module Main ( main ) where

import IOMaybe
import Control.Exception ( handle, IOException )
import System.Directory
import System.IO
import Control.Monad
import Control.Applicative
import Data.Maybe
import System.Environment ( getArgs )
import System.FilePath

liftIOWHandle :: IO a -> IOMaybe a
liftIOWHandle act = IOMaybe $ handle h (Just <$> act)
  where
    h :: IOException -> IO (Maybe a)
    h ex = do
        hPrint stderr (show ex)
        return Nothing

withDefault :: a -> IOMaybe a -> IOMaybe a
withDefault x act = IOMaybe $ do
    val <- runIOMaybe act
    return . Just $ fromMaybe x val

main = void . runIOMaybe $ do
    [dir] <- liftIOWHandle getArgs
    cont <- liftIOWHandle $ getDirectoryContents dir
    forM_ cont $ \x -> withDefault () . liftIOWHandle $ do
        let path = dir </> x
        isDir  <- doesDirectoryExist path
        isFile <- doesFileExist path
        when isFile $ do
            line <- withFile path ReadMode hGetLine
            putStrLn $ x ++ ": \t" ++ line
        when isDir . putStrLn $ x ++ ": \t<directory>"