    {-# OPTIONS -cpp #-}
    -----------------------------------------------------------------------------
    -- |
    -- Module      :  Distribution.Simple.Hugs
    -- Copyright   :  Isaac Jones 2003-2006
    --
    -- Maintainer  :  Isaac Jones <ijones@syntaxpolice.org>
    -- Stability   :  alpha
    -- Portability :  portable
    --
    -- Build and install functionality for Hugs.

    {- 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.Hugs (
    	configure, build, install
     ) where

    import Distribution.PackageDescription
    				( PackageDescription(..), BuildInfo(..),
    				  withLib,
    				  Executable(..), withExe, Library(..),
    				  libModules, hcOptions, autogenModuleName )
    import Distribution.Simple.Compiler 	( Compiler(..), CompilerFlavor(..), Flag )
    import Distribution.Simple.Program     ( ProgramConfiguration, userMaybeSpecifyPath,
                                      requireProgram, rawSystemProgramConf,
                                      ffihugsProgram, hugsProgram )
    import Distribution.Version	( Version(..), VersionRange(AnyVersion) )
    import Distribution.Simple.PreProcess 	( ppCpp, runSimplePreProcessor )
    import Distribution.Simple.PreProcess.Unlit
    				( unlit )
    import Distribution.Simple.LocalBuildInfo
    				( LocalBuildInfo(..), autogenModulesDir )
    import Distribution.Simple.Utils( createDirectoryIfMissingVerbose, dotToSep,
    				  moduleToFilePath, die, info, notice,
    				  smartCopySources, findFile, dllExtension )
    import Language.Haskell.Extension
    				( Extension(..) )
    import Distribution.Compat.Directory
    				( copyFile, removeDirectoryRecursive )
    import System.FilePath        	( (</>), takeExtension, (<.>),
                                      searchPathSeparator, normalise, takeDirectory )
    import Distribution.System
    import Distribution.Verbosity
    import Distribution.Package	( PackageIdentifier(..) )

    import Data.Char		( isSpace )
    import Data.Maybe		( mapMaybe )
    import Control.Monad		( unless, when, filterM )
    #ifndef __NHC__
    import Control.Exception	( try )
    #else
    import IO			( try )
    #endif
    import Data.List		( nub, sort, isSuffixOf )
    import System.Directory		( Permissions(..), getPermissions,
    				  setPermissions )

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

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

      (_ffihugsProg, conf') <- requireProgram verbosity ffihugsProgram AnyVersion
                                (userMaybeSpecifyPath "ffihugs" hcPath conf)
      (_hugsProg, conf'')   <- requireProgram verbosity hugsProgram AnyVersion conf'

      let comp = Compiler {
            compilerFlavor         = Hugs,
            compilerId             = PackageIdentifier "hugs" (Version [] []),
            compilerExtensions     = hugsLanguageExtensions
          }
      return (comp, conf'')

    -- | The flags for the supported extensions
    hugsLanguageExtensions :: [(Extension, Flag)]
    hugsLanguageExtensions =
        [(OverlappingInstances       , "+o")
        ,(IncoherentInstances        , "+oO")
        ,(HereDocuments              , "+H")
        ,(TypeSynonymInstances       , "-98")
        ,(RecursiveDo                , "-98")
        ,(ParallelListComp           , "-98")
        ,(MultiParamTypeClasses      , "-98")
        ,(FunctionalDependencies     , "-98")
        ,(Rank2Types                 , "-98")
        ,(PolymorphicComponents      , "-98")
        ,(ExistentialQuantification  , "-98")
        ,(ScopedTypeVariables        , "-98")
        ,(ImplicitParams             , "-98")
        ,(ExtensibleRecords          , "-98")
        ,(RestrictedTypeSynonyms     , "-98")
        ,(FlexibleContexts           , "-98")
        ,(FlexibleInstances          , "-98")
        ,(ForeignFunctionInterface   , "")
        ,(EmptyDataDecls             , "")
        ,(CPP                        , "")
        ]

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

    -- |Building a package for Hugs.
    build :: PackageDescription -> LocalBuildInfo -> Verbosity -> IO ()
    build pkg_descr lbi verbosity = do
        let pref = scratchDir lbi
        createDirectoryIfMissingVerbose verbosity True pref
        withLib pkg_descr () $ \ l -> do
    	copyFile (autogenModulesDir lbi </> paths_modulename)
    		(pref </> paths_modulename)
    	compileBuildInfo pref [] (libModules pkg_descr) (libBuildInfo l)
        withExe pkg_descr $ compileExecutable (pref </> "programs")
      where
    	srcDir = buildDir lbi

    	paths_modulename = autogenModuleName pkg_descr ++ ".hs"

    	compileExecutable :: FilePath -> Executable -> IO ()
    	compileExecutable destDir (exe@Executable {modulePath=mainPath, buildInfo=bi}) = do
                let exeMods = otherModules bi
    	    srcMainFile <- findFile (hsSourceDirs bi) mainPath
    	    let exeDir = destDir </> exeName exe
    	    let destMainFile = exeDir </> hugsMainFilename exe
    	    copyModule (CPP `elem` extensions bi) bi srcMainFile destMainFile
    	    let destPathsFile = exeDir </> paths_modulename
    	    copyFile (autogenModulesDir lbi </> paths_modulename)
    		     destPathsFile
    	    compileBuildInfo exeDir (maybe [] (hsSourceDirs . libBuildInfo) (library pkg_descr)) exeMods bi
    	    compileFiles bi exeDir [destMainFile, destPathsFile]

    	compileBuildInfo :: FilePath -- ^output directory
                             -> [FilePath] -- ^library source dirs, if building exes
                             -> [String] -- ^Modules
                             -> BuildInfo -> IO ()
    	compileBuildInfo destDir mLibSrcDirs mods bi = do
    	    -- Pass 1: copy or cpp files from build directory to scratch directory
    	    let useCpp = CPP `elem` extensions bi
    	    let srcDirs = nub $ srcDir : hsSourceDirs bi ++ mLibSrcDirs
                info verbosity $ "Source directories: " ++ show srcDirs
                flip mapM_ mods $ \ m -> do
                    fs <- moduleToFilePath srcDirs m suffixes
                    case fs of
                      [] ->
                        die ("can't find source for module " ++ m)
                      srcFile:_ -> do
                        let ext = takeExtension srcFile
                        copyModule useCpp bi srcFile
                            (destDir </> dotToSep m <.> ext)
    	    -- Pass 2: compile foreign stubs in scratch directory
    	    stubsFileLists <- sequence [moduleToFilePath [destDir] modu suffixes |
    			modu <- mods]
                compileFiles bi destDir (concat stubsFileLists)

    	suffixes = ["hs", "lhs"]

    	-- Copy or cpp a file from the source directory to the build directory.
    	copyModule :: Bool -> BuildInfo -> FilePath -> FilePath -> IO ()
    	copyModule cppAll bi srcFile destFile = do
    	    createDirectoryIfMissingVerbose verbosity True (takeDirectory destFile)
    	    (exts, opts, _) <- getOptionsFromSource srcFile
    	    let ghcOpts = hcOptions GHC opts
    	    if cppAll || CPP `elem` exts || "-cpp" `elem` ghcOpts then do
    	    	runSimplePreProcessor (ppCpp bi lbi) srcFile destFile verbosity
    	    	return ()
    	      else
    	    	copyFile srcFile destFile

            compileFiles :: BuildInfo -> FilePath -> [FilePath] -> IO ()
            compileFiles bi modDir fileList = do
    	    ffiFileList <- filterM testFFI fileList
                unless (null ffiFileList) $ do
                    notice verbosity "Compiling FFI stubs"
                    mapM_ (compileFFI bi modDir) ffiFileList

            -- Only compile FFI stubs for a file if it contains some FFI stuff
            testFFI :: FilePath -> IO Bool
            testFFI file = do
                inp <- readHaskellFile file
                return ("foreign" `elem` symbols (stripComments False inp))

            compileFFI :: BuildInfo -> FilePath -> FilePath -> IO ()
            compileFFI bi modDir file = do
                (_, opts, file_incs) <- getOptionsFromSource file
                let ghcOpts = hcOptions GHC opts
                let pkg_incs = ["\"" ++ inc ++ "\"" | inc <- includes bi]
                let incs = nub (sort (file_incs ++ includeOpts ghcOpts ++ pkg_incs))
                let pathFlag = "-P" ++ modDir ++ [searchPathSeparator]
                let hugsArgs = "-98" : pathFlag : map ("-i" ++) incs
                cfiles <- getCFiles file
                let cArgs =
                        ["-I" ++ dir | dir <- includeDirs bi] ++
                        ccOptions bi ++
                        cfiles ++
                        ["-L" ++ dir | dir <- extraLibDirs bi] ++
                        ldOptions bi ++
                        ["-l" ++ lib | lib <- extraLibs bi] ++
                        concat [["-framework", f] | f <- frameworks bi]
                rawSystemProgramConf verbosity ffihugsProgram (withPrograms lbi)
    	      (hugsArgs ++ file : cArgs)

    	includeOpts :: [String] -> [String]
    	includeOpts [] = []
    	includeOpts ("-#include" : arg : opts) = arg : includeOpts opts
    	includeOpts (_ : opts) = includeOpts opts

    	-- get C file names from CFILES pragmas throughout the source file
    	getCFiles :: FilePath -> IO [String]
    	getCFiles file = do
    	    inp <- readHaskellFile file
    	    return [normalise cfile |
    		"{-#" : "CFILES" : rest <-
    			map words $ lines $ stripComments True inp,
    		last rest == "#-}",
    		cfile <- init rest]

    	-- List of terminal symbols in a source file.
    	symbols :: String -> [String]
    	symbols cs = case lex cs of
    	    (sym, cs'):_ | not (null sym) -> sym : symbols cs'
    	    _ -> []

    	-- Get the non-literate source of a Haskell module.
    	readHaskellFile :: FilePath -> IO String
    	readHaskellFile file = do
    	    text <- readFile file
    	    return $ if ".lhs" `isSuffixOf` file then unlit file text else text

    -- ------------------------------------------------------------
    -- * options in source files
    -- ------------------------------------------------------------

    -- |Read the initial part of a source file, before any Haskell code,
    -- and return the contents of any LANGUAGE, OPTIONS and INCLUDE pragmas.
    getOptionsFromSource
        :: FilePath
        -> IO ([Extension],                 -- LANGUAGE pragma, if any
               [(CompilerFlavor,[String])], -- OPTIONS_FOO pragmas
               [String]                     -- INCLUDE pragmas
              )
    getOptionsFromSource file = do
        text <- readFile file
        return $ foldr appendOptions ([],[],[]) $ map getOptions $
    	takeWhileJust $ map getPragma $
    	filter textLine $ map (dropWhile isSpace) $ lines $
    	stripComments True $
    	if ".lhs" `isSuffixOf` file then unlit file text else text
      where textLine [] = False
    	textLine ('#':_) = False
    	textLine _ = True

    	getPragma :: String -> Maybe [String]
    	getPragma line = case words line of
    	    ("{-#" : rest) | last rest == "#-}" -> Just (init rest)
    	    _ -> Nothing

    	getOptions ("OPTIONS":opts) = ([], [(GHC, opts)], [])
    	getOptions ("OPTIONS_GHC":opts) = ([], [(GHC, opts)], [])
    	getOptions ("OPTIONS_NHC98":opts) = ([], [(NHC, opts)], [])
    	getOptions ("OPTIONS_HUGS":opts) = ([], [(Hugs, opts)], [])
    	getOptions ("LANGUAGE":ws) = (mapMaybe readExtension ws, [], [])
    	  where	readExtension :: String -> Maybe Extension
    		readExtension w = case reads w of
    		    [(ext, "")] -> Just ext
    		    [(ext, ",")] -> Just ext
    		    _ -> Nothing
    	getOptions ("INCLUDE":ws) = ([], [], ws)
    	getOptions _ = ([], [], [])

    	appendOptions (exts, opts, incs) (exts', opts', incs')
              = (exts++exts', opts++opts', incs++incs')

    -- takeWhileJust f = map fromJust . takeWhile isJust
    takeWhileJust :: [Maybe a] -> [a]
    takeWhileJust (Just x:xs) = x : takeWhileJust xs
    takeWhileJust _ = []

    -- |Strip comments from Haskell source.
    stripComments
        :: Bool	-- ^ preserve pragmas?
        -> String	-- ^ input source text
        -> String
    stripComments keepPragmas = stripCommentsLevel 0
      where stripCommentsLevel :: Int -> String -> String
    	stripCommentsLevel 0 ('"':cs) = '"':copyString cs
    	stripCommentsLevel 0 ('-':'-':cs) =	-- FIX: symbols like -->
    	    stripCommentsLevel 0 (dropWhile (/= '\n') cs)
    	stripCommentsLevel 0 ('{':'-':'#':cs)
    	  | keepPragmas = '{' : '-' : '#' : copyPragma cs
    	stripCommentsLevel n ('{':'-':cs) = stripCommentsLevel (n+1) cs
    	stripCommentsLevel 0 (c:cs) = c : stripCommentsLevel 0 cs
    	stripCommentsLevel n ('-':'}':cs) = stripCommentsLevel (n-1) cs
    	stripCommentsLevel n (_:cs) = stripCommentsLevel n cs
    	stripCommentsLevel _ [] = []

    	copyString ('\\':c:cs) = '\\' : c : copyString cs
    	copyString ('"':cs) = '"' : stripCommentsLevel 0 cs
    	copyString (c:cs) = c : copyString cs
    	copyString [] = []

    	copyPragma ('#':'-':'}':cs) = '#' : '-' : '}' : stripCommentsLevel 0 cs
    	copyPragma (c:cs) = c : copyPragma cs
    	copyPragma [] = []

    -- -----------------------------------------------------------------------------
    -- |Install for Hugs.
    -- For install, copy-prefix = prefix, but for copy they're different.
    -- The library goes in \<copy-prefix>\/lib\/hugs\/packages\/\<pkgname>
    -- (i.e. \<prefix>\/lib\/hugs\/packages\/\<pkgname> on the target system).
    -- Each executable goes in \<copy-prefix>\/lib\/hugs\/programs\/\<exename>
    -- (i.e. \<prefix>\/lib\/hugs\/programs\/\<exename> on the target system)
    -- with a script \<copy-prefix>\/bin\/\<exename> pointing at
    -- \<prefix>\/lib\/hugs\/programs\/\<exename>.
    install
        :: Verbosity -- ^verbosity
        -> FilePath  -- ^Library install location
        -> FilePath  -- ^Program install location
        -> FilePath  -- ^Executable install location
        -> FilePath  -- ^Program location on target system
        -> FilePath  -- ^Build location
        -> PackageDescription
        -> IO ()
    install verbosity libDir installProgDir binDir targetProgDir buildPref pkg_descr = do
        try $ removeDirectoryRecursive libDir
        smartCopySources verbosity [buildPref] libDir (libModules pkg_descr) hugsInstallSuffixes True False
        let buildProgDir = buildPref </> "programs"
        when (any (buildable . buildInfo) (executables pkg_descr)) $
            createDirectoryIfMissingVerbose verbosity True binDir
        withExe pkg_descr $ \ exe -> do
            let theBuildDir = buildProgDir </> exeName exe
            let installDir = installProgDir </> exeName exe
            let targetDir = targetProgDir </> exeName exe
            try $ removeDirectoryRecursive installDir
            smartCopySources verbosity [theBuildDir] installDir
                ("Main" : autogenModuleName pkg_descr : otherModules (buildInfo exe)) hugsInstallSuffixes True False
            let targetName = "\"" ++ (targetDir </> hugsMainFilename exe) ++ "\""
            -- FIX (HUGS): use extensions, and options from file too?
            -- see http://hackage.haskell.org/trac/hackage/ticket/43
            let hugsOptions = hcOptions Hugs (options (buildInfo exe))
            let exeFile = case os of
                              Windows _ -> binDir </> exeName exe <.> ".bat"
                              _         -> binDir </> exeName exe
            let script = case os of
                             Windows _ ->
                                 let args = hugsOptions ++ [targetName, "%*"]
                                 in unlines ["@echo off",
                                             unwords ("runhugs" : args)]
                             _ ->
                                 let args = hugsOptions ++ [targetName, "\"$@\""]
                                 in unlines ["#! /bin/sh",
                                             unwords ("runhugs" : args)]
            writeFile exeFile script
            perms <- getPermissions exeFile
            setPermissions exeFile perms { executable = True, readable = True }

    hugsInstallSuffixes :: [String]
    hugsInstallSuffixes = [".hs", ".lhs", dllExtension]

    -- |Filename used by Hugs for the main module of an executable.
    -- This is a simple filename, so that Hugs will look for any auxiliary
    -- modules it uses relative to the directory it's in.
    hugsMainFilename :: Executable -> FilePath
    hugsMainFilename exe = "Main" <.> ext
      where ext = takeExtension (modulePath exe)