{-# LANGUAGE RankNTypes #-}

module Data.Conduit.Filesystem

    ( sourceDirectory

    , sourceDirectoryDeep

    ) where

import Data.Conduit

import Control.Monad.Trans.Resource (MonadResource)

import Control.Monad.IO.Class (liftIO)

import System.FilePath (())

import qualified Data.Streaming.Filesystem as F

-- | Stream the contents of the given directory, without traversing deeply.

--

-- This function will return /all/ of the contents of the directory, whether

-- they be files, directories, etc.

--

-- Note that the generated filepaths will be the complete path, not just the

-- filename. In other words, if you have a directory @foo@ containing files

-- @bar@ and @baz@, and you use @sourceDirectory@ on @foo@, the results will be

-- @foo/bar@ and @foo/baz@.

--

-- Since 1.1.0

sourceDirectory :: MonadResource m => FilePath -> Producer m FilePath

sourceDirectory dir =

    bracketP (F.openDirStream dir) F.closeDirStream go

  where

    go ds =

        loop

      where

        loop = do

            mfp <- liftIO $ F.readDirStream ds

            case mfp of

                Nothing -> return ()

                Just fp -> do

                    yield $ dir  fp

                    loop

-- | Deeply stream the contents of the given directory.

--

-- This works the same as @sourceDirectory@, but will not return directories at

-- all. This function also takes an extra parameter to indicate whether

-- symlinks will be followed.

--

-- Since 1.1.0

sourceDirectoryDeep :: MonadResource m

                    => Bool -- ^ Follow directory symlinks

                    -> FilePath -- ^ Root directory

                    -> Producer m FilePath

sourceDirectoryDeep followSymlinks =

    start

  where

    start :: MonadResource m => FilePath -> Producer m FilePath

    start dir = sourceDirectory dir =$= awaitForever go

    go :: MonadResource m => FilePath -> Producer m FilePath

    go fp = do

        ft <- liftIO $ F.getFileType fp

        case ft of

            F.FTFile -> yield fp

            F.FTFileSym -> yield fp

            F.FTDirectory -> start fp

            F.FTDirectorySym

                | followSymlinks -> start fp

                | otherwise -> return ()

            F.FTOther -> return ()