module Main where

import Prelude hiding ( catch )
import Control.Exception ( AsyncException(..), catch )
import Control.Monad.Error

import Data.ByteString.Lazy.Char8 ()

import Data.Version

import System.Environment
import System.Directory (getHomeDirectory)
import System.FilePath ((</>))
import System.Console.Haskeline hiding (handle, catch, throwTo)
import System.Console.GetOpt
import System.Exit (ExitCode (..), exitWith, exitFailure)

import Language.Egison
import Language.Egison.Util

main :: IO ()
main = do args <- getArgs
          let (actions, nonOpts, _) = getOpt Permute options args
          let opts = foldl (flip id) defaultOptions actions
          case opts of
            Options {optShowHelp = True} -> printHelp
            Options {optShowVersion = True} -> printVersionNumber
            Options {optPrompt = prompt, optShowBanner = bannerFlag, optNoIO = noIOFlag} -> do
              env <-if noIOFlag then initialEnvNoIO else initialEnv
              case nonOpts of
                [] -> do
                  when bannerFlag showBanner >> repl env prompt >> when bannerFlag showByebyeMessage
                (file:args) -> do
                  case opts of
                    Options {optLoadOnly = True} -> do
                      result <- evalEgisonTopExprs env [LoadFile file]
                      either print (const $ return ()) result
                    Options {optLoadOnly = False} -> do
                      result <- evalEgisonTopExprs env [LoadFile file, Execute (ApplyExpr (VarExpr "main") (CollectionExpr (map (ElementExpr . StringExpr) args)))]
                      either print (const $ return ()) result

data Options = Options {
    optShowVersion :: Bool,
    optShowHelp :: Bool,
    optNoIO :: Bool,
    optShowBanner :: Bool,
    optLoadOnly :: Bool,
    optPrompt :: String
    }

defaultOptions :: Options
defaultOptions = Options {
    optShowVersion = False,
    optShowHelp = False,
    optNoIO = False,
    optShowBanner = True,
    optLoadOnly = False,
    optPrompt = "> "
    }

options :: [OptDescr (Options -> Options)]
options = [
  Option ['v', 'V'] ["version"]
    (NoArg (\opts -> opts {optShowVersion = True}))
    "show version number",
  Option ['h', '?'] ["help"]
    (NoArg (\opts -> opts {optShowHelp = True}))
    "show usage information",
  Option [] ["no-io"]
    (NoArg (\opts -> opts {optNoIO = True}))
    "show usage information",
  Option [] ["no-banner"]
    (NoArg (\opts -> opts {optShowBanner = False}))
    "show usage information",
  Option ['l'] ["load"]
    (NoArg (\opts -> opts {optLoadOnly = True}))
    "show usage information",
  Option ['p'] ["prompt"]
    (ReqArg (\prompt opts -> opts {optPrompt = prompt})
            "String")
    "prompt string"
  ]

printHelp :: IO ()
printHelp = do
  putStrLn "Usage: egison [options] file"
  putStrLn ""
  putStrLn "Options:"
  putStrLn "  --help                Display this information"
  putStrLn "  --version             Display egison version information"
  putStrLn "  --no-io               No IO primitives"
  putStrLn "  --no-banner           Don't show banner"
  putStrLn "  --load                Don't execute main function"
  putStrLn "  --prompt string       Set prompt of the interpreter"
  putStrLn ""
  exitWith ExitSuccess

printVersionNumber :: IO ()
printVersionNumber = do
  putStrLn $ showVersion version 
  exitWith ExitSuccess

showBanner :: IO ()
showBanner = do
  putStrLn $ "Egison Version " ++ showVersion version ++ " (C) 2011-2014 Satoshi Egi"
  putStrLn $ "http://www.egison.org"
  putStrLn $ "Welcome to Egison Interpreter!"
  putStrLn $ "** Info **"
  putStrLn $ "We can use a \'Tab\' key to complete keywords on the interpreter."
  putStrLn $ "If we type a \'Tab\' key after a closed parenthesis, the next closed parenthesis will be completed."

showByebyeMessage :: IO ()
showByebyeMessage = do
  putStrLn $ "Leaving Egison Interpreter."
  exitWith ExitSuccess

onAbort :: EgisonError -> IO (Either EgisonError a)
onAbort e = return $ Left e


repl :: Env -> String -> IO ()
repl env prompt = do
  loop env
 where
  settings :: MonadIO m => FilePath -> Settings m
  settings home = setComplete completeEgison $ defaultSettings { historyFile = Just (home </> ".egison_history") }
    
  loop :: Env -> IO ()
  loop env = (do 
    home <- getHomeDirectory
    input <- liftIO $ runInputT (settings home) $ getEgisonExpr prompt
    case input of
      Nothing -> return ()
      Just (Left (topExpr, _)) -> do
        result <- liftIO $ runEgisonTopExpr env topExpr
        case result of
          Left err -> do
            liftIO $ putStrLn $ show err
            loop env
          Right env' -> loop env'
      Just (Right (expr, _)) -> do
        result <- liftIO $ runEgisonExpr env expr
        case result of
          Left err -> do
            liftIO $ putStrLn $ show err
            loop env
          Right val -> do
            liftIO $ putStrLn $ show val
            loop env)
    `catch`
    (\e -> case e of
             UserInterrupt -> putStrLn "" >> loop env
             StackOverflow -> putStrLn "Stack over flow!" >> loop env
             HeapOverflow -> putStrLn "Heap over flow!" >> loop env
             _ -> putStrLn "error!" >> loop env
     )