars, nVarID, osSubdatasetName.c_str());
        poDS->CreateSubDatasetList(cdfid);
    }

    // Open the NETCDF subdataset NETCDF:"filename":subdataset.
    int var = -1;
    NCDFOpenSubDataset(cdfid, osSubdatasetName.c_str(), &nGroupID, &var);
    // Now we can forget the root cdfid and only use the selected group.
    cdfid = nGroupID;
    int nd = 0;
    nc_inq_varndims(cdfid, var, &nd);

    int *paDimIds = static_cast<int *>(CPLCalloc(nd, sizeof(int)));

    // X, Y, Z position in array
    int *panBandDimPos = static_cast<int *>(CPLCalloc(nd, sizeof(int)));

    nc_inq_vardimid(cdfid, var, paDimIds);

    // Check if somebody tried to pass a variable with less than 1D.
    if (nd < 1)
    {
        CPLError(CE_Warning, CPLE_AppDefined,
                 "Variable has %d dimension(s) - not supported.", nd);
        CPLFree(paDimIds);
        CPLFree(panBandDimPos);
        CPLReleaseMutex(hNCMutex);  // Release mutex otherwise we'll deadlock
                                    // with GDALDataset own mutex.
        delete poDS;
        CPLAcquireMutex(hNCMutex, 1000.0);
        return nullptr;
    }

    // CF-1 Convention
    //
    // Dimensions to appear in the relative order T, then Z, then Y,
    // then X  to the file. All other dimensions should, whenever
    // possible, be placed to the left of the spatiotemporal
    // dimensions.

    // Verify that dimensions are in the {T,Z,Y,X} or {T,Z,Y,X} order
    // Ideally we should detect for other ordering and act accordingly
    // Only done if file has Conventions=CF-* and only prints warning
    // To disable set GDAL_NETCDF_VERIFY_DIMS=NO and to use only
    // attributes (not varnames) set GDAL_NETCDF_VERIFY_DIMS=STRICT
    const bool bCheckDims =
        CPLTestBool(CPLGetConfigOption("GDAL_NETCDF_VERIFY_DIMS", "YES")) &&
        STARTS_WITH_CI(szConventions, "CF");

    if (nd >= 2 && bCheckDims)
    {
        char szDimName1[NC_MAX_NAME + 1] = {};
        char szDimName2[NC_MAX_NAME + 1] = {};
        status = nc_inq_dimname(cdfid, paDimIds[nd - 1], szDimName1);
        NCDF_ERR(status);
        status = nc_inq_dimname(cdfid, paDimIds[nd - 2], szDimName2);
        NCDF_ERR(status);
        if (NCDFIsVarLongitude(cdfid, -1, szDimName1) == false &&
            NCDFIsVarProjectionX(cdfid, -1, szDimName1) == false)
        {
            CPLError(CE_Warning, CPLE_AppDefined,
                     "dimension #%d (%s) is not a Longitude/X dimension.",
                     nd - 1, szDimName1);
        }
        if (NCDFIsVarLatitude(cdfid, -1, szDimName2) == false &&
            NCDFIsVarProjectionY(cdfid, -1, szDimName2) == false)
        {
            CPLError(CE_Warning, CPLE_AppDefined,
                     "dimension #%d (%s) is not a Latitude/Y dimension.",
                     nd - 2, szDimName2);
        }
        if ((NCDFIsVarLongitude(cdfid, -1, szDimName2) ||
             NCDFIsVarProjectionX(cdfid, -1, szDimName2)) &&
            (NCDFIsVarLatitude(cdfid, -1, szDimName1) ||
             NCDFIsVarProjectionY(cdfid, -1, szDimName1)))
        {
            poDS->bSwitchedXY = true;
        }
        if (nd >= 3)
        {
            char szDimName3[NC_MAX_NAME + 1] = {};
            status = nc_inq_dimname(cdfid, paDimIds[nd - 3], szDimName3);
            NCDF_ERR(status);
            if (nd >= 4)
            {
                char szDimName4[NC_MAX_NAME + 1] = {};
                status = nc_inq_dimname(cdfid, paDimIds[nd - 4], szDimName4);
                NCDF_ERR(status);
                if (NCDFIsVarVerticalCoord(cdfid, -1, szDimName3) == false)
                {
                    CPLError(CE_Warning, CPLE_AppDefined,
                             "dimension #%d (%s) is not a Time dimension.",
                             nd - 3, szDimName3);
                }
                if (NCDFIsVarTimeCoord(cdfid, -1, szDimName4) == false)
                {
                    CPLError(CE_Warning, CPLE_AppDefined,
                             "dimension #%d (%s) is not a Time dimension.",
                             nd - 4, szDimName4);
                }
            }
            else
            {
                if (NCDFIsVarVerticalCoord(cdfid, -1, szDimName3) == false &&
                    NCDFIsVarTimeCoord(cdfid, -1, szDimName3) == false)
                {
                    CPLError(CE_Warning, CPLE_AppDefined,
                             "dimension #%d (%s) is not a "
                             "Time or Vertical dimension.",
                             nd - 3, szDimName3);
                }
            }
        }
    }

    // Get X dimensions information.
    size_t xdim;
    poDS->nXDimID = paDimIds[nd - 1];
    nc_inq_dimlen(cdfid, poDS->nXDimID, &xdim);

    // Get Y dimension information.
    size_t ydim;
    if (nd >= 2)
    {
        poDS->nYDimID = paDimIds[nd - 2];
        nc_inq_dimlen(cdfid, poDS->nYDimID, &ydim);
    }
    else
    {
        poDS->nYDimID = -1;
        ydim = 1;
    }

    if (xdim > INT_MAX || ydim > INT_MAX)
    {
        CPLError(CE_Failure, CPLE_AppDefined,
                 "Invalid raster dimensions: " CPL_FRMT_GUIB "x" CPL_FRMT_GUIB,
                 static_cast<GUIntBig>(xdim), static_cast<GUIntBig>(ydim));
        CPLFree(paDimIds);
        CPLFree(panBandDimPos);
        CPLReleaseMutex(hNCMutex);  // Release mutex otherwise we'll deadlock
                                    // with GDALDataset own mutex.
        delete poDS;
        CPLAcquireMutex(hNCMutex, 1000.0);
        return nullptr;
    }

    poDS->nRasterXSize = static_cast<int>(xdim);
    poDS->nRasterYSize = static_cast<int>(ydim);

    unsigned int k = 0;
    for (int j = 0; j < nd; j++)
    {
        if (paDimIds[j] == poDS->nXDimID)
        {
            panBandDimPos[0] = j;  // Save Position of XDim
            k++;
        }
        if (paDimIds[j] == poDS->nYDimID)
        {
            panBandDimPos[1] = j;  // Save Position of YDim
            k++;
        }
    }
    // X and Y Dimension Ids were not found!
    if ((nd >= 2 && k != 2) || (nd == 1 && k != 1))
    {
        CPLFree(paDimIds);
        CPLFree(panBandDimPos);
        CPLReleaseMutex(hNCMutex);  // Release mutex otherwise we'll deadlock
                                    // with GDALDataset own mutex.
        delete poDS;
        CPLAcquireMutex(hNCMutex, 1000.0);
        return nullptr;
    }

    // Read Metadata for this variable.

    // Should disable as is also done at band level, except driver needs the
    // variables as metadata (e.g. projection).
    poDS->ReadAttributes(cdfid, var);

    // Read Metadata for each dimension.
    int *panDimIds = nullptr;
    NCDFGetVisibleDims(cdfid, &ndims, &panDimIds);
    // With NetCDF-4 groups panDimIds is not always [0..dim_count-1] like
    // in NetCDF-3 because we see only the dimensions of the selected group
    // and its parents.
    // poDS->papszDimName is indexed by dim IDs, so it must contains all IDs
    // [0..max(panDimIds)], but they are not all useful so we fill names
    // of useless dims with empty string.
    if (panDimIds)
    {
        const int nMaxDimId = *std::max_element(panDimIds, panDimIds + ndims);
        std::set<int> oSetExistingDimIds;
        for (int i = 0; i < ndims; i++)
        {
            oSetExistingDimIds.insert(panDimIds[i]);
        }
        std::set<int> oSetDimIdsUsedByVar;
        for (int i = 0; i < nd; i++)
        {
            oSetDimIdsUsedByVar.insert(paDimIds[i]);
        }
        for (int j = 0; j <= nMaxDimId; j++)
        {
            // Is j dim used?
            if (oSetExistingDimIds.find(j) != oSetExistingDimIds.end())
            {
                // Useful dim.
                char szTemp[NC_MAX_NAME + 1] = {};
                status = nc_inq_dimname(cdfid, j, szTemp);
                if (status != NC_NOERR)
                {
                    CPLFree(paDimIds);
                    CPLFree(panBandDimPos);
                    CPLReleaseMutex(hNCMutex);  // Release mutex otherwise we'll
                                                // deadlock with GDALDataset own
                                                // mutex.
                    delete poDS;
                    CPLAcquireMutex(hNCMutex, 1000.0);
                    return nullptr;
                }
                poDS->papszDimName.AddString(szTemp);

                if (oSetDimIdsUsedByVar.find(j) != oSetDimIdsUsedByVar.end())
                {
                    int nDimGroupId = -1;
                    int nDimVarId = -1;
                    if (NCDFResolveVar(cdfid, poDS->papszDimName[j],
                                       &nDimGroupId, &nDimVarId) == CE_None)
                    {
                        poDS->ReadAttributes(nDimGroupId, nDimVarId);
                    }
                }
            }
            else
            {
                // Useless dim.
                poDS->papszDimName.AddString("");
            }
        }
        CPLFree(panDimIds);
    }

    // Set projection info.
    if (nd > 1)
    {
        poDS->SetProjectionFromVar(cdfid, var, false);
    }

    // Override bottom-up with GDAL_NETCDF_BOTTOMUP config option.
    const char *pszValue = CPLGetConfigOption("GDAL_NETCDF_BOTTOMUP", nullptr);
    if (pszValue)
    {
        poDS->bBottomUp = CPLTestBool(pszValue);
        CPLDebug("GDAL_netCDF",
                 "set bBottomUp=%d because GDAL_NETCDF_BOTTOMUP=%s",
                 static_cast<int>(poDS->bBottomUp), pszValue);
    }

    // Save non-spatial dimension info.

    int *panBandZLev = nullptr;
    int nDim = (nd >= 2) ? 2 : 1;
    size_t lev_count;
    size_t nTotLevCount = 1;
    nc_type nType = NC_NAT;

    CPLString osExtraDimNames;
    int anExtraDimVarIds[NC_MAX_NAME] = {-1};
    int anExtraDimGroupIds[NC_MAX_NAME] = {-1};

    if (nd > 2)
    {
        nDim = 2;
        panBandZLev = static_cast<int *>(CPLCalloc(nd - 2, sizeof(int)));

        osExtraDimNames = "{";

        char szDimName[NC_MAX_NAME + 1] = {};

        for (int j = 0; j < nd; j++)
        {
            if ((paDimIds[j] != poDS->nXDimID) &&
                (paDimIds[j] != poDS->nYDimID))
            {
                nc_inq_dimlen(cdfid, paDimIds[j], &lev_count);
                nTotLevCount *= lev_count;
                panBandZLev[nDim - 2] = static_cast<int>(lev_count);
                panBandDimPos[nDim] = j;  // Save Position of ZDim
                // Save non-spatial dimension names.
                if (nc_inq_dimname(cdfid, paDimIds[j], szDimName) == NC_NOERR)
                {
                    osExtraDimNames += szDimName;
                    if (j < nd - 3)
                    {
                        osExtraDimNames += ",";
                    }

                    int nIdxGroupID = -1;
                    int nIdxVarID = Get1DVariableIndexedByDimension(
                        cdfid, paDimIds[j], szDimName, true, &nIdxGroupID);
                    anExtraDimGroupIds[nDim - 2] = nIdxGroupID;
                    anExtraDimVarIds[nDim - 2] = nIdxVarID;

                    if (nIdxVarID >= 0)
                    {
                        nc_inq_vartype(nIdxGroupID, nIdxVarID, &nType);
                        char szExtraDimDef[NC_MAX_NAME + 1];
                        snprintf(szExtraDimDef, sizeof(szExtraDimDef),
                                 "{%ld,%d}", (long)lev_count, nType);
                        char szTemp[NC_MAX_NAME + 32 + 1];
                        snprintf(szTemp, sizeof(szTemp), "NETCDF_DIM_%s_DEF",
                                 szDimName);
                        poDS->papszMetadata = CSLSetNameValue(
                            poDS->papszMetadata, szTemp, szExtraDimDef);
                        char *pszTemp = nullptr;
                        if (NCDFGet1DVar(nIdxGroupID, nIdxVarID, &pszTemp) ==
                            CE_None)
                        {
                            snprintf(szTemp, sizeof(szTemp),
                                     "NETCDF_DIM_%s_VALUES", szDimName);
                            poDS->papszMetadata = CSLSetNameValue(
                                poDS->papszMetadata, szTemp, pszTemp);
                            CPLFree(pszTemp);
                        }
                    }
                }
                else
                {
                    anExtraDimGroupIds[nDim - 2] = -1;
                    anExtraDimVarIds[nDim - 2] = -1;
                }

                nDim++;
            }
        }
        osExtraDimNames += "}";
        poDS->papszMetadata = CSLSetNameValue(
            poDS->papszMetadata, "NETCDF_DIM_EXTRA", osExtraDimNames);
    }

    // Store Metadata.
    poDS->GDALPamDataset::SetMetadata(poDS->papszMetadata);

    // Create bands.

    // Arbitrary threshold.
    int nMaxBandCount =
        atoi(CPLGetConfigOption("GDAL_MAX_BAND_COUNT", "32768"));
    if (nMaxBandCount <= 0)
        nMaxBandCount = 32768;
    if (nTotLevCount > static_cast<unsigned int>(nMaxBandCount))
    {
        CPLError(CE_Warning, CPLE_AppDefined,
                 "Limiting number of bands to %d instead of %u", nMaxBandCount,
                 static_cast<unsigned int>(nTotLevCount));
        nTotLevCount = static_cast<unsigned int>(nMaxBandCount);
    }
    if (poDS->nRasterXSize == 0 || poDS->nRasterYSize == 0)
    {
        poDS->nRasterXSize = 0;
        poDS->nRasterYSize = 0;
        nTotLevCount = 0;
        if (poDS->GetLayerCount() == 0)
        {
            CPLFree(paDimIds);
            CPLFree(panBandDimPos);
            CPLFree(panBandZLev);
            CPLReleaseMutex(hNCMutex);  // Release mutex otherwise we'll
                                        // deadlock with GDALDataset own mutex.
            delete poDS;
            CPLAcquireMutex(hNCMutex, 1000.0);
            return nullptr;
        }
    }
    if (bSeveralVariablesAsBands)
    {
        const auto &listVariables = oMap2DDimsToGroupAndVar.begin()->second;
        for (int iBand = 0; iBand < static_cast<int>(listVariables.size());
             ++iBand)
        {
            int bandVarGroupId = listVariables[iBand].first;
            int bandVarId = listVariables[iBand].second;
            netCDFRasterBand *poBand = new netCDFRasterBand(
                netCDFRasterBand::CONSTRUCTOR_OPEN(), poDS, bandVarGroupId,
                bandVarId, nDim, 0, nullptr, panBandDimPos, paDimIds, iBand + 1,
                anExtraDimGroupIds, anExtraDimVarIds);
            poDS->SetBand(iBand + 1, poBand);
        }
    }
    else
    {
        for (unsigned int lev = 0; lev < nTotLevCount; lev++)
        {
            netCDFRasterBand *poBand = new netCDFRasterBand(
                netCDFRasterBand::CONSTRUCTOR_OPEN(), poDS, cdfid, var, nDim,
                lev, panBandZLev, panBandDimPos, paDimIds, lev + 1,
                anExtraDimGroupIds, anExtraDimVarIds);
            poDS->SetBand(lev + 1, poBand);
        }
    }

    CPLFree(paDimIds);
    CPLFree(panBandDimPos);
    if (panBandZLev)
        CPLFree(panBandZLev);
    // Handle angular geographic coordinates here

    // Initialize any PAM information.
    if (bTreatAsSubdataset)
    {
        poDS->SetPhysicalFilename(poDS->osFilename);
        poDS->SetSubdatasetName(osSubdatasetName);
    }

    CPLReleaseMutex(hNCMutex);  // Release mutex otherwise we'll deadlock with
                                // GDALDataset own mutex.
    poDS->TryLoadXML();

    if (bTreatAsSubdataset)
        poDS->oOvManager.Initialize(poDS, ":::VIRTUAL:::");
    else
        poDS->oOvManager.Initialize(poDS, poDS->osFilename);

    CPLAcquireMutex(hNCMutex, 1000.0);

    return poDS;
}

/************************************************************************/
/*                            CopyMetadata()                            */
/*                                                                      */
/*      Create a copy of metadata for NC_GLOBAL or a variable           */
/************************************************************************/

static void CopyMetadata(GDALDataset *poSrcDS, GDALRasterBand *poSrcBand,
                         GDALRasterBand *poDstBand, int nCdfId, int CDFVarID,
                         const char *pszPrefix)
{
    char **papszFieldData = nullptr;

    // Remove the following band meta but set them later from band data.
    const char *const papszIgnoreBand[] = {
        CF_ADD_OFFSET, CF_SCALE_FACTOR, "valid_range", "_Unsigned",
        _FillValue,    "coordinates",   nullptr};
    const char *const papszIgnoreGlobal[] = {"NETCDF_DIM_EXTRA", nullptr};

    char **papszMetadata = nullptr;
    if (poSrcDS)
    {
        papszMetadata = poSrcDS->GetMetadata();
    }
    else if (poSrcBand)
    {
        papszMetadata = poSrcBand->GetMetadata();
    }

    const int nItems = CSLCount(papszMetadata);

    for (int k = 0; k < nItems; k++)
    {
        const char *pszField = CSLGetField(papszMetadata, k);
        if (papszFieldData)
            CSLDestroy(papszFieldData);
        papszFieldData = CSLTokenizeString2(pszField, "=", CSLT_HONOURSTRINGS);
        if (papszFieldData[1] != nullptr)
        {
#ifdef NCDF_DEBUG
            CPLDebug("GDAL_netCDF", "copy metadata [%s]=[%s]",
                     papszFieldData[0], papszFieldData[1]);
#endif

            CPLString osMetaName(papszFieldData[0]);
            CPLString osMetaValue(papszFieldData[1]);

            // Check for items that match pszPrefix if applicable.
            if (pszPrefix != nullptr && !EQUAL(pszPrefix, ""))
            {
                // Remove prefix.
                if (EQUALN(osMetaName, pszPrefix, strlen(pszPrefix)))
                {
                    osMetaName = osMetaName.substr(strlen(pszPrefix));
                }
                // Only copy items that match prefix.
                else
                {
                    continue;
                }
            }

            // Fix various issues with metadata translation.
            if (CDFVarID == NC_GLOBAL)
            {
                // Do not copy items in papszIgnoreGlobal and NETCDF_DIM_*.
                if ((CSLFindString(papszIgnoreGlobal, osMetaName) != -1) ||
                    (STARTS_WITH(osMetaName, "NETCDF_DIM_")))
                    continue;
                // Remove NC_GLOBAL prefix for netcdf global Metadata.
                else if (STARTS_WITH(osMetaName, "NC_GLOBAL#"))
                {
                    osMetaName = osMetaName.substr(strlen("NC_GLOBAL#"));
                }
                // GDAL Metadata renamed as GDAL-[meta].
                else if (strstr(osMetaName, "#") == nullptr)
                {
                    osMetaName = "GDAL_" + osMetaName;
                }
                // Keep time, lev and depth information for safe-keeping.
                // Time and vertical coordinate handling need improvements.
                /*
                else if( STARTS_WITH(szMetaName, "time#") )
                {
                    szMetaName[4] = '-';
                }
                else if( STARTS_WITH(szMetaName, "lev#") )
                {
                    szMetaName[3] = '-';
                }
                else if( STARTS_WITH(szMetaName, "depth#") )
                {
                    szMetaName[5] = '-';
                }
                */
                // Only copy data without # (previously all data was copied).
                if (strstr(osMetaName, "#") != nullptr)
                    continue;
                // netCDF attributes do not like the '#' character.
                // for( unsigned int h=0; h < strlen(szMetaName) -1 ; h++ ) {
                //     if( szMetaName[h] == '#') szMetaName[h] = '-';
                // }
            }
            else
            {
                // Do not copy varname, stats, NETCDF_DIM_*, nodata
                // and items in papszIgnoreBand.
                if (STARTS_WITH(osMetaName, "NETCDF_VARNAME") ||
                    STARTS_WITH(osMetaName, "STATISTICS_") ||
                    STARTS_WITH(osMetaName, "NETCDF_DIM_") ||
                    STARTS_WITH(osMetaName, "missing_value") ||
                    STARTS_WITH(osMetaName, "_FillValue") ||
                    CSLFindString(papszIgnoreBand, osMetaName) != -1)
                    continue;
            }

#ifdef NCDF_DEBUG
            CPLDebug("GDAL_netCDF", "copy name=[%s] value=[%s]",
                     osMetaName.c_str(), osMetaValue.c_str());
#endif
            if (NCDFPutAttr(nCdfId, CDFVarID, osMetaName, osMetaValue) !=
                CE_None)
                CPLDebug("GDAL_netCDF", "NCDFPutAttr(%d, %d, %s, %s) failed",
                         nCdfId, CDFVarID, osMetaName.c_str(),
                         osMetaValue.c_str());
        }
    }

    if (papszFieldData)
        CSLDestroy(papszFieldData);

    // Set add_offset and scale_factor here if present.
    if (poSrcBand && poDstBand)
    {

        int bGotAddOffset = FALSE;
        const double dfAddOffset = poSrcBand->GetOffset(&bGotAddOffset);
        int bGotScale = FALSE;
        const double dfScale = poSrcBand->GetScale(&bGotScale);

        if (bGotAddOffset && dfAddOffset != 0.0)
            poDstBand->SetOffset(dfAddOffset);
        if (bGotScale && dfScale != 1.0)
            poDstBand->SetScale(dfScale);
    }
}

/************************************************************************/
/*                            CreateLL()                                */
/*                                                                      */
/*      Shared functionality between netCDFDataset::Create() and        */
/*      netCDF::CreateCopy() for creating netcdf file based on a set of */
/*      options and a configuration.                                    */
/************************************************************************/

netCDFDataset *netCDFDataset::CreateLL(const char *pszFilename, int nXSize,
                                       int nYSize, int nBandsIn,
                                       char **papszOptions)
{
    if (!((nXSize == 0 && nYSize == 0 && nBandsIn == 0) ||
          (nXSize > 0 && nYSize > 0 && nBandsIn > 0)))
    {
        return nullptr;
    }

    CPLReleaseMutex(hNCMutex);  // Release mutex otherwise we'll deadlock with
                                // GDALDataset own mutex.
    netCDFDataset *poDS = new netCDFDataset();
    CPLAcquireMutex(hNCMutex, 1000.0);

    poDS->nRasterXSize = nXSize;
    poDS->nRasterYSize = nYSize;
    poDS->eAccess = GA_Update;
    poDS->osFilename = pszFilename;

    // From gtiff driver, is this ok?
    /*
    poDS->nBlockXSize = nXSize;
    poDS->nBlockYSize = 1;
    poDS->nBlocksPerBand =
        ((nYSize + poDS->nBlockYSize - 1) / poDS->nBlockYSize)
        * ((nXSize + poDS->nBlockXSize - 1) / poDS->nBlockXSize);
        */

    // process options.
    poDS->papszCreationOptions = CSLDuplicate(papszOptions);
    poDS->ProcessCreationOptions();

    if (poDS->eMultipleLayerBehavior == SEPARATE_FILES)
    {
        VSIStatBuf sStat;
        if (VSIStat(pszFilename, &sStat) == 0)
        {
            if (!VSI_ISDIR(sStat.st_mode))
            {
                CPLError(CE_Failure, CPLE_FileIO,
                         "%s is an existing file, but not a directory",
                         pszFilename);
                CPLReleaseMutex(hNCMutex);  // Release mutex otherwise we'll
                                            // deadlock with GDALDataset own
                                            // mutex.
                delete poDS;
                CPLAcquireMutex(hNCMutex, 1000.0);
                return nullptr;
            }
        }
        else if (VSIMkdir(pszFilename, 0755) != 0)
        {
            CPLError(CE_Failure, CPLE_FileIO, "Cannot create %s directory",
                     pszFilename);
            CPLReleaseMutex(hNCMutex);  // Release mutex otherwise we'll
                                        // deadlock with GDALDataset own mutex.
            delete poDS;
            CPLAcquireMutex(hNCMutex, 1000.0);
            return nullptr;
        }

        return poDS;
    }

    // Create the dataset.
    CPLString osFilenameForNCCreate(pszFilename);
#if defined(WIN32) && !defined(NETCDF_USES_UTF8)
    if (CPLTestBool(CPLGetConfigOption("GDAL_FILENAME_IS_UTF8", "YES")))
    {
        char *pszTemp =
            CPLRecode(osFilenameForNCCreate, CPL_ENC_UTF8, "CP_ACP");
        osFilenameForNCCreate = pszTemp;
        CPLFree(pszTemp);
    }
#endif

#if defined(WIN32)
    {
        // Works around bug of msys2 netCDF 4.9.0 package where nc_create()
        // crashes
        VSIStatBuf sStat;
        const char *pszDir = CPLGetDirname(osFilenameForNCCreate.c_str());
        if (VSIStat(pszDir, &sStat) != 0)
        {
            CPLError(CE_Failure, CPLE_OpenFailed,
                     "Unable to create netCDF file %s: non existing output "
                     "directory",
                     pszFilename);
            CPLReleaseMutex(hNCMutex);  // Release mutex otherwise we'll
                                        // deadlock with GDALDataset own mutex.
            delete poDS;
            CPLAcquireMutex(hNCMutex, 1000.0);
            return nullptr;
        }
    }
#endif

    int status =
        nc_create(osFilenameForNCCreate, poDS->nCreateMode, &(poDS->cdfid));

    // Put into define mode.
    poDS->SetDefineMode(true);

    if (status != NC_NOERR)
    {
        CPLError(CE_Failure, CPLE_OpenFailed,
                 "Unable to create netCDF file %s (Error code %d): %s .",
                 pszFilename, status, nc_strerror(status));
        CPLReleaseMutex(hNCMutex);  // Release mutex otherwise we'll deadlock
                                    // with GDALDataset own mutex.
        delete poDS;
        CPLAcquireMutex(hNCMutex, 1000.0);
        return nullptr;
    }

    // Define dimensions.
    if (nXSize > 0 && nYSize > 0)
    {
        poDS->papszDimName.AddString(NCDF_DIMNAME_X);
        status =
            nc_def_dim(poDS->cdfid, NCDF_DIMNAME_X, nXSize, &(poDS->nXDimID));
        NCDF_ERR(status);
        CPLDebug("GDAL_netCDF", "status nc_def_dim(%d, %s, %d, -) got id %d",
                 poDS->cdfid, NCDF_DIMNAME_X, nXSize, poDS->nXDimID);

        poDS->papszDimName.AddString(NCDF_DIMNAME_Y);
        status =
            nc_def_dim(poDS->cdfid, NCDF_DIMNAME_Y, nYSize, &(poDS->nYDimID));
        NCDF_ERR(status);
        CPLDebug("GDAL_netCDF", "status nc_def_dim(%d, %s, %d, -) got id %d",
                 poDS->cdfid, NCDF_DIMNAME_Y, nYSize, poDS->nYDimID);
    }

    return poDS;
}

/************************************************************************/
/*                            Create()                                  */
/************************************************************************/

GDALDataset *netCDFDataset::Create(const char *pszFilename, int nXSize,
                                   int nYSize, int nBandsIn, GDALDataType eType,
                                   char **papszOptions)
{
    CPLDebug("GDAL_netCDF", "\n=====\nnetCDFDataset::Create(%s, ...)",
             pszFilename);

    const char *legacyCreationOp =
        CSLFetchNameValueDef(papszOptions, "GEOMETRY_ENCODING", "CF_1.8");
    std::string legacyCreationOp_s = std::string(legacyCreationOp);

    // Check legacy creation op FIRST

    bool legacyCreateMode = false;

    if (nXSize != 0 || nYSize != 0 || nBandsIn != 0)
    {
        legacyCreateMode = true;
    }
    else if (legacyCreationOp_s == "CF_1.8")
    {
        legacyCreateMode = false;
    }

    else if (legacyCreationOp_s == "WKT")
    {
        legacyCreateMode = true;
    }

    else
    {
        CPLError(
            CE_Failure, CPLE_NotSupported,
            "Dataset creation option GEOMETRY_ENCODING=%s is not supported.",
            legacyCreationOp_s.c_str());
        return nullptr;
    }

    CPLMutexHolderD(&hNCMutex);

    CPLStringList aosOptions(CSLDuplicate(papszOptions));
#ifdef NETCDF_HAS_NC4
    if (aosOptions.FetchNameValue("FORMAT") == nullptr &&
        (eType == GDT_UInt16 || eType == GDT_UInt32 || eType == GDT_UInt64 ||
         eType == GDT_Int64))
    {
        CPLDebug("netCDF", "Selecting FORMAT=NC4 due to data type");
        aosOptions.SetNameValue("FORMAT", "NC4");
    }
#endif
    netCDFDataset *poDS = netCDFDataset::CreateLL(pszFilename, nXSize, nYSize,
                                                  nBandsIn, aosOptions.List());

    if (!poDS)
        return nullptr;

    if (!legacyCreateMode)
    {
        poDS->bSGSupport = true;
        poDS->vcdf.enableFullVirtualMode();
    }

    else
    {
        poDS->bSGSupport = false;
    }

    // Should we write signed or unsigned byte?
    // TODO should this only be done in Create()
    poDS->bSignedData = true;
    const char *pszValue = CSLFetchNameValueDef(papszOptions, "PIXELTYPE", "");
    if (eType == GDT_Byte && !EQUAL(pszValue, "SIGNEDBYTE"))
        poDS->bSignedData = false;

    // Add Conventions, GDAL info and history.
    if (poDS->cdfid >= 0)
    {
        const char *CF_Vector_Conv = poDS->bSGSupport
                                         ? NCDF_CONVENTIONS_CF_V1_8
                                         : NCDF_CONVENTIONS_CF_V1_6;
        poDS->bWriteGDALVersion = CPLTestBool(
            CSLFetchNameValueDef(papszOptions, "WRITE_GDAL_VERSION", "YES"));
        poDS->bWriteGDALHistory = CPLTestBool(
            CSLFetchNameValueDef(papszOptions, "WRITE_GDAL_HISTORY", "YES"));
        NCDFAddGDALHistory(poDS->cdfid, pszFilename, poDS->bWriteGDALVersion,
                           poDS->bWriteGDALHistory, "", "Create",
                           (nBandsIn == 0) ? CF_Vector_Conv
                                           : GDAL_DEFAULT_NCDF_CONVENTIONS);
    }

    // Define bands.
    for (int iBand = 1; iBand <= nBandsIn; iBand++)
    {
        poDS->SetBand(
            iBand, new netCDFRasterBand(netCDFRasterBand::CONSTRUCTOR_CREATE(),
                                        poDS, eType, iBand, poDS->bSignedData));
    }

    CPLDebug("GDAL_netCDF", "netCDFDataset::Create(%s, ...) done", pszFilename);
    // Return same dataset.
    return poDS;
}

template <class T>
static CPLErr NCDFCopyBand(GDALRasterBand *poSrcBand, GDALRasterBand *poDstBand,
                           int nXSize, int nYSize, GDALProgressFunc pfnProgress,
                           void *pProgressData)
{
    GDALDataType eDT = poSrcBand->GetRasterDataType();
    CPLErr eErr = CE_None;
    T *patScanline = static_cast<T *>(CPLMalloc(nXSize * sizeof(T)));

    for (int iLine = 0; iLine < nYSize && eErr == CE_None; iLine++)
    {
        eErr = poSrcBand->RasterIO(GF_Read, 0, iLine, nXSize, 1, patScanline,
                                   nXSize, 1, eDT, 0, 0, nullptr);
        if (eErr != CE_None)
        {
            CPLDebug(
                "GDAL_netCDF",
                "NCDFCopyBand(), poSrcBand->RasterIO() returned error code %d",
                eErr);
        }
        else
        {
            eErr =
                poDstBand->RasterIO(GF_Write, 0, iLine, nXSize, 1, patScanline,
                                    nXSize, 1, eDT, 0, 0, nullptr);
            if (eErr != CE_None)
                CPLDebug("GDAL_netCDF",
                         "NCDFCopyBand(), poDstBand->RasterIO() returned error "
                         "code %d",
                         eErr);
        }

        if (nYSize > 10 && (iLine % (nYSize / 10) == 1))
        {
            if (!pfnProgress(1.0 * iLine / nYSize, nullptr, pProgressData))
            {
                eErr = CE_Failure;
                CPLError(CE_Failure, CPLE_UserInterrupt,
                         "User terminated CreateCopy()");
            }
        }
    }

    CPLFree(patScanline);

    pfnProgress(1.0, nullptr, pProgressData);

    return eErr;
}

/************************************************************************/
/*                            CreateCopy()                              */
/************************************************************************/

GDALDataset *
netCDFDataset::CreateCopy(const char *pszFilename, GDALDataset *poSrcDS,
                          CPL_UNUSED int bStrict, char **papszOptions,
                          GDALProgressFunc pfnProgress, void *pProgressData)
{
    CPLMutexHolderD(&hNCMutex);

    CPLDebug("GDAL_netCDF", "\n=====\nnetCDFDataset::CreateCopy(%s, ...)",
             pszFilename);

    if (poSrcDS->GetRootGroup())
    {
        auto poDrv = GDALDriver::FromHandle(GDALGetDriverByName("netCDF"));
        if (poDrv)
        {
            return poDrv->DefaultCreateCopy(pszFilename, poSrcDS, bStrict,
                                            papszOptions, pfnProgress,
                                            pProgressData);
        }
    }

    const int nBands = poSrcDS->GetRasterCount();
    const int nXSize = poSrcDS->GetRasterXSize();
    const int nYSize = poSrcDS->GetRasterYSize();
    const char *pszWKT = poSrcDS->GetProjectionRef();

    // Check input bands for errors.
    if (nBands == 0)
    {
        CPLError(CE_Failure, CPLE_NotSupported,
                 "NetCDF driver does not support "
                 "source dataset with zero band.");
        return nullptr;
    }

    GDALDataType eDT = GDT_Unknown;
    GDALRasterBand *poSrcBand = nullptr;
    for (int iBand = 1; iBand <= nBands; iBand++)
    {
        poSrcBand = poSrcDS->GetRasterBand(iBand);
        eDT = poSrcBand->GetRasterDataType();
        if (eDT == GDT_Unknown || GDALDataTypeIsComplex(eDT))
        {
            CPLError(CE_Failure, CPLE_NotSupported,
                     "NetCDF driver does not support source dataset with band "
                     "of complex type.");
            return nullptr;
        }
    }

    if (!pfnProgress(0.0, nullptr, pProgressData))
        return nullptr;

    // Same as in Create().
    CPLStringList aosOptions(CSLDuplicate(papszOptions));
#ifdef NETCDF_HAS_NC4
    if (aosOptions.FetchNameValue("FORMAT") == nullptr &&
        (eDT == GDT_UInt16 || eDT == GDT_UInt32 || eDT == GDT_UInt64 ||
         eDT == GDT_Int64))
    {
        CPLDebug("netCDF", "Selecting FORMAT=NC4 due to data type");
        aosOptions.SetNameValue("FORMAT", "NC4");
    }
#endif
    netCDFDataset *poDS = netCDFDataset::CreateLL(pszFilename, nXSize, nYSize,
                                                  nBands, aosOptions.List());
    if (!poDS)
        return nullptr;

    // Copy global metadata.
    // Add Conventions, GDAL info and history.
    CopyMetadata(poSrcDS, nullptr, nullptr, poDS->cdfid, NC_GLOBAL, nullptr);
    const bool bWriteGDALVersion = CPLTestBool(
        CSLFetchNameValueDef(papszOptions, "WRITE_GDAL_VERSION", "YES"));
    const bool bWriteGDALHistory = CPLTestBool(
        CSLFetchNameValueDef(papszOptions, "WRITE_GDAL_HISTORY", "YES"));
    NCDFAddGDALHistory(
        poDS->cdfid, pszFilename, bWriteGDALVersion, bWriteGDALHistory,
        poSrcDS->GetMetadataItem("NC_GLOBAL#history"), "CreateCopy",
        poSrcDS->GetMetadataItem("NC_GLOBAL#Conventions"));

    pfnProgress(0.1, nullptr, pProgressData);

    // Check for extra dimensions.
    int nDim = 2;
    char **papszExtraDimNames =
        NCDFTokenizeArray(poSrcDS->GetMetadataItem("NETCDF_DIM_EXTRA", ""));
    char **papszExtraDimValues = nullptr;

    if (papszExtraDimNames != nullptr && CSLCount(papszExtraDimNames) > 0)
    {
        size_t nDimSizeTot = 1;
        // first make sure dimensions lengths compatible with band count
        // for( int i=0; i<CSLCount(papszExtraDimNames ); i++ ) {
        for (int i = CSLCount(papszExtraDimNames) - 1; i >= 0; i--)
        {
            char szTemp[NC_MAX_NAME + 32 + 1];
            snprintf(szTemp, sizeof(szTemp), "NETCDF_DIM_%s_DEF",
                     papszExtraDimNames[i]);
            papszExtraDimValues =
                NCDFTokenizeArray(poSrcDS->GetMetadataItem(szTemp, ""));
            const size_t nDimSize = atol(papszExtraDimValues[0]);
            CSLDestroy(papszExtraDimValues);
            nDimSizeTot *= nDimSize;
        }
        if (nDimSizeTot == (size_t)nBands)
        {
            nDim = 2 + CSLCount(papszExtraDimNames);
        }
        else
        {
            // if nBands != #bands computed raise a warning
            // just issue a debug message, because it was probably intentional
            CPLDebug("GDAL_netCDF",
                     "Warning: Number of bands (%d) is not compatible with "
                     "dimensions "
                     "(total=%ld names=%s)",
                     nBands, (long)nDimSizeTot,
                     poSrcDS->GetMetadataItem("NETCDF_DIM_EXTRA", ""));
            CSLDestroy(papszExtraDimNames);
            papszExtraDimNames = nullptr;
        }
    }

    int *panDimIds = static_cast<int *>(CPLCalloc(nDim, sizeof(int)));
    int *panBandDimPos = static_cast<int *>(CPLCalloc(nDim, sizeof(int)));

    nc_type nVarType;
    int *panBandZLev = nullptr;
    int *panDimVarIds = nullptr;

    if (nDim > 2)
    {
        panBandZLev = static_cast<int *>(CPLCalloc(nDim - 2, sizeof(int)));
        panDimVarIds = static_cast<int *>(CPLCalloc(nDim - 2, sizeof(int)));

        // Define all dims.
        for (int i = CSLCount(papszExtraDimNames) - 1; i >= 0; i--)
        {
            poDS->papszDimName.AddString(papszExtraDimNames[i]);
            char szTemp[NC_MAX_NAME + 32 + 1];
            snprintf(szTemp, sizeof(szTemp), "NETCDF_DIM_%s_DEF",
                     papszExtraDimNames[i]);
            papszExtraDimValues =
                NCDFTokenizeArray(poSrcDS->GetMetadataItem(szTemp, ""));
            const int nDimSize = papszExtraDimValues && papszExtraDimValues[0]
                                     ? atoi(papszExtraDimValues[0])
                                     : 0;
            // nc_type is an enum in netcdf-3, needs casting.
            nVarType = static_cast<nc_type>(papszExtraDimValues &&
                                                    papszExtraDimValues[0] &&
                                                    papszExtraDimValues[1]
                                                ? atol(papszExtraDimValues[1])
                                                : 0);
            CSLDestroy(papszExtraDimValues);
            panBandZLev[i] = nDimSize;
            panBandDimPos[i + 2] = i;  // Save Position of ZDim.

            // Define dim.
            int status = nc_def_dim(poDS->cdfid, papszExtraDimNames[i],
                                    nDimSize, &(panDimIds[i]));
            NCDF_ERR(status);

            // Define dim var.
            int anDim[1] = {panDimIds[i]};
            status = nc_def_var(poDS->cdfid, papszExtraDimNames[i], nVarType, 1,
                                anDim, &(panDimVarIds[i]));
            NCDF_ERR(status);

            // Add dim metadata, using global var# items.
            snprintf(szTemp, sizeof(szTemp), "%s#", papszExtraDimNames[i]);
            CopyMetadata(poSrcDS, nullptr, nullptr, poDS->cdfid,
                         panDimVarIds[i], szTemp);
        }
    }

    // Copy GeoTransform and Projection.

    // Copy geolocation info.
    char **papszGeolocationInfo = poSrcDS->GetMetadata("GEOLOCATION");
    if (papszGeolocationInfo != nullptr)
        poDS->GDALPamDataset::SetMetadata(papszGeolocationInfo, "GEOLOCATION");

    // Copy geotransform.
    bool bGotGeoTransform = false;
    double adfGeoTransform[6];
    CPLErr eErr = poSrcDS->GetGeoTransform(adfGeoTransform);
    if (eErr == CE_None)
    {
        poDS->SetGeoTransform(adfGeoTransform);
        // Disable AddProjectionVars() from being called.
        bGotGeoTransform = true;
        poDS->m_bHasGeoTransform = false;
    }

    // Copy projection.
    void *pScaledProgress = nullptr;
    if (bGotGeoTransform || (pszWKT && pszWKT[0] != 0))
    {
        poDS->SetProjection(pszWKT ? pszWKT : "");

        // Now we can call AddProjectionVars() directly.
        poDS->m_bHasGeoTransform = bGotGeoTransform;
        poDS->AddProjectionVars(true, nullptr, nullptr);
        pScaledProgress =
            GDALCreateScaledProgress(0.1, 0.25, pfnProgress, pProgressData);
        poDS->AddProjectionVars(false, GDALScaledProgress, pScaledProgress);
        // Save X,Y dim positions.
        panDimIds[nDim - 1] = poDS->nXDimID;
        panBandDimPos[0] = nDim - 1;
        panDimIds[nDim - 2] = poDS->nYDimID;
        panBandDimPos[1] = nDim - 2;
        GDALDestroyScaledProgress(pScaledProgress);
    }
    else
    {
        poDS->bBottomUp =
            CPL_TO_BOOL(CSLFetchBoolean(papszOptions, "WRITE_BOTTOMUP", TRUE));
        if (papszGeolocationInfo)
        {
            poDS->AddProjectionVars(true, nullptr, nullptr);
            poDS->AddProjectionVars(false, nullptr, nullptr);
        }
    }

    // Write extra dim values - after projection for optimization.
    if (nDim > 2)
    {
        // Make sure we are in data mode.
        static_cast<netCDFDataset *>(poDS)->SetDefineMode(false);
        for (int i = CSLCount(papszExtraDimNames) - 1; i >= 0; i--)
        {
            char szTemp[NC_MAX_NAME + 32 + 1];
            snprintf(szTemp, sizeof(szTemp), "NETCDF_DIM_%s_VALUES",
                     papszExtraDimNames[i]);
            if (poSrcDS->GetMetadataItem(szTemp) != nullptr)
            {
                NCDFPut1DVar(poDS->cdfid, panDimVarIds[i],
                             poSrcDS->GetMetadataItem(szTemp));
            }
        }
    }

    pfnProgress(0.25, nullptr, pProgressData);

    // Define Bands.
    netCDFRasterBand *poBand = nullptr;
    int nBandID = -1;

    for (int iBand = 1; iBand <= nBands; iBand++)
    {
        CPLDebug("GDAL_netCDF", "creating band # %d/%d nDim = %d", iBand,
                 nBands, nDim);

        poSrcBand = poSrcDS->GetRasterBand(iBand);
        eDT = poSrcBand->GetRasterDataType();

        // Get var name from NETCDF_VARNAME.
        const char *tmpMetadata = poSrcBand->GetMetadataItem("NETCDF_VARNAME");
        char szBandName[NC_MAX_NAME + 1];
        if (tmpMetadata != nullptr)
        {
            if (nBands > 1 && papszExtraDimNames == nullptr)
                snprintf(szBandName, sizeof(szBandName), "%s%d", tmpMetadata,
                         iBand);
            else
                snprintf(szBandName, sizeof(szBandName), "%s", tmpMetadata);
        }
        else
        {
            szBandName[0] = '\0';
        }

        // Get long_name from <var>#long_name.
        char szLongName[NC_MAX_NAME + 1];
        snprintf(szLongName, sizeof(szLongName), "%s#%s",
                 poSrcBand->GetMetadataItem("NETCDF_VARNAME"), CF_LNG_NAME);
        tmpMetadata = poSrcDS->GetMetadataItem(szLongName);
        if (tmpMetadata != nullptr)
            snprintf(szLongName, sizeof(szLongName), "%s", tmpMetadata);
        else
            szLongName[0] = '\0';

        bool bSignedData = true;
        if (eDT == GDT_Byte)
        {
            // GDAL defaults to unsigned bytes, but check if metadata says its
            // signed, as NetCDF can support this for certain formats.
            bSignedData = false;
            tmpMetadata =
                poSrcBand->GetMetadataItem("PIXELTYPE", "IMAGE_STRUCTURE");
            if (tmpMetadata && EQUAL(tmpMetadata, "SIGNEDBYTE"))
                bSignedData = true;
        }

        if (nDim > 2)
            poBand = new netCDFRasterBand(
                netCDFRasterBand::CONSTRUCTOR_CREATE(), poDS, eDT, iBand,
                bSignedData, szBandName, szLongName, nBandID, nDim, iBand - 1,
                panBandZLev, panBandDimPos, panDimIds);
        else
            poBand = new netCDFRasterBand(
                netCDFRasterBand::CONSTRUCTOR_CREATE(), poDS, eDT, iBand,
                bSignedData, szBandName, szLongName);

        poDS->SetBand(iBand, poBand);

        // Set nodata value, if any.
        GDALCopyNoDataValue(poBand, poSrcBand);

        // Copy Metadata for band.
        CopyMetadata(nullptr, poSrcDS->GetRasterBand(iBand), poBand,
                     poDS->cdfid, poBand->nZId);

        // If more than 2D pass the first band's netcdf var ID to subsequent
        // bands.
        if (nDim > 2)
            nBandID = poBand->nZId;
    }

    // Write projection variable to band variable.
    poDS->AddGridMappingRef();

    pfnProgress(0.5, nullptr, pProgressData);

    // Write bands.

    // Make sure we are in data mode.
    poDS->SetDefineMode(false);

    double dfTemp = 0.5;

    eErr = CE_None;

    for (int iBand = 1; iBand <= nBands && eErr == CE_None; iBand++)
    {
        const double dfTemp2 = dfTemp + 0.4 / nBands;
        pScaledProgress = GDALCreateScaledProgress(dfTemp, dfTemp2, pfnProgress,
                                                   pProgressData);
        dfTemp = dfTemp2;

        CPLDebug("GDAL_netCDF", "copying band data # %d/%d ", iBand, nBands);

        poSrcBand = poSrcDS->GetRasterBand(iBand);
        eDT = poSrcBand->GetRasterDataType();

        GDALRasterBand *poDstBand = poDS->GetRasterBand(iBand);

        // Copy band data.
        if (eDT == GDT_Byte)
        {
            CPLDebug("GDAL_netCDF", "GByte Band#%d", iBand);
            eErr = NCDFCopyBand<GByte>(poSrcBand, poDstBand, nXSize, nYSize,
                                       GDALScaledProgress, pScaledProgress);
        }
        else if (eDT == GDT_UInt16)
        {
            CPLDebug("GDAL_netCDF", "GUInt16 Band#%d", iBand);
            eErr = NCDFCopyBand<GInt16>(poSrcBand, poDstBand, nXSize, nYSize,
                                        GDALScaledProgress, pScaledProgress);
        }
        else if (eDT == GDT_Int16)
        {
            CPLDebug("GDAL_netCDF", "GInt16 Band#%d", iBand);
            eErr = NCDFCopyBand<GUInt16>(poSrcBand, poDstBand, nXSize, nYSize,
                                         GDALScaledProgress, pScaledProgress);
        }
        else if (eDT == GDT_UInt32)
        {
            CPLDebug("GDAL_netCDF", "GUInt32 Band#%d", iBand);
            eErr = NCDFCopyBand<GUInt32>(poSrcBand, poDstBand, nXSize, nYSize,
                                         GDALScaledProgress, pScaledProgress);
        }
        else if (eDT == GDT_Int32)
        {
            CPLDebug("GDAL_netCDF", "GInt32 Band#%d", iBand);
            eErr = NCDFCopyBand<GInt32>(poSrcBand, poDstBand, nXSize, nYSize,
                                        GDALScaledProgress, pScaledProgress);
        }
        else if (eDT == GDT_UInt64)
        {
            CPLDebug("GDAL_netCDF", "GUInt64 Band#%d", iBand);
            eErr = NCDFCopyBand<std::uint64_t>(poSrcBand, poDstBand, nXSize,
                                               nYSize, GDALScaledProgress,
                                               pScaledProgress);
        }
        else if (eDT == GDT_Int64)
        {
            CPLDebug("GDAL_netCDF", "GInt64 Band#%d", iBand);
            eErr =
                NCDFCopyBand<std::int64_t>(poSrcBand, poDstBand, nXSize, nYSize,
                                           GDALScaledProgress, pScaledProgress);
        }
        else if (eDT == GDT_Float32)
        {
            CPLDebug("GDAL_netCDF", "float Band#%d", iBand);
            eErr = NCDFCopyBand<float>(poSrcBand, poDstBand, nXSize, nYSize,
                                       GDALScaledProgress, pScaledProgress);
        }
        else if (eDT == GDT_Float64)
        {
            CPLDebug("GDAL_netCDF", "double Band#%d", iBand);
            eErr = NCDFCopyBand<double>(poSrcBand, poDstBand, nXSize, nYSize,
                                        GDALScaledProgress, pScaledProgress);
        }
        else
        {
            CPLError(CE_Failure, CPLE_NotSupported,
                     "The NetCDF driver does not support GDAL data type %d",
                     eDT);
        }

        GDALDestroyScaledProgress(pScaledProgress);
    }

    delete (poDS);

    CPLFree(panDimIds);
    CPLFree(panBandDimPos);
    CPLFree(panBandZLev);
    CPLFree(panDimVarIds);
    if (papszExtraDimNames)
        CSLDestroy(papszExtraDimNames);

    if (eErr != CE_None)
        return nullptr;

    pfnProgress(0.95, nullptr, pProgressData);

    // Re-open dataset so we can return it.
    CPLStringList aosOpenOptions;
    aosOpenOptions.AddString("VARIABLES_AS_BANDS=YES");
    GDALOpenInfo oOpenInfo(pszFilename, GA_Update);
    oOpenInfo.nOpenFlags = GDAL_OF_RASTER | GDAL_OF_UPDATE;
    oOpenInfo.papszOpenOptions = aosOpenOptions.List();
    auto poRetDS = Open(&oOpenInfo);

    // PAM cloning is disabled. See bug #4244.
    // if( poDS )
    //     poDS->CloneInfo(poSrcDS, GCIF_PAM_DEFAULT);

    pfnProgress(1.0, nullptr, pProgressData);

    return poRetDS;
}

// Note: some logic depends on bIsProjected and bIsGeoGraphic.
// May not be known when Create() is called, see AddProjectionVars().
void netCDFDataset::ProcessCreationOptions()
{
    const char *pszConfig =
        CSLFetchNameValue(papszCreationOptions, "CONFIG_FILE");
    if (pszConfig != nullptr)
    {
        if (oWriterConfig.Parse(pszConfig))
        {
            // Override dataset creation options from the config file
            std::map<CPLString, CPLString>::iterator oIter;
            for (oIter = oWriterConfig.m_oDatasetCreationOptions.begin();
                 oIter != oWriterConfig.m_oDatasetCreationOptions.end();
                 ++oIter)
            {
                papszCreationOptions = CSLSetNameValue(
                    papszCreationOptions, oIter->first, oIter->second);
            }
        }
    }

    // File format.
    eFormat = NCDF_FORMAT_NC;
    const char *pszValue = CSLFetchNameValue(papszCreationOptions, "FORMAT");
    if (pszValue != nullptr)
    {
        if (EQUAL(pszValue, "NC"))
        {
            eFormat = NCDF_FORMAT_NC;
        }
#ifdef NETCDF_HAS_NC2
        else if (EQUAL(pszValue, "NC2"))
        {
            eFormat = NCDF_FORMAT_NC2;
        }
#endif
#ifdef NETCDF_HAS_NC4
        else if (EQUAL(pszValue, "NC4"))
        {
            eFormat = NCDF_FORMAT_NC4;
        }
        else if (EQUAL(pszValue, "NC4C"))
        {
            eFormat = NCDF_FORMAT_NC4C;
        }
#endif
        else
        {
            CPLError(CE_Failure, CPLE_NotSupported,
                     "FORMAT=%s in not supported, using the default NC format.",
                     pszValue);
        }
    }

    // Compression only available for NC4.
#ifdef NETCDF_HAS_NC4

    // COMPRESS option.
    pszValue = CSLFetchNameValue(papszCreationOptions, "COMPRESS");
    if (pszValue != nullptr)
    {
        if (EQUAL(pszValue, "NONE"))
        {
            eCompress = NCDF_COMPRESS_NONE;
        }
        else if (EQUAL(pszValue, "DEFLATE"))
        {
            eCompress = NCDF_COMPRESS_DEFLATE;
            if (!((eFormat == NCDF_FORMAT_NC4) ||
                  (eFormat == NCDF_FORMAT_NC4C)))
            {
                CPLError(CE_Warning, CPLE_IllegalArg,
                         "NOTICE: Format set to NC4C because compression is "
                         "set to DEFLATE.");
                eFormat = NCDF_FORMAT_NC4C;
            }
        }
        else
        {
            CPLError(CE_Failure, CPLE_NotSupported,
                     "COMPRESS=%s is not supported.", pszValue);
        }
    }

    // ZLEVEL option.
    pszValue = CSLFetchNameValue(papszCreationOptions, "ZLEVEL");
    if (pszValue != nullptr)
    {
        nZLevel = atoi(pszValue);
        if (!(nZLevel >= 1 && nZLevel <= 9))
        {
            CPLError(CE_Warning, CPLE_IllegalArg,
                     "ZLEVEL=%s value not recognised, ignoring.", pszValue);
            nZLevel = NCDF_DEFLATE_LEVEL;
        }
    }

    // CHUNKING option.
    bChunking =
        CPL_TO_BOOL(CSLFetchBoolean(papszCreationOptions, "CHUNKING", TRUE));

#endif

    // MULTIPLE_LAYERS option.
    const char *pszMultipleLayerBehavior =
        CSLFetchNameValueDef(papszCreationOptions, "MULTIPLE_LAYERS", "NO");
    const char *pszGeometryEnc = CSLFetchNameValueDef(
        papszCreationOptions, "GEOMETRY_ENCODING", "CF_1.8");
    if (EQUAL(pszMultipleLayerBehavior, "NO") ||
        EQUAL(pszGeometryEnc, "CF_1.8"))
    {
        eMultipleLayerBehavior = SINGLE_LAYER;
    }
    else if (EQUAL(pszMultipleLayerBehavior, "SEPARATE_FILES"))
    {
        eMultipleLayerBehavior = SEPARATE_FILES;
    }
#ifdef NETCDF_HAS_NC4
    else if (EQUAL(pszMultipleLayerBehavior, "SEPARATE_GROUPS"))
    {
        if (eFormat == NCDF_FORMAT_NC4)
        {
            eMultipleLayerBehavior = SEPARATE_GROUPS;
        }
        else
        {
            CPLError(CE_Warning, CPLE_IllegalArg,
                     "MULTIPLE_LAYERS=%s is recognised only with FORMAT=NC4",
                     pszMultipleLayerBehavior);
        }
    }
#endif
    else
    {
        CPLError(CE_Warning, CPLE_IllegalArg,
                 "MULTIPLE_LAYERS=%s not recognised", pszMultipleLayerBehavior);
    }

    // Set nCreateMode based on eFormat.
    switch (eFormat)
    {
#ifdef NETCDF_HAS_NC2
        case NCDF_FORMAT_NC2:
            nCreateMode = NC_CLOBBER | NC_64BIT_OFFSET;
            break;
#endif
#ifdef NETCDF_HAS_NC4
        case NCDF_FORMAT_NC4:
            nCreateMode = NC_CLOBBER | NC_NETCDF4;
            break;
        case NCDF_FORMAT_NC4C:
            nCreateMode = NC_CLOBBER | NC_NETCDF4 | NC_CLASSIC_MODEL;
            break;
#endif
        case NCDF_FORMAT_NC:
        default:
            nCreateMode = NC_CLOBBER;
            break;
    }

    CPLDebug("GDAL_netCDF", "file options: format=%d compress=%d zlevel=%d",
             eFormat, eCompress, nZLevel);
}

int netCDFDataset::DefVarDeflate(
#ifdef NETCDF_HAS_NC4
    int nVarId, bool bChunkingArg
#else
    int /* nVarId */, bool /* bChunkingArg */
#endif
)
{
#ifdef NETCDF_HAS_NC4
    if (eCompress == NCDF_COMPRESS_DEFLATE)
    {
        // Must set chunk size to avoid huge performance hit (set
        // bChunkingArg=TRUE)
        // perhaps another solution it to change the chunk cache?
        // http://www.unidata.ucar.edu/software/netcdf/docs/netcdf.html#Chunk-Cache
        // TODO: make sure this is okay.
        CPLDebug("GDAL_netCDF", "DefVarDeflate(%d, %d) nZlevel=%d", nVarId,
                 static_cast<int>(bChunkingArg), nZLevel);

        int status = nc_def_var_deflate(cdfid, nVarId, 1, 1, nZLevel);
        NCDF_ERR(status);

        if (status == NC_NOERR && bChunkingArg && bChunking)
        {
            // set chunking to be 1 for all dims, except X dim
            // size_t chunksize[] = { 1, (size_t)nRasterXSize };
            size_t chunksize[MAX_NC_DIMS];
            int nd;
            nc_inq_varndims(cdfid, nVarId, &nd);
            chunksize[0] = (size_t)1;
            chunksize[1] = (size_t)1;
            for (int i = 2; i < nd; i++)
                chunksize[i] = (size_t)1;
            chunksize[nd - 1] = (size_t)nRasterXSize;

            // Config options just for testing purposes
            const char *pszBlockXSize =
                CPLGetConfigOption("BLOCKXSIZE", nullptr);
            if (pszBlockXSize)
                chunksize[nd - 1] = (size_t)atoi(pszBlockXSize);

            const char *pszBlockYSize =
                CPLGetConfigOption("BLOCKYSIZE", nullptr);
            if (nd >= 2 && pszBlockYSize)
                chunksize[nd - 2] = (size_t)atoi(pszBlockYSize);

            CPLDebug("GDAL_netCDF",
                     "DefVarDeflate() chunksize={%ld, %ld} chunkX=%ld nd=%d",
                     (long)chunksize[0], (long)chunksize[1],
                     (long)chunksize[nd - 1], nd);
#ifdef NCDF_DEBUG
            for (int i = 0; i < nd; i++)
                CPLDebug("GDAL_netCDF", "DefVarDeflate() chunk[%d]=%ld", i,
                         chunksize[i]);
#endif

            status = nc_def_var_chunking(cdfid, nVarId, NC_CHUNKED, chunksize);
            NCDF_ERR(status);
        }
        else
        {
            CPLDebug("GDAL_netCDF", "chunksize not set");
        }
        return status;
    }
#endif
    return NC_NOERR;
}

/************************************************************************/
/*                           NCDFUnloadDriver()                         */
/************************************************************************/

static void NCDFUnloadDriver(CPL_UNUSED GDALDriver *poDriver)
{
    if (hNCMutex != nullptr)
        CPLDestroyMutex(hNCMutex);
    hNCMutex = nullptr;
}

/************************************************************************/
/*                          GDALRegister_netCDF()                       */
/************************************************************************/

void GDALRegister_netCDF()

{
    if (!GDAL_CHECK_VERSION("netCDF driver"))
        return;

    if (GDALGetDriverByName("netCDF") != nullptr)
        return;

    GDALDriver *poDriver = new GDALDriver();

    // Set the driver details.
    poDriver->SetDescription("netCDF");
    poDriver->SetMetadataItem(GDAL_DCAP_RASTER, "YES");
    poDriver->SetMetadataItem(GDAL_DCAP_VECTOR, "YES");
    poDriver->SetMetadataItem(GDAL_DCAP_CREATE_LAYER, "YES");
    poDriver->SetMetadataItem(GDAL_DCAP_CREATE_FIELD, "YES");
    poDriver->SetMetadataItem(GDAL_DCAP_Z_GEOMETRIES, "YES");
    poDriver->SetMetadataItem(GDAL_DMD_LONGNAME, "Network Common Data Format");
    poDriver->SetMetadataItem(GDAL_DMD_HELPTOPIC, "drivers/raster/netcdf.html");
    poDriver->SetMetadataItem(GDAL_DMD_EXTENSION, "nc");
    poDriver->SetMetadataItem(GDAL_DMD_CREATIONDATATYPES,
#ifdef NETCDF_HAS_NC4
                              "Byte UInt16 Int16 UInt32 Int32 Int64 UInt64 "
#else
                              "Byte Int16 Int32 "
#endif
                              "Float32 Float64 "
                              "CInt16 CInt32 CFloat32 CFloat64");
    poDriver->SetMetadataItem(
        GDAL_DMD_CREATIONOPTIONLIST,
        "<CreationOptionList>"
        "   <Option name='FORMAT' type='string-select' default='NC'>"
        "     <Value>NC</Value>"
#ifdef NETCDF_HAS_NC2
        "     <Value>NC2</Value>"
#endif
#ifdef NETCDF_HAS_NC4
        "     <Value>NC4</Value>"
        "     <Value>NC4C</Value>"
#endif
        "   </Option>"
#ifdef NETCDF_HAS_NC4
        "   <Option name='COMPRESS' type='string-select' scope='raster' "
        "default='NONE'>"
        "     <Value>NONE</Value>"
        "     <Value>DEFLATE</Value>"
        "   </Option>"
        "   <Option name='ZLEVEL' type='int' scope='raster' "
        "description='DEFLATE compression level 1-9' default='1'/>"
#endif
        "   <Option name='WRITE_BOTTOMUP' type='boolean' scope='raster' "
        "default='YES'>"
        "   </Option>"
        "   <Option name='WRITE_GDAL_TAGS' type='boolean' default='YES'>"
        "   </Option>"
        "   <Option name='WRITE_LONLAT' type='string-select' scope='raster'>"
        "     <Value>YES</Value>"
        "     <Value>NO</Value>"
        "     <Value>IF_NEEDED</Value>"
        "   </Option>"
        "   <Option name='TYPE_LONLAT' type='string-select' scope='raster'>"
        "     <Value>float</Value>"
        "     <Value>double</Value>"
        "   </Option>"
        "   <Option name='PIXELTYPE' type='string-select' scope='raster' "
        "description='only used in Create()'>"
        "       <Value>DEFAULT</Value>"
        "       <Value>SIGNEDBYTE</Value>"
        "   </Option>"
        "   <Option name='CHUNKING' type='boolean' scope='raster' "
        "default='YES' description='define chunking when creating netcdf4 "
        "file'/>"
        "   <Option name='MULTIPLE_LAYERS' type='string-select' scope='vector' "
        "description='Behaviour regarding multiple vector layer creation' "
        "default='NO'>"
        "       <Value>NO</Value>"
        "       <Value>SEPARATE_FILES</Value>"
#ifdef NETCDF_HAS_NC4
        "       <Value>SEPARATE_GROUPS</Value>"
#endif
        "   </Option>"
        "   <Option name='GEOMETRY_ENCODING' type='string' scope='vector' "
        "default='CF_1.8' description='Specifies the type of geometry encoding "
        "when creating a netCDF dataset'>"
        "       <Value>WKT</Value>"
        "       <Value>CF_1.8</Value>"
        "   </Option>"
        "   <Option name='CONFIG_FILE' type='string' scope='vector' "
        "description='Path to a XML configuration file (or content inlined)'/>"
        "   <Option name='WRITE_GDAL_VERSION' type='boolean' default='YES'/>"
        "   <Option name='WRITE_GDAL_HISTORY' type='boolean' default='YES'/>"
        "</CreationOptionList>");
    poDriver->SetMetadataItem(GDAL_DMD_SUBDATASETS, "YES");

    poDriver->SetMetadataItem(
        GDAL_DS_LAYER_CREATIONOPTIONLIST,
        "<LayerCreationOptionList>"
        "   <Option name='RECORD_DIM_NAME' type='string' description='Name of "
        "the unlimited dimension' default='record'/>"
        "   <Option name='STRING_DEFAULT_WIDTH' type='int' description='"
#ifdef NETCDF_HAS_NC4
        "For non-NC4 format, "
#endif
        "default width of strings. Default is 10 in autogrow mode, 80 "
        "otherwise.'/>"
        "   <Option name='WKT_DEFAULT_WIDTH' type='int' description='"
#ifdef NETCDF_HAS_NC4
        "For non-NC4 format, "
#endif
        "default width of WKT strings. Default is 1000 in autogrow mode, 10000 "
        "otherwise.'/>"
        "   <Option name='AUTOGROW_STRINGS' type='boolean' "
        "description='Whether to auto-grow non-bounded string fields of "
        "bidimensional char variable' default='YES'/>"
#ifdef NETCDF_HAS_NC4
        "   <Option name='USE_STRING_IN_NC4' type='boolean' "
        "description='Whether to use NetCDF string type for strings in NC4 "
        "format. If NO, bidimensional char variable are used' default='YES'/>"
#if 0
"   <Option name='NCDUMP_COMPAT' type='boolean' description='When USE_STRING_IN_NC4=YEs, whether to use empty string instead of null string to avoid crashes with ncdump' default='NO'/>"
#endif
#endif
        "   <Option name='FEATURE_TYPE' type='string-select' description='CF "
        "FeatureType' default='AUTO'>"
        "       <Value>AUTO</Value>"
        "       <Value>POINT</Value>"
        "       <Value>PROFILE</Value>"
        "   </Option>"
        "   <Option name='BUFFER_SIZE' type='int' default='' "
        "description='Specifies the soft limit of buffer translation in bytes. "
        "Minimum size is 4096. Does not apply to datasets with CF version less "
        "than 1.8.'/>"
        "   <Option name='GROUPLESS_WRITE_BACK' type='boolean' default='NO' "
        "description='Enables or disables array building write back for "
        "CF-1.8.'/>"
        "   <Option name='PROFILE_DIM_NAME' type='string' description='Name of "
        "the profile dimension and variable' default='profile'/>"
        "   <Option name='PROFILE_DIM_INIT_SIZE' type='string' "
        "description='Initial size of profile dimension (default 100), or "
        "UNLIMITED for NC4 files'/>"
        "   <Option name='PROFILE_VARIABLES' type='string' description='Comma "
        "separated list of field names that must be indexed by the profile "
        "dimension'/>"
        "</LayerCreationOptionList>");

    poDriver->SetMetadataItem(
        GDAL_DMD_OPENOPTIONLIST,
        "<OpenOptionList>"
        "   <Option name='HONOUR_VALID_RANGE' type='boolean' scope='raster' "
        "description='Whether to set to nodata pixel values outside of the "
        "validity range' default='YES'/>"
        "   <Option name='IGNORE_XY_AXIS_NAME_CHECKS' type='boolean' "
        "scope='raster' "
        "description='Whether X/Y dimensions should be always considered as "
        "geospatial axis, even if the lack conventional attributes confirming "
        "it.'"
        " default='NO'/>"
        "   <Option name='VARIABLES_AS_BANDS' type='boolean' scope='raster' "
        "description='Whether 2D variables that share the same indexing "
        "dimensions "
        "should be exposed as several bands of a same dataset instead of "
        "several "
        "subdatasets.' default='NO'/>"
        "</OpenOptionList>");

    // Make driver config and capabilities available.
    poDriver->SetMetadataItem("NETCDF_VERSION", nc_inq_libvers());
    poDriver->SetMetadataItem("NETCDF_CONVENTIONS",
                              GDAL_DEFAULT_NCDF_CONVENTIONS);
#ifdef NETCDF_HAS_NC2
    poDriver->SetMetadataItem("NETCDF_HAS_NC2", "YES");
#endif
#ifdef NETCDF_HAS_NC4
    poDriver->SetMetadataItem("NETCDF_HAS_NC4", "YES");
#endif
#ifdef NETCDF_HAS_HDF4
    poDriver->SetMetadataItem("NETCDF_HAS_HDF4", "YES");
#endif
#ifdef HAVE_HDF4
    poDriver->SetMetadataItem("GDAL_HAS_HDF4", "YES");
#endif
#ifdef HAVE_HDF5
    poDriver->SetMetadataItem("GDAL_HAS_HDF5", "YES");
#endif
#ifdef HAVE_NETCDF_MEM
    poDriver->SetMetadataItem("NETCDF_HAS_NETCDF_MEM", "YES");
#endif

#ifdef ENABLE_NCDUMP
    poDriver->SetMetadataItem("ENABLE_NCDUMP", "YES");
#endif

#ifdef ENABLE_UFFD
    if (CPLIsUserFaultMappingSupported())
    {
        poDriver->SetMetadataItem(GDAL_DCAP_VIRTUALIO, "YES");
    }
#endif

#ifdef NETCDF_HAS_NC4
    poDriver->SetMetadataItem(GDAL_DCAP_MULTIDIM_RASTER, "YES");

    poDriver->SetMetadataItem(
        GDAL_DMD_MULTIDIM_DATASET_CREATIONOPTIONLIST,
        "<MultiDimDatasetCreationOptionList>"
        "   <Option name='FORMAT' type='string-select' default='NC4'>"
        "     <Value>NC</Value>"
#ifdef NETCDF_HAS_NC2
        "     <Value>NC2</Value>"
#endif
        "     <Value>NC4</Value>"
        "     <Value>NC4C</Value>"
        "   </Option>"
        "   <Option name='CONVENTIONS' type='string' default='CF-1.6' "
        "description='Value of the Conventions attribute'/>"
        "</MultiDimDatasetCreationOptionList>");

    poDriver->SetMetadataItem(
        GDAL_DMD_MULTIDIM_DIMENSION_CREATIONOPTIONLIST,
        "<MultiDimDimensionCreationOptionList>"
        "   <Option name='UNLIMITED' type='boolean' description='Whether the "
        "dimension should be unlimited' default='false'/>"
        "</MultiDimDimensionCreationOptionList>");

    poDriver->SetMetadataItem(
        GDAL_DMD_MULTIDIM_ARRAY_CREATIONOPTIONLIST,
        "<MultiDimArrayCreationOptionList>"
        "   <Option name='BLOCKSIZE' type='int' description='Block size in "
        "pixels'/>"
        "   <Option name='COMPRESS' type='string-select' default='NONE'>"
        "     <Value>NONE</Value>"
        "     <Value>DEFLATE</Value>"
        "   </Option>"
        "   <Option name='ZLEVEL' type='int' description='DEFLATE compression "
        "level 1-9' default='1'/>"
        "   <Option name='NC_TYPE' type='string-select' default='netCDF data "
        "type'>"
        "     <Value>AUTO</Value>"
        "     <Value>NC_BYTE</Value>"
        "     <Value>NC_INT64</Value>"
        "     <Value>NC_UINT64</Value>"
        "   </Option>"
        "</MultiDimArrayCreationOptionList>");

    poDriver->SetMetadataItem(
        GDAL_DMD_MULTIDIM_ARRAY_OPENOPTIONLIST,
        "<MultiDimArrayOpenOptionList>"
        "   <Option name='USE_DEFAULT_FILL_AS_NODATA' type='boolean' "
        "description='Whether the default fill value should be used as nodata "
        "when there is no _FillValue or missing_value attribute' default='NO'/>"
        "</MultiDimArrayOpenOptionList>");

    poDriver->SetMetadataItem(GDAL_DMD_MULTIDIM_ATTRIBUTE_CREATIONOPTIONLIST,
                              "<MultiDimAttributeCreationOptionList>"
                              "   <Option name='NC_TYPE' type='string-select' "
                              "default='netCDF data type'>"
                              "     <Value>AUTO</Value>"
                              "     <Value>NC_BYTE</Value>"
                              "     <Value>NC_CHAR</Value>"
                              "     <Value>NC_INT64</Value>"
                              "     <Value>NC_UINT64</Value>"
                              "   </Option>"
                              "</MultiDimAttributeCreationOptionList>");
#endif

    poDriver->SetMetadataItem(GDAL_DMD_CREATIONFIELDDATATYPES,
                              "Integer Integer64 Real String Date DateTime");

    poDriver->SetMetadataItem(GDAL_DMD_SUPPORTED_SQL_DIALECTS, "OGRSQL SQLITE");

    // Set pfns and register driver.
    poDriver->pfnOpen = netCDFDataset::Open;
    poDriver->pfnCreateCopy = netCDFDataset::CreateCopy;
    poDriver->pfnCreate = netCDFDataset::Create;
#ifdef NETCDF_HAS_NC4
    poDriver->pfnCreateMultiDimensional = netCDFDataset::CreateMultiDimensional;
#endif
    poDriver->pfnIdentify = netCDFDataset::Identify;
    poDriver->pfnUnloadDriver = NCDFUnloadDriver;

    GetGDALDriverManager()->RegisterDriver(poDriver);
}

/************************************************************************/
/*                          New functions                               */
/************************************************************************/

/* Test for GDAL version string >= target */
static bool NCDFIsGDALVersionGTE(const char *pszVersion, int nTarget)
{

    // Valid strings are "GDAL 1.9dev, released 2011/01/18" and "GDAL 1.8.1 ".
    if (pszVersion == nullptr || EQUAL(pszVersion, ""))
        return false;
    else if (!STARTS_WITH_CI(pszVersion, "GDAL "))
        return false;
    // 2.0dev of 2011/12/29 has been later renamed as 1.10dev.
    else if (EQUAL("GDAL 2.0dev, released 2011/12/29", pszVersion))
        return nTarget <= GDAL_COMPUTE_VERSION(1, 10, 0);
    else if (STARTS_WITH_CI(pszVersion, "GDAL 1.9dev"))
        return nTarget <= 1900;
    else if (STARTS_WITH_CI(pszVersion, "GDAL 1.8dev"))
        return nTarget <= 1800;

    char **papszTokens = CSLTokenizeString2(pszVersion + 5, ".", 0);

    int nVersions[] = {0, 0, 0, 0};
    for (int iToken = 0; papszTokens && iToken < 4 && papszTokens[iToken];
         iToken++)
    {
        nVersions[iToken] = atoi(papszTokens[iToken]);
        if (nVersions[iToken] < 0)
            nVersions[iToken] = 0;
        else if (nVersions[iToken] > 99)
            nVersions[iToken] = 99;
    }

    int nVersion = 0;
    if (nVersions[0] > 1 || nVersions[1] >= 10)
        nVersion =
            GDAL_COMPUTE_VERSION(nVersions[0], nVersions[1], nVersions[2]);
    else
        nVersion = nVersions[0] * 1000 + nVersions[1] * 100 +
                   nVersions[2] * 10 + nVersions[3];

    CSLDestroy(papszTokens);
    return nTarget <= nVersion;
}

// Add Conventions, GDAL version and history.
static void NCDFAddGDALHistory(int fpImage, const char *pszFilename,
                               bool bWriteGDALVersion, bool bWriteGDALHistory,
                               const char *pszOldHist,
                               const char *pszFunctionName,
                               const char *pszCFVersion)
{
    if (pszCFVersion == nullptr)
    {
        pszCFVersion = GDAL_DEFAULT_NCDF_CONVENTIONS;
    }
    int status = nc_put_att_text(fpImage, NC_GLOBAL, "Conventions",
                                 strlen(pszCFVersion), pszCFVersion);
    NCDF_ERR(status);

    if (bWriteGDALVersion)
    {
        const char *pszNCDF_GDAL = GDALVersionInfo("--version");
        status = nc_put_att_text(fpImage, NC_GLOBAL, "GDAL",
                                 strlen(pszNCDF_GDAL), pszNCDF_GDAL);
        NCDF_ERR(status);
    }

    if (bWriteGDALHistory)
    {
        // Add history.
        CPLString osTmp;
#ifdef GDAL_SET_CMD_LINE_DEFINED_TMP
        if (!EQUAL(GDALGetCmdLine(), ""))
            osTmp = GDALGetCmdLine();
        else
            osTmp =
                CPLSPrintf("GDAL %s( %s, ... )", pszFunctionName, pszFilename);
#else
        osTmp = CPLSPrintf("GDAL %s( %s, ... )", pszFunctionName, pszFilename);
#endif

        NCDFAddHistory(fpImage, osTmp.c_str(), pszOldHist);
    }
    else if (pszOldHist != nullptr)
    {
        status = nc_put_att_text(fpImage, NC_GLOBAL, "history",
                                 strlen(pszOldHist), pszOldHist);
        NCDF_ERR(status);
    }
}

// Code taken from cdo and libcdi, used for writing the history attribute.

// void cdoDefHistory(int fileID, char *histstring)
static void NCDFAddHistory(int fpImage, const char *pszAddHist,
                           const char *pszOldHist)
{
    // Check pszOldHist - as if there was no previous history, it will be
    // a null pointer - if so set as empty.
    if (nullptr == pszOldHist)
    {
        pszOldHist = "";
    }

    char strtime[32];
    strtime[0] = '\0';

    time_t tp = time(nullptr);
    if (tp != -1)
    {
        struct tm *ltime = localtime(&tp);
        (void)strftime(strtime, sizeof(strtime),
                       "%a %b %d %H:%M:%S %Y: ", ltime);
    }

    // status = nc_get_att_text(fpImage, NC_GLOBAL,
    //                           "history", pszOldHist);
    // printf("status: %d pszOldHist: [%s]\n",status,pszOldHist);

    size_t nNewHistSize =
        strlen(pszOldHist) + strlen(strtime) + strlen(pszAddHist) + 1 + 1;
    char *pszNewHist =
        static_cast<char *>(CPLMalloc(nNewHistSize * sizeof(char)));

    strcpy(pszNewHist, strtime);
    strcat(pszNewHist, pszAddHist);

    // int disableHistory = FALSE;
    // if( !disableHistory )
    {
        if (!EQUAL(pszOldHist, ""))
            strcat(pszNewHist, "\n");
        strcat(pszNewHist, pszOldHist);
    }

    const int status = nc_put_att_text(fpImage, NC_GLOBAL, "history",
                                       strlen(pszNewHist), pszNewHist);
    NCDF_ERR(status);

    CPLFree(pszNewHist);
}

static bool NCDFIsCfProjection(const char *pszProjection)
{
    // Find the appropriate mapping.
    for (int iMap = 0; poNetcdfSRS_PT[iMap].WKT_SRS != nullptr; iMap++)
    {
#ifdef NCDF_DEBUG
        CPLDebug("GDAL_netCDF", "now at %d, proj=%s", iMap,
                 poNetcdfSRS_PT[iMap].WKT_SRS);
#endif
        if (EQUAL(pszProjection, poNetcdfSRS_PT[iMap].WKT_SRS))
        {
            return poNetcdfSRS_PT[iMap].mappings != nullptr;
        }
    }
    return false;
}

/* Write any needed projection attributes *
 * poPROJCS: ptr to proj crd system
 * pszProjection: name of projection system in GDAL WKT
 *
 * The function first looks for the oNetcdfSRS_PP mapping object
 * that corresponds to the input projection name. If none is found
 * the generic mapping is used.  In the case of specific mappings,
 * the driver looks for each attribute listed in the mapping object
 * and then looks up the value within the OGR_SRSNode. In the case
 * of the generic mapping, the lookup is reversed (projection params,
 * then mapping).  For more generic code, GDAL->NETCDF
 * mappings and the associated value are saved in std::map objects.
 */

// NOTE: modifications by ET to combine the specific and generic mappings.

static std::vector<std::pair<std::string, double>>
NCDFGetProjAttribs(const OGR_SRSNode *poPROJCS, const char *pszProjection)
{
    const oNetcdfSRS_PP *poMap = nullptr;
    int nMapIndex = -1;

    // Find the appropriate mapping.
    for (int iMap = 0; poNetcdfSRS_PT[iMap].WKT_SRS != nullptr; iMap++)
    {
        if (EQUAL(pszProjection, poNetcdfSRS_PT[iMap].WKT_SRS))
        {
            nMapIndex = iMap;
            poMap = poNetcdfSRS_PT[iMap].mappings;
            break;
        }
    }

    // ET TODO if projection name is not found, should we do something special?
    if (nMapIndex == -1)
    {
        CPLError(CE_Warning, CPLE_AppDefined,
                 "projection name %s not found in the lookup tables!",
                 pszProjection);
    }
    // If no mapping was found or assigned, set the generic one.
    if (!poMap)
    {
        CPLError(CE_Warning, CPLE_AppDefined,
                 "projection name %s in not part of the CF standard, "
                 "will not be supported by CF!",
                 pszProjection);
        poMap = poGenericMappings;
    }

    // Initialize local map objects.

    // Attribute <GDAL,NCDF> and Value <NCDF,value> mappings
    std::map<std::string, std::string> oAttMap;
    for (int iMap = 0; poMap[iMap].WKT_ATT != nullptr; iMap++)
    {
        oAttMap[poMap[iMap].WKT_ATT] = poMap[iMap].CF_ATT;
    }

    const char *pszParamVal = nullptr;
    std::map<std::string, double> oValMap;
    for (int iChild = 0; iChild < poPROJCS->GetChildCount(); iChild++)
    {
        const OGR_SRSNode *poNode = poPROJCS->GetChild(iChild);
        if (!EQUAL(poNode->GetValue(), "PARAMETER") ||
            poNode->GetChildCount() != 2)
            continue;
        const char *pszParamStr = poNode->GetChild(0)->GetValue();
        pszParamVal = poNode->GetChild(1)->GetValue();

        oValMap[pszParamStr] = CPLAtof(pszParamVal);
    }

    const std::string *posGDALAtt;
    std::map<std::string, std::string>::iterator oAttIter;
    std::map<std::string, double>::iterator oValIter, oValIter2;

    // Results to write.
    std::vector<std::pair<std::string, double>> oOutList;

    // Lookup mappings and fill output vector.
    if (poMap != poGenericMappings)
    {
        // special case for PS (Polar Stereographic) grid.
        if (EQUAL(pszProjection, SRS_PT_POLAR_STEREOGRAPHIC))
        {
            const double dfLat = oValMap[SRS_PP_LATITUDE_OF_ORIGIN];

            auto oScaleFactorIter = oValMap.find(SRS_PP_SCALE_FACTOR);
            if (oScaleFactorIter != oValMap.end())
            {
                // Polar Stereographic (variant A)
                const double dfScaleFactor = oScaleFactorIter->second;
                // dfLat should be +/- 90
                oOutList.push_back(
                    std::make_pair(std::string(CF_PP_LAT_PROJ_ORIGIN), dfLat));
                oOutList.push_back(std::make_pair(
                    std::string(CF_PP_SCALE_FACTOR_ORIGIN), dfScaleFactor));
            }
            else
            {
                // Polar Stereographic (variant B)
                const double dfLatPole = (dfLat > 0) ? 90.0 : -90.0;
                oOutList.push_back(std::make_pair(
                    std::string(CF_PP_LAT_PROJ_ORIGIN), dfLatPole));
                oOutList.push_back(
                    std::make_pair(std::string(CF_PP_STD_PARALLEL), dfLat));
            }
        }

        // Specific mapping, loop over mapping values.
        for (oAttIter = oAttMap.begin(); oAttIter != oAttMap.end(); ++oAttIter)
        {
            posGDALAtt = &(oAttIter->first);
            const std::string *posNCDFAtt = &(oAttIter->second);
            oValIter = oValMap.find(*posGDALAtt);

            if (oValIter != oValMap.end())
            {
                double dfValue = oValIter->second;
                bool bWriteVal = true;

                // special case for LCC-1SP
                //   See comments in netcdfdataset.h for this projection.
                if (EQUAL(SRS_PP_SCALE_FACTOR, posGDALAtt->c_str()) &&
                    EQUAL(pszProjection, SRS_PT_LAMBERT_CONFORMAL_CONIC_1SP))
                {
                    // Default is to not write as it is not CF-1.
                    bWriteVal = false;
                    // Test if there is no standard_parallel1.
                    if (oValMap.find(std::string(CF_PP_STD_PARALLEL_1)) ==
                        oValMap.end())
                    {
                        // If scale factor != 1.0, write value for GDAL, but
                        // this is not supported by CF-1.
                        if (!CPLIsEqual(dfValue, 1.0))
                        {
                            CPLError(
                                CE_Failure, CPLE_NotSupported,
                                "NetCDF driver export of LCC-1SP with scale "
                                "factor != 1.0 and no standard_parallel1 is "
                                "not CF-1 (bug #3324).  Use the 2SP variant "
                                "which is supported by CF.");
                            bWriteVal = true;
                        }
                        // Else copy standard_parallel1 from
                        // latitude_of_origin, because scale_factor=1.0.
                        else
                        {
                            oValIter2 = oValMap.find(
                                std::string(SRS_PP_LATITUDE_OF_ORIGIN));
                            if (oValIter2 != oValMap.end())
                            {
                                oOutList.push_back(std::make_pair(
                                    std::string(CF_PP_STD_PARALLEL_1),
                                    oValIter2->second));
                            }
                            else
                            {
                                CPLError(CE_Failure, CPLE_NotSupported,
                                         "NetCDF driver export of LCC-1SP with "
                                         "no standard_parallel1 "
                                         "and no latitude_of_origin is not "
                                         "supported (bug #3324).");
                            }
                        }
                    }
                }
                if (bWriteVal)
                    oOutList.push_back(std::make_pair(*posNCDFAtt, dfValue));
            }
#ifdef NCDF_DEBUG
            else
            {
                CPLDebug("GDAL_netCDF", "NOT FOUND!");
            }
#endif
        }
    }
    else
    {
        // Generic mapping, loop over projected values.
        for (oValIter = oValMap.begin(); oValIter != oValMap.end(); ++oValIter)
        {
            posGDALAtt = &(oValIter->first);
            double dfValue = oValIter->second;

            oAttIter = oAttMap.find(*posGDALAtt);

            if (oAttIter != oAttMap.end())
            {
                oOutList.push_back(std::make_pair(oAttIter->second, dfValue));
            }
            /* for SRS_PP_SCALE_FACTOR write 2 mappings */
            else if (EQUAL(posGDALAtt->c_str(), SRS_PP_SCALE_FACTOR))
            {
                oOutList.push_back(std::make_pair(
                    std::string(CF_PP_SCALE_FACTOR_MERIDIAN), dfValue));
                oOutList.push_back(std::make_pair(
                    std::string(CF_PP_SCALE_FACTOR_ORIGIN), dfValue));
            }
            /* if not found insert the GDAL name */
            else
            {
                oOutList.push_back(std::make_pair(*posGDALAtt, dfValue));
            }
        }
    }

    return oOutList;
}

static CPLErr NCDFSafeStrcat(char **ppszDest, const char *pszSrc,
                             size_t *nDestSize)
{
    /* Reallocate the data string until the content fits */
    while (*nDestSize < (strlen(*ppszDest) + strlen(pszSrc) + 1))
    {
        (*nDestSize) *= 2;
        *ppszDest = static_cast<char *>(
            CPLRealloc(reinterpret_cast<void *>(*ppszDest), *nDestSize));
#ifdef NCDF_DEBUG
        CPLDebug("GDAL_netCDF", "NCDFSafeStrcat() resized str from %ld to %ld",
                 (*nDestSize) / 2, *nDestSize);
#endif
    }
    strcat(*ppszDest, pszSrc);

    return CE_None;
}

/* helper function for NCDFGetAttr() */
/* if pdfValue != nullptr, sets *pdfValue to first value returned */
/* if ppszValue != nullptr, sets *ppszValue with all attribute values */
/* *ppszValue is the responsibility of the caller and must be freed */
static CPLErr NCDFGetAttr1(int nCdfId, int nVarId, const char *pszAttrName,
                           double *pdfValue, char **ppszValue)
{
    nc_type nAttrType = NC_NAT;
    size_t nAttrLen = 0;

    int status = nc_inq_att(nCdfId, nVarId, pszAttrName, &nAttrType, &nAttrLen);
    if (status != NC_NOERR)
        return CE_Failure;

#ifdef NCDF_DEBUG
    CPLDebug("GDAL_netCDF", "NCDFGetAttr1(%s) len=%ld type=%d", pszAttrName,
             nAttrLen, nAttrType);
#endif
    if (nAttrLen == 0 && nAttrType != NC_CHAR)
        return CE_Failure;

    /* Allocate guaranteed minimum size (use 10 or 20 if not a string) */
    size_t nAttrValueSize = nAttrLen + 1;
    if (nAttrType != NC_CHAR && nAttrValueSize < 10)
        nAttrValueSize = 10;
    if (nAttrType == NC_DOUBLE && nAttrValueSize < 20)
        nAttrValueSize = 20;
#ifdef NETCDF_HAS_NC4
    if (nAttrType == NC_INT64 && nAttrValueSize < 20)
        nAttrValueSize = 22;
#endif
    char *pszAttrValue =
        static_cast<char *>(CPLCalloc(nAttrValueSize, sizeof(char)));
    *pszAttrValue = '\0';

    if (nAttrLen > 1 && nAttrType != NC_CHAR)
        NCDFSafeStrcat(&pszAttrValue, "{", &nAttrValueSize);

    double dfValue = 0.0;
    size_t m;
    char szTemp[256];
    bool bSetDoubleFromStr = false;

    switch (nAttrType)
    {
        case NC_CHAR:
            CPL_IGNORE_RET_VAL(
                nc_get_att_text(nCdfId, nVarId, pszAttrName, pszAttrValue));
            pszAttrValue[nAttrLen] = '\0';
            bSetDoubleFromStr = true;
            dfValue = 0.0;
            break;
        case NC_BYTE:
        {
            signed char *pscTemp = static_cast<signed char *>(
                CPLCalloc(nAttrLen, sizeof(signed char)));
            nc_get_att_schar(nCdfId, nVarId, pszAttrName, pscTemp);
            dfValue = static_cast<double>(pscTemp[0]);
            for (m = 0; m < nAttrLen - 1; m++)
            {
                snprintf(szTemp, sizeof(szTemp), "%d,", pscTemp[m]);
                NCDFSafeStrcat(&pszAttrValue, szTemp, &nAttrValueSize);
            }
            snprintf(szTemp, sizeof(szTemp), "%d", pscTemp[m]);
            NCDFSafeStrcat(&pszAttrValue, szTemp, &nAttrValueSize);
            CPLFree(pscTemp);
            break;
        }
        case NC_SHORT:
        {
            short *psTemp =
                static_cast<short *>(CPLCalloc(nAttrLen, sizeof(short)));
            nc_get_att_short(nCdfId, nVarId, pszAttrName, psTemp);
            dfValue = static_cast<double>(psTemp[0]);
            for (m = 0; m < nAttrLen - 1; m++)
            {
                snprintf(szTemp, sizeof(szTemp), "%d,", psTemp[m]);
                NCDFSafeStrcat(&pszAttrValue, szTemp, &nAttrValueSize);
            }
            snprintf(szTemp, sizeof(szTemp), "%d", psTemp[m]);
            NCDFSafeStrcat(&pszAttrValue, szTemp, &nAttrValueSize);
            CPLFree(psTemp);
            break;
        }
        case NC_INT:
        {
            int *pnTemp = static_cast<int *>(CPLCalloc(nAttrLen, sizeof(int)));
            nc_get_att_int(nCdfId, nVarId, pszAttrName, pnTemp);
            dfValue = static_cast<double>(pnTemp[0]);
            for (m = 0; m < nAttrLen - 1; m++)
            {
                snprintf(szTemp, sizeof(szTemp), "%d,", pnTemp[m]);
                NCDFSafeStrcat(&pszAttrValue, szTemp, &nAttrValueSize);
            }
            snprintf(szTemp, sizeof(szTemp), "%d", pnTemp[m]);
            NCDFSafeStrcat(&pszAttrValue, szTemp, &nAttrValueSize);
            CPLFree(pnTemp);
            break;
        }
        case NC_FLOAT:
        {
            float *pfTemp =
                static_cast<float *>(CPLCalloc(nAttrLen, sizeof(float)));
            nc_get_att_float(nCdfId, nVarId, pszAttrName, pfTemp);
            dfValue = static_cast<double>(pfTemp[0]);
            for (m = 0; m < nAttrLen - 1; m++)
            {
                CPLsnprintf(szTemp, sizeof(szTemp), "%.8g,", pfTemp[m]);
                NCDFSafeStrcat(&pszAttrValue, szTemp, &nAttrValueSize);
            }
            CPLsnprintf(szTemp, sizeof(szTemp), "%.8g", pfTemp[m]);
            NCDFSafeStrcat(&pszAttrValue, szTemp, &nAttrValueSize);
            CPLFree(pfTemp);
            break;
        }
        case NC_DOUBLE:
        {
            double *pdfTemp =
                static_cast<double *>(CPLCalloc(nAttrLen, sizeof(double)));
            nc_get_att_double(nCdfId, nVarId, pszAttrName, pdfTemp);
            dfValue = pdfTemp[0];
            for (m = 0; m < nAttrLen - 1; m++)
            {
                CPLsnprintf(szTemp, sizeof(szTemp), "%.16g,", pdfTemp[m]);
                NCDFSafeStrcat(&pszAttrValue, szTemp, &nAttrValueSize);
            }
            CPLsnprintf(szTemp, sizeof(szTemp), "%.16g", pdfTemp[m]);
            NCDFSafeStrcat(&pszAttrValue, szTemp, &nAttrValueSize);
            CPLFree(pdfTemp);
            break;
        }
#ifdef NETCDF_HAS_NC4
        case NC_STRING:
        {
            char **ppszTemp =
                static_cast<char **>(CPLCalloc(nAttrLen, sizeof(char *)));
            nc_get_att_string(nCdfId, nVarId, pszAttrName, ppszTemp);
            bSetDoubleFromStr = true;
            dfValue = 0.0;
            for (m = 0; m < nAttrLen - 1; m++)
            {
                NCDFSafeStrcat(&pszAttrValue,
                               ppszTemp[m] ? ppszTemp[m] : "{NULL}",
                               &nAttrValueSize);
                NCDFSafeStrcat(&pszAttrValue, ",", &nAttrValueSize);
            }
            NCDFSafeStrcat(&pszAttrValue, ppszTemp[m] ? ppszTemp[m] : "{NULL}",
                           &nAttrValueSize);
            nc_free_string(nAttrLen, ppszTemp);
            CPLFree(ppszTemp);
            break;
        }
        case NC_UBYTE:
        {
            unsigned char *pucTemp = static_cast<unsigned char *>(
                CPLCalloc(nAttrLen, sizeof(unsigned char)));
            nc_get_att_uchar(nCdfId, nVarId, pszAttrName, pucTemp);
            dfValue = static_cast<double>(pucTemp[0]);
            for (m = 0; m < nAttrLen - 1; m++)
            {
                CPLsnprintf(szTemp, sizeof(szTemp), "%u,", pucTemp[m]);
                NCDFSafeStrcat(&pszAttrValue, szTemp, &nAttrValueSize);
            }
            CPLsnprintf(szTemp, sizeof(szTemp), "%u", pucTemp[m]);
            NCDFSafeStrcat(&pszAttrValue, szTemp, &nAttrValueSize);
            CPLFree(pucTemp);
            break;
        }
        case NC_USHORT:
        {
            unsigned short *pusTemp;
            pusTemp = static_cast<unsigned short *>(
                CPLCalloc(nAttrLen, sizeof(unsigned short)));
            nc_get_att_ushort(nCdfId, nVarId, pszAttrName, pusTemp);
            dfValue = static_cast<double>(pusTemp[0]);
            for (m = 0; m < nAttrLen - 1; m++)
            {
                CPLsnprintf(szTemp, sizeof(szTemp), "%u,", pusTemp[m]);
                NCDFSafeStrcat(&pszAttrValue, szTemp, &nAttrValueSize);
            }
            CPLsnprintf(szTemp, sizeof(szTemp), "%u", pusTemp[m]);
            NCDFSafeStrcat(&pszAttrValue, szTemp, &nAttrValueSize);
            CPLFree(pusTemp);
            break;
        }
        case NC_UINT:
        {
            unsigned int *punTemp =
                static_cast<unsigned int *>(CPLCalloc(nAttrLen, sizeof(int)));
            nc_get_att_uint(nCdfId, nVarId, pszAttrName, punTemp);
            dfValue = static_cast<double>(punTemp[0]);
            for (m = 0; m < nAttrLen - 1; m++)
            {
                CPLsnprintf(szTemp, sizeof(szTemp), "%u,", punTemp[m]);
                NCDFSafeStrcat(&pszAttrValue, szTemp, &nAttrValueSize);
            }
            CPLsnprintf(szTemp, sizeof(szTemp), "%u", punTemp[m]);
            NCDFSafeStrcat(&pszAttrValue, szTemp, &nAttrValueSize);
            CPLFree(punTemp);
            break;
        }
        case NC_INT64:
        {
            GIntBig *panTemp =
                static_cast<GIntBig *>(CPLCalloc(nAttrLen, sizeof(GIntBig)));
            nc_get_att_longlong(nCdfId, nVarId, pszAttrName, panTemp);
            dfValue = static_cast<double>(panTemp[0]);
            for (m = 0; m < nAttrLen - 1; m++)
            {
                CPLsnprintf(szTemp, sizeof(szTemp), CPL_FRMT_GIB ",",
                            panTemp[m]);
                NCDFSafeStrcat(&pszAttrValue, szTemp, &nAttrValueSize);
            }
            CPLsnprintf(szTemp, sizeof(szTemp), CPL_FRMT_GIB, panTemp[m]);
            NCDFSafeStrcat(&pszAttrValue, szTemp, &nAttrValueSize);
            CPLFree(panTemp);
            break;
        }
        case NC_UINT64:
        {
            GUIntBig *panTemp =
                static_cast<GUIntBig *>(CPLCalloc(nAttrLen, sizeof(GUIntBig)));
            nc_get_att_ulonglong(nCdfId, nVarId, pszAttrName, panTemp);
            dfValue = static_cast<double>(panTemp[0]);
            for (m = 0; m < nAttrLen - 1; m++)
            {
                CPLsnprintf(szTemp, sizeof(szTemp), CPL_FRMT_GUIB ",",
                            panTemp[m]);
                NCDFSafeStrcat(&pszAttrValue, szTemp, &nAttrValueSize);
            }
            CPLsnprintf(szTemp, sizeof(szTemp), CPL_FRMT_GUIB, panTemp[m]);
            NCDFSafeStrcat(&pszAttrValue, szTemp, &nAttrValueSize);
            CPLFree(panTemp);
            break;
        }
#endif
        default:
            CPLDebug("GDAL_netCDF",
                     "NCDFGetAttr unsupported type %d for attribute %s",
                     nAttrType, pszAttrName);
            break;
    }

    if (nAttrLen > 1 && nAttrType != NC_CHAR)
        NCDFSafeStrcat(&pszAttrValue, "}", &nAttrValueSize);

    if (bSetDoubleFromStr)
    {
        if (CPLGetValueType(pszAttrValue) == CPL_VALUE_STRING)
        {
            if (ppszValue == nullptr && pdfValue != nullptr)
            {
                CPLFree(pszAttrValue);
                return CE_Failure;
            }
        }
        dfValue = CPLAtof(pszAttrValue);
    }

    /* set return values */
    if (ppszValue)
        *ppszValue = pszAttrValue;
    else
        CPLFree(pszAttrValue);

    if (pdfValue)
        *pdfValue = dfValue;

    return CE_None;
}

/* sets pdfValue to first value found */
CPLErr NCDFGetAttr(int nCdfId, int nVarId, const char *pszAttrName,
                   double *pdfValue)
{
    return NCDFGetAttr1(nCdfId, nVarId, pszAttrName, pdfValue, nullptr);
}

/* pszValue is the responsibility of the caller and must be freed */
CPLErr NCDFGetAttr(int nCdfId, int nVarId, const char *pszAttrName,
                   char **pszValue)
{
    return NCDFGetAttr1(nCdfId, nVarId, pszAttrName, nullptr, pszValue);
}

/* By default write NC_CHAR, but detect for int/float/double and */
/* NC4 string arrays */
static CPLErr NCDFPutAttr(int nCdfId, int nVarId, const char *pszAttrName,
                          const char *pszValue)
{
    int status = 0;
    char *pszTemp = nullptr;

    /* get the attribute values as tokens */
    char **papszValues = NCDFTokenizeArray(pszValue);
    if (papszValues == nullptr)
        return CE_Failure;

    size_t nAttrLen = CSLCount(papszValues);

    /* first detect type */
    nc_type nAttrType = NC_CHAR;
    nc_type nTmpAttrType = NC_CHAR;
    for (size_t i = 0; i < nAttrLen; i++)
    {
        nTmpAttrType = NC_CHAR;
        bool bFoundType = false;
        errno = 0;
        int nValue = static_cast<int>(strtol(papszValues[i], &pszTemp, 10));
        /* test for int */
        /* TODO test for Byte and short - can this be done safely? */
        if (errno == 0 && papszValues[i] != pszTemp && *pszTemp == 0)
        {
            char szTemp[256];
            CPLsnprintf(szTemp, sizeof(szTemp), "%d", nValue);
            if (EQUAL(szTemp, papszValues[i]))
            {
                bFoundType = true;
                nTmpAttrType = NC_INT;
            }
#ifdef NETCDF_HAS_NC4
            else
            {
                unsigned int unValue = static_cast<unsigned int>(
                    strtoul(papszValues[i], &pszTemp, 10));
                CPLsnprintf(szTemp, sizeof(szTemp), "%u", unValue);
                if (EQUAL(szTemp, papszValues[i]))
                {
                    bFoundType = true;
                    nTmpAttrType = NC_UINT;
                }
            }
#endif
        }
        if (!bFoundType)
        {
            /* test for double */
            errno = 0;
            double dfValue = CPLStrtod(papszValues[i], &pszTemp);
            if ((errno == 0) && (papszValues[i] != pszTemp) && (*pszTemp == 0))
            {
                // Test for float instead of double.
                // strtof() is C89, which is not available in MSVC.
                // See if we loose precision if we cast to float and write to
                // char*.
                float fValue = float(dfValue);
                char szTemp[256];
                CPLsnprintf(szTemp, sizeof(szTemp), "%.8g", fValue);
                if (EQUAL(szTemp, papszValues[i]))
                    nTmpAttrType = NC_FLOAT;
                else
                    nTmpAttrType = NC_DOUBLE;
            }
        }
        if ((nTmpAttrType <= NC_DOUBLE && nAttrType <= NC_DOUBLE &&
             nTmpAttrType > nAttrType)
#ifdef NETCDF_HAS_NC4
            || (nTmpAttrType == NC_UINT && nAttrType < NC_FLOAT) ||
            (nTmpAttrType >= NC_FLOAT && nAttrType == NC_UINT)
#endif
        )
            nAttrType = nTmpAttrType;
    }

#ifdef DEBUG
    if (EQUAL(pszAttrName, "DEBUG_EMPTY_DOUBLE_ATTR"))
    {
        nAttrType = NC_DOUBLE;
        nAttrLen = 0;
    }
#endif

    /* now write the data */
    if (nAttrType == NC_CHAR)
    {
#ifdef NETCDF_HAS_NC4
        int nTmpFormat = 0;
        if (nAttrLen > 1)
        {
            status = nc_inq_format(nCdfId, &nTmpFormat);
            NCDF_ERR(status);
        }
        if (nAttrLen > 1 && nTmpFormat == NCDF_FORMAT_NC4)
            status = nc_put_att_string(nCdfId, nVarId, pszAttrName, nAttrLen,
                                       const_cast<const char **>(papszValues));
        else
#endif
            status = nc_put_att_text(nCdfId, nVarId, pszAttrName,
                                     strlen(pszValue), pszValue);
        NCDF_ERR(status);
    }
    else
    {
        switch (nAttrType)
        {
            case NC_INT:
            {
                int *pnTemp =
                    static_cast<int *>(CPLCalloc(nAttrLen, sizeof(int)));
                for (size_t i = 0; i < nAttrLen; i++)
                {
                    pnTemp[i] =
                        static_cast<int>(strtol(papszValues[i], &pszTemp, 10));
                }
                status = nc_put_att_int(nCdfId, nVarId, pszAttrName, NC_INT,
                                        nAttrLen, pnTemp);
                NCDF_ERR(status);
                CPLFree(pnTemp);
                break;
            }
#ifdef NETCDF_HAS_NC4
            case NC_UINT:
            {
                unsigned int *punTemp = static_cast<unsigned int *>(
                    CPLCalloc(nAttrLen, sizeof(unsigned int)));
                for (size_t i = 0; i < nAttrLen; i++)
                {
                    punTemp[i] = static_cast<unsigned int>(
                        strtol(papszValues[i], &pszTemp, 10));
                }
                status = nc_put_att_uint(nCdfId, nVarId, pszAttrName, NC_UINT,
                                         nAttrLen, punTemp);
                NCDF_ERR(status);
                CPLFree(punTemp);
                break;
            }
#endif
            case NC_FLOAT:
            {
                float *pfTemp =
                    static_cast<float *>(CPLCalloc(nAttrLen, sizeof(float)));
                for (size_t i = 0; i < nAttrLen; i++)
                {
                    pfTemp[i] =
                        static_cast<float>(CPLStrtod(papszValues[i], &pszTemp));
                }
                status = nc_put_att_float(nCdfId, nVarId, pszAttrName, NC_FLOAT,
                                          nAttrLen, pfTemp);
                NCDF_ERR(status);
                CPLFree(pfTemp);
                break;
            }
            case NC_DOUBLE:
            {
                double *pdfTemp =
                    static_cast<double *>(CPLCalloc(nAttrLen, sizeof(double)));
                for (size_t i = 0; i < nAttrLen; i++)
                {
                    pdfTemp[i] = CPLStrtod(papszValues[i], &pszTemp);
                }
                status = nc_put_att_double(nCdfId, nVarId, pszAttrName,
                                           NC_DOUBLE, nAttrLen, pdfTemp);
                NCDF_ERR(status);
                CPLFree(pdfTemp);
                break;
            }
            default:
                if (papszValues)
                    CSLDestroy(papszValues);
                return CE_Failure;
                break;
        }
    }

    if (papszValues)
        CSLDestroy(papszValues);

    return CE_None;
}

static CPLErr NCDFGet1DVar(int nCdfId, int nVarId, char **pszValue)
{
    /* get var information */
    int nVarDimId = -1;
    int status = nc_inq_varndims(nCdfId, nVarId, &nVarDimId);
    if (status != NC_NOERR || nVarDimId != 1)
        return CE_Failure;

    status = nc_inq_vardimid(nCdfId, nVarId, &nVarDimId);
    if (status != NC_NOERR)
        return CE_Failure;

    nc_type nVarType = NC_NAT;
    status = nc_inq_vartype(nCdfId, nVarId, &nVarType);
    if (status != NC_NOERR)
        return CE_Failure;

    size_t nVarLen = 0;
    status = nc_inq_dimlen(nCdfId, nVarDimId, &nVarLen);
    if (status != NC_NOERR)
        return CE_Failure;

    size_t start[1] = {0};
    size_t count[1] = {nVarLen};

    /* Allocate guaranteed minimum size */
    size_t nVarValueSize = NCDF_MAX_STR_LEN;
    char *pszVarValue =
        static_cast<char *>(CPLCalloc(nVarValueSize, sizeof(char)));
    *pszVarValue = '\0';

    if (nVarLen == 0)
    {
        /* set return values */
        *pszValue = pszVarValue;

        return CE_None;
    }

    if (nVarLen > 1 && nVarType != NC_CHAR)
        NCDFSafeStrcat(&pszVarValue, "{", &nVarValueSize);

    switch (nVarType)
    {
        case NC_CHAR:
            nc_get_vara_text(nCdfId, nVarId, start, count, pszVarValue);
            pszVarValue[nVarLen] = '\0';
            break;
        case NC_BYTE:
        {
            signed char *pscTemp = static_cast<signed char *>(
                CPLCalloc(nVarLen, sizeof(signed char)));
            nc_get_vara_schar(nCdfId, nVarId, start, count, pscTemp);
            char szTemp[256];
            size_t m = 0;
            for (; m < nVarLen - 1; m++)
            {
                snprintf(szTemp, sizeof(szTemp), "%d,", pscTemp[m]);
                NCDFSafeStrcat(&pszVarValue, szTemp, &nVarValueSize);
            }
            snprintf(szTemp, sizeof(szTemp), "%d", pscTemp[m]);
            NCDFSafeStrcat(&pszVarValue, szTemp, &nVarValueSize);
            CPLFree(pscTemp);
            break;
        }
        case NC_SHORT:
        {
            short *psTemp =
                static_cast<short *>(CPLCalloc(nVarLen, sizeof(short)));
            nc_get_vara_short(nCdfId, nVarId, start, count, psTemp);
            char szTemp[256];
            size_t m = 0;
            for (; m < nVarLen - 1; m++)
            {
                snprintf(szTemp, sizeof(szTemp), "%d,", psTemp[m]);
                NCDFSafeStrcat(&pszVarValue, szTemp, &nVarValueSize);
            }
            snprintf(szTemp, sizeof(szTemp), "%d", psTemp[m]);
            NCDFSafeStrcat(&pszVarValue, szTemp, &nVarValueSize);
            CPLFree(psTemp);
            break;
        }
        case NC_INT:
        {
            int *pnTemp = static_cast<int *>(CPLCalloc(nVarLen, sizeof(int)));
            nc_get_vara_int(nCdfId, nVarId, start, count, pnTemp);
            char szTemp[256];
            size_t m = 0;
            for (; m < nVarLen - 1; m++)
            {
                snprintf(szTemp, sizeof(szTemp), "%d,", pnTemp[m]);
                NCDFSafeStrcat(&pszVarValue, szTemp, &nVarValueSize);
            }
            snprintf(szTemp, sizeof(szTemp), "%d", pnTemp[m]);
            NCDFSafeStrcat(&pszVarValue, szTemp, &nVarValueSize);
            CPLFree(pnTemp);
            break;
        }
        case NC_FLOAT:
        {
            float *pfTemp =
                static_cast<float *>(CPLCalloc(nVarLen, sizeof(float)));
            nc_get_vara_float(nCdfId, nVarId, start, count, pfTemp);
            char szTemp[256];
            size_t m = 0;
            for (; m < nVarLen - 1; m++)
            {
                CPLsnprintf(szTemp, sizeof(szTemp), "%.8g,", pfTemp[m]);
                NCDFSafeStrcat(&pszVarValue, szTemp, &nVarValueSize);
            }
            CPLsnprintf(szTemp, sizeof(szTemp), "%.8g", pfTemp[m]);
            NCDFSafeStrcat(&pszVarValue, szTemp, &nVarValueSize);
            CPLFree(pfTemp);
            break;
        }
        case NC_DOUBLE:
        {
            double *pdfTemp =
                static_cast<double *>(CPLCalloc(nVarLen, sizeof(double)));
            nc_get_vara_double(nCdfId, nVarId, start, count, pdfTemp);
            char szTemp[256];
            size_t m = 0;
            for (; m < nVarLen - 1; m++)
            {
                CPLsnprintf(szTemp, sizeof(szTemp), "%.16g,", pdfTemp[m]);
                NCDFSafeStrcat(&pszVarValue, szTemp, &nVarValueSize);
            }
            CPLsnprintf(szTemp, sizeof(szTemp), "%.16g", pdfTemp[m]);
            NCDFSafeStrcat(&pszVarValue, szTemp, &nVarValueSize);
            CPLFree(pdfTemp);
            break;
        }
#ifdef NETCDF_HAS_NC4
        case NC_STRING:
        {
            char **ppszTemp =
                static_cast<char **>(CPLCalloc(nVarLen, sizeof(char *)));
            nc_get_vara_string(nCdfId, nVarId, start, count, ppszTemp);
            size_t m = 0;
            for (; m < nVarLen - 1; m++)
            {
                NCDFSafeStrcat(&pszVarValue, ppszTemp[m], &nVarValueSize);
                NCDFSafeStrcat(&pszVarValue, ",", &nVarValueSize);
            }
            NCDFSafeStrcat(&pszVarValue, ppszTemp[m], &nVarValueSize);
            nc_free_string(nVarLen, ppszTemp);
            CPLFree(ppszTemp);
            break;
        }
        case NC_UBYTE:
        {
            unsigned char *pucTemp;
            pucTemp = static_cast<unsigned char *>(
                CPLCalloc(nVarLen, sizeof(unsigned char)));
            nc_get_vara_uchar(nCdfId, nVarId, start, count, pucTemp);
            char szTemp[256];
            size_t m = 0;
            for (; m < nVarLen - 1; m++)
            {
                CPLsnprintf(szTemp, sizeof(szTemp), "%u,", pucTemp[m]);
                NCDFSafeStrcat(&pszVarValue, szTemp, &nVarValueSize);
            }
            CPLsnprintf(szTemp, sizeof(szTemp), "%u", pucTemp[m]);
            NCDFSafeStrcat(&pszVarValue, szTemp, &nVarValueSize);
            CPLFree(pucTemp);
            break;
        }
        case NC_USHORT:
        {
            unsigned short *pusTemp;
            pusTemp = static_cast<unsigned short *>(
                CPLCalloc(nVarLen, sizeof(unsigned short)));
            nc_get_vara_ushort(nCdfId, nVarId, start, count, pusTemp);
            char szTemp[256];
            size_t m = 0;
            for (; m < nVarLen - 1; m++)
            {
                CPLsnprintf(szTemp, sizeof(szTemp), "%u,", pusTemp[m]);
                NCDFSafeStrcat(&pszVarValue, szTemp, &nVarValueSize);
            }
            CPLsnprintf(szTemp, sizeof(szTemp), "%u", pusTemp[m]);
            NCDFSafeStrcat(&pszVarValue, szTemp, &nVarValueSize);
            CPLFree(pusTemp);
            break;
        }
        case NC_UINT:
        {
            unsigned int *punTemp;
            punTemp = static_cast<unsigned int *>(
                CPLCalloc(nVarLen, sizeof(unsigned int)));
            nc_get_vara_uint(nCdfId, nVarId, start, count, punTemp);
            char szTemp[256];
            size_t m = 0;
            for (; m < nVarLen - 1; m++)
            {
                CPLsnprintf(szTemp, sizeof(szTemp), "%u,", punTemp[m]);
                NCDFSafeStrcat(&pszVarValue, szTemp, &nVarValueSize);
            }
            CPLsnprintf(szTemp, sizeof(szTemp), "%u", punTemp[m]);
            NCDFSafeStrcat(&pszVarValue, szTemp, &nVarValueSize);
            CPLFree(punTemp);
            break;
        }
        case NC_INT64:
        {
            long long *pnTemp =
                static_cast<long long *>(CPLCalloc(nVarLen, sizeof(long long)));
            nc_get_vara_longlong(nCdfId, nVarId, start, count, pnTemp);
            char szTemp[256];
            size_t m = 0;
            for (; m < nVarLen - 1; m++)
            {
                snprintf(szTemp, sizeof(szTemp), CPL_FRMT_GIB ",", pnTemp[m]);
                NCDFSafeStrcat(&pszVarValue, szTemp, &nVarValueSize);
            }
            snprintf(szTemp, sizeof(szTemp), CPL_FRMT_GIB, pnTemp[m]);
            NCDFSafeStrcat(&pszVarValue, szTemp, &nVarValueSize);
            CPLFree(pnTemp);
            break;
        }
        case NC_UINT64:
        {
            unsigned long long *pnTemp = static_cast<unsigned long long *>(
                CPLCalloc(nVarLen, sizeof(unsigned long long)));
            nc_get_vara_ulonglong(nCdfId, nVarId, start, count, pnTemp);
            char szTemp[256];
            size_t m = 0;
            for (; m < nVarLen - 1; m++)
            {
                snprintf(szTemp, sizeof(szTemp), CPL_FRMT_GUIB ",", pnTemp[m]);
                NCDFSafeStrcat(&pszVarValue, szTemp, &nVarValueSize);
            }
            snprintf(szTemp, sizeof(szTemp), CPL_FRMT_GUIB, pnTemp[m]);
            NCDFSafeStrcat(&pszVarValue, szTemp, &nVarValueSize);
            CPLFree(pnTemp);
            break;
        }
#endif
        default:
            CPLDebug("GDAL_netCDF", "NCDFGetVar1D unsupported type %d",
                     nVarType);
            CPLFree(pszVarValue);
            pszVarValue = nullptr;
            break;
    }

    if (pszVarValue != nullptr && nVarLen > 1 && nVarType != NC_CHAR)
        NCDFSafeStrcat(&pszVarValue, "}", &nVarValueSize);

    /* set return values */
    *pszValue = pszVarValue;

    return CE_None;
}

static CPLErr NCDFPut1DVar(int nCdfId, int nVarId, const char *pszValue)
{
    if (EQUAL(pszValue, ""))
        return CE_Failure;

    /* get var information */
    int nVarDimId = -1;
    int status = nc_inq_varndims(nCdfId, nVarId, &nVarDimId);
    if (status != NC_NOERR || nVarDimId != 1)
        return CE_Failure;

    status = nc_inq_vardimid(nCdfId, nVarId, &nVarDimId);
    if (status != NC_NOERR)
        return CE_Failure;

    nc_type nVarType = NC_CHAR;
    status = nc_inq_vartype(nCdfId, nVarId, &nVarType);
    if (status != NC_NOERR)
        return CE_Failure;

    size_t nVarLen = 0;
    status = nc_inq_dimlen(nCdfId, nVarDimId, &nVarLen);
    if (status != NC_NOERR)
        return CE_Failure;

    size_t start[1] = {0};
    size_t count[1] = {nVarLen};

    /* get the values as tokens */
    char **papszValues = NCDFTokenizeArray(pszValue);
    if (papszValues == nullptr)
        return CE_Failure;

    nVarLen = CSLCount(papszValues);

    /* now write the data */
    if (nVarType == NC_CHAR)
    {
        status = nc_put_vara_text(nCdfId, nVarId, start, count, pszValue);
        NCDF_ERR(status);
    }
    else
    {
        switch (nVarType)
        {
            case NC_BYTE:
            {
                signed char *pscTemp = static_cast<signed char *>(
                    CPLCalloc(nVarLen, sizeof(signed char)));
                for (size_t i = 0; i < nVarLen; i++)
                {
                    char *pszTemp = nullptr;
                    pscTemp[i] = static_cast<signed char>(
                        strtol(papszValues[i], &pszTemp, 10));
                }
                status =
                    nc_put_vara_schar(nCdfId, nVarId, start, count, pscTemp);
                NCDF_ERR(status);
                CPLFree(pscTemp);
                break;
            }
            case NC_SHORT:
            {
                short *psTemp =
                    static_cast<short *>(CPLCalloc(nVarLen, sizeof(short)));
                for (size_t i = 0; i < nVarLen; i++)
                {
                    char *pszTemp = nullptr;
                    psTemp[i] = static_cast<short>(
                        strtol(papszValues[i], &pszTemp, 10));
                }
                status =
                    nc_put_vara_short(nCdfId, nVarId, start, count, psTemp);
                NCDF_ERR(status);
                CPLFree(psTemp);
                break;
            }
            case NC_INT:
            {
                int *pnTemp =
                    static_cast<int *>(CPLCalloc(nVarLen, sizeof(int)));
                for (size_t i = 0; i < nVarLen; i++)
                {
                    char *pszTemp = nullptr;
                    pnTemp[i] =
                        static_cast<int>(strtol(papszValues[i], &pszTemp, 10));
                }
                status = nc_put_vara_int(nCdfId, nVarId, start, count, pnTemp);
                NCDF_ERR(status);
                CPLFree(pnTemp);
                break;
            }
            case NC_FLOAT:
            {
                float *pfTemp =
                    static_cast<float *>(CPLCalloc(nVarLen, sizeof(float)));
                for (size_t i = 0; i < nVarLen; i++)
                {
                    char *pszTemp = nullptr;
                    pfTemp[i] =
                        static_cast<float>(CPLStrtod(papszValues[i], &pszTemp));
                }
                status =
                    nc_put_vara_float(nCdfId, nVarId, start, count, pfTemp);
                NCDF_ERR(status);
                CPLFree(pfTemp);
                break;
            }
            case NC_DOUBLE:
            {
                double *pdfTemp =
                    static_cast<double *>(CPLCalloc(nVarLen, sizeof(double)));
                for (size_t i = 0; i < nVarLen; i++)
                {
                    char *pszTemp = nullptr;
                    pdfTemp[i] = CPLStrtod(papszValues[i], &pszTemp);
                }
                status =
                    nc_put_vara_double(nCdfId, nVarId, start, count, pdfTemp);
                NCDF_ERR(status);
                CPLFree(pdfTemp);
                break;
            }
            default:
#ifdef NETCDF_HAS_NC4
                int nTmpFormat = 0;
                status = nc_inq_format(nCdfId, &nTmpFormat);
                NCDF_ERR(status);
                if (nTmpFormat == NCDF_FORMAT_NC4)
                {
                    switch (nVarType)
                    {
                        case NC_STRING:
                        {
                            status =
                                nc_put_vara_string(nCdfId, nVarId, start, count,
                                                   (const char **)papszValues);
                            NCDF_ERR(status);
                            break;
                        }
                        case NC_UBYTE:
                        {
                            unsigned char *pucTemp =
                                static_cast<unsigned char *>(
                                    CPLCalloc(nVarLen, sizeof(unsigned char)));
                            for (size_t i = 0; i < nVarLen; i++)
                            {
                                char *pszTemp = nullptr;
                                pucTemp[i] = static_cast<unsigned char>(
                                    strtoul(papszValues[i], &pszTemp, 10));
                            }
                            status = nc_put_vara_uchar(nCdfId, nVarId, start,
                                                       count, pucTemp);
                            NCDF_ERR(status);
                            CPLFree(pucTemp);
                            break;
                        }
                        case NC_USHORT:
                        {
                            unsigned short *pusTemp =
                                static_cast<unsigned short *>(
                                    CPLCalloc(nVarLen, sizeof(unsigned short)));
                            for (size_t i = 0; i < nVarLen; i++)
                            {
                                char *pszTemp = nullptr;
                                pusTemp[i] = static_cast<unsigned short>(
                                    strtoul(papszValues[i], &pszTemp, 10));
                            }
                            status = nc_put_vara_ushort(nCdfId, nVarId, start,
                                                        count, pusTemp);
                            NCDF_ERR(status);
                            CPLFree(pusTemp);
                            break;
                        }
                        case NC_UINT:
                        {
                            unsigned int *punTemp = static_cast<unsigned int *>(
                                CPLCalloc(nVarLen, sizeof(unsigned int)));
                            for (size_t i = 0; i < nVarLen; i++)
                            {
                                char *pszTemp = nullptr;
                                punTemp[i] = static_cast<unsigned int>(
                                    strtoul(papszValues[i], &pszTemp, 10));
                            }
                            status = nc_put_vara_uint(nCdfId, nVarId, start,
                                                      count, punTemp);
                            NCDF_ERR(status);
                            CPLFree(punTemp);
                            break;
                        }
                        default:
#endif
                            if (papszValues)
                                CSLDestroy(papszValues);
                            return CE_Failure;
                            break;
#ifdef NETCDF_HAS_NC4
                    }
                }
#endif
        }
    }

    if (papszValues)
        CSLDestroy(papszValues);

    return CE_None;
}

/************************************************************************/
/*                           GetDefaultNoDataValue()                    */
/************************************************************************/

double NCDFGetDefaultNoDataValue(int nCdfId, int nVarId, int nVarType,
                                 bool &bGotNoData)

{
    int nNoFill = 0;
    double dfNoData = 0.0;

    switch (nVarType)
    {
        case NC_CHAR:
        case NC_BYTE:
#ifdef NETCDF_HAS_NC4
        case NC_UBYTE:
#endif
            // Don't do default fill-values for bytes, too risky.
            // This function should not be called in those cases.
            CPLAssert(false);
            break;
        case NC_SHORT:
        {
            short nFillVal = 0;
            if (nc_inq_var_fill(nCdfId, nVarId, &nNoFill, &nFillVal) ==
                NC_NOERR)
            {
                if (!nNoFill)
                {
                    bGotNoData = true;
                    dfNoData = nFillVal;
                }
            }
            else
                dfNoData = NC_FILL_SHORT;
            break;
        }
        case NC_INT:
        {
            int nFillVal = 0;
            if (nc_inq_var_fill(nCdfId, nVarId, &nNoFill, &nFillVal) ==
                NC_NOERR)
            {
                if (!nNoFill)
                {
                    bGotNoData = true;
                    dfNoData = nFillVal;
                }
            }
            else
                dfNoData = NC_FILL_INT;
            break;
        }
        case NC_FLOAT:
        {
            float fFillVal = 0;
            if (nc_inq_var_fill(nCdfId, nVarId, &nNoFill, &fFillVal) ==
                NC_NOERR)
            {
                if (!nNoFill)
                {
                    bGotNoData = true;
                    dfNoData = fFillVal;
                }
            }
            else
                dfNoData = NC_FILL_FLOAT;
            break;
        }
        case NC_DOUBLE:
        {
            if (nc_inq_var_fill(nCdfId, nVarId, &nNoFill, &dfNoData) ==
                NC_NOERR)
            {
                if (!nNoFill)
                {
                    bGotNoData = true;
                }
            }
            else
                dfNoData = NC_FILL_DOUBLE;
            break;
        }
#ifdef NETCDF_HAS_NC4
        case NC_USHORT:
        {
            unsigned short nFillVal = 0;
            if (nc_inq_var_fill(nCdfId, nVarId, &nNoFill, &nFillVal) ==
                NC_NOERR)
            {
                if (!nNoFill)
                {
                    bGotNoData = true;
                    dfNoData = nFillVal;
                }
            }
            else
                dfNoData = NC_FILL_USHORT;
            break;
        }
        case NC_UINT:
        {
            unsigned int nFillVal = 0;
            if (nc_inq_var_fill(nCdfId, nVarId, &nNoFill, &nFillVal) ==
                NC_NOERR)
            {
                if (!nNoFill)
                {
                    bGotNoData = true;
                    dfNoData = nFillVal;
                }
            }
            else
                dfNoData = NC_FILL_UINT;
            break;
        }
#endif
        default:
            dfNoData = 0.0;
            break;
    }

    return dfNoData;
}

#ifdef NETCDF_HAS_NC4

/************************************************************************/
/*                      NCDFGetDefaultNoDataValueAsInt64()              */
/************************************************************************/

int64_t NCDFGetDefaultNoDataValueAsInt64(int nCdfId, int nVarId,
                                         bool &bGotNoData)

{
    int nNoFill = 0;
    long long nFillVal = 0;
    if (nc_inq_var_fill(nCdfId, nVarId, &nNoFill, &nFillVal) == NC_NOERR)
    {
        if (!nNoFill)
        {
            bGotNoData = true;
            return static_cast<int64_t>(nFillVal);
        }
    }
    else
        return static_cast<int64_t>(NC_FILL_INT64);
    return 0;
}

/************************************************************************/
/*                     NCDFGetDefaultNoDataValueAsUInt64()              */
/************************************************************************/

uint64_t NCDFGetDefaultNoDataValueAsUInt64(int nCdfId, int nVarId,
                                           bool &bGotNoData)

{
    int nNoFill = 0;
    unsigned long long nFillVal = 0;
    if (nc_inq_var_fill(nCdfId, nVarId, &nNoFill, &nFillVal) == NC_NOERR)
    {
        if (!nNoFill)
        {
            bGotNoData = true;
            return static_cast<uint64_t>(nFillVal);
        }
    }
    else
        return static_cast<uint64_t>(NC_FILL_UINT64);
    return 0;
}

#endif

static int NCDFDoesVarContainAttribVal(int nCdfId,
                                       const char *const *papszAttribNames,
                                       const char *const *papszAttribValues,
                                       int nVarId, const char *pszVarName,
                                       bool bStrict = true)
{
    if (nVarId == -1 && pszVarName != nullptr)
        NCDFResolveVar(nCdfId, pszVarName, &nCdfId, &nVarId);

    if (nVarId == -1)
        return -1;

    bool bFound = false;
    for (int i = 0; !bFound && papszAttribNames != nullptr &&
                    papszAttribNames[i] != nullptr;
         i++)
    {
        char *pszTemp = nullptr;
        if (NCDFGetAttr(nCdfId, nVarId, papszAttribNames[i], &pszTemp) ==
                CE_None &&
            pszTemp != nullptr)
        {
            if (bStrict)
            {
                if (EQUAL(pszTemp, papszAttribValues[i]))
                    bFound = true;
            }
            else
            {
                if (EQUALN(pszTemp, papszAttribValues[i],
                           strlen(papszAttribValues[i])))
                    bFound = true;
            }
            CPLFree(pszTemp);
        }
    }
    return bFound;
}

static int NCDFDoesVarContainAttribVal2(int nCdfId, const char *papszAttribName,
                                        const char *const *papszAttribValues,
                                        int nVarId, const char *pszVarName,
                                        int bStrict = true)
{
    if (nVarId == -1 && pszVarName != nullptr)
        NCDFResolveVar(nCdfId, pszVarName, &nCdfId, &nVarId);

    if (nVarId == -1)
        return -1;

    bool bFound = false;
    char *pszTemp = nullptr;
    if (NCDFGetAttr(nCdfId, nVarId, papszAttribName, &pszTemp) != CE_None ||
        pszTemp == nullptr)
        return FALSE;

    for (int i = 0; !bFound && i < CSLCount(papszAttribValues); i++)
    {
        if (bStrict)
        {
            if (EQUAL(pszTemp, papszAttribValues[i]))
                bFound = true;
        }
        else
        {
            if (EQUALN(pszTemp, papszAttribValues[i],
                       strlen(papszAttribValues[i])))
                bFound = true;
        }
    }

    CPLFree(pszTemp);

    return bFound;
}

static bool NCDFEqual(const char *papszName, const char *const *papszValues)
{
    if (papszName == nullptr || EQUAL(papszName, ""))
        return false;

    for (int i = 0; papszValues && papszValues[i]; ++i)
    {
        if (EQUAL(papszName, papszValues[i]))
            return true;
    }

    return false;
}

// Test that a variable is longitude/latitude coordinate,
// following CF 4.1 and 4.2.
bool NCDFIsVarLongitude(int nCdfId, int nVarId, const char *pszVarName)
{
    // Check for matching attributes.
    int bVal = NCDFDoesVarContainAttribVal(nCdfId, papszCFLongitudeAttribNames,
                                           papszCFLongitudeAttribValues, nVarId,
                                           pszVarName);
    // If not found using attributes then check using var name
    // unless GDAL_NETCDF_VERIFY_DIMS=STRICT.
    if (bVal == -1)
    {
        if (!EQUAL(CPLGetConfigOption("GDAL_NETCDF_VERIFY_DIMS", "YES"),
                   "STRICT"))
            bVal = NCDFEqual(pszVarName, papszCFLongitudeVarNames);
        else
            bVal = FALSE;
    }
    else if (bVal)
    {
        // Check that the units is not 'm' or '1'. See #6759
        char *pszTemp = nullptr;
        if (NCDFGetAttr(nCdfId, nVarId, "units", &pszTemp) == CE_None &&
            pszTemp != nullptr)
        {
            if (EQUAL(pszTemp, "m") || EQUAL(pszTemp, "1"))
                bVal = false;
            CPLFree(pszTemp);
        }
    }

    return CPL_TO_BOOL(bVal);
}

bool NCDFIsVarLatitude(int nCdfId, int nVarId, const char *pszVarName)
{
    int bVal = NCDFDoesVarContainAttribVal(nCdfId, papszCFLatitudeAttribNames,
                                           papszCFLatitudeAttribValues, nVarId,
                                           pszVarName);
    if (bVal == -1)
    {
        if (!EQUAL(CPLGetConfigOption("GDAL_NETCDF_VERIFY_DIMS", "YES"),
                   "STRICT"))
            bVal = NCDFEqual(pszVarName, papszCFLatitudeVarNames);
        else
            bVal = FALSE;
    }
    else if (bVal)
    {
        // Check that the units is not 'm' or '1'. See #6759
        char *pszTemp = nullptr;
        if (NCDFGetAttr(nCdfId, nVarId, "units", &pszTemp) == CE_None &&
            pszTemp != nullptr)
        {
            if (EQUAL(pszTemp, "m") || EQUAL(pszTemp, "1"))
                bVal = false;
            CPLFree(pszTemp);
        }
    }

    return CPL_TO_BOOL(bVal);
}

bool NCDFIsVarProjectionX(int nCdfId, int nVarId, const char *pszVarName)
{
    int bVal = NCDFDoesVarContainAttribVal(
        nCdfId, papszCFProjectionXAttribNames, papszCFProjectionXAttribValues,
        nVarId, pszVarName);
    if (bVal == -1)
    {
        if (!EQUAL(CPLGetConfigOption("GDAL_NETCDF_VERIFY_DIMS", "YES"),
                   "STRICT"))
            bVal = NCDFEqual(pszVarName, papszCFProjectionXVarNames);
        else
            bVal = FALSE;
    }
    else if (bVal)
    {
        // Check that the units is not '1'
        char *pszTemp = nullptr;
        if (NCDFGetAttr(nCdfId, nVarId, "units", &pszTemp) == CE_None &&
            pszTemp != nullptr)
        {
            if (EQUAL(pszTemp, "1"))
                bVal = false;
            CPLFree(pszTemp);
        }
    }

    return CPL_TO_BOOL(bVal);
}

bool NCDFIsVarProjectionY(int nCdfId, int nVarId, const char *pszVarName)
{
    int bVal = NCDFDoesVarContainAttribVal(
        nCdfId, papszCFProjectionYAttribNames, papszCFProjectionYAttribValues,
        nVarId, pszVarName);
    if (bVal == -1)
    {
        if (!EQUAL(CPLGetConfigOption("GDAL_NETCDF_VERIFY_DIMS", "YES"),
                   "STRICT"))
            bVal = NCDFEqual(pszVarName, papszCFProjectionYVarNames);
        else
            bVal = FALSE;
    }
    else if (bVal)
    {
        // Check that the units is not '1'
        char *pszTemp = nullptr;
        if (NCDFGetAttr(nCdfId, nVarId, "units", &pszTemp) == CE_None &&
            pszTemp != nullptr)
        {
            if (EQUAL(pszTemp, "1"))
                bVal = false;
            CPLFree(pszTemp);
        }
    }

    return CPL_TO_BOOL(bVal);
}

/* test that a variable is a vertical coordinate, following CF 4.3 */
bool NCDFIsVarVerticalCoord(int nCdfId, int nVarId, const char *pszVarName)
{
    /* check for matching attributes */
    if (NCDFDoesVarContainAttribVal(nCdfId, papszCFVerticalAttribNames,
                                    papszCFVerticalAttribValues, nVarId,
                                    pszVarName))
        return true;
    /* check for matching units */
    else if (NCDFDoesVarContainAttribVal2(nCdfId, CF_UNITS,
                                          papszCFVerticalUnitsValues, nVarId,
                                          pszVarName))
        return true;
    /* check for matching standard name */
    else if (NCDFDoesVarContainAttribVal2(nCdfId, CF_STD_NAME,
                                          papszCFVerticalStandardNameValues,
                                          nVarId, pszVarName))
        return true;
    else
        return false;
}

/* test that a variable is a time coordinate, following CF 4.4 */
bool NCDFIsVarTimeCoord(int nCdfId, int nVarId, const char *pszVarName)
{
    /* check for matching attributes */
    if (NCDFDoesVarContainAttribVal(nCdfId, papszCFTimeAttribNames,
                                    papszCFTimeAttribValues, nVarId,
                                    pszVarName))
        return true;
    /* check for matching units */
    else if (NCDFDoesVarContainAttribVal2(nCdfId, CF_UNITS,
                                          papszCFTimeUnitsValues, nVarId,
                                          pszVarName, false))
        return true;
    else
        return false;
}

// Parse a string, and return as a string list.
// If it an array of the form {a,b}, then tokenize it.
// Otherwise, return a copy.
static char **NCDFTokenizeArray(const char *pszValue)
{
    if (pszValue == nullptr || EQUAL(pszValue, ""))
        return nullptr;

    char **papszValues = nullptr;
    const int nLen = static_cast<int>(strlen(pszValue));

    if (pszValue[0] == '{' && nLen > 2 && pszValue[nLen - 1] == '}')
    {
        char *pszTemp = static_cast<char *>(CPLMalloc((nLen - 2) + 1));
        strncpy(pszTemp, pszValue + 1, nLen - 2);
        pszTemp[nLen - 2] = '\0';
        papszValues = CSLTokenizeString2(pszTemp, ",", CSLT_ALLOWEMPTYTOKENS);
        CPLFree(pszTemp);
    }
    else
    {
        papszValues = reinterpret_cast<char **>(CPLCalloc(2, sizeof(char *)));
        papszValues[0] = CPLStrdup(pszValue);
        papszValues[1] = nullptr;
    }

    return papszValues;
}

// Open a NetCDF subdataset from full path /group1/group2/.../groupn/var.
// Leading slash is optional.
static CPLErr NCDFOpenSubDataset(int nCdfId, const char *pszSubdatasetName,
                                 int *pnGroupId, int *pnVarId)
{
    *pnGroupId = -1;
    *pnVarId = -1;

    // Open group.
    char *pszGroupFullName = CPLStrdup(CPLGetPath(pszSubdatasetName));
    // Add a leading slash if needed.
    if (pszGroupFullName[0] != '/')
    {
        char *old = pszGroupFullName;
        pszGroupFullName = CPLStrdup(CPLSPrintf("/%s", pszGroupFullName));
        CPLFree(old);
    }
    // Detect root group.
    if (EQUAL(pszGroupFullName, "/"))
    {
        *pnGroupId = nCdfId;
        CPLFree(pszGroupFullName);
    }
#ifdef NETCDF_HAS_NC4
    else
    {
        int status = nc_inq_grp_full_ncid(nCdfId, pszGroupFullName, pnGroupId);
        CPLFree(pszGroupFullName);
        NCDF_ERR_RET(status);
    }
#endif

    // Open var.
    const char *pszVarName = CPLGetFilename(pszSubdatasetName);
    NCDF_ERR_RET(nc_inq_varid(*pnGroupId, pszVarName, pnVarId));

    return CE_None;
}

// Get all dimensions visible from a given NetCDF (or group) ID and any of
// its parents.
static CPLErr NCDFGetVisibleDims(int nGroupId, int *pnDims, int **ppanDimIds)
{
    int nDims = 0;
    int *panDimIds = nullptr;
#ifdef NETCDF_HAS_NC4
    NCDF_ERR_RET(nc_inq_dimids(nGroupId, &nDims, nullptr, true));
#else
    NCDF_ERR_RET(nc_inq_ndims(nGroupId, &nDims));
#endif

    panDimIds = static_cast<int *>(CPLMalloc(nDims * sizeof(int)));

#ifdef NETCDF_HAS_NC4
    int status = nc_inq_dimids(nGroupId, nullptr, panDimIds, true);
    if (status != NC_NOERR)
        CPLFree(panDimIds);
    NCDF_ERR_RET(status);
#else
    for (int i = 0; i < nDims; i++)
    {
        panDimIds[i] = i;
    }
#endif

    *pnDims = nDims;
    *ppanDimIds = panDimIds;

    return CE_None;
}

// Get direct sub-groups IDs of a given NetCDF (or group) ID.
// Consider only direct children, does not get children of children.
static CPLErr NCDFGetSubGroups(int nGroupId, int *pnSubGroups,
                               int **ppanSubGroupIds)
{
    *pnSubGroups = 0;
    *ppanSubGroupIds = nullptr;

#ifdef NETCDF_HAS_NC4
    int nSubGroups;
    NCDF_ERR_RET(nc_inq_grps(nGroupId, &nSubGroups, nullptr));
    int *panSubGroupIds =
        static_cast<int *>(CPLMalloc(nSubGroups * sizeof(int)));
    NCDF_ERR_RET(nc_inq_grps(nGroupId, nullptr, panSubGroupIds));
    *pnSubGroups = nSubGroups;
    *ppanSubGroupIds = panSubGroupIds;
#endif

    return CE_None;
}

// Get the full name of a given NetCDF (or group) ID
// (e.g. /group1/group2/.../groupn).
// bNC3Compat remove the leading slash for top-level variables for
// backward compatibility (top-level variables are the ones in the root group).
static CPLErr NCDFGetGroupFullName(int nGroupId, char **ppszFullName,
                                   bool bNC3Compat)
{
    *ppszFullName = nullptr;

#ifdef NETCDF_HAS_NC4
    size_t nFullNameLen;
    NCDF_ERR_RET(nc_inq_grpname_len(nGroupId, &nFullNameLen));
    *ppszFullName =
        static_cast<char *>(CPLMalloc((nFullNameLen + 1) * sizeof(char)));
    int status = nc_inq_grpname_full(nGroupId, &nFullNameLen, *ppszFullName);
    if (status != NC_NOERR)
    {
        CPLFree(*ppszFullName);
        *ppszFullName = nullptr;
        NCDF_ERR_RET(status);
    }
#else
    *ppszFullName = CPLStrdup("/");
#endif

    if (bNC3Compat && EQUAL(*ppszFullName, "/"))
        (*ppszFullName)[0] = '\0';

    return CE_None;
}

CPLString NCDFGetGroupFullName(int nGroupId)
{
    char *pszFullname = nullptr;
    NCDFGetGroupFullName(nGroupId, &pszFullname, false);
    CPLString osRet(pszFullname ? pszFullname : "");
    CPLFree(pszFullname);
    return osRet;
}

// Get the full name of a given NetCDF variable ID
// (e.g. /group1/group2/.../groupn/var).
// Handle also NC_GLOBAL as nVarId.
// bNC3Compat remove the leading slash for top-level variables for
// backward compatibility (top-level variables are the ones in the root group).
static CPLErr NCDFGetVarFullName(int nGroupId, int nVarId, char **ppszFullName,
                                 bool bNC3Compat)
{
    *ppszFullName = nullptr;
    char *pszGroupFullName = nullptr;
    ERR_RET(NCDFGetGroupFullName(nGroupId, &pszGroupFullName, bNC3Compat));
    char szVarName[NC_MAX_NAME + 1];
    if (nVarId == NC_GLOBAL)
    {
        strcpy(szVarName, "NC_GLOBAL");
    }
    else
    {
        int status = nc_inq_varname(nGroupId, nVarId, szVarName);
        if (status != NC_NOERR)
        {
            CPLFree(pszGroupFullName);
            NCDF_ERR_RET(status);
        }
    }
    const char *pszSep = "/";
    if (EQUAL(pszGroupFullName, "/") || EQUAL(pszGroupFullName, ""))
        pszSep = "";
    *ppszFullName =
        CPLStrdup(CPLSPrintf("%s%s%s", pszGroupFullName, pszSep, szVarName));
    CPLFree(pszGroupFullName);
    return CE_None;
}

// Get the NetCDF root group ID of a given group ID.
static CPLErr NCDFGetRootGroup(int nStartGroupId, int *pnRootGroupId)
{
    *pnRootGroupId = -1;
#ifdef NETCDF_HAS_NC4
    // Recurse on parent group.
    int nParentGroupId;
    int status = nc_inq_grp_parent(nStartGroupId, &nParentGroupId);
    if (status == NC_NOERR)
        return NCDFGetRootGroup(nParentGroupId, pnRootGroupId);
    else if (status != NC_ENOGRP)
        NCDF_ERR_RET(status);
    else  // No more parent group.
#endif
    {
        *pnRootGroupId = nStartGroupId;
    }

    return CE_None;
}

// Implementation of NCDFResolveVar/Att.
static CPLErr NCDFResolveElem(int nStartGroupId, const char *pszVar,
                              const char *pszAtt, int *pnGroupId, int *pnId,
                              bool bMandatory)
{
    if (!pszVar && !pszAtt)
    {
        CPLError(CE_Failure, CPLE_IllegalArg,
                 "pszVar and pszAtt NCDFResolveElem() args are both null.");
        return CE_Failure;
    }

#ifdef NETCDF_HAS_NC4
    enum
    {
        NCRM_PARENT,
        NCRM_WIDTH_WISE
    } eNCResolveMode = NCRM_PARENT;
#endif

    std::queue<int> aoQueueGroupIdsToVisit;
    aoQueueGroupIdsToVisit.push(nStartGroupId);

    while (!aoQueueGroupIdsToVisit.empty())
    {
        // Get the first group of the FIFO queue.
        *pnGroupId = aoQueueGroupIdsToVisit.front();
        aoQueueGroupIdsToVisit.pop();

        // Look if this group contains the searched element.
        int status;
        if (pszVar)
            status = nc_inq_varid(*pnGroupId, pszVar, pnId);
        else  // pszAtt != nullptr.
            status = nc_inq_attid(*pnGroupId, NC_GLOBAL, pszAtt, pnId);

        if (status == NC_NOERR)
        {
            return CE_None;
        }
        else if ((pszVar && status != NC_ENOTVAR) ||
                 (pszAtt && status != NC_ENOTATT))
        {
            NCDF_ERR(status);
        }
#ifdef NETCDF_HAS_NC4
        // Element not found, in NC4 case we must search in other groups
        // following the CF logic.

        // The first resolve mode consists to search on parent groups.
        if (eNCResolveMode == NCRM_PARENT)
        {
            int nParentGroupId = -1;
            int status2 = nc_inq_grp_parent(*pnGroupId, &nParentGroupId);
            if (status2 == NC_NOERR)
                aoQueueGroupIdsToVisit.push(nParentGroupId);
            else if (status2 != NC_ENOGRP)
                NCDF_ERR(status2);
            if (pszVar)
                // When resolving a variable, if there is no more
                // parent group then we switch to width-wise search mode
                // starting from the latest found parent group.
                eNCResolveMode = NCRM_WIDTH_WISE;
        }

        // The second resolve mode is a width-wise search.
        if (eNCResolveMode == NCRM_WIDTH_WISE)
        {
            // Enqueue all direct sub-groups.
            int nSubGroups = 0;
            int *panSubGroupIds = nullptr;
            NCDFGetSubGroups(*pnGroupId, &nSubGroups, &panSubGroupIds);
            for (int i = 0; i < nSubGroups; i++)
                aoQueueGroupIdsToVisit.push(panSubGroupIds[i]);
            CPLFree(panSubGroupIds);
        }
#endif
    }

    if (bMandatory)
    {
        char *pszStartGroupFullName = nullptr;
        NCDFGetGroupFullName(nStartGroupId, &pszStartGroupFullName);
        CPLError(CE_Failure, CPLE_AppDefined,
                 "Cannot resolve mandatory %s %s from group %s",
                 (pszVar ? pszVar : pszAtt),
                 (pszVar ? "variable" : "attribute"),
                 (pszStartGroupFullName ? pszStartGroupFullName : ""));
        CPLFree(pszStartGroupFullName);
    }

    *pnGroupId = -1;
    *pnId = -1;
    return CE_Failure;
}

// Resolve a variable name from a given starting group following the CF logic:
// - if var name is an absolute path then directly open it
// - first search in the starting group and its parent groups
// - then if there is no more parent group we switch to a width-wise search
//   mode starting from the latest found parent group.
// The full CF logic is described here:
// https://github.com/diwg/cf2/blob/master/group/cf2-group.adoc#scope
// If bMandatory then print an error if resolving fails.
// TODO: implement support of relative paths.
// TODO: to follow strictly the CF logic, when searching for a coordinate
//       variable, we must stop the parent search mode once the corresponding
//       dimension is found and start the width-wise search from this group.
// TODO: to follow strictly the CF logic, when searching in width-wise mode
//       we should skip every groups already visited during the parent
//       search mode (but revisiting them should have no impact so we could
//       let as it is if it is simpler...)
// TODO: CF specifies that the width-wise search order is "left-to-right" so
//       maybe we must sort sibling groups alphabetically? but maybe not
//       necessary if nc_inq_grps() already sort them?
CPLErr NCDFResolveVar(int nStartGroupId, const char *pszVar, int *pnGroupId,
                      int *pnVarId, bool bMandatory)
{
    *pnGroupId = -1;
    *pnVarId = -1;
    int nGroupId = nStartGroupId, nVarId;
    if (pszVar[0] == '/')
    {
        // This is an absolute path: we can open the var directly.
        int nRootGroupId;
        ERR_RET(NCDFGetRootGroup(nStartGroupId, &nRootGroupId));
        ERR_RET(NCDFOpenSubDataset(nRootGroupId, pszVar, &nGroupId, &nVarId));
    }
    else
    {
        // We have to search the variable following the CF logic.
        ERR_RET(NCDFResolveElem(nStartGroupId, pszVar, nullptr, &nGroupId,
                                &nVarId, bMandatory));
    }
    *pnGroupId = nGroupId;
    *pnVarId = nVarId;
    return CE_None;
}

// Like NCDFResolveVar but returns directly the var full name.
static CPLErr NCDFResolveVarFullName(int nStartGroupId, const char *pszVar,
                                     char **ppszFullName, bool bMandatory)
{
    *ppszFullName = nullptr;
    int nGroupId, nVarId;
    ERR_RET(
        NCDFResolveVar(nStartGroupId, pszVar, &nGroupId, &nVarId, bMandatory));
    return NCDFGetVarFullName(nGroupId, nVarId, ppszFullName);
}

// Like NCDFResolveVar but resolves an attribute instead a variable and
// returns its integer value.
// Only GLOBAL attributes are supported for the moment.
static CPLErr NCDFResolveAttInt(int nStartGroupId, int nStartVarId,
                                const char *pszAtt, int *pnAtt, bool bMandatory)
{
    int nGroupId = nStartGroupId, nAttId = nStartVarId;
    ERR_RET(NCDFResolveElem(nStartGroupId, nullptr, pszAtt, &nGroupId, &nAttId,
                            bMandatory));
    NCDF_ERR_RET(nc_get_att_int(nGroupId, NC_GLOBAL, pszAtt, pnAtt));
    return CE_None;
}

// Filter variables to keep only valid 2+D raster bands and vector fields in
// a given a NetCDF (or group) ID and its sub-groups.
// Coordinate or boundary variables are ignored.
// It also creates corresponding vector layers.
CPLErr netCDFDataset::FilterVars(
    int nCdfId, bool bKeepRasters, bool bKeepVectors, char **papszIgnoreVars,
    int *pnRasterVars, int *pnGroupId, int *pnVarId, int *pnIgnoredVars,
    std::map<std::array<int, 3>, std::vector<std::pair<int, int>>>
        &oMap2DDimsToGroupAndVar)
{
    int nVars = 0;
    int nRasterVars = 0;
    NCDF_ERR(nc_inq(nCdfId, nullptr, &nVars, nullptr, nullptr));

    std::vector<int> anPotentialVectorVarID;
    // oMapDimIdToCount[x] = number of times dim x is the first dimension of
    // potential vector variables
    std::map<int, int> oMapDimIdToCount;
    int nVarXId = -1;
    int nVarYId = -1;
    int nVarZId = -1;
    bool bIsVectorOnly = true;
    int nProfileDimId = -1;
    int nParentIndexVarID = -1;

    for (int v = 0; v < nVars; v++)
    {
        int nVarDims;
        NCDF_ERR_RET(nc_inq_varndims(nCdfId, v, &nVarDims));
        // Should we ignore this variable?
        char szTemp[NC_MAX_NAME + 1];
        szTemp[0] = '\0';
        NCDF_ERR_RET(nc_inq_varname(nCdfId, v, szTemp));

        if (strstr(szTemp, "_node_coordinates") ||
            strstr(szTemp, "_node_count"))
        {
            // Ignore CF-1.8 Simple Geometries helper variables
            continue;
        }

        if (nVarDims == 1 && (NCDFIsVarLongitude(nCdfId, -1, szTemp) ||
                              NCDFIsVarProjectionX(nCdfId, -1, szTemp)))
        {
            nVarXId = v;
        }
        else if (nVarDims == 1 && (NCDFIsVarLatitude(nCdfId, -1, szTemp) ||
                                   NCDFIsVarProjectionY(nCdfId, -1, szTemp)))
        {
            nVarYId = v;
        }
        else if (nVarDims == 1 && NCDFIsVarVerticalCoord(nCdfId, -1, szTemp))
        {
            nVarZId = v;
        }
        else
        {
            char *pszVarFullName = nullptr;
            CPLErr eErr = NCDFGetVarFullName(nCdfId, v, &pszVarFullName);
            if (eErr != CE_None)
            {
                CPLFree(pszVarFullName);
                continue;
            }
            bool bIgnoreVar =
                (CSLFindString(papszIgnoreVars, pszVarFullName) != -1);
            CPLFree(pszVarFullName);
            if (bIgnoreVar)
            {
                (*pnIgnoredVars)++;
                CPLDebug("GDAL_netCDF", "variable #%d [%s] was ignored", v,
                         szTemp);
            }
            // Only accept 2+D vars.
            else if (nVarDims >= 2)
            {
                bool bRasterCandidate = true;
                // Identify variables that might be vector variables
                if (nVarDims == 2)
                {
                    int anDimIds[2] = {-1, -1};
                    nc_inq_vardimid(nCdfId, v, anDimIds);

                    nc_type vartype = NC_NAT;
                    nc_inq_vartype(nCdfId, v, &vartype);

                    char szDimNameFirst[NC_MAX_NAME + 1];
                    char szDimNameSecond[NC_MAX_NAME + 1];
                    szDimNameFirst[0] = '\0';
                    szDimNameSecond[0] = '\0';
                    if (vartype == NC_CHAR &&
                        nc_inq_dimname(nCdfId, anDimIds[0], szDimNameFirst) ==
                            NC_NOERR &&
                        nc_inq_dimname(nCdfId, anDimIds[1], szDimNameSecond) ==
                            NC_NOERR &&
                        !NCDFIsVarLongitude(nCdfId, -1, szDimNameSecond) &&
                        !NCDFIsVarProjectionX(nCdfId, -1, szDimNameSecond) &&
                        !NCDFIsVarLatitude(nCdfId, -1, szDimNameFirst) &&
                        !NCDFIsVarProjectionY(nCdfId, -1, szDimNameFirst))
                    {
                        anPotentialVectorVarID.push_back(v);
                        oMapDimIdToCount[anDimIds[0]]++;
                        if (strstr(szDimNameSecond, "_max_width"))
                        {
                            bRasterCandidate = false;
                        }
                        else
                        {
                            std::array<int, 3> oKey{anDimIds[0], anDimIds[1],
                                                    vartype};
                            oMap2DDimsToGroupAndVar[oKey].emplace_back(
                                std::pair<int, int>(nCdfId, v));
                        }
                    }
                    else
                    {
                        std::array<int, 3> oKey{anDimIds[0], anDimIds[1],
                                                vartype};
                        oMap2DDimsToGroupAndVar[oKey].emplace_back(
                            std::pair<int, int>(nCdfId, v));
                        bIsVectorOnly = false;
                    }
                }
                else
                {
                    bIsVectorOnly = false;
                }
                if (bKeepRasters && bRasterCandidate)
                {
                    *pnGroupId = nCdfId;
                    *pnVarId = v;
                    nRasterVars++;
                }
            }
            else if (nVarDims == 1)
            {
                nc_type atttype = NC_NAT;
                size_t attlen = 0;
                if (nc_inq_att(nCdfId, v, "instance_dimension", &atttype,
                               &attlen) == NC_NOERR &&
                    atttype == NC_CHAR && attlen < NC_MAX_NAME)
                {
                    char szInstanceDimension[NC_MAX_NAME + 1];
                    if (nc_get_att_text(nCdfId, v, "instance_dimension",
                                        szInstanceDimension) == NC_NOERR)
                    {
                        szInstanceDimension[attlen] = 0;
                        int status = nc_inq_dimid(nCdfId, szInstanceDimension,
                                                  &nProfileDimId);
                        if (status == NC_NOERR)
                            nParentIndexVarID = v;
                        else
                            nProfileDimId = -1;
                        if (status == NC_EBADDIM)
                            CPLError(CE_Warning, CPLE_AppDefined,
                                     "Attribute instance_dimension='%s' refers "
                                     "to a non existing dimension",
                                     szInstanceDimension);
                        else
                            NCDF_ERR(status);
                    }
                }
                if (v != nParentIndexVarID)
                {
                    anPotentialVectorVarID.push_back(v);
                    int nDimId = -1;
                    nc_inq_vardimid(nCdfId, v, &nDimId);
                    oMapDimIdToCount[nDimId]++;
                }
            }
        }
    }

    // If we are opened in raster-only mode and that there are only 1D or 2D
    // variables and that the 2D variables have no X/Y dim, and all
    // variables refer to the same main dimension (or 2 dimensions for
    // featureType=profile), then it is a pure vector dataset
    CPLString osFeatureType(
        CSLFetchNameValueDef(papszMetadata, "NC_GLOBAL#featureType", ""));
    if (bKeepRasters && !bKeepVectors && bIsVectorOnly && nRasterVars > 0 &&
        !anPotentialVectorVarID.empty() &&
        (oMapDimIdToCount.size() == 1 ||
         (EQUAL(osFeatureType, "profile") && oMapDimIdToCount.size() == 2 &&
          nProfileDimId >= 0)))
    {
        anPotentialVectorVarID.resize(0);
    }
    else
    {
        *pnRasterVars += nRasterVars;
    }

    if (!anPotentialVectorVarID.empty() && bKeepVectors &&
        nccfdriver::getCFVersion(nCdfId) <= 1.6)
    {
        // Take the dimension that is referenced the most times.
        if (!(oMapDimIdToCount.size() == 1 ||
              (EQUAL(osFeatureType, "profile") &&
               oMapDimIdToCount.size() == 2 && nProfileDimId >= 0)))
        {
            CPLError(CE_Warning, CPLE_AppDefined,
                     "The dataset has several variables that could be "
                     "identified as vector fields, but not all share the same "
                     "primary dimension. Consequently they will be ignored.");
        }
        else
        {
            CreateGrpVectorLayers(nCdfId, osFeatureType, anPotentialVectorVarID,
                                  oMapDimIdToCount, nVarXId, nVarYId, nVarZId,
                                  nProfileDimId, nParentIndexVarID,
                                  bKeepRasters);
        }
    }

    // Recurse on sub-groups.
    int nSubGroups = 0;
    int *panSubGroupIds = nullptr;
    NCDFGetSubGroups(nCdfId, &nSubGroups, &panSubGroupIds);
    for (int i = 0; i < nSubGroups; i++)
    {
        FilterVars(panSubGroupIds[i], bKeepRasters, bKeepVectors,
                   papszIgnoreVars, pnRasterVars, pnGroupId, pnVarId,
                   pnIgnoredVars, oMap2DDimsToGroupAndVar);
    }
    CPLFree(panSubGroupIds);

    return CE_None;
}

// Create vector layers from given potentially identified vector variables
// resulting from the scanning of a NetCDF (or group) ID.
CPLErr netCDFDataset::CreateGrpVectorLayers(
    int nCdfId, CPLString osFeatureType,
    std::vector<int> anPotentialVectorVarID,
    std::map<int, int> oMapDimIdToCount, int nVarXId, int nVarYId, int nVarZId,
    int nProfileDimId, int nParentIndexVarID, bool bKeepRasters)
{
    char *pszGroupName = nullptr;
    NCDFGetGroupFullName(nCdfId, &pszGroupName);
    if (pszGroupName == nullptr || pszGroupName[0] == '\0')
    {
        CPLFree(pszGroupName);
        pszGroupName = CPLStrdup(CPLGetBasename(osFilename));
    }
    OGRwkbGeometryType eGType = wkbUnknown;
    CPLString osLayerName = CSLFetchNameValueDef(
        papszMetadata, "NC_GLOBAL#ogr_layer_name", pszGroupName);
    CPLFree(pszGroupName);
    papszMetadata =
        CSLSetNameValue(papszMetadata, "NC_GLOBAL#ogr_layer_name", nullptr);

    if (EQUAL(osFeatureType, "point") || EQUAL(osFeatureType, "profile"))
    {
        papszMetadata =
            CSLSetNameValue(papszMetadata, "NC_GLOBAL#featureType", nullptr);
        eGType = wkbPoint;
    }

    const char *pszLayerType =
        CSLFetchNameValue(papszMetadata, "NC_GLOBAL#ogr_layer_type");
    if (pszLayerType != nullptr)
    {
        eGType = OGRFromOGCGeomType(pszLayerType);
        papszMetadata =
            CSLSetNameValue(papszMetadata, "NC_GLOBAL#ogr_layer_type", nullptr);
    }

    CPLString osGeometryField =
        CSLFetchNameValueDef(papszMetadata, "NC_GLOBAL#ogr_geometry_field", "");
    papszMetadata =
        CSLSetNameValue(papszMetadata, "NC_GLOBAL#ogr_geometry_field", nullptr);

    int nFirstVarId = -1;
    int nVectorDim = oMapDimIdToCount.rbegin()->first;
    if (EQUAL(osFeatureType, "profile") && oMapDimIdToCount.size() == 2)
    {
        if (nVectorDim == nProfileDimId)
            nVectorDim = oMapDimIdToCount.begin()->first;
    }
    else
    {
        nProfileDimId = -1;
    }
    for (size_t j = 0; j < anPotentialVectorVarID.size(); j++)
    {
        int anDimIds[2] = {-1, -1};
        nc_inq_vardimid(nCdfId, anPotentialVectorVarID[j], anDimIds);
        if (nVectorDim == anDimIds[0])
        {
            nFirstVarId = anPotentialVectorVarID[j];
            break;
        }
    }

    // In case where coordinates are explicitly specified for one of the
    // field/variable, use them in priority over the ones that might have been
    // identified above.
    char *pszCoordinates = nullptr;
    if (NCDFGetAttr(nCdfId, nFirstVarId, "coordinates", &pszCoordinates) ==
        CE_None)
    {
        char **papszTokens = CSLTokenizeString2(pszCoordinates, " ", 0);
        for (int i = 0; papszTokens != nullptr && papszTokens[i] != nullptr;
             i++)
        {
            if (NCDFIsVarLongitude(nCdfId, -1, papszTokens[i]) ||
                NCDFIsVarProjectionX(nCdfId, -1, papszTokens[i]))
            {
                nVarXId = -1;
                CPL_IGNORE_RET_VAL(
                    nc_inq_varid(nCdfId, papszTokens[i], &nVarXId));
            }
            else if (NCDFIsVarLatitude(nCdfId, -1, papszTokens[i]) ||
                     NCDFIsVarProjectionY(nCdfId, -1, papszTokens[i]))
            {
                nVarYId = -1;
                CPL_IGNORE_RET_VAL(
                    nc_inq_varid(nCdfId, papszTokens[i], &nVarYId));
            }
            else if (NCDFIsVarVerticalCoord(nCdfId, -1, papszTokens[i]))
            {
                nVarZId = -1;
                CPL_IGNORE_RET_VAL(
                    nc_inq_varid(nCdfId, papszTokens[i], &nVarZId));
            }
        }
        CSLDestroy(papszTokens);
    }
    CPLFree(pszCoordinates);

    // Check that the X,Y,Z vars share 1D and share the same dimension as
    // attribute variables.
    if (nVarXId >= 0 && nVarYId >= 0)
    {
        int nVarDimCount = -1;
        int nVarDimId = -1;
        if (nc_inq_varndims(nCdfId, nVarXId, &nVarDimCount) != NC_NOERR ||
            nVarDimCount != 1 ||
            nc_inq_vardimid(nCdfId, nVarXId, &nVarDimId) != NC_NOERR ||
            nVarDimId != ((nProfileDimId >= 0) ? nProfileDimId : nVectorDim) ||
            nc_inq_varndims(nCdfId, nVarYId, &nVarDimCount) != NC_NOERR ||
            nVarDimCount != 1 ||
            nc_inq_vardimid(nCdfId, nVarYId, &nVarDimId) != NC_NOERR ||
            nVarDimId != ((nProfileDimId >= 0) ? nProfileDimId : nVectorDim))
        {
            nVarXId = nVarYId = -1;
        }
        else if (nVarZId >= 0 &&
                 (nc_inq_varndims(nCdfId, nVarZId, &nVarDimCount) != NC_NOERR ||
                  nVarDimCount != 1 ||
                  nc_inq_vardimid(nCdfId, nVarZId, &nVarDimId) != NC_NOERR ||
                  nVarDimId != nVectorDim))
        {
            nVarZId = -1;
        }
    }

    if (eGType == wkbUnknown && nVarXId >= 0 && nVarYId >= 0)
    {
        eGType = wkbPoint;
    }
    if (eGType == wkbPoint && nVarXId >= 0 && nVarYId >= 0 && nVarZId >= 0)
    {
        eGType = wkbPoint25D;
    }
    if (eGType == wkbUnknown && osGeometryField.empty())
    {
        eGType = wkbNone;
    }

    // Read projection info
    char **papszMetadataBackup = CSLDuplicate(papszMetadata);
    ReadAttributes(nCdfId, nFirstVarId);
    if (!this->bSGSupport)
        SetProjectionFromVar(nCdfId, nFirstVarId, true);
    const char *pszValue = FetchAttr(nCdfId, nFirstVarId, CF_GRD_MAPPING);
    char *pszGridMapping = (pszValue ? CPLStrdup(pszValue) : nullptr);
    CSLDestroy(papszMetadata);
    papszMetadata = papszMetadataBackup;

    OGRSpatialReference *poSRS = nullptr;
    if (!m_oSRS.IsEmpty())
    {
        poSRS = m_oSRS.Clone();
    }
    // Reset if there's a 2D raster
    m_bHasProjection = false;
    m_bHasGeoTransform = false;

    if (!bKeepRasters)
    {
        // Strip out uninteresting metadata.
        papszMetadata =
            CSLSetNameValue(papszMetadata, "NC_GLOBAL#Conventions", nullptr);
        papszMetadata =
            CSLSetNameValue(papszMetadata, "NC_GLOBAL#GDAL", nullptr);
        papszMetadata =
            CSLSetNameValue(papszMetadata, "NC_GLOBAL#history", nullptr);
    }

    std::shared_ptr<netCDFLayer> poLayer(
        new netCDFLayer(this, nCdfId, osLayerName, eGType, poSRS));
    if (poSRS != nullptr)
        poSRS->Release();
    poLayer->SetRecordDimID(nVectorDim);
    if (wkbFlatten(eGType) == wkbPoint && nVarXId >= 0 && nVarYId >= 0)
    {
        poLayer->SetXYZVars(nVarXId, nVarYId, nVarZId);
    }
    else if (!osGeometryField.empty())
    {
        poLayer->SetWKTGeometryField(osGeometryField);
    }
    if (pszGridMapping != nullptr)
    {
        poLayer->SetGridMapping(pszGridMapping);
        CPLFree(pszGridMapping);
    }
    poLayer->SetProfile(nProfileDimId, nParentIndexVarID);

    for (size_t j = 0; j < anPotentialVectorVarID.size(); j++)
    {
        int anDimIds[2] = {-1, -1};
        nc_inq_vardimid(nCdfId, anPotentialVectorVarID[j], anDimIds);
        if (anDimIds[0] == nVectorDim ||
            (nProfileDimId >= 0 && anDimIds[0] == nProfileDimId))
        {
#ifdef NCDF_DEBUG
            char szTemp2[NC_MAX_NAME + 1] = {};
            CPL_IGNORE_RET_VAL(
                nc_inq_varname(nCdfId, anPotentialVectorVarID[j], szTemp2));
            CPLDebug("GDAL_netCDF", "Variable %s is a vector field", szTemp2);
#endif
            poLayer->AddField(anPotentialVectorVarID[j]);
        }
    }

    if (poLayer->GetLayerDefn()->GetFieldCount() != 0 ||
        poLayer->GetGeomType() != wkbNone)
    {
        papoLayers.push_back(poLayer);
    }

    return CE_None;
}

// Get all coordinate and boundary variables full names referenced in
// a given a NetCDF (or group) ID and its sub-groups.
// These variables are identified in other variable's
// "coordinates" and "bounds" attribute.
// Searching coordinate and boundary variables may need to explore
// parents groups (or other groups in case of reference given in form of an
// absolute path).
// See CF sections 5.2, 5.6 and 7.1
static CPLErr NCDFGetCoordAndBoundVarFullNames(int nCdfId, char ***ppapszVars)
{
    int nVars = 0;
    NCDF_ERR(nc_inq(nCdfId, nullptr, &nVars, nullptr, nullptr));

    for (int v = 0; v < nVars; v++)
    {
        char *pszTemp = nullptr;
        char **papszTokens = nullptr;
        if (NCDFGetAttr(nCdfId, v, "coordinates", &pszTemp) == CE_None)
            papszTokens = CSLTokenizeString2(pszTemp, " ", 0);
        CPLFree(pszTemp);
        pszTemp = nullptr;
        if (NCDFGetAttr(nCdfId, v, "bounds", &pszTemp) == CE_None &&
            pszTemp != nullptr && !EQUAL(pszTemp, ""))
            papszTokens = CSLAddString(papszTokens, pszTemp);
        CPLFree(pszTemp);
        for (int i = 0; papszTokens != nullptr && papszTokens[i] != nullptr;
             i++)
        {
            char *pszVarFullName = nullptr;
            if (NCDFResolveVarFullName(nCdfId, papszTokens[i],
                                       &pszVarFullName) == CE_None)
                *ppapszVars = CSLAddString(*ppapszVars, pszVarFullName);
            CPLFree(pszVarFullName);
        }
        CSLDestroy(papszTokens);
    }

    // Recurse on sub-groups.
    int nSubGroups;
    int *panSubGroupIds = nullptr;
    NCDFGetSubGroups(nCdfId, &nSubGroups, &panSubGroupIds);
    for (int i = 0; i < nSubGroups; i++)
    {
        NCDFGetCoordAndBoundVarFullNames(panSubGroupIds[i], ppapszVars);
    }
    CPLFree(panSubGroupIds);

    return CE_None;
}

// Check if give type is user defined
bool NCDFIsUserDefinedType(int ncid, int type)
{
    // Adapted from OPENDAP netcdf_handler
    // To circumvent use of NC_FIRSTUSERTYPEID
    // Which is not a part of netcdf 4.1.1 installed on RH
    // In all later version, type >= NC_FIRSTUSERTYPEID works
#if NETCDF_HAS_NC4
#ifdef NC_FIRSTUSERTYPEID
    CPL_IGNORE_RET_VAL(ncid);
    return type >= NC_FIRSTUSERTYPEID;
#else
    int ntypes;
    int typeids[NC_MAX_VARS];

    while (true)
    {
        int err = nc_inq_typeids(ncid, &ntypes, typeids);
        if (err != NC_NOERR)
            CPLError(CE_Failure, CPLE_AppDefined,
                     "Could not get user defined type information");

        for (int i = 0; i < ntypes; ++i)
        {
            if (type == typeids[i])
                return true;
        }

        int nParentGroupId;
        int status = nc_inq_grp_parent(ncid, &nParentGroupId);
        if (status != NC_NOERR)
            break;
        ncid = nParentGroupId;
    }
    return false;
#endif
#else
    return false;
#endif
}
