'''
DDS File library
================

This library can be used to parse and save DDS
(`DirectDraw Surface <https://en.wikipedia.org/wiki/DirectDraw_Surface>`)
files.

The initial version was written by::

    Alexey Borzenkov (snaury@gmail.com)

All the initial work credits go to him! Thank you :)

This version uses structs instead of ctypes.


DDS Format
----------

::

    [DDS ][SurfaceDesc][Data]

    [SurfaceDesc]:: (everything is uint32)
        Size
        Flags
        Height
        Width
        PitchOrLinearSize
        Depth
        MipmapCount
        Reserved1 * 11
        [PixelFormat]::
            Size
            Flags
            FourCC
            RGBBitCount
            RBitMask
            GBitMask
            BBitMask
            ABitMask
        [Caps]::
            Caps1
            Caps2
            Reserved1 * 2
        Reserverd2

.. warning::

    This is an external library and Kivy does not provide any support for it.
    It might change in the future and we advise you don't rely on it in your
    code.

'''

from struct import pack, unpack, calcsize

# DDSURFACEDESC2 dwFlags
DDSD_CAPS                  = 0x00000001
DDSD_HEIGHT                = 0x00000002
DDSD_WIDTH                 = 0x00000004
DDSD_PITCH                 = 0x00000008
DDSD_PIXELFORMAT           = 0x00001000
DDSD_MIPMAPCOUNT           = 0x00020000
DDSD_LINEARSIZE            = 0x00080000
DDSD_DEPTH                 = 0x00800000

# DDPIXELFORMAT dwFlags
DDPF_ALPHAPIXELS           = 0x00000001
DDPF_FOURCC                = 0x00000004
DDPF_RGB                   = 0x00000040
DDPF_LUMINANCE             = 0x00020000

# DDSCAPS2 dwCaps1
DDSCAPS_COMPLEX            = 0x00000008
DDSCAPS_TEXTURE            = 0x00001000
DDSCAPS_MIPMAP             = 0x00400000

# DDSCAPS2 dwCaps2
DDSCAPS2_CUBEMAP           = 0x00000200
DDSCAPS2_CUBEMAP_POSITIVEX = 0x00000400
DDSCAPS2_CUBEMAP_NEGATIVEX = 0x00000800
DDSCAPS2_CUBEMAP_POSITIVEY = 0x00001000
DDSCAPS2_CUBEMAP_NEGATIVEY = 0x00002000
DDSCAPS2_CUBEMAP_POSITIVEZ = 0x00004000
DDSCAPS2_CUBEMAP_NEGATIVEZ = 0x00008000
DDSCAPS2_VOLUME            = 0x00200000

# Common FOURCC codes
DDS_DXTN = 0x00545844
DDS_DXT1 = 0x31545844
DDS_DXT2 = 0x32545844
DDS_DXT3 = 0x33545844
DDS_DXT4 = 0x34545844
DDS_DXT5 = 0x35545844

def dxt_to_str(dxt):
    if dxt == DDS_DXT1:
        return 's3tc_dxt1'
    elif dxt == DDS_DXT2:
        return 's3tc_dxt2'
    elif dxt == DDS_DXT3:
        return 's3tc_dxt3'
    elif dxt == DDS_DXT4:
        return 's3tc_dxt4'
    elif dxt == DDS_DXT5:
        return 's3tc_dxt5'
    elif dxt == 0:
        return 'rgba'
    elif dxt == 1:
        return 'alpha'
    elif dxt == 2:
        return 'luminance'
    elif dxt == 3:
        return 'luminance_alpha'

def str_to_dxt(dxt):
    if dxt == 's3tc_dxt1':
        return DDS_DXT1
    if dxt == 's3tc_dxt2':
        return DDS_DXT2
    if dxt == 's3tc_dxt3':
        return DDS_DXT3
    if dxt == 's3tc_dxt4':
        return DDS_DXT4
    if dxt == 's3tc_dxt5':
        return DDS_DXT5
    if dxt == 'rgba':
        return 0
    if dxt == 'alpha':
        return 1
    if dxt == 'luminance':
        return 2
    if dxt == 'luminance_alpha':
        return 3

def align_value(val, b):
    return val + (-val % b)

def check_flags(val, fl):
    return (val & fl) == fl

def dxt_size(w, h, dxt):
    w = max(1, w // 4)
    h = max(1, h // 4)
    if dxt == DDS_DXT1:
        return w * h * 8
    elif dxt in (DDS_DXT2, DDS_DXT3, DDS_DXT4, DDS_DXT5):
        return w * h * 16
    return -1

class QueryDict(dict):
    def __getattr__(self, attr):
        try:
            return self.__getitem__(attr)
        except KeyError:
            try:
                return super(QueryDict, self).__getattr__(attr)
            except AttributeError:
                raise KeyError(attr)

    def __setattr__(self, attr, value):
        self.__setitem__(attr, value)

class DDSException(Exception):
    pass


class DDSFile(object):
    fields = (
        ('size', 0), ('flags', 1), ('height', 2),
        ('width', 3), ('pitchOrLinearSize', 4), ('depth', 5),
        ('mipmapCount', 6), ('pf_size', 18), ('pf_flags', 19),
        ('pf_fourcc', 20), ('pf_rgbBitCount', 21), ('pf_rBitMask', 22),
        ('pf_gBitMask', 23), ('pf_bBitMask', 24), ('pf_aBitMask', 25),
        ('caps1', 26), ('caps2', 27))

    def __init__(self, filename=None):
        super(DDSFile, self).__init__()
        self._dxt = 0
        self._fmt = None
        self.meta = meta = QueryDict()
        self.count = 0
        self.images = []
        self.images_size = []
        for field, index in DDSFile.fields:
            meta[field] = 0
        if filename:
            self.load(filename)

    def load(self, filename):
        self.filename = filename
        with open(filename, 'rb') as fd:
            data = fd.read()

        # ensure magic
        if data[:4] != 'DDS ':
            raise DDSException('Invalid magic header')

        # read header
        fmt = 'I' * 31
        fmt_size = calcsize(fmt)
        pf_size = calcsize('I' * 8)
        header, data = data[4:4+fmt_size], data[4+fmt_size:]
        if len(header) != fmt_size:
            raise DDSException('Truncated header in')

        # depack
        header = unpack(fmt, header)
        meta = self.meta
        for name, index in DDSFile.fields:
            meta[name] = header[index]

        # check header validity
        if meta.size != fmt_size:
            raise DDSException('Invalid header size (%d instead of %d)' %
                    (meta.size, fmt_size))
        if meta.pf_size != pf_size:
            raise DDSException('Invalid pixelformat size (%d instead of %d)' %
                    (meta.pf_size, pf_size))
        if not check_flags(meta.flags,
                DDSD_CAPS | DDSD_PIXELFORMAT | DDSD_WIDTH | DDSD_HEIGHT):
            raise DDSException('Not enough flags')
        if not check_flags(meta.caps1, DDSCAPS_TEXTURE):
            raise DDSException('Not a DDS texture')

        self.count = 1
        if check_flags(meta.flags, DDSD_MIPMAPCOUNT):
            if not check_flags(meta.caps1, DDSCAPS_COMPLEX | DDSCAPS_MIPMAP):
                raise DDSException('Invalid mipmap without flags')
            self.count = meta.mipmapCount

        hasrgb = check_flags(meta.pf_flags, DDPF_RGB)
        hasalpha = check_flags(meta.pf_flags, DDPF_ALPHAPIXELS)
        hasluminance = check_flags(meta.pf_flags, DDPF_LUMINANCE)
        bpp = None
        dxt = block = pitch = 0
        if hasrgb or hasalpha or hasluminance:
            bpp = meta.pf_rgbBitCount

        if hasrgb and hasluminance:
            raise DDSException('File have RGB and Luminance')

        if hasrgb:
            dxt = 0
        elif hasalpha and not hasluminance:
            dxt = 1
        elif hasluminance and not hasalpha:
            dxt = 2
        elif hasalpha and hasluminance:
            dxt = 3
        elif check_flags(meta.pf_flags, DDPF_FOURCC):
            dxt = meta.pf_fourcc
            if dxt not in (DDS_DXT1, DDS_DXT2, DDS_DXT3, DDS_DXT4, DDS_DXT5):
                raise DDSException('Unsupported FOURCC')
        else:
            raise DDSException('Unsupported format specified')

        if bpp:
            block = align_value(bpp, 8) // 8
            pitch = align_value(block * meta.width, 4)

        if check_flags(meta.flags, DDSD_LINEARSIZE):
            if dxt in (0, 1, 2, 3):
                size = pitch * meta.height
            else:
                size = dxt_size(meta.width, meta.height, dxt)

        w = meta.width
        h = meta.height
        images = self.images
        images_size = self.images_size
        for i in range(self.count):
            if dxt in (0, 1, 2, 3):
                size = align_value(block * w, 4) * h
            else:
                size = dxt_size(w, h, dxt)
            image, data = data[:size], data[size:]
            if len(image) < size:
                raise DDSException('Truncated image for mipmap %d' % i)
            images_size.append((w, h))
            images.append(image)
            if w == 1 and h == 1:
                break
            w = max(1, w // 2)
            h = max(1, h // 2)

        if len(images) == 0:
            raise DDSException('No images available')
        if len(images) < self.count:
            raise DDSException('Not enough images')

        self._dxt = dxt

    def save(self, filename):
        if len(self.images) == 0:
            raise DDSException('No images to save')

        fields = dict(DDSFile.fields)
        fields_keys = list(fields.keys())
        fields_index = list(fields.values())
        mget = self.meta.get
        header = []
        for idx in range(31):
            if idx in fields_index:
                value = mget(fields_keys[fields_index.index(idx)], 0)
            else:
                value = 0
            header.append(value)

        with open(filename, 'wb') as fd:
            fd.write('DDS ')
            fd.write(pack('I' * 31, *header))
            for image in self.images:
                fd.write(image)

    def add_image(self, level, bpp, fmt, width, height, data):
        assert(bpp == 32)
        assert(fmt in ('rgb', 'rgba', 'dxt1', 'dxt2', 'dxt3', 'dxt4', 'dxt5'))
        assert(width > 0)
        assert(height > 0)
        assert(level >= 0)

        meta = self.meta
        images = self.images
        if len(images) == 0:
            assert(level == 0)

            # first image, set defaults !
            for k in meta.keys():
                meta[k] = 0

            self._fmt = fmt
            meta.size = calcsize('I' * 31)
            meta.pf_size = calcsize('I' * 8)
            meta.pf_flags = 0
            meta.flags = DDSD_CAPS | DDSD_PIXELFORMAT | DDSD_WIDTH | DDSD_HEIGHT
            meta.width = width
            meta.height = height
            meta.caps1 = DDSCAPS_TEXTURE

            meta.flags |= DDSD_LINEARSIZE
            meta.pitchOrLinearSize = len(data)

            meta.pf_rgbBitCount = 32
            meta.pf_rBitMask = 0x00ff0000
            meta.pf_gBitMask = 0x0000ff00
            meta.pf_bBitMask = 0x000000ff
            meta.pf_aBitMask = 0xff000000

            if fmt in ('rgb', 'rgba'):
                assert(True)
                assert(bpp == 32)
                meta.pf_flags |= DDPF_RGB
                meta.pf_rgbBitCount = 32
                meta.pf_rBitMask = 0x00ff0000
                meta.pf_gBitMask = 0x0000ff00
                meta.pf_bBitMask = 0x000000ff
                meta.pf_aBitMask = 0x00000000
                if fmt == 'rgba':
                    meta.pf_flags |= DDPF_ALPHAPIXELS
                    meta.pf_aBitMask = 0xff000000
            else:
                meta.pf_flags |= DDPF_FOURCC
                if fmt == 'dxt1':
                    meta.pf_fourcc = DDS_DXT1
                elif fmt == 'dxt2':
                    meta.pf_fourcc = DDS_DXT2
                elif fmt == 'dxt3':
                    meta.pf_fourcc = DDS_DXT3
                elif fmt == 'dxt4':
                    meta.pf_fourcc = DDS_DXT4
                elif fmt == 'dxt5':
                    meta.pf_fourcc = DDS_DXT5

            images.append(data)
        else:
            assert(level == len(images))
            assert(fmt == self._fmt)

            images.append(data)

            meta.flags |= DDSD_MIPMAPCOUNT
            meta.caps1 |= DDSCAPS_COMPLEX | DDSCAPS_MIPMAP
            meta.mipmapCount = len(images)

    def __repr__(self):
        return '<DDSFile filename=%r size=%r dxt=%r len(images)=%r>' % (
                self.filename, self.size, self.dxt, len(self.images))

    def _get_size(self):
        meta = self.meta
        return meta.width, meta.height
    def _set_size(self, size):
        self.meta.update({'width': size[0], 'height': size[1]})
    size = property(_get_size, _set_size)

    def _get_dxt(self):
        return dxt_to_str(self._dxt)
    def _set_dxt(self, dxt):
        self._dxt = str_to_dxt(dxt)
    dxt = property(_get_dxt, _set_dxt)

if __name__ == '__main__':
    import sys
    if len(sys.argv) == 1:
        print('Usage: python ddsfile.py <file1> <file2> ...')
        sys.exit(0)
    for filename in sys.argv[1:]:
        print('=== Loading', filename)
        try:
            dds = DDSFile(filename=filename)
            print(dds)
            dds.save('bleh.dds')
        except IOError as e:
            print('ERR>', e)
        except DDSException as e:
            print('DDS>', e)
