module GHCApi (
    withGHC
  , withGHCDummyFile
  , initializeFlags
  , initializeFlagsWithCradle
  , setTargetFile
  , getDynamicFlags
  , getFastCheck
  ) where

import CabalApi
import Control.Applicative
import Control.Exception
import Control.Monad
import CoreMonad
import Data.Maybe (isJust)
import DynFlags
import ErrMsg
import Exception
import GHC
import GHC.Paths (libdir)
import HeaderInfo
import System.Exit
import System.IO
import Types

----------------------------------------------------------------

withGHCDummyFile :: Alternative m => Ghc (m a) -> IO (m a)
withGHCDummyFile = withGHC "Dummy"

withGHC :: Alternative m => FilePath -> Ghc (m a) -> IO (m a)
withGHC file body = ghandle ignore $ runGhc (Just libdir) $ do
    dflags <- getSessionDynFlags
    defaultCleanupHandler dflags body
  where
    ignore :: Alternative m => SomeException -> IO (m a)
    ignore e = do
        hPutStr stderr $ file ++ ":0:0:Error:"
        hPrint stderr e
        exitSuccess

----------------------------------------------------------------

importDirs :: [IncludeDir]
importDirs = [".","..","../..","../../..","../../../..","../../../../.."]

initializeFlagsWithCradle :: Options -> Cradle -> FilePath -> [GHCOption] -> Bool -> Ghc LogReader
initializeFlagsWithCradle opt cradle fileName ghcOptions logging
  | cabal     = do
      (gopts,idirs,depPkgs,hdrExts) <- liftIO $ fromCabalFile ghcOptions cradle
      initSession opt gopts idirs (Just depPkgs) (Just hdrExts) logging fileName
  | otherwise =
      initSession opt ghcOptions importDirs Nothing Nothing logging fileName
  where
    cabal = isJust $ cradleCabalFile cradle

----------------------------------------------------------------

initSession :: Options
            -> [GHCOption]
            -> [IncludeDir]
            -> Maybe [Package]
            -> Maybe [LangExt]
            -> Bool
            -> FilePath
            -> Ghc LogReader
initSession opt cmdOpts idirs mDepPkgs mLangExts logging file = do
    dflags0 <- getSessionDynFlags
    (dflags1,readLog) <- setupDynamicFlags dflags0
    _ <- setSessionDynFlags dflags1
    return readLog
  where
    setupDynamicFlags df0 = do
        df1 <- modifyFlagsWithOpts df0 cmdOpts
        fast <- liftIO $ getFastCheck df0 file mLangExts
        let df2 = modifyFlags df1 idirs mDepPkgs fast (expandSplice opt)
        df3 <- modifyFlagsWithOpts df2 $ ghcOpts opt
        liftIO $ setLogger logging df3

----------------------------------------------------------------

initializeFlags :: Options -> Ghc ()
initializeFlags opt = do
    dflags0 <- getSessionDynFlags
    dflags1 <- modifyFlagsWithOpts dflags0 $ ghcOpts opt
    void $ setSessionDynFlags dflags1

----------------------------------------------------------------

getHeaderExtension :: DynFlags -> FilePath -> IO [HeaderExt]
getHeaderExtension dflags file = map unLoc <$> getOptionsFromFile dflags file

----------------------------------------------------------------

getFastCheck :: DynFlags -> FilePath -> Maybe [LangExt] -> IO Bool
getFastCheck dflags file mLangExts = do
    hdrExts <- getHeaderExtension dflags file
    return . not $ useTemplateHaskell mLangExts hdrExts

useTemplateHaskell :: Maybe [LangExt] -> [HeaderExt] -> Bool
useTemplateHaskell mLangExts hdrExts = th1 || th2
  where
    th1 = "-XTemplateHaskell" `elem` hdrExts
    th2 = maybe False ("TemplateHaskell" `elem`) mLangExts

----------------------------------------------------------------

-- FIXME removing Options
modifyFlags :: DynFlags -> [IncludeDir] -> Maybe [Package] -> Bool -> Bool -> DynFlags
modifyFlags d0 idirs mDepPkgs fast splice
  | splice    = setSplice d3
  | otherwise = d3
  where
    d1 = d0 { importPaths = idirs }
    d2 = setFastOrNot d1 fast
    d3 = maybe d2 (addDevPkgs d2) mDepPkgs

setSplice :: DynFlags -> DynFlags
setSplice dflag = dopt_set dflag Opt_D_dump_splices

setFastOrNot :: DynFlags -> Bool -> DynFlags
setFastOrNot dflags False = dflags {
    ghcLink   = LinkInMemory
  , hscTarget = HscInterpreted
  }
setFastOrNot dflags True = dflags {
    ghcLink   = NoLink
  , hscTarget = HscNothing
  }

addDevPkgs :: DynFlags -> [Package] -> DynFlags
addDevPkgs df pkgs = df''
  where
    df' = dopt_set df Opt_HideAllPackages
    df'' = df' {
        packageFlags = map ExposePackage pkgs ++ packageFlags df
      }

----------------------------------------------------------------

modifyFlagsWithOpts :: DynFlags -> [String] -> Ghc DynFlags
modifyFlagsWithOpts dflags cmdOpts =
    tfst <$> parseDynamicFlags dflags (map noLoc cmdOpts)
  where
    tfst (a,_,_) = a

----------------------------------------------------------------

setTargetFile :: (GhcMonad m) => String -> m ()
setTargetFile file = do
    target <- guessTarget file Nothing
    setTargets [target]

----------------------------------------------------------------

getDynamicFlags :: IO DynFlags
getDynamicFlags = runGhc (Just libdir) getSessionDynFlags