-- ghc-mod: Making Haskell development *more* fun
-- Copyright (C) 2015  Daniel Gröber <dxld ÄT darkboxed DOT org>
--
-- This program is free software: you can redistribute it and/or modify
-- it under the terms of the GNU Affero General Public License as published by
-- the Free Software Foundation, either version 3 of the License, or
-- (at your option) any later version.
--
-- This program is distributed in the hope that it will be useful,
-- but WITHOUT ANY WARRANTY; without even the implied warranty of
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-- GNU Affero General Public License for more details.
--
-- You should have received a copy of the GNU Affero General Public License
-- along with this program.  If not, see <http://www.gnu.org/licenses/>.

{-# LANGUAGE CPP #-}
{-# LANGUAGE DoAndIfThenElse #-}

module Language.Haskell.GhcMod.Utils (
    module Language.Haskell.GhcMod.Utils
  , module Utils
  , readProcess
  ) where

import Control.Applicative
import Data.Char
import qualified Data.Map as M
import Data.Maybe (fromMaybe)
import Data.Either (rights)
import Data.List (inits)
import System.FilePath (joinPath, splitPath, normalise)
import Exception
import Language.Haskell.GhcMod.Error
import Language.Haskell.GhcMod.Types
import Language.Haskell.GhcMod.Monad.Types
import System.Directory (getCurrentDirectory, setCurrentDirectory, doesFileExist,
                         getTemporaryDirectory, canonicalizePath)
import System.Environment
import System.FilePath (splitDrive, takeDirectory, takeFileName, pathSeparators,
                        (</>), makeRelative)
import System.IO.Temp (createTempDirectory)
import System.Process (readProcess)
import Text.Printf

import Paths_ghc_mod (getLibexecDir)
import Utils
import Prelude

-- dropWhileEnd is not provided prior to base 4.5.0.0.
dropWhileEnd :: (a -> Bool) -> [a] -> [a]
dropWhileEnd p = foldr (\x xs -> if p x && null xs then [] else x : xs) []

withDirectory_ :: (MonadIO m, ExceptionMonad m) => FilePath -> m a -> m a
withDirectory_ dir action =
  gbracket
    (liftIO getCurrentDirectory)
    (liftIO . setCurrentDirectory)
    (\_ -> liftIO (setCurrentDirectory dir) >> action)

uniqTempDirName :: FilePath -> FilePath
uniqTempDirName dir =
  "ghc-mod" ++ map escapeDriveChar drive ++ map escapePathChar path
  where
    (drive, path) = splitDrive dir
    escapeDriveChar :: Char -> Char
    escapeDriveChar c
      | isAlphaNum c = c
      | otherwise     = '-'
    escapePathChar :: Char -> Char
    escapePathChar c
      | c `elem` pathSeparators = '-'
      | otherwise               = c

newTempDir :: FilePath -> IO FilePath
newTempDir dir =
  flip createTempDirectory (uniqTempDirName dir) =<< getTemporaryDirectory

whenM :: Monad m => m Bool -> m () -> m ()
whenM mb ma = mb >>= flip when ma

-- | Returns the path to the currently running ghc-mod executable. With ghc<7.6
-- this is a guess but >=7.6 uses 'getExecutablePath'.
ghcModExecutable :: IO FilePath
#ifndef SPEC
ghcModExecutable = do
    dir <- takeDirectory <$> getExecutablePath'
    return $ (if dir == "." then "" else dir) </> "ghc-mod"
#else
ghcModExecutable = fmap (</> "dist/build/ghc-mod/ghc-mod") getCurrentDirectory
#endif

findLibexecExe :: String -> IO FilePath
findLibexecExe "cabal-helper-wrapper" = do
  libexecdir <- getLibexecDir
  let exeName = "cabal-helper-wrapper"
      exe = libexecdir </> exeName

  exists <- doesFileExist exe

  if exists
  then return exe
  else do
    mdir <- tryFindGhcModTreeDataDir
    case mdir of
      Nothing ->
        error $ libexecNotExitsError exeName libexecdir
      Just dir ->
        return $ dir </> "dist" </> "build" </> exeName </> exeName
findLibexecExe exe = error $ "findLibexecExe: Unknown executable: " ++ exe

libexecNotExitsError :: String -> FilePath -> String
libexecNotExitsError exe dir = printf
 ( "Could not find $libexecdir/%s\n"
 ++"\n"
 ++"If you are a developer set the environment variable `ghc_mod_libexecdir'\n"
 ++"to override $libexecdir[1] the following will work in the ghc-mod tree:\n"
 ++"\n"
 ++"    $ export ghc_mod_libexecdir=$PWD/dist/build/%s\n"
 ++"\n"
 ++"[1]: %s\n"
 ++"\n"
 ++"If you don't know what I'm talking about something went wrong with your\n"
 ++"installation. Please report this problem here:\n"
 ++"\n"
 ++"    https://github.com/kazu-yamamoto/ghc-mod/issues") exe exe dir

tryFindGhcModTreeLibexecDir :: IO (Maybe FilePath)
tryFindGhcModTreeLibexecDir  = do
  exe <- getExecutablePath'
  dir <- case takeFileName exe of
    "ghc" -> getCurrentDirectory -- we're probably in ghci; try CWD
    _     -> return $ (!!4) $ iterate takeDirectory exe
  exists <- doesFileExist $ dir </> "ghc-mod.cabal"
  return $ if exists
           then Just dir
           else Nothing

tryFindGhcModTreeDataDir :: IO (Maybe FilePath)
tryFindGhcModTreeDataDir  = do
  dir <- (!!4) . iterate takeDirectory <$> getExecutablePath'
  exists <- doesFileExist $ dir </> "ghc-mod.cabal"
  return $ if exists
           then Just dir
           else Nothing

readLibExecProcess' :: (MonadIO m, ExceptionMonad m)
                    => String -> [String] -> m String
readLibExecProcess' cmd args = do
  exe <- liftIO $ findLibexecExe cmd
  liftIO $ readProcess exe args ""

getExecutablePath' :: IO FilePath
#if __GLASGOW_HASKELL__ >= 706
getExecutablePath' = getExecutablePath
#else
getExecutablePath' = getProgName
#endif

canonFilePath :: FilePath -> IO FilePath
canonFilePath f = do
  p <- canonicalizePath f
  e <- doesFileExist p
  when (not e) $ error $ "canonFilePath: not a file: " ++ p
  return p

withMappedFile :: (IOish m, GmState m, GmEnv m) =>
                  forall a. FilePath -> (FilePath -> m a) -> m a
withMappedFile file action = getCanonicalFileNameSafe file >>= lookupMMappedFile >>= runWithFile
  where
    runWithFile (Just to) = action $ fmPath to
    runWithFile _ = action file

getCanonicalFileNameSafe :: (IOish m, GmEnv m) => FilePath -> m FilePath
getCanonicalFileNameSafe fn = do
  let fn' = normalise fn
  pl <- liftIO $ rights <$> (mapM ((try :: IO FilePath -> IO (Either SomeException FilePath)) . canonicalizePath . joinPath) $ reverse $ inits $ splitPath' fn')
  return $
    if (length pl > 0)
    then joinPath $ (head pl):(drop (length pl - 1) (splitPath fn'))
    else error "Current dir doesn't seem to exist?"
  where
#if __GLASGOW_HASKELL__ < 710
    splitPath' = (".":) . splitPath
#else
    splitPath' = splitPath
#endif

mkRevRedirMapFunc :: (Functor m, GmState m, GmEnv m) => m (FilePath -> FilePath)
mkRevRedirMapFunc = do
  rm <- M.fromList <$> map (uncurry mf) <$> M.toList <$> getMMappedFiles
  crdl <- cradle
  return $ \key ->
    fromMaybe key
    $ makeRelative (cradleRootDir crdl)
    <$> M.lookup key rm
  where
    mf :: FilePath -> FileMapping -> (FilePath, FilePath)
    mf from to = (fmPath to, from)