module Main( main ) where

import System.Console.GetOpt

import System.Environment

import System.Exit

import System.IO

import Data.Maybe( fromMaybe, isJust, fromJust )

import Data.List (find)

import Control.Monad

import Pas2C

main = do

    args <- getArgs

    if length args == 0

    then do

        name <- getProgName

        hPutStrLn stderr $ usageInfo header options

        exitFailure

    else do

        case getOpt RequireOrder options args of

          (flags, [],      []) | enoughFlags flags -> do

                let m = flag flags isName

                let i = flag flags isInput

                let o = flag flags isOutput

                let a = fromMaybe o $ liftM extractString $ find isAlt flags

                hPutStrLn stdout $ "--------Pas2C Config--------"

                hPutStrLn stdout $ "Main module: " ++ m

                hPutStrLn stdout $ "Input path : " ++ i

                hPutStrLn stdout $ "Output path: " ++ o

                hPutStrLn stdout $ "Altern path: " ++ a

                hPutStrLn stdout $ "----------------------------"

                pas2C m (i++"/") (o++"/") (a++"/")

                hPutStrLn stdout $ "----------------------------"

                      | otherwise ->  error $ usageInfo header options

          (_,     nonOpts, [])     -> error $ "unrecognized arguments: " ++ unwords nonOpts

          (_,     _,       msgs)   -> error $ usageInfo header options

    where 

        header = "Freepascal to C conversion! Please specify -n -i -o options.\n"

        enoughFlags f = and $ map (isJust . flip find f) [isName, isInput, isOutput]

        flag f = extractString . fromJust . flip find f

data Flag = HelpMessage | Name String | Input String | Output String | Alternate String

extractString :: Flag -> String

extractString (Name s) = s

extractString (Input s) = s

extractString (Output s) = s

extractString (Alternate s) = s

extractString _ = undefined

isName, isInput, isOutput, isAlt :: Flag -> Bool

isName (Name _) = True

isName _ = False

isInput (Input _) = True

isInput _ = False

isOutput (Output _) = True

isOutput _ = False

isAlt (Alternate _) = True

isAlt _ = False

options :: [OptDescr Flag]

options = [

    Option ['h'] ["help"]      (NoArg HelpMessage)      "print this help message",

    Option ['n'] ["name"]      (ReqArg Name "MAIN")     "name of the main Pascal module",

    Option ['i'] ["input"]     (ReqArg Input "DIR")     "input directory, where .pas files will be read",

    Option ['o'] ["output"]    (ReqArg Output "DIR")    "output directory, where .c/.h files will be written",

    Option ['a'] ["alternate"] (ReqArg Alternate "DIR") "alternate input directory, for out of source builds"

  ]