{-# LANGUAGE MultiParamTypeClasses, GeneralizedNewtypeDeriving, ScopedTypeVariables, DeriveDataTypeable, RecordWildCards #-}

module Development.Shake.Directory(
    doesFileExist, doesDirectoryExist,
    getDirectoryContents, getDirectoryFiles, getDirectoryDirs,
    defaultRuleDirectory
    ) where

import Control.Monad
import Control.Monad.IO.Class
import Data.Binary
import Data.List
import qualified System.Directory as IO

import Development.Shake.Core
import Development.Shake.Classes
import Development.Shake.FilePath
import Development.Shake.FilePattern


newtype DoesFileExistQ = DoesFileExistQ FilePath
    deriving (Typeable,Eq,Hashable,Binary,NFData)

instance Show DoesFileExistQ where
    show (DoesFileExistQ a) = "Exists? " ++ a

newtype DoesFileExistA = DoesFileExistA Bool
    deriving (Typeable,Eq,Hashable,Binary,NFData)

instance Show DoesFileExistA where
    show (DoesFileExistA a) = show a


newtype DoesDirectoryExistQ = DoesDirectoryExistQ FilePath
    deriving (Typeable,Eq,Hashable,Binary,NFData)

instance Show DoesDirectoryExistQ where
    show (DoesDirectoryExistQ a) = "Exists dir? " ++ a

newtype DoesDirectoryExistA = DoesDirectoryExistA Bool
    deriving (Typeable,Eq,Hashable,Binary,NFData)

instance Show DoesDirectoryExistA where
    show (DoesDirectoryExistA a) = show a


data GetDirectoryQ
    = GetDir {dir :: FilePath}
    | GetDirFiles {dir :: FilePath, pat :: [FilePattern]}
    | GetDirDirs {dir :: FilePath}
    deriving (Typeable,Eq)
newtype GetDirectoryA = GetDirectoryA [FilePath]
    deriving (Typeable,Show,Eq,Hashable,Binary,NFData)

instance Show GetDirectoryQ where
    show (GetDir x) = "Listing " ++ x
    show (GetDirFiles a b) = "Files " ++ a </> ['{'|m] ++ unwords b ++ ['}'|m]
        where m = length b > 1
    show (GetDirDirs x) = "Dirs " ++ x

instance NFData GetDirectoryQ where
    rnf (GetDir a) = rnf a
    rnf (GetDirFiles a b) = rnf a `seq` rnf b
    rnf (GetDirDirs a) = rnf a

instance Hashable GetDirectoryQ where
    hashWithSalt salt = hashWithSalt salt . f
        where f (GetDir x) = (0 :: Int, x, [])
              f (GetDirFiles x y) = (1, x, y)
              f (GetDirDirs x) = (2, x, [])

instance Binary GetDirectoryQ where
    get = do
        i <- getWord8
        case i of
            0 -> liftM  GetDir get
            1 -> liftM2 GetDirFiles get get
            2 -> liftM  GetDirDirs get

    put (GetDir x) = putWord8 0 >> put x
    put (GetDirFiles x y) = putWord8 1 >> put x >> put y
    put (GetDirDirs x) = putWord8 2 >> put x


instance Rule DoesFileExistQ DoesFileExistA where
    storedValue (DoesFileExistQ x) = fmap (Just . DoesFileExistA) $ IO.doesFileExist x
    -- invariant _ = True

instance Rule DoesDirectoryExistQ DoesDirectoryExistA where
    storedValue (DoesDirectoryExistQ x) = fmap (Just . DoesDirectoryExistA) $ IO.doesDirectoryExist x
    -- invariant _ = True

instance Rule GetDirectoryQ GetDirectoryA where
    storedValue x = fmap Just $ getDir x
    -- invariant _ = True


-- | This function is not actually exported, but Haddock is buggy. Please ignore.
defaultRuleDirectory :: Rules ()
defaultRuleDirectory = do
    defaultRule $ \(DoesFileExistQ x) -> Just $
        liftIO $ fmap DoesFileExistA $ IO.doesFileExist x
    defaultRule $ \(DoesDirectoryExistQ x) -> Just $
        liftIO $ fmap DoesDirectoryExistA $ IO.doesDirectoryExist x
    defaultRule $ \(x :: GetDirectoryQ) -> Just $
        liftIO $ getDir x


-- | Returns 'True' if the file exists.
doesFileExist :: FilePath -> Action Bool
doesFileExist file = do
    DoesFileExistA res <- apply1 $ DoesFileExistQ file
    return res

-- | Returns 'True' if the directory exists.
doesDirectoryExist :: FilePath -> Action Bool
doesDirectoryExist file = do
    DoesDirectoryExistA res <- apply1 $ DoesDirectoryExistQ file
    return res

-- | Get the contents of a directory. The result will be sorted, and will not contain
--   the entries @.@ or @..@ (unlike the standard Haskell version). The resulting paths will be relative
--   to the first argument.
--
--   It is usually simpler to call either 'getDirectoryFiles' or 'getDirectoryDirs'.
getDirectoryContents :: FilePath -> Action [FilePath]
getDirectoryContents x = getDirAction $ GetDir x

-- | Get the files anywhere under a directory that match any of a set of patterns.
--   For the interpretation of the patterns see '?=='. All results will be
--   relative to the 'FilePath' argument. Some examples:
--
-- > getDirectoryFiles "Config" ["//*.xml"]
-- >     -- All .xml files anywhere under the Config directory
-- >     -- If Config/foo/bar.xml exists it will return ["foo/bar.xml"]
-- > getDirectoryFiles "Modules" ["*.hs","*.lhs"]
-- >     -- All .hs or .lhs in the Modules directory
-- >     -- If Modules/foo.hs and Modules/foo.lhs exist, it will return ["foo.hs","foo.lhs"]
getDirectoryFiles :: FilePath -> [FilePattern] -> Action [FilePath]
getDirectoryFiles x f = getDirAction $ GetDirFiles x f

-- | Get the directories in a directory, not including @.@ or @..@.
--   All directories are relative to the argument directory.
--
-- > getDirectoryDirs "/Users"
-- >    -- Return all directories in the /Users directory
-- >    -- e.g. ["Emily","Henry","Neil"]
getDirectoryDirs :: FilePath -> Action [FilePath]
getDirectoryDirs x = getDirAction $ GetDirDirs x

getDirAction x = do GetDirectoryA y <- apply1 x; return y

contents :: FilePath -> IO [FilePath]
contents = fmap (filter $ not . all (== '.')) . IO.getDirectoryContents


answer :: [FilePath] -> GetDirectoryA
answer = GetDirectoryA . sort

getDir :: GetDirectoryQ -> IO GetDirectoryA
getDir GetDir{..} = fmap answer $ contents dir

getDir GetDirDirs{..} = fmap answer $ filterM f =<< contents dir
    where f x = IO.doesDirectoryExist $ dir </> x

getDir GetDirFiles{..} = fmap answer $ concatMapM f $ directories pat
    where
        test = let ps = map (?==) pat in \x -> any ($ x) ps

        f (dir2,False) = do
            xs <- fmap (map (dir2 </>)) $ contents $ dir </> dir2
            flip filterM xs $ \x -> if not $ test x then return False else IO.doesFileExist $ dir </> x

        f (dir2,True) = do
            xs <- fmap (map (dir2 </>)) $ contents $ dir </> dir2
            (files,dirs) <- partitionM (\x -> IO.doesFileExist $ dir </> x) xs
            rest <- concatMapM (\d -> f (d, True)) dirs
            return $ filter test files ++ rest


concatMapM f xs = fmap concat $ mapM f xs

partitionM f [] = return ([], [])
partitionM f (x:xs) = do
    t <- f x
    (a,b) <- partitionM f xs
    return $ if t then (x:a,b) else (a,x:b)