content: -----------------------------------------------------------------------------
  -- |
  -- Module      :  Distribution.Simple.Haddock
  -- Copyright   :  Isaac Jones 2003-2005
  --
  -- Maintainer  :  cabal-devel@haskell.org
  -- Portability :  portable
  --
  -- This module deals with the @haddock@ and @hscolour@ commands. Sadly this is
  -- a rather complicated module. It deals with two versions of haddock (0.x and
  -- 2.x). It has to do pre-processing for haddock 0.x which involves
  -- \'unlit\'ing and using @-DHADDOCK@ for any source code that uses @cpp@. It
  -- uses information about installed packages (from @ghc-pkg@) to find the
  -- locations of documentation for dependent packages, so it can create links.
  --
  -- The @hscolour@ support allows generating html versions of the original
  -- source, with coloured syntax highlighting.
  
  {- 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.Haddock (
    haddock, hscolour
    ) where
  
  -- local
  import Distribution.Package
           ( PackageIdentifier, Package(..), packageName )
  import qualified Distribution.ModuleName as ModuleName
  import Distribution.PackageDescription as PD
           ( PackageDescription(..), BuildInfo(..), allExtensions
           , Library(..), hasLibs, Executable(..) )
  import Distribution.Simple.Compiler
           ( Compiler(..), compilerVersion )
  import Distribution.Simple.GHC ( ghcLibDir )
  import Distribution.Simple.Program
           ( ConfiguredProgram(..), requireProgramVersion
           , rawSystemProgram, rawSystemProgramStdout
           , hscolourProgram, haddockProgram )
  import Distribution.Simple.PreProcess (ppCpp', ppUnlit
                                        , PPSuffixHandler, runSimplePreProcessor
                                        , preprocessComponent)
  import Distribution.Simple.Setup
          ( defaultHscolourFlags, Flag(..), flagToMaybe, fromFlag
          , HaddockFlags(..), HscolourFlags(..) )
  import Distribution.Simple.Build (initialBuildSteps)
  import Distribution.Simple.InstallDirs (InstallDirs(..), PathTemplateEnv, PathTemplate,
                                          PathTemplateVariable(..),
                                          toPathTemplate, fromPathTemplate,
                                          substPathTemplate,
                                          initialPathTemplateEnv)
  import Distribution.Simple.LocalBuildInfo
           ( LocalBuildInfo(..), externalPackageDeps
           , Component(..), ComponentLocalBuildInfo(..), withComponentsLBI )
  import Distribution.Simple.BuildPaths ( haddockName,
                                          hscolourPref, autogenModulesDir,
                                          )
  import Distribution.Simple.PackageIndex (dependencyClosure)
  import qualified Distribution.Simple.PackageIndex as PackageIndex
  import qualified Distribution.InstalledPackageInfo as InstalledPackageInfo
           ( InstalledPackageInfo_(..) )
  import Distribution.InstalledPackageInfo
           ( InstalledPackageInfo )
  import Distribution.Simple.Utils
           ( die, warn, notice, intercalate, setupMessage
           , createDirectoryIfMissingVerbose, withTempFile, copyFileVerbose
           , withTempDirectory
           , findFileWithExtension, findFile )
  import Distribution.Simple.GHC (ghcOptions)
  import Distribution.Text
           ( display, simpleParse )
  
  import Distribution.Verbosity
  import Language.Haskell.Extension
  -- Base
  import System.Directory(removeFile, doesFileExist, createDirectoryIfMissing)
  
  import Control.Monad ( when, guard )
  import Control.Exception (assert)
  import Data.Monoid
  import Data.Maybe    ( fromMaybe, listToMaybe )
  
  import System.FilePath((</>), (<.>), splitFileName, splitExtension,
                         normalise, splitPath, joinPath)
  import System.IO (hClose, hPutStrLn)
  import Distribution.Version
  
  -- Types
  
  -- | record that represents the arguments to the haddock executable, a product monoid.
  data HaddockArgs = HaddockArgs {
   argInterfaceFile :: Flag FilePath,               -- ^ path of the interface file, relative to argOutputDir, required.
   argPackageName :: Flag PackageIdentifier,        -- ^ package name,                                         required.
   argHideModules :: (All,[ModuleName.ModuleName]), -- ^ (hide modules ?, modules to hide)
   argIgnoreExports :: Any,                         -- ^ ingore export lists in modules?
   argLinkSource :: Flag (Template,Template),       -- ^ (template for modules, template for symbols)
   argCssFile :: Flag FilePath,                     -- ^ optinal custom css file.
   argContents :: Flag String,                      -- ^ optional url to contents page
   argVerbose :: Any,
   argOutput :: Flag [Output],                      -- ^ Html or Hoogle doc or both?                                   required.
   argInterfaces :: [(FilePath, Maybe FilePath)],   -- ^ [(interface file, path to the html docs for links)]
   argOutputDir :: Directory,                       -- ^ where to generate the documentation.
   argTitle :: Flag String,                         -- ^ page's title,                                         required.
   argPrologue :: Flag String,                      -- ^ prologue text,                                        required.
   argGhcFlags :: [String],                         -- ^ additional flags to pass to ghc for haddock-2
   argGhcLibDir :: Flag FilePath,                   -- ^ to find the correct ghc,                              required by haddock-2.
   argTargets :: [FilePath]                         -- ^ modules to process.
  }
  
  -- | the FilePath of a directory, it's a monoid under (</>)
  newtype Directory = Dir { unDir' :: FilePath } deriving (Read,Show,Eq,Ord)
  
  unDir :: Directory -> FilePath
  unDir = joinPath . filter (\p -> p /="./" && p /= ".") . splitPath . unDir'
  
  type Template = String
  
  data Output = Html | Hoogle
  
  -- --------------------------------------------------------------------------
  -- Haddock support
  
  haddock :: PackageDescription -> LocalBuildInfo -> [PPSuffixHandler] -> HaddockFlags -> IO ()
  haddock pkg_descr _ _ haddockFlags
    |    not (hasLibs pkg_descr)
      && not (fromFlag $ haddockExecutables haddockFlags) =
        warn (fromFlag $ haddockVerbosity haddockFlags) $
             "No documentation was generated as this package does not contain "
          ++ "a library. Perhaps you want to use the --executables flag."
  
  haddock pkg_descr lbi suffixes flags = do
  
      setupMessage verbosity "Running Haddock for" (packageId pkg_descr)
      (confHaddock, version, _) <-
        requireProgramVersion verbosity haddockProgram
          (orLaterVersion (Version [0,6] [])) (withPrograms lbi)
  
      -- various sanity checks
      let isVersion2   = version >= Version [2,0] []
  
      when ( flag haddockHoogle
             && version > Version [2] []
             && version < Version [2,2] []) $
           die "haddock 2.0 and 2.1 do not support the --hoogle flag."
  
      when (flag haddockHscolour && version < Version [0,8] []) $
           die "haddock --hyperlink-source requires Haddock version 0.8 or later"
  
      when isVersion2 $ do
        haddockGhcVersionStr <- rawSystemProgramStdout verbosity confHaddock
                                  ["--ghc-version"]
        case simpleParse haddockGhcVersionStr of
          Nothing -> die "Could not get GHC version from Haddock"
          Just haddockGhcVersion
            | haddockGhcVersion == ghcVersion -> return ()
            | otherwise -> die $
                   "Haddock's internal GHC version must match the configured "
                ++ "GHC version.\n"
                ++ "The GHC version is " ++ display ghcVersion ++ " but "
                ++ "haddock is using GHC version " ++ display haddockGhcVersion
            where ghcVersion = compilerVersion (compiler lbi)
  
      -- the tools match the requests, we can proceed
  
      initialBuildSteps (flag haddockDistPref) pkg_descr lbi verbosity
  
      when (flag haddockHscolour) $ hscolour' pkg_descr lbi suffixes $
           defaultHscolourFlags `mappend` haddockToHscolour flags
  
      args <- fmap mconcat . sequence $
              [ getInterfaces verbosity lbi (flagToMaybe (haddockHtmlLocation flags))
              , getGhcLibDir  verbosity lbi isVersion2 ]
             ++ map return
              [ fromFlags (haddockTemplateEnv lbi (packageId pkg_descr)) flags
              , fromPackageDescription pkg_descr ]
  
      let pre c = preprocessComponent pkg_descr c lbi False verbosity suffixes
      withComponentsLBI pkg_descr lbi $ \comp clbi -> do
        pre comp
        case comp of
          CLib lib -> do
            withTempDirectory verbosity (buildDir lbi) "tmp" $ \tmp -> do
              let bi = libBuildInfo lib
              libArgs  <- fromLibrary tmp lbi lib clbi
              libArgs' <- prepareSources verbosity tmp
                            lbi isVersion2 bi (args `mappend` libArgs)
              runHaddock verbosity confHaddock libArgs'
          CExe exe -> when (flag haddockExecutables) $ do
            withTempDirectory verbosity (buildDir lbi) "tmp" $ \tmp -> do
              let bi = buildInfo exe
              exeArgs  <- fromExecutable tmp lbi exe clbi
              exeArgs' <- prepareSources verbosity tmp
                            lbi isVersion2 bi (args `mappend` exeArgs)
              runHaddock verbosity confHaddock exeArgs'
          _ -> return ()
    where
      verbosity = flag haddockVerbosity
      flag f    = fromFlag $ f flags
  
  -- | performs cpp and unlit preprocessing where needed on the files in
  -- | argTargets, which must have an .hs or .lhs extension.
  prepareSources :: Verbosity
                    -> FilePath
                    -> LocalBuildInfo
                    -> Bool            -- haddock == 2.*
                    -> BuildInfo
                    -> HaddockArgs
                    -> IO HaddockArgs
  prepareSources verbosity tmp lbi isVersion2 bi args@HaddockArgs{argTargets=files} =
                mapM (mockPP tmp) files >>= \targets -> return args {argTargets=targets}
            where
              mockPP pref file = do
                   let (filePref, fileName) = splitFileName file
                       targetDir  = pref </> filePref
                       targetFile = targetDir </> fileName
                       (targetFileNoext, targetFileExt) = splitExtension $ targetFile
                       hsFile = targetFileNoext <.> "hs"
  
                   assert (targetFileExt `elem` [".lhs",".hs"]) $ return ()
  
                   createDirectoryIfMissing True targetDir
  
                   if needsCpp
                      then do
                        runSimplePreProcessor (ppCpp' defines bi lbi)
                                              file targetFile verbosity
                      else
                        copyFileVerbose verbosity file targetFile
  
                   when (targetFileExt == ".lhs") $ do
                       runSimplePreProcessor ppUnlit targetFile hsFile verbosity
                       removeFile targetFile
  
                   return hsFile
              needsCpp = EnableExtension CPP `elem` allExtensions bi
              defines | isVersion2 = []
                      | otherwise  = ["-D__HADDOCK__"]
  
  --------------------------------------------------------------------------------------------------
  -- constributions to HaddockArgs
  
  fromFlags :: PathTemplateEnv -> HaddockFlags -> HaddockArgs
  fromFlags env flags =
      mempty {
        argHideModules = (maybe mempty (All . not) $ flagToMaybe (haddockInternal flags), mempty),
        argLinkSource = if fromFlag (haddockHscolour flags)
                                 then Flag ("src/%{MODULE/./-}.html"
                                           ,"src/%{MODULE/./-}.html#%{NAME}")
                                 else NoFlag,
        argCssFile = haddockCss flags,
        argContents = fmap (fromPathTemplate . substPathTemplate env) (haddockContents flags),
        argVerbose = maybe mempty (Any . (>= deafening)) . flagToMaybe $ haddockVerbosity flags,
        argOutput = 
            Flag $ case [ Html | Flag True <- [haddockHtml flags] ] ++
                        [ Hoogle | Flag True <- [haddockHoogle flags] ]
                   of [] -> [ Html ]
                      os -> os,
        argOutputDir = maybe mempty Dir . flagToMaybe $ haddockDistPref flags
      }
  
  fromPackageDescription :: PackageDescription -> HaddockArgs
  fromPackageDescription pkg_descr =
        mempty {
                  argInterfaceFile = Flag $ haddockName pkg_descr,
                  argPackageName = Flag $ packageId $ pkg_descr,
                  argOutputDir = Dir $ "doc" </> "html" </> display (packageName pkg_descr),
                  argPrologue = Flag $ if null desc then synopsis pkg_descr else desc,
                  argTitle = Flag $ showPkg ++ subtitle
               }
        where
          desc = PD.description pkg_descr
          showPkg = display (packageId pkg_descr)
          subtitle | null (synopsis pkg_descr) = ""
                   | otherwise                 = ": " ++ synopsis pkg_descr
  
  fromLibrary :: FilePath
              -> LocalBuildInfo -> Library -> ComponentLocalBuildInfo
              -> IO HaddockArgs
  fromLibrary tmp lbi lib clbi =
              do inFiles <- map snd `fmap` getLibSourceFiles lbi lib
                 return $ mempty {
                              argHideModules = (mempty,otherModules $ bi),
                              argGhcFlags = ghcOptions lbi bi clbi (buildDir lbi)
                                         -- Noooooooooo!!!!!111
                                         -- haddock stomps on our precious .hi
                                         -- and .o files. Workaround by telling
                                         -- haddock to write them elsewhere.
                                         ++ [ "-odir", tmp, "-hidir", tmp
                                            , "-stubdir", tmp ],
                              argTargets = inFiles
                            }
      where
        bi = libBuildInfo lib
  
  fromExecutable :: FilePath
                 -> LocalBuildInfo -> Executable -> ComponentLocalBuildInfo
                 -> IO HaddockArgs
  fromExecutable tmp lbi exe clbi =
              do inFiles <- map snd `fmap` getExeSourceFiles lbi exe
                 return $ mempty {
                              argGhcFlags = ghcOptions lbi bi clbi (buildDir lbi)
                                         -- Noooooooooo!!!!!111
                                         -- haddock stomps on our precious .hi
                                         -- and .o files. Workaround by telling
                                         -- haddock to write them elsewhere.
                                         ++ [ "-odir", tmp, "-hidir", tmp
                                            , "-stubdir", tmp ],
                              argOutputDir = Dir (exeName exe),
                              argTitle = Flag (exeName exe),
                              argTargets = inFiles
                            }
      where
        bi = buildInfo exe
  
  getInterfaces :: Verbosity
                   -> LocalBuildInfo
                   -> Maybe String -- ^ template for html location
                   -> IO HaddockArgs
  getInterfaces verbosity lbi location = do
      let htmlTemplate = fmap toPathTemplate $ location
      (packageFlags, warnings) <- haddockPackageFlags lbi htmlTemplate
      maybe (return ()) (warn verbosity) warnings
      return $ mempty {
                   argInterfaces = packageFlags
                 }
  
  getGhcLibDir :: Verbosity -> LocalBuildInfo
               -> Bool -- ^ are we using haddock-2.x ?
               -> IO HaddockArgs
  getGhcLibDir verbosity lbi isVersion2
      | isVersion2 =
          do l <- ghcLibDir verbosity lbi
             return $ mempty { argGhcLibDir = Flag l }
      | otherwise  =
          return mempty
  
  ----------------------------------------------------------------------------------------------
  
  -- | Call haddock with the specified arguments.
  runHaddock :: Verbosity -> ConfiguredProgram -> HaddockArgs -> IO ()
  runHaddock verbosity confHaddock args = do
    let haddockVersion = fromMaybe (error "unable to determine haddock version")
                         (programVersion confHaddock)
    renderArgs verbosity haddockVersion args $ \(flags,result)-> do
  
        rawSystemProgram verbosity confHaddock flags
  
        notice verbosity $ "Documentation created: " ++ result
  
  
  renderArgs :: Verbosity
                -> Version
                -> HaddockArgs
                -> (([[Char]], FilePath) -> IO a)
                -> IO a
  renderArgs verbosity version args k = do
    createDirectoryIfMissingVerbose verbosity True outputDir
    withTempFile outputDir "haddock-prolog.txt" $ \prologFileName h -> do
            do
               hPutStrLn h $ fromFlag $ argPrologue args
               hClose h
               let pflag = (:[]).("--prologue="++) $ prologFileName
               k $ (pflag ++ renderPureArgs version args, result)
      where
        isVersion2 = version >= Version [2,0] []
        outputDir = (unDir $ argOutputDir args)
        result = intercalate ", "
               . map (\o -> outputDir </>
                              case o of
                                Html -> "index.html"
                                Hoogle -> pkgstr <.> "txt")
               $ arg argOutput
              where
                pkgstr | isVersion2 = display $ packageName pkgid
                       | otherwise = display pkgid
                pkgid = arg argPackageName
        arg f = fromFlag $ f args
  
  renderPureArgs :: Version -> HaddockArgs -> [[Char]]
  renderPureArgs version args = concat
      [
       (:[]) . (\f -> "--dump-interface="++ unDir (argOutputDir args) </> f)
       . fromFlag . argInterfaceFile $ args,
       (\pkgName -> if isVersion2
                    then ["--optghc=-package-name", "--optghc=" ++ pkgName]
                    else ["--package=" ++ pkgName]) . display . fromFlag . argPackageName $ args,
       (\(All b,xs) -> bool (map (("--hide=" ++). display) xs) [] b) . argHideModules $ args,
       bool ["--ignore-all-exports"] [] . getAny . argIgnoreExports $ args,
       maybe [] (\(m,e) -> ["--source-module=" ++ m
                           ,"--source-entity=" ++ e]) . flagToMaybe . argLinkSource $ args,
       maybe [] ((:[]).("--css="++)) . flagToMaybe . argCssFile $ args,
       maybe [] ((:[]).("--use-contents="++)) . flagToMaybe . argContents $ args,
       bool [] [verbosityFlag] . getAny . argVerbose $ args,
       map (\o -> case o of Hoogle -> "--hoogle"; Html -> "--html") . fromFlag . argOutput $ args,
       renderInterfaces . argInterfaces $ args,
       (:[]).("--odir="++) . unDir . argOutputDir $ args,
       (:[]).("--title="++) . (bool (++" (internal documentation)") id (getAny $ argIgnoreExports args))
                . fromFlag . argTitle $ args,
       bool id (const []) isVersion2 . map ("--optghc=" ++) . argGhcFlags $ args,
       maybe [] (\l -> ["-B"++l]) $ guard isVersion2 >> flagToMaybe (argGhcLibDir args), -- error if isVersion2 and Nothing?
       argTargets $ args
      ]
      where
        renderInterfaces = map (\(i,mh) -> "--read-interface=" ++ maybe "" (++",") mh ++ i)
        bool a b c = if c then a else b
        isVersion2 = version >= Version [2,0] []
        isVersion2_5 = version >= Version [2,5] []
        verbosityFlag
         | isVersion2_5 = "--verbosity=1"
         | otherwise = "--verbose"
  
  -----------------------------------------------------------------------------------------------------------
  
  haddockPackageFlags :: LocalBuildInfo
                      -> Maybe PathTemplate
                      -> IO ([(FilePath,Maybe FilePath)], Maybe String)
  haddockPackageFlags lbi htmlTemplate = do
    let allPkgs = installedPkgs lbi
        directDeps = map fst (externalPackageDeps lbi)
    transitiveDeps <- case dependencyClosure allPkgs directDeps of
      Left x    -> return x
      Right inf -> die $ "internal error when calculating transative "
                      ++ "package dependencies.\nDebug info: " ++ show inf
    interfaces <- sequence
      [ case interfaceAndHtmlPath ipkg of
          Nothing -> return (Left (packageId ipkg))
          Just (interface, html) -> do
            exists <- doesFileExist interface
            if exists
              then return (Right (interface, html))
              else return (Left (packageId ipkg))
      | ipkg <- PackageIndex.allPackages transitiveDeps ]
  
    let missing = [ pkgid | Left pkgid <- interfaces ]
        warning = "The documentation for the following packages are not "
               ++ "installed. No links will be generated to these packages: "
               ++ intercalate ", " (map display missing)
        flags = [ (interface, if null html then Nothing else Just html)
                | Right (interface, html) <- interfaces ]
  
    return (flags, if null missing then Nothing else Just warning)
  
    where
      interfaceAndHtmlPath :: InstalledPackageInfo -> Maybe (FilePath, FilePath)
      interfaceAndHtmlPath pkg = do
        interface <- listToMaybe (InstalledPackageInfo.haddockInterfaces pkg)
        html <- case htmlTemplate of
          Nothing -> listToMaybe (InstalledPackageInfo.haddockHTMLs pkg)
          Just htmlPathTemplate -> Just (expandTemplateVars htmlPathTemplate)
        return (interface, html)
  
        where expandTemplateVars = fromPathTemplate . substPathTemplate env
              env = haddockTemplateEnv lbi (packageId pkg)
  
  haddockTemplateEnv :: LocalBuildInfo -> PackageIdentifier -> PathTemplateEnv
  haddockTemplateEnv lbi pkg_id = (PrefixVar, prefix (installDirTemplates lbi))
                                  : initialPathTemplateEnv pkg_id (compilerId (compiler lbi))
  
  -- --------------------------------------------------------------------------
  -- hscolour support
  
  hscolour :: PackageDescription -> LocalBuildInfo -> [PPSuffixHandler] -> HscolourFlags -> IO ()
  hscolour pkg_descr lbi suffixes flags = do
    -- we preprocess even if hscolour won't be found on the machine
    -- will this upset someone?
    initialBuildSteps distPref pkg_descr lbi verbosity
    hscolour' pkg_descr lbi suffixes flags
   where
     verbosity  = fromFlag (hscolourVerbosity flags)
     distPref = fromFlag $ hscolourDistPref flags
  
  hscolour' :: PackageDescription
            -> LocalBuildInfo
            -> [PPSuffixHandler]
            -> HscolourFlags
            -> IO ()
  hscolour' pkg_descr lbi suffixes flags = do
      let distPref = fromFlag $ hscolourDistPref flags
      (hscolourProg, _, _) <-
        requireProgramVersion
          verbosity hscolourProgram
          (orLaterVersion (Version [1,8] [])) (withPrograms lbi)
  
      setupMessage verbosity "Running hscolour for" (packageId pkg_descr)
      createDirectoryIfMissingVerbose verbosity True $ hscolourPref distPref pkg_descr
  
      let pre c = preprocessComponent pkg_descr c lbi False verbosity suffixes
      withComponentsLBI pkg_descr lbi $ \comp _ -> do
        pre comp
        case comp of
          CLib lib -> do
            let outputDir = hscolourPref distPref pkg_descr </> "src"
            runHsColour hscolourProg outputDir =<< getLibSourceFiles lbi lib
          CExe exe | fromFlag (hscolourExecutables flags) -> do
            let outputDir = hscolourPref distPref pkg_descr </> exeName exe </> "src"
            runHsColour hscolourProg outputDir =<< getExeSourceFiles lbi exe
          _ -> return ()
    where
      stylesheet = flagToMaybe (hscolourCSS flags)
  
      verbosity  = fromFlag (hscolourVerbosity flags)
  
      runHsColour prog outputDir moduleFiles = do
           createDirectoryIfMissingVerbose verbosity True outputDir
  
           case stylesheet of -- copy the CSS file
             Nothing | programVersion prog >= Just (Version [1,9] []) ->
                         rawSystemProgram verbosity prog
                            ["-print-css", "-o" ++ outputDir </> "hscolour.css"]
                     | otherwise -> return ()
             Just s -> copyFileVerbose verbosity s (outputDir </> "hscolour.css")
  
           flip mapM_ moduleFiles $ \(m, inFile) ->
               rawSystemProgram verbosity prog
                      ["-css", "-anchor", "-o" ++ outFile m, inFile]
          where
            outFile m = outputDir </> intercalate "-" (ModuleName.components m) <.> "html"
  
  haddockToHscolour :: HaddockFlags -> HscolourFlags
  haddockToHscolour flags =
      HscolourFlags {
        hscolourCSS         = haddockHscolourCss flags,
        hscolourExecutables = haddockExecutables flags,
        hscolourVerbosity   = haddockVerbosity   flags,
        hscolourDistPref    = haddockDistPref    flags
      }
  ----------------------------------------------------------------------------------------------
  -- TODO these should be moved elsewhere.
  
  getLibSourceFiles :: LocalBuildInfo
                       -> Library
                       -> IO [(ModuleName.ModuleName, FilePath)]
  getLibSourceFiles lbi lib = getSourceFiles searchpaths modules
    where
      bi               = libBuildInfo lib
      modules          = PD.exposedModules lib ++ otherModules bi
      searchpaths      = autogenModulesDir lbi : buildDir lbi : hsSourceDirs bi
  
  getExeSourceFiles :: LocalBuildInfo
                       -> Executable
                       -> IO [(ModuleName.ModuleName, FilePath)]
  getExeSourceFiles lbi exe = do
      moduleFiles <- getSourceFiles searchpaths modules
      srcMainPath <- findFile (hsSourceDirs bi) (modulePath exe)
      return ((ModuleName.main, srcMainPath) : moduleFiles)
    where
      bi          = buildInfo exe
      modules     = otherModules bi
      searchpaths = autogenModulesDir lbi : exeBuildDir lbi exe : hsSourceDirs bi
  
  getSourceFiles :: [FilePath]
                    -> [ModuleName.ModuleName]
                    -> IO [(ModuleName.ModuleName, FilePath)]
  getSourceFiles dirs modules = flip mapM modules $ \m -> fmap ((,) m) $
      findFileWithExtension ["hs", "lhs"] dirs (ModuleName.toFilePath m)
        >>= maybe (notFound m) (return . normalise)
    where
      notFound module_ = die $ "can't find source for module " ++ display module_
  
  -- | The directory where we put build results for an executable
  exeBuildDir :: LocalBuildInfo -> Executable -> FilePath
  exeBuildDir lbi exe = buildDir lbi </> exeName exe </> exeName exe ++ "-tmp"
  
  ---------------------------------------------------------------------------------------------
  
  
  
  
  -- boilerplate monoid instance.
  instance Monoid HaddockArgs where
      mempty = HaddockArgs {
                  argInterfaceFile = mempty,
                  argPackageName = mempty,
                  argHideModules = mempty,
                  argIgnoreExports = mempty,
                  argLinkSource = mempty,
                  argCssFile = mempty,
                  argContents = mempty,
                  argVerbose = mempty,
                  argOutput = mempty,
                  argInterfaces = mempty,
                  argOutputDir = mempty,
                  argTitle = mempty,
                  argPrologue = mempty,
                  argGhcFlags = mempty,
                  argGhcLibDir = mempty,
                  argTargets = mempty
               }
      mappend a b = HaddockArgs {
                  argInterfaceFile = mult argInterfaceFile,
                  argPackageName = mult argPackageName,
                  argHideModules = mult argHideModules,
                  argIgnoreExports = mult argIgnoreExports,
                  argLinkSource = mult argLinkSource,
                  argCssFile = mult argCssFile,
                  argContents = mult argContents,
                  argVerbose = mult argVerbose,
                  argOutput = mult argOutput,
                  argInterfaces = mult argInterfaces,
                  argOutputDir = mult argOutputDir,
                  argTitle = mult argTitle,
                  argPrologue = mult argPrologue,
                  argGhcFlags = mult argGhcFlags,
                  argGhcLibDir = mult argGhcLibDir,
                  argTargets = mult argTargets
               }
        where mult f = f a `mappend` f b
  
  instance Monoid Directory where
      mempty = Dir "."
      mappend (Dir m) (Dir n) = Dir $ m </> n
  