import Data.Version
import Control.Exception
import System.Cmd
import System.IO
import System.Exit
import System.Directory
import Distribution.Setup
import Distribution.Simple
import Distribution.Simple.Utils
import Distribution.Simple.LocalBuildInfo
import Distribution.PackageDescription


main = do
  descFile <- defaultPackageDesc
  desc <- readPackageDescription descFile
  let ver = (pkgVersion (package desc))
  defaultMainWithHooks (mkHooks desc ver)

mkHooks :: PackageDescription
        -> Version
        -> UserHooks
mkHooks desc ver = 
  defaultUserHooks
  { readDesc  = return (Just desc)
  , postConf  = doPostConf ver
  , postBuild = createTemplates
  , postClean = cleanDerivedFiles
  }


templateFiles :: [String]
templateFiles =
  [ "HappyTemplate"
  , "HappyTemplate-ghc"
  , "HappyTemplate-coerce"
  , "HappyTemplate-arrays"
  , "HappyTemplate-arrays-ghc"
  , "HappyTemplate-arrays-coerce"
  , "HappyTemplate-arrays-debug"
  , "HappyTemplate-arrays-ghc-debug"
  , "HappyTemplate-arrays-coerce-debug"
  , "GLR_Base"
  , "GLR_Lib"
  , "GLR_Lib-ghc"
  , "GLR_Lib-ghc-debug"
  ]


cleanDerivedFiles :: Args
                  -> Int
                  -> LocalBuildInfo
                  -> IO ExitCode
cleanDerivedFiles args _ buildInfo = do
  sequence_ $ map (delFile . (\x -> "templates/"++x++".hspp")) $ templateFiles
  sequence_ $ map (delFile . (\x -> "templates/"++x)) $ templateFiles
  removeFile "src/Version.hs"
  return ExitSuccess
 where delFile path = try (removeFile path) >> return ()


doPostConf :: Version
           -> Args 
           -> ConfigFlags
           -> LocalBuildInfo 
           -> IO ExitCode

doPostConf version args flags buildInfo = do
  case (compilerFlavor (compiler buildInfo)) of
     GHC -> do
       createVersionModule version
       return ExitSuccess

     _ -> do
       putStrLn "Currently only GHC is supported as a build platform for Happy"
       return (ExitFailure 1)


createVersionModule :: Version -> IO ()
createVersionModule version = do
  h <- openFile "src/Version.hs" WriteMode
  hPutStr h "module Version where\n"
  hPutStr h ("version = \""++(showVersion version)++"\"")
  hClose h


createTemplates :: Args
                -> Int
                -> LocalBuildInfo
                -> IO ExitCode
createTemplates args _ buildInfo = do
  putStrLn "building parser templates..."

  pwd <- getCurrentDirectory
  setCurrentDirectory (pwd++"/templates")

  defaultTemplate "HappyTemplate" []
  defaultTemplate "HappyTemplate-ghc" [ghcOpt]
  defaultTemplate "HappyTemplate-coerce" [ghcOpt,coerceOpt]
  defaultTemplate "HappyTemplate-arrays" [arrayOpt]
  defaultTemplate "HappyTemplate-arrays-ghc" [ghcOpt,arrayOpt]
  defaultTemplate "HappyTemplate-arrays-coerce" [ghcOpt,arrayOpt,coerceOpt]
  defaultTemplate "HappyTemplate-arrays-debug" [arrayOpt,debugOpt]
  defaultTemplate "HappyTemplate-arrays-ghc-debug" [arrayOpt,ghcOpt,debugOpt]
  defaultTemplate "HappyTemplate-arrays-coerce-debug" [ghcOpt,arrayOpt,coerceOpt,debugOpt]
  runCpp "GLR_Base" [] "GLR_Base.lhs"
  glrTemplate "GLR_Lib" []
  glrTemplate "GLR_Lib-ghc" [ghcOpt]
  glrTemplate "GLR_Lib-ghc-debug" [ghcOpt,debugOpt]

  setCurrentDirectory pwd
  return ExitSuccess

 where ghc = compilerPath (compiler buildInfo)
       ghcOpt    = "-DHAPPY_GHC"
       coerceOpt = "-DHAPPY_COERCE"
       arrayOpt  = "-DHAPPY_ARRAY"
       debugOpt  = "-DHAPPY_DEBUG"
       cppArgs = 
          if (compilerVersion (compiler buildInfo)) >= Version{ versionBranch = [4,11,4], versionTags = [] }
            then ["-E","-cpp","-o"]
            else ["-E","-cpp",">"]

       perlRE = "s/^#\\s+(\\d+)\\s+(\\\"[^\\\"]*\\\")/{-# LINE \\1 \\2 #-}/g;s/\\$$(Id:.*)\\$$/\\1/g"

       runCpp file args template = do
           rawSystem ghc (concat [cppArgs,[file],args,[template]])
	   rawSystem "perl" ["-pi.hspp","-e",perlRE,file]

       defaultTemplate file args = runCpp file args "GenericTemplate.hs"
       glrTemplate file args     = runCpp file args "GLR_Lib.lhs"