    -----------------------------------------------------------------------------
    -- |
    -- Module      :  Distribution.Simple.UHC
    -- Copyright   :  Andres Loeh 2009
    --
    -- Maintainer  :  cabal-devel@haskell.org
    -- Portability :  portable
    --
    -- This module contains most of the UHC-specific code for configuring, building
    -- and installing packages.
    --
    -- Thanks to the authors of the other implementation-specific files, in
    -- particular to Isaac Jones, Duncan Coutts and Henning Thielemann, for
    -- inspiration on how to design this module.

    {-
    Copyright (c) 2009, Andres Loeh
    Copyright (c) 2003-2005, Isaac Jones
    All rights reserved.

    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions are
    met:

        * Redistributions of source code must retain the above copyright
          notice, this list of conditions and the following disclaimer.

        * Redistributions in binary form must reproduce the above
          copyright notice, this list of conditions and the following
          disclaimer in the documentation and/or other materials provided
          with the distribution.

        * Neither the name of Isaac Jones nor the names of other
          contributors may be used to endorse or promote products derived
          from this software without specific prior written permission.

    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
    A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
    OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
    SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
    LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
    DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
    THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
    (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
    OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. -}

    module Distribution.Simple.UHC (
        configure, getInstalledPackages,
        buildLib, buildExe, installLib, registerPackage
      ) where

    import Control.Monad
    import Data.List
    import Distribution.Compat.ReadP
    import Distribution.InstalledPackageInfo
    import Distribution.Package
    import Distribution.PackageDescription
    import Distribution.Simple.BuildPaths
    import Distribution.Simple.Compiler as C
    import Distribution.Simple.LocalBuildInfo
    import Distribution.Simple.PackageIndex
    import Distribution.Simple.Program
    import Distribution.Simple.Utils
    import Distribution.Text
    import Distribution.Verbosity
    import Distribution.Version
    import Language.Haskell.Extension
    import System.Directory
    import System.FilePath

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

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

      (_uhcProg, uhcVersion, conf') <-
        requireProgramVersion verbosity uhcProgram
        (orLaterVersion (Version [1,0,2] []))
        (userMaybeSpecifyPath "uhc" hcPath conf)

      let comp = Compiler {
                   compilerId          =  CompilerId UHC uhcVersion,
                   compilerLanguages   =  uhcLanguages,
                   compilerExtensions  =  uhcLanguageExtensions
                 }
      return (comp, conf')

    uhcLanguages :: [(Language, C.Flag)]
    uhcLanguages = [(Haskell98, "")]

    -- | The flags for the supported extensions.
    uhcLanguageExtensions :: [(Extension, C.Flag)]
    uhcLanguageExtensions =
        [(CPP, "--cpp"),
         (PolymorphicComponents, ""),
         (ExistentialQuantification, ""),
         (ForeignFunctionInterface, ""),
         (UndecidableInstances, ""),
         (MultiParamTypeClasses, ""),
         (Rank2Types, ""),
         (PatternSignatures, ""),
         (EmptyDataDecls, ""),
         (NoImplicitPrelude, "--no-prelude"),
         (TypeOperators, ""),
         (OverlappingInstances, ""),
         (FlexibleInstances, "")]

    getInstalledPackages :: Verbosity -> Compiler -> PackageDBStack -> ProgramConfiguration
                         -> IO PackageIndex
    getInstalledPackages verbosity comp packagedbs conf = do
      let compilerid = compilerId comp
      systemPkgDir <- rawSystemProgramStdoutConf verbosity uhcProgram conf ["--meta-pkgdir-system"]
      userPkgDir   <- getUserPackageDir
      let pkgDirs    = nub (concatMap (packageDbPaths userPkgDir systemPkgDir) packagedbs)
      -- putStrLn $ "pkgdirs: " ++ show pkgDirs
      -- call to "lines" necessary, because pkgdir contains an extra newline at the end
      pkgs <- liftM (map addBuiltinVersions . concat) .
              mapM (\ d -> getDirectoryContents d >>= filterM (isPkgDir (display compilerid) d)) .
              concatMap lines $ pkgDirs
      -- putStrLn $ "pkgs: " ++ show pkgs
      let iPkgs =
            map mkInstalledPackageInfo $
            concatMap parsePackage $
            pkgs
      -- putStrLn $ "installed pkgs: " ++ show iPkgs
      return (fromList iPkgs)

    getUserPackageDir :: IO FilePath
    getUserPackageDir =
      do
        homeDir <- getHomeDirectory
        return $ homeDir </> ".cabal" </> "lib"  -- TODO: determine in some other way

    packageDbPaths :: FilePath -> FilePath -> PackageDB -> [FilePath]
    packageDbPaths user system db =
      case db of
        GlobalPackageDB         ->  [ system ]
        UserPackageDB           ->  [ user ]
        SpecificPackageDB path  ->  [ path ]

    -- | Hack to add version numbers to UHC-builtin packages. This should sooner or
    -- later be fixed on the UHC side.
    addBuiltinVersions :: String -> String
    {-
    addBuiltinVersions "uhcbase"  = "uhcbase-1.0"
    addBuiltinVersions "base"  = "base-3.0"
    addBuiltinVersions "array" = "array-0.2"
    -}
    addBuiltinVersions xs      = xs

    -- | Name of the installed package config file.
    installedPkgConfig :: String
    installedPkgConfig = "installed-pkg-config"

    -- | Check if a certain dir contains a valid package. Currently, we are
    -- looking only for the presence of an installed package configuration.
    -- TODO: Actually make use of the information provided in the file.
    isPkgDir :: String -> String -> String -> IO Bool
    isPkgDir _ _   ('.' : _)  = return False  -- ignore files starting with a .
    isPkgDir c dir xs         = do
                                  let candidate = dir </> uhcPackageDir xs c
                                  -- putStrLn $ "trying: " ++ candidate
                                  doesFileExist (candidate </> installedPkgConfig)

    parsePackage :: String -> [PackageId]
    parsePackage x = map fst (filter (\ (_,y) -> null y) (readP_to_S parse x))

    -- | Create a trivial package info from a directory name.
    mkInstalledPackageInfo :: PackageId -> InstalledPackageInfo
    mkInstalledPackageInfo p = emptyInstalledPackageInfo
      { installedPackageId = InstalledPackageId (display p),
        sourcePackageId    = p }

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

    buildLib :: Verbosity -> PackageDescription -> LocalBuildInfo
                          -> Library            -> ComponentLocalBuildInfo -> IO ()
    buildLib verbosity pkg_descr lbi lib clbi = do

      systemPkgDir <- rawSystemProgramStdoutConf verbosity uhcProgram (withPrograms lbi) ["--meta-pkgdir-system"]
      userPkgDir   <- getUserPackageDir
      let runUhcProg = rawSystemProgramConf verbosity uhcProgram (withPrograms lbi)
      let uhcArgs =    -- set package name
                       ["--pkg-build=" ++ display (packageId pkg_descr)]
                       -- common flags lib/exe
                    ++ constructUHCCmdLine userPkgDir systemPkgDir
                                           lbi (libBuildInfo lib) clbi
                                           (buildDir lbi) verbosity
                       -- source files
                       -- suboptimal: UHC does not understand module names, so
                       -- we replace periods by path separators
                    ++ map (map (\ c -> if c == '.' then pathSeparator else c))
                           (map display (libModules lib))

      runUhcProg uhcArgs

      return ()

    buildExe :: Verbosity -> PackageDescription -> LocalBuildInfo
                          -> Executable         -> ComponentLocalBuildInfo -> IO ()
    buildExe verbosity _pkg_descr lbi exe clbi = do
      systemPkgDir <- rawSystemProgramStdoutConf verbosity uhcProgram (withPrograms lbi) ["--meta-pkgdir-system"]
      userPkgDir   <- getUserPackageDir
      let runUhcProg = rawSystemProgramConf verbosity uhcProgram (withPrograms lbi)
      let uhcArgs =    -- common flags lib/exe
                       constructUHCCmdLine userPkgDir systemPkgDir
                                           lbi (buildInfo exe) clbi
                                           (buildDir lbi) verbosity
                       -- output file
                    ++ ["--output", buildDir lbi </> exeName exe]
                       -- main source module
                    ++ [modulePath exe]
      runUhcProg uhcArgs

    constructUHCCmdLine :: FilePath -> FilePath
                        -> LocalBuildInfo -> BuildInfo -> ComponentLocalBuildInfo
                        -> FilePath -> Verbosity -> [String]
    constructUHCCmdLine user system lbi bi clbi odir verbosity =
         -- verbosity
         (if      verbosity >= deafening then ["-v4"]
          else if verbosity >= normal    then []
          else                                ["-v0"])
      ++ hcOptions UHC bi
         -- flags for language extensions
      ++ languageToFlags   (compiler lbi) (defaultLanguage bi)
      ++ extensionsToFlags (compiler lbi) (usedExtensions bi)
         -- packages
      ++ ["--hide-all-packages"]
      ++ uhcPackageDbOptions user system (withPackageDB lbi)
      ++ ["--package=uhcbase"]
      ++ ["--package=" ++ display (pkgName pkgid) | (_, pkgid) <- componentPackageDeps clbi ]
         -- search paths
      ++ ["-i" ++ odir]
      ++ ["-i" ++ l | l <- nub (hsSourceDirs bi)]
      ++ ["-i" ++ autogenModulesDir lbi]
         -- output path
      ++ ["--odir=" ++ odir]
         -- optimization
      ++ (case withOptimization lbi of
            NoOptimisation       ->  ["-O0"]
            NormalOptimisation   ->  ["-O1"]
            MaximumOptimisation  ->  ["-O2"])

    uhcPackageDbOptions :: FilePath -> FilePath -> PackageDBStack -> [String]
    uhcPackageDbOptions user system db = map (\ x -> "--pkg-searchpath=" ++ x)
                                             (concatMap (packageDbPaths user system) db)

    -- -----------------------------------------------------------------------------
    -- Installation

    installLib :: Verbosity -> LocalBuildInfo
               -> FilePath -> FilePath -> FilePath
               -> PackageDescription -> Library -> IO ()
    installLib verbosity _lbi targetDir _dynlibTargetDir builtDir pkg _library = do
        -- putStrLn $ "dest:  " ++ targetDir
        -- putStrLn $ "built: " ++ builtDir
        installDirectoryContents verbosity (builtDir </> display (packageId pkg)) targetDir

    -- currently hardcoded UHC code generator and variant to use
    uhcTarget, uhcTargetVariant :: String
    uhcTarget        = "bc"
    uhcTargetVariant = "plain"

    -- root directory for a package in UHC
    uhcPackageDir    :: String -> String -> FilePath
    uhcPackageSubDir ::           String -> FilePath
    uhcPackageDir    pkgid compilerid = pkgid </> uhcPackageSubDir compilerid
    uhcPackageSubDir       compilerid = compilerid </> uhcTarget </> uhcTargetVariant

    -- -----------------------------------------------------------------------------
    -- Registering

    registerPackage
      :: Verbosity
      -> InstalledPackageInfo
      -> PackageDescription
      -> LocalBuildInfo
      -> Bool
      -> PackageDBStack
      -> IO ()
    registerPackage verbosity installedPkgInfo pkg lbi inplace _packageDbs = do
        let installDirs = absoluteInstallDirs pkg lbi NoCopyDest
            pkgdir  | inplace   = buildDir lbi       </> uhcPackageDir    (display pkgid) (display compilerid)
                    | otherwise = libdir installDirs </> uhcPackageSubDir                 (display compilerid)
        createDirectoryIfMissingVerbose verbosity True pkgdir
        writeUTF8File (pkgdir </> installedPkgConfig)
                      (showInstalledPackageInfo installedPkgInfo)
      where
        pkgid      = packageId pkg
        compilerid = compilerId (compiler lbi)