#!/usr/bin/env runhaskell
\begin{code}
{-# OPTIONS -Wall -cpp #-}

import Control.Monad
import Data.List
import Distribution.PackageDescription
import Distribution.Simple
import Distribution.Simple.LocalBuildInfo
import Distribution.Simple.Utils
import Distribution.Simple.Setup
import System.Cmd
import System.FilePath
import System.Console.GetOpt
import System.Exit
import System.Directory
import Control.Exception

main :: IO ()
main = do
   let hooks = simpleUserHooks {
                 preConf   = generateConfigHs
            }
   defaultMainWithHooks hooks
\end{code}


\begin{code}

data CoreLinkerFlag = TopDir FilePath | PkgConf FilePath
  deriving (Eq, Show)

coreLinkerOptions :: [OptDescr CoreLinkerFlag]
coreLinkerOptions = 
  [Option [] ["topdir"] (ReqArg TopDir "DIRECTORY")
     ("Directory d that contains the library files for your stage 2 GHC build.\n"
      ++ "In an inplace build of GHC, this will be inplace_datadir inside your\n"
      ++ "top-level GHC build tree."),
   Option [] ["pkgconf"] (ReqArg PkgConf "FILEPATH")
     ("Location of the package.conf file pointing to your packages for the GHC\n"
     ++ "standard libraries that you've built ext-core for. If you built your\n"
     ++ "External Core libraries under $GHC, this file should live in $GHC/inplace-datadir/package.conf.")]

getDirs :: [CoreLinkerFlag] -> Maybe (FilePath, FilePath)
getDirs args = case findTopDir args of
  Just (TopDir f) -> case findPkgConf args of
              Just (PkgConf f1) -> Just (f,f1)
              _ -> Nothing
  _ -> Nothing

findTopDir, findPkgConf :: [CoreLinkerFlag] -> Maybe CoreLinkerFlag
findTopDir  = find isTopDir
findPkgConf = find isPkgConf

isTopDir, isPkgConf :: CoreLinkerFlag -> Bool
isTopDir (TopDir _) = True
isTopDir _          = False
isPkgConf (PkgConf _) = True
isPkgConf _ = False

generateConfigHs :: Args -> ConfigFlags -> IO HookedBuildInfo
generateConfigHs _ confFlags = do
  let userConfigArgs = configConfigureArgs confFlags
  case getOpt Permute coreLinkerOptions userConfigArgs of
    (opts,_,_) -> case getDirs opts of
                    Just (topDir,pkgConf) -> writeConfigHs topDir pkgConf
                    Nothing -> error "To build the Core linker, you must supply a top-level directory containing your stage 2 GHC build, as well as the location of your packageconf file. For example: --configure-option=--topdir=your_ghc_build/inplace-datadir/ --configure-option=--pkgconf=your_stage1_ghc_build/inplace-datadir/package.conf"
  return emptyHookedBuildInfo

writeConfigHs :: FilePath -> FilePath -> IO ()
writeConfigHs topDir pkgConf = writeFile "Config.hs" 
  ("module Config where\nimport System.FilePath\nghcTopDir::FilePath\nghcTopDir =\""
   ++ topDir ++ "\"\npkgConf::FilePath\npkgConf=\"" ++ pkgConf ++ "\"\n")

type Hook a = PackageDescription -> LocalBuildInfo -> UserHooks -> a -> IO ()


-- Hack: If PrimEnv.hs exists *and* genprimopcode or
-- primops.txt doesn't exist, don't rebuild PrimEnv.hs

build_primitive_sources :: Hook a -> Hook a
build_primitive_sources f pd lbi uhs x
 = do when (compilerFlavor (compiler lbi) == GHC) $ do
          let genprimopcode = joinPath ["..", "..", "utils",
                                        "genprimopcode", "genprimopcode"]
              primops = joinPath ["..", "..", "compiler", "prelude",
                                  "primops.txt"]
              primhs = joinPath ["Language", "Core", "PrimEnv.hs"]
              primhs_tmp = addExtension primhs "tmp"
          primEnvExists <- doesFileExist primhs
          genprimopcodeExists <- doesFileExist genprimopcode
          primopsExists <- doesFileExist primops
          unless (primEnvExists && not genprimopcodeExists && not primopsExists) $ do
             maybeExit $ system (genprimopcode ++ " --make-ext-core-source < "
                           ++ primops ++ " > " ++ primhs_tmp)
             maybeUpdateFile primhs_tmp primhs
             maybeExit $ system ("make -C lib/GHC_ExtCore")
      f pd lbi uhs x

-- Replace a file only if the new version is different from the old.
-- This prevents make from doing unnecessary work after we run 'setup makefile'
maybeUpdateFile :: FilePath -> FilePath -> IO ()
maybeUpdateFile source target = do
  r <- rawSystem "cmp" ["-s" {-quiet-}, source, target]
  case r of
    ExitSuccess   -> removeFile source
    ExitFailure _ -> do 
#if __GLASGOW_HASKELL__ >= 610
      (try :: IO () -> IO (Either IOException ()))
#else
      try
#endif 
       (removeFile target)
      renameFile source target
\end{code}