-- Choose feature sets based on Cabal version
#if CABAL_MAJOR == 1
# if CABAL_MINOR <= 14
#  define OLD_GHC_OPTIONS
#  define OLD_LBI_COMPONENTS
# elif CABAL_MINOR <= 16
#  define NEW_GHC_OPTIONS
#  define OLD_LBI_COMPONENTS
# else
#  if CABAL_MINOR > 18
#   warning "Building with an unrecognized version of Cabal"
#  endif
#  define NEW_GHC_OPTIONS
#  define NEW_LBI_COMPONENTS
#  error "Unsupported Cabal version"
# endif
#else
# error "Unsupported Cabal version"
#endif
    

import Control.Applicative
import Control.Exception(IOException, catch, bracket)
import Control.Monad
import Data.Char
import Data.Maybe
import Distribution.PackageDescription
import Distribution.Simple
import Distribution.Simple.Build
import Distribution.Simple.BuildPaths
import Distribution.Simple.GHC
import Distribution.Simple.LocalBuildInfo
import Distribution.Simple.PreProcess
import Distribution.Simple.Program
#ifdef NEW_GHC_OPTIONS
import Distribution.Simple.Program.GHC
#endif
import Distribution.Simple.Setup
import Distribution.Simple.Utils
import qualified Distribution.Verbosity as Verbosity
import System.Cmd
import System.Directory
import System.Exit(ExitCode(..))
import System.IO
import System.FilePath((</>), (<.>), takeExtension, takeDirectory)
import System.Process

-- Recover from IO exceptions
recover :: IO a -> IO a -> IO a
f `recover` h = f `Control.Exception.catch` handler
  where
    handler e = let _ = e :: IOException
                in h

-------------------------------------------------------------------------------
-- Filenames and constants

-- Record whether we're building the Omega library here
useInstalledOmegaFlagPath = "build" </> "UseInstalledOmega"

-- We will call 'autoconf' and 'make'
autoconfProgram = simpleProgram "autoconf"
makeProgram = simpleProgram "make"

-- Our single C++ source file and corresponding object file are here
cppSourceName = "src" </> "C_omega.cc"
cppObjectName = "build" </> "C_omega.o"

-- If we're building the Omega library, it's here
omegaLibPath = "src" </> "the-omega-project" </> "omega_lib" </> "obj" </> "libomega.a"

-- Unpack the Omega library into this directory
omegaUnpackPath = "build" </> "unpack_omega"

-- Path where Cabal builds files
cabalBuildPath = "dist" </> "build"

-- Main test file
testSourceName = "test" </> "runtests.hs"

-- Extra files produced by configuration
configFiles = ["configure", "config.log", "config.status", "Makefile",
               useInstalledOmegaFlagPath]

-------------------------------------------------------------------------------
-- Helpful IO procedures

noGHCiLib =
    die $ "Sorry, this package does not support GHCi.\n" ++
          "Please configure with --disable-library-for-ghci to disable."

noSharedLib =
    die $ "Sorry, this package does not support shared library output.\n" ++
          "Please configure with --disable-shared to disable."

writeUseInstalledOmegaFlag :: Bool -> IO ()
writeUseInstalledOmegaFlag b = do
  createDirectoryIfMissing False "build"
  writeFile useInstalledOmegaFlagPath (show b)

readUseInstalledOmegaFlag :: IO Bool
readUseInstalledOmegaFlag = do
  text <- readFile useInstalledOmegaFlagPath `recover`
          die "Configuration file missing; try reconfiguring"
  return $! read text

-- Attempt to remove a file, ignoring errors
lenientRemoveFile f = removeFile f `recover` return ()

lenientRemoveFiles = mapM_ lenientRemoveFile

-- Attempt to remove a directory and its contents
-- (one level of recursion only), ignoring errors
lenientRemoveDirectory f = do
  b <- doesDirectoryExist f
  when b $ do lenientRemoveFiles . map (f </>) =<< getDirectoryContents f
              removeDirectory f `recover` return ()

-------------------------------------------------------------------------------
-- Configuration

configureOmega pkgDesc originalFlags = do
  -- Disable unsupported configuratoins
  when (flagToMaybe (configGHCiLib originalFlags) == Just True) $
       notice verbosity $ "** Sorry, this package does not support GHCi.\n" ++
                          "** Disabling GHCi library output."

  when (flagToMaybe (configSharedLib originalFlags) == Just True) $
       notice verbosity $ "** Sorry, this package does not support " ++
                             "shared library output.\n" ++
                          "** Disabling shared library output."

  -- Run Cabal configuration
  lbi <- confHook simpleUserHooks pkgDesc flags

  -- Run autoconf configuration
  runAutoconf lbi
  runConfigure lbi

  -- Save this flag for later use
  writeUseInstalledOmegaFlag useInstalledOmega

  return lbi
    where
      verbosity = fromFlagOrDefault Verbosity.normal $ configVerbosity flags
      flags = originalFlags { configSharedLib = toFlag False
                            , configGHCiLib = toFlag False
                            }

      -- Will build the Omega library?
      useInstalledOmega = fromMaybe False $
                          lookup (FlagName "useinstalledomega") $
                          configConfigurationsFlags flags

      -- Configure programs
      runAutoconf lbi = do
        runDbProgram verbosity autoconfProgram (withPrograms lbi) []

      -- Run 'configure' with the extra arguments that were passed to
      -- Setup.hs
      runConfigure lbi = do
        currentDir <- getCurrentDirectory

        let opts = autoConfigureOptions lbi useInstalledOmega
            configProgramName = currentDir </> "configure"

        rawSystemExit verbosity configProgramName opts

-- Configuration: extract options to pass to 'configure'
autoConfigureOptions :: LocalBuildInfo -> Bool -> [String]
autoConfigureOptions localBuildInfo useInstalledOmega =
    withOmega ++ [libdirs, includedirs]
    where
      withOmega = if useInstalledOmega
                  then ["--with-omega"]
                  else []

      libraryDescr = case library $ localPkgDescr localBuildInfo
                     of Nothing -> error "Library description is missing"
                        Just l -> l

      buildinfo = libBuildInfo libraryDescr

      -- Create a string "-L/usr/foo -L/usr/bar"
      ldflagsString =
          intercalate " " ["-L" ++ dir | dir <- extraLibDirs buildinfo]

      libdirs = "LDFLAGS=" ++ ldflagsString

      -- Create a string "-I/usr/foo -I/usr/bar"
      cppflagsString =
          intercalate " " ["-I" ++ dir | dir <- includeDirs buildinfo]

      includedirs = "CPPFLAGS=" ++ cppflagsString

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

buildOmega pkgDesc lbi userhooks flags = do

  let verb = fromFlagOrDefault Verbosity.normal $ buildVerbosity flags
  useInstalledOmega <- readUseInstalledOmegaFlag

  -- Build the C++ source file (and Omega library, if configured)
  -- Makefile's behavior is controlled by output of 'configure'
  runDbProgram verb makeProgram (withPrograms lbi) ["all"]

  -- Custom build procedure for test suite
  buildTestSuites useInstalledOmega pkgDesc lbi flags

  -- Default build procedure for hs files in library
  -- Tests are already built, so they won't be built again
  buildHook simpleUserHooks pkgDesc (hideTestComponents lbi) userhooks flags

  -- Get 'ar' and 'ld' programs
  let runAr = runDbProgram verb arProgram (withPrograms lbi)

  -- Add other object files to libraries
  let pkgId   = package $ localPkgDescr lbi

  let -- Add extra files into an archive file
      addStaticObjectFiles libName = do
          -- Add the C++ interface file
          addStaticObjectFile cppObjectName libName

          -- Add contents of libomega.a
          unless useInstalledOmega $
              transferArFiles verb runAr omegaLibPath libName

          where
            addStaticObjectFile objName libName =
                runAr ["r", libName, objName]

  when (withVanillaLib lbi) $
       let libName = buildDir lbi </> mkLibName pkgId
       in addStaticObjectFiles libName

  when (withProfLib lbi) $
       let libName = buildDir lbi </> mkProfLibName pkgId
       in addStaticObjectFiles libName

  when (withGHCiLib lbi) noGHCiLib
  when (withSharedLib lbi) noSharedLib

  return ()

-- | Hide the test suite so Cabal doesn't try to use its default build 
--   procedure with it.
hideTestComponents :: LocalBuildInfo -> LocalBuildInfo

hideTestComponents lbi =
#if defined(OLD_LBI_COMPONENTS)
  lbi {compBuildOrder = filter (not . isTestComponent) $ compBuildOrder lbi
      , testSuiteConfigs = []}
#elif defined(NEW_LBI_COMPONENTS)
  lbi {componentsConfigs = mapMaybe removeTests $ componentsConfigs lbi}
  where
    removeTests (cname, clbi, deps)
      | isTestComponent cname = Nothing
      | otherwise = Just (cname, clbi, filter (not . isTestComponent) deps)
#else
#error
#endif

isTestComponent :: ComponentName -> Bool
isTestComponent (CTestName {}) = True
isTestComponent _              = False

-- | Get command line options for invoking GHC
genericGhcOptions :: Version -> Verbosity.Verbosity -> LocalBuildInfo
                  -> BuildInfo -> ComponentLocalBuildInfo -> FilePath
                  -> [String]

genericGhcOptions ver verb lbi bi clbi build_path =
#if defined(OLD_GHC_OPTIONS)
  ghcOptions lbi bi clbi cabalBuildPath
#elif defined(NEW_GHC_OPTIONS)
  renderGhcOptions ver $ componentGhcOptions verb lbi bi clbi cabalBuildPath
#else
#error
#endif

buildTestSuites useInstalledOmega pkgDesc lbi flags =
  withTestLBI pkgDesc lbi $ \test clbi -> do
    let verb = fromFlagOrDefault Verbosity.normal $ buildVerbosity flags

    -- Run preprocessors
    writeAutogenFiles verb pkgDesc lbi
    preprocessComponent pkgDesc (CTest test) lbi False verb knownSuffixHandlers

    -- Run compiler
    (ghcProg, ghcVersion) <- configureGHC verb lbi

    let bi = testBuildInfo test
        opts = genericGhcOptions ghcVersion verb lbi bi clbi cabalBuildPath

        build_opts = ["--make", "-o",
                      cabalBuildPath </> testName test </> testName test]

        -- If building Omega library locally, link to the local archive
        local_link_opt = if useInstalledOmega
                         then []
                         else ["-L" ++ takeDirectory omegaLibPath]

        input_opts = [testSourceName, -- Source file
                      cppObjectName,  -- Compiled C++ file
                      "-lomega",      -- Omega library
                      "-lstdc++"      -- C++ libarry
                     ]
        all_opts = build_opts ++ opts ++ local_link_opt ++ input_opts

    createDirectoryIfMissing True (cabalBuildPath </> testName test)
    runProgram verb ghcProg all_opts

configureGHC verb lbi = do
  (ghcProg, _) <- requireProgram verb ghcProgram (withPrograms lbi)
  ghcVersion <- case programVersion ghcProg
                of Just x  -> return x
                   Nothing -> die "Can't determine GHC vesion"
  return (ghcProg, ghcVersion)

-- Transfer the contents of one archive to another
transferArFiles verb runAr src dst = do
  srcCan <- canonicalizePath src
  dstCan <- canonicalizePath dst

  -- Create/remove a temporary directory
  bracket createUnpackDirectory (\_ -> removeUnpackDirectory) $ \_ ->

    -- Save/restore the current working directory
    bracket getCurrentDirectory setCurrentDirectory $ \_ -> do

      -- Go to temporary directory
      setCurrentDirectory omegaUnpackPath

      -- Unpack source archive
      runAr ["x", srcCan]

      -- Find object files
      objs <- liftM (filter isObjectFile) $ getDirectoryContents "."
      when (null objs) $ warn verb "No object files found in Omega library; build may be incomplete"

      -- Insert into destination archive
      runAr (["r", dstCan] ++ objs)
    where
      isObjectFile f = takeExtension f == ".o"

      createUnpackDirectory = createDirectoryIfMissing True omegaUnpackPath
      removeUnpackDirectory = removeDirectoryRecursive omegaUnpackPath

-------------------------------------------------------------------------------
-- Cleaning

cleanOmega pkgDesc mlbi userhooks flags = do
  let verb = fromFlagOrDefault Verbosity.normal $ cleanVerbosity flags

  -- run 'make clean', which will clean the Omega library if appropriate
  pgmConf <- configureProgram verb makeProgram defaultProgramConfiguration
  makeExists <- doesFileExist "Makefile"
  when makeExists $
    runDbProgram verb makeProgram pgmConf ["clean"]

  -- Clean extra files if we don't need to save configuration
  -- (Other temp files are automatically cleaned)
  unless (fromFlag $ cleanSaveConf flags) $ do
    lenientRemoveFiles configFiles
    lenientRemoveDirectory "autom4te.cache"

  -- Do default clean procedure
  cleanHook simpleUserHooks pkgDesc mlbi userhooks flags

-------------------------------------------------------------------------------
-- Hooks

hooks =
    simpleUserHooks
    { hookedPrograms = [arProgram, autoconfProgram, makeProgram]
    , confHook = configureOmega
    , buildHook = buildOmega
    , cleanHook = cleanOmega
    }

main = defaultMainWithHooks hooks