{-# LANGUAGE OverloadedStrings #-}

module Main where

import System.Console.GetOpt

import System.Environment (getArgs, getProgName)
import System.Exit (exitSuccess)

import Paths_keyword_args (version)

import Data.Version (showVersion)

import Data.ByteString.Lazy.Char8 (unpack)

import Data.KeywordArgs.Parse

import Text.Parsec

import Data.Csv (encode)

data Options = Options
    { optShowVersion :: Bool
    , optShowHelp    :: Bool
    } deriving Show

defaultOptions :: Options
defaultOptions = Options
    { optShowVersion = False
    , optShowHelp    = False
    }

options :: [OptDescr (Options -> Options)]
options =
  [ Option "V" ["version"] (NoArg (\opts -> opts { optShowVersion = True }))
    "show version number"

  , Option "h" ["help"]    (NoArg (\opts -> opts { optShowHelp = True }))
    "show help"
  ]

showHelp :: IO ()
showHelp = do
  prg <- getProgName
  putStrLn (usageInfo prg options)
  exitSuccess

headerMessage :: String -> String
headerMessage progName =
  unlines [
    progName ++ " " ++
    "cleans up whitespace and comments in keyword-argument input " ++
    "and emits CSV output.\n"
    , "Usage: " ++ progName ++ " [OPTION...]"]

lintOpts :: [String] -> IO (Options, [String])
lintOpts argv = do
  name <- getProgName

  case getOpt Permute options argv of
    (o, n, []  ) -> return (foldl (flip id) defaultOptions o, n)
    (_, _, errs) ->
      ioError (userError (concat errs ++ usageInfo (headerMessage name) options))

parseConfig :: String -> Either ParseError [(String, String)]
parseConfig = parse configParser "(unknown)"

runCheck :: IO ()
runCheck = do
  f <- getContents

  case parseConfig f of
    Left e -> ioError $ userError $ "Parse error: " ++ show e

    Right config -> putStr $ unpack $ encode config

main :: IO ()
main = do
  opts <- getArgs >>= lintOpts

  name <- getProgName

  if optShowHelp $ fst opts
  then
    putStrLn $ usageInfo (headerMessage name) options
  else
    if optShowVersion $ fst opts then
      putStrLn $ name ++ " " ++ showVersion version ++
      " (C) 2015 Stack Builders Inc."
    else
      runCheck