module Main where

import System
import System.Console.GetOpt

-- Default script options 
defaultOptions :: Options
defaultOptions = Options {
     runScript = runLexer
   , lexerPath = "lexer.lex"
   , txtFiles  = []
}

-- Main function : does argument parsing
main = do
      args <- getArgs
      let (optHelpers, nonOpt, msg) = getOpt Permute options args
      let scriptOptions = compose optHelpers defaultOptions
      -- this next line is not perfect, but I'm not shure I can do better...
      runScript scriptOptions scriptOptions

-- Main script : use a lexer on stdin
runLexer :: Options -> IO ()
runLexer opt = do
                 let files = txtFiles opt
                 wds <- if not $ null $ txtFiles opt
                         then do cs <- mapM readFile $ txtFiles opt
                                 return $ concatMap lines cs
                         else getContents >>= return . lines
                 return ()

mkLexer :: Options -> IO ()
mkLexer opt = undefined

-- Options declaration
options :: [OptDescr (Options -> Options)]
options = [ 
     Option ['V'] ["version"] (NoArg showVersion)           
                  "show version number"
   , Option []    ["mklexer"] (NoArg setMkLexer) 
                  "build a lexer from a lexicon"
   ]

-- Option parsing machinery

-- Options type
-- the main function is in the options so we can switch it according to the option given (ex: the --version option)
data Options = Options {
     runScript :: Options -> IO ()
   , lexerPath :: String
   , txtFiles  :: [String]
   }

-- Options helpers
showVersion :: Options -> Options
showVersion o = o { runScript = \_ -> do
     putStrLn $ "gfdoc : GF documentation tool version " ++ "???"--_VERSION
     exitWith ExitSuccess
   }

setMkLexer :: Options -> Options
setMkLexer o = o { runScript = mkLexer }

-- Utilities
-- this compose a list of function together
compose :: [a -> a] -> a -> a
compose fs v = foldl (flip (.)) id fs $ v