    -----------------------------------------------------------------------------
    -- |
    -- Module      :  Distribution.Simple.JHC
    -- Copyright   :  Isaac Jones 2003-2006
    -- License     :  BSD3
    --
    -- Maintainer  :  cabal-devel@haskell.org
    -- Portability :  portable
    --
    -- This module contains most of the JHC-specific code for configuring, building
    -- and installing packages.

    module Distribution.Simple.JHC (
            configure, getInstalledPackages,
            buildLib, buildExe,
            installLib, installExe
     ) where

    import Distribution.PackageDescription as PD hiding (Flag)
    import Distribution.InstalledPackageInfo
    import qualified Distribution.InstalledPackageInfo as InstalledPackageInfo
    import Distribution.Simple.PackageIndex (InstalledPackageIndex)
    import qualified Distribution.Simple.PackageIndex as PackageIndex
    import Distribution.Simple.LocalBuildInfo
    import Distribution.Simple.BuildPaths
    import Distribution.Simple.Compiler
    import Language.Haskell.Extension
    import Distribution.Simple.Program
    import Distribution.Version
    import Distribution.Package
    import Distribution.Simple.Utils
    import Distribution.Verbosity
    import Distribution.Text

    import System.FilePath          ( (</>) )
    import Distribution.Compat.ReadP
        ( readP_to_S, string, skipSpaces )
    import Distribution.System ( Platform )

    import Data.List                ( nub )
    import Data.Char                ( isSpace )
    import qualified Data.Map as M  ( empty )
    import Data.Maybe               ( fromMaybe )

    import qualified Data.ByteString.Lazy.Char8 as BS.Char8

    -- -----------------------------------------------------------------------------
    -- Configuring

    configure :: Verbosity -> Maybe FilePath -> Maybe FilePath
              -> ProgramConfiguration -> IO (Compiler, Maybe Platform, ProgramConfiguration)
    configure verbosity hcPath _hcPkgPath conf = do

      (jhcProg, _, conf') <- requireProgramVersion verbosity
                               jhcProgram (orLaterVersion (Version [0,7,2] []))
                               (userMaybeSpecifyPath "jhc" hcPath conf)

      let Just version = programVersion jhcProg
          comp = Compiler {
            compilerId             = CompilerId JHC version,
            compilerAbiTag         = NoAbiTag,
            compilerCompat         = [],
            compilerLanguages      = jhcLanguages,
            compilerExtensions     = jhcLanguageExtensions,
            compilerProperties     = M.empty
          }
          compPlatform = Nothing
      return (comp, compPlatform, conf')

    jhcLanguages :: [(Language, Flag)]
    jhcLanguages = [(Haskell98, "")]

    -- | The flags for the supported extensions
    jhcLanguageExtensions :: [(Extension, Flag)]
    jhcLanguageExtensions =
        [(EnableExtension  TypeSynonymInstances       , "")
        ,(DisableExtension TypeSynonymInstances       , "")
        ,(EnableExtension  ForeignFunctionInterface   , "")
        ,(DisableExtension ForeignFunctionInterface   , "")
        ,(EnableExtension  ImplicitPrelude            , "") -- Wrong
        ,(DisableExtension ImplicitPrelude            , "--noprelude")
        ,(EnableExtension  CPP                        , "-fcpp")
        ,(DisableExtension CPP                        , "-fno-cpp")
        ]

    getInstalledPackages :: Verbosity -> PackageDBStack -> ProgramConfiguration
                        -> IO InstalledPackageIndex
    getInstalledPackages verbosity _packageDBs conf = do
       -- jhc --list-libraries lists all available libraries.
       -- How shall I find out, whether they are global or local
       -- without checking all files and locations?
       str <- rawSystemProgramStdoutConf verbosity jhcProgram conf ["--list-libraries"]
       let pCheck :: [(a, String)] -> [a]
           pCheck rs = [ r | (r,s) <- rs, all isSpace s ]
       let parseLine ln =
              pCheck (readP_to_S
                 (skipSpaces >> string "Name:" >> skipSpaces >> parse) ln)
       return $
          PackageIndex.fromList $
          map (\p -> emptyInstalledPackageInfo {
                        InstalledPackageInfo.installedUnitId = mkLegacyUnitId p,
                        InstalledPackageInfo.sourcePackageId = p
                     }) $
          concatMap parseLine $
          lines str

    -- -----------------------------------------------------------------------------
    -- Building

    -- | Building a package for JHC.
    -- Currently C source files are not supported.
    buildLib :: Verbosity -> PackageDescription -> LocalBuildInfo
                          -> Library            -> ComponentLocalBuildInfo -> IO ()
    buildLib verbosity pkg_descr lbi lib clbi = do
      let Just jhcProg = lookupProgram jhcProgram (withPrograms lbi)
      let libBi = libBuildInfo lib
      let args  = constructJHCCmdLine lbi libBi clbi (buildDir lbi) verbosity
      let pkgid = display (packageId pkg_descr)
          pfile = buildDir lbi </> "jhc-pkg.conf"
          hlfile= buildDir lbi </> (pkgid ++ ".hl")
      writeFileAtomic pfile . BS.Char8.pack $ jhcPkgConf pkg_descr
      rawSystemProgram verbosity jhcProg $
         ["--build-hl="++pfile, "-o", hlfile] ++
         args ++ map display (libModules lib)

    -- | Building an executable for JHC.
    -- Currently C source files are not supported.
    buildExe :: Verbosity -> PackageDescription -> LocalBuildInfo
                          -> Executable         -> ComponentLocalBuildInfo -> IO ()
    buildExe verbosity _pkg_descr lbi exe clbi = do
      let Just jhcProg = lookupProgram jhcProgram (withPrograms lbi)
      let exeBi = buildInfo exe
      let out   = buildDir lbi </> exeName exe
      let args  = constructJHCCmdLine lbi exeBi clbi (buildDir lbi) verbosity
      rawSystemProgram verbosity jhcProg (["-o",out] ++ args ++ [modulePath exe])

    constructJHCCmdLine :: LocalBuildInfo -> BuildInfo -> ComponentLocalBuildInfo
                        -> FilePath -> Verbosity -> [String]
    constructJHCCmdLine lbi bi clbi _odir verbosity =
            (if verbosity >= deafening then ["-v"] else [])
         ++ hcOptions JHC bi
         ++ languageToFlags (compiler lbi) (defaultLanguage bi)
         ++ extensionsToFlags (compiler lbi) (usedExtensions bi)
         ++ ["--noauto","-i-"]
         ++ concat [["-i", l] | l <- nub (hsSourceDirs bi)]
         ++ ["-i", autogenModulesDir lbi]
         ++ ["-optc" ++ opt | opt <- PD.ccOptions bi]
         -- It would be better if JHC would accept package names with versions,
         -- but JHC-0.7.2 doesn't accept this.
         -- Thus, we have to strip the version with 'pkgName'.
         ++ (concat [ ["-p", display (pkgName pkgid)]
                    | (_, pkgid) <- componentPackageDeps clbi ])

    jhcPkgConf :: PackageDescription -> String
    jhcPkgConf pd =
      let sline name sel = name ++ ": "++sel pd
          lib = fromMaybe (error "no library available") . library
          comma = intercalate "," . map display
      in unlines [sline "name" (display . pkgName . packageId)
                 ,sline "version" (display . pkgVersion . packageId)
                 ,sline "exposed-modules" (comma . PD.exposedModules . lib)
                 ,sline "hidden-modules" (comma . otherModules . libBuildInfo . lib)
                 ]

    installLib :: Verbosity
               -> LocalBuildInfo
               -> FilePath
               -> FilePath
               -> FilePath
               -> PackageDescription
               -> Library
               -> ComponentLocalBuildInfo
               -> IO ()
    installLib verb _lbi dest _dyn_dest build_dir pkg_descr _lib _clbi = do
        let p = display (packageId pkg_descr)++".hl"
        createDirectoryIfMissingVerbose verb True dest
        installOrdinaryFile verb (build_dir </> p) (dest </> p)

    installExe :: Verbosity -> FilePath -> FilePath -> (FilePath,FilePath) -> PackageDescription -> Executable -> IO ()
    installExe verb dest build_dir (progprefix,progsuffix) _ exe = do
        let exe_name = exeName exe
            src = exe_name </> exeExtension
            out   = (progprefix ++ exe_name ++ progsuffix) </> exeExtension
        createDirectoryIfMissingVerbose verb True dest
        installExecutableFile verb (build_dir </> src) (dest </> out)