-----------------------------------------------------------------------------
-- |
-- Module      :  Distribution.Simple.Build.Macros
-- Copyright   :  Isaac Jones 2003-2005,
--                Ross Paterson 2006,
--                Duncan Coutts 2007-2008
--
-- Maintainer  :  cabal-devel@haskell.org
-- Portability :  portable
--
-- Generating the Paths_pkgname module.
--
-- This is a module that Cabal generates for the benefit of packages. It
-- enables them to find their version number and find any installed data files
-- at runtime. This code should probably be split off into another module.
--
module Distribution.Simple.Build.PathsModule (
    generatePathsModule, pkgPathEnvVar
  ) where

import Distribution.Compat.Prelude
import Prelude ()

import Distribution.Package
import Distribution.PackageDescription
import Distribution.Simple.Compiler
import Distribution.Simple.LocalBuildInfo
import Distribution.Simple.Utils          (shortRelativePath)
import Distribution.System
import Distribution.Version

import qualified Distribution.Simple.Build.PathsModule.Z as Z

-- ------------------------------------------------------------
-- * Building Paths_<pkg>.hs
-- ------------------------------------------------------------

generatePathsModule :: PackageDescription -> LocalBuildInfo -> ComponentLocalBuildInfo -> String
generatePathsModule pkg_descr lbi clbi = Z.render Z.Z
    { Z.zPackageName                = packageName pkg_descr
    , Z.zVersionDigits              = show $ versionNumbers $ packageVersion pkg_descr
    , Z.zSupportsCpp                = supports_cpp
    , Z.zSupportsNoRebindableSyntax = supports_rebindable_syntax
    , Z.zAbsolute                   = absolute
    , Z.zRelocatable                = relocatable lbi
    , Z.zIsWindows                  = isWindows
    , Z.zIsI386                     = buildArch == I386
    , Z.zIsX8664                    = buildArch == X86_64
    , Z.zNot                        = not
    , Z.zManglePkgName              = showPkgName

    , Z.zPrefix     = show flat_prefix
    , Z.zBindir     = zBindir
    , Z.zLibdir     = zLibdir
    , Z.zDynlibdir  = zDynlibdir
    , Z.zDatadir    = zDatadir
    , Z.zLibexecdir = zLibexecdir
    , Z.zSysconfdir = zSysconfdir
    }
  where
    supports_cpp                 = supports_language_pragma
    supports_rebindable_syntax   = ghc_newer_than (mkVersion [7,0,1])
    supports_language_pragma     = ghc_newer_than (mkVersion [6,6,1])

    ghc_newer_than minVersion =
        case compilerCompatVersion GHC (compiler lbi) of
            Nothing      -> False
            Just version -> version `withinRange` orLaterVersion minVersion

    -- In several cases we cannot make relocatable installations
    absolute =
         hasLibs pkg_descr        -- we can only make progs relocatable
      || isNothing flat_bindirrel -- if the bin dir is an absolute path
      || not (supportsRelocatableProgs (compilerFlavor (compiler lbi)))

    -- TODO: Here, and with zIsI386 & zIs8664 we should use TARGET platform
    isWindows = case buildOS of
        Windows   -> True
        _         -> False

    supportsRelocatableProgs GHC   = isWindows
    supportsRelocatableProgs GHCJS = isWindows
    supportsRelocatableProgs _     = False

    cid = componentUnitId clbi

    InstallDirs
        { bindir     = flat_bindir
        , libdir     = flat_libdir
        , dynlibdir  = flat_dynlibdir
        , datadir    = flat_datadir
        , libexecdir = flat_libexecdir
        , sysconfdir = flat_sysconfdir
        , prefix     = flat_prefix
        } = absoluteInstallCommandDirs pkg_descr lbi cid NoCopyDest

    InstallDirs
        { bindir     = flat_bindirrel
        , libdir     = flat_libdirrel
        , dynlibdir  = flat_dynlibdirrel
        , datadir    = flat_datadirrel
        , libexecdir = flat_libexecdirrel
        , sysconfdir = flat_sysconfdirrel
        } = prefixRelativeComponentInstallDirs (packageId pkg_descr) lbi cid

    zBindir, zLibdir, zDynlibdir, zDatadir, zLibexecdir, zSysconfdir :: String
    (zBindir, zLibdir, zDynlibdir, zDatadir, zLibexecdir, zSysconfdir)
        | relocatable lbi =
            ( show flat_bindir_reloc
            , show flat_libdir_reloc
            , show flat_dynlibdir_reloc
            , show flat_datadir_reloc
            , show flat_libexecdir_reloc
            , show flat_sysconfdir_reloc
            )
        | absolute        =
            ( show flat_bindir
            , show flat_libdir
            , show flat_dynlibdir
            , show flat_datadir
            , show flat_libexecdir
            , show flat_sysconfdir
            )
        | isWindows       =
            ( "maybe (error \"PathsModule.generate\") id (" ++ show flat_bindirrel ++ ")"
            , mkGetDir flat_libdir flat_libdirrel
            , mkGetDir flat_dynlibdir flat_dynlibdirrel
            , mkGetDir flat_datadir flat_datadirrel
            , mkGetDir flat_libexecdir flat_libexecdirrel
            , mkGetDir flat_sysconfdir flat_sysconfdirrel
            )
        | otherwise       =
            error "panic! generatePathsModule: should never happen"

    mkGetDir :: FilePath -> Maybe FilePath -> String
    mkGetDir _   (Just dirrel) = "getPrefixDirRel " ++ show dirrel
    mkGetDir dir Nothing       = "return " ++ show dir

    flat_bindir_reloc     = shortRelativePath flat_prefix flat_bindir
    flat_libdir_reloc     = shortRelativePath flat_prefix flat_libdir
    flat_dynlibdir_reloc  = shortRelativePath flat_prefix flat_dynlibdir
    flat_datadir_reloc    = shortRelativePath flat_prefix flat_datadir
    flat_libexecdir_reloc = shortRelativePath flat_prefix flat_libexecdir
    flat_sysconfdir_reloc = shortRelativePath flat_prefix flat_sysconfdir

-- | Generates the name of the environment variable controlling the path
-- component of interest.
--
-- Note: The format of these strings is part of Cabal's public API;
-- changing this function constitutes a *backwards-compatibility* break.
pkgPathEnvVar
    :: PackageDescription
    -> String     -- ^ path component; one of \"bindir\", \"libdir\", -- \"datadir\", \"libexecdir\", or \"sysconfdir\"
    -> String     -- ^ environment variable name
pkgPathEnvVar pkg_descr var =
    showPkgName (packageName pkg_descr) ++ "_" ++ var

showPkgName :: PackageName -> String
showPkgName = map fixchar . unPackageName

fixchar :: Char -> Char
fixchar '-' = '_'
fixchar c   = c
