import Control.Monad
import Data.List
import System.Directory
import System.IO
import System.Environment
import System.Process


runProcessWithInput :: FilePath -> [String] -> String -> IO String
runProcessWithInput cmd args input = do
    (pin, pout, perr, ph) <- runInteractiveProcess cmd args Nothing Nothing
    hPutStr pin input
    hClose pin
    output <- hGetContents pout
    when (output==output) $ return ()
    hClose pout
    hClose perr
    waitForProcess ph
    return output

getShellCompl :: String -> IO [String]
getShellCompl s
    | s /= "" && last s /= ' ' = do
  f <- fmap lines $ runProcessWithInput "/bin/bash" [] ("compgen -A file " ++ s ++ "\n")
  c <- commandCompletionFunction s
  return . map escape . sort . nub $ f ++ c
    | otherwise = return []

commandCompletionFunction :: String -> IO [String]
commandCompletionFunction str
    | '/' `elem` str = return []
    | otherwise      = do
  p  <- getEnv "PATH" `catch` const (return [])
  let ds = split ':' p
      fp d f = d ++ "/" ++ f
  es <- forM ds $ \d -> do
          exists <- doesDirectoryExist d
          if exists
             then getDirectoryContents d >>= filterM (isExecutable . fp d)
             else return []
  return . filter (isPrefixOf str) . concat $ es

isExecutable :: FilePath ->IO Bool
isExecutable f = do
    fe <- doesFileExist f
    if fe
        then fmap executable $ getPermissions f
        else return False

split :: Eq a => a -> [a] -> [[a]]
split _ [] = []
split e l =
    f : split e (rest ls)
        where
          (f,ls) = span (/=e) l
          rest s | s == []   = []
                 | otherwise = tail s

escape :: String -> String
escape []       = ""
escape (' ':xs) = "\\ " ++ escape xs
escape (x:xs)
    | isSpecialChar x = '\\' : x : escape xs
    | otherwise       = x : escape xs

isSpecialChar :: Char -> Bool
isSpecialChar =  flip elem "\\@\"'#?$*()[]{};"

main = do
  a <- getArgs
  putStrLn =<< fmap (show . length) (getShellCompl $ a !! 0)