module Main where

import Network

import IO

import System.IO

import Control.Concurrent

import Control.Concurrent.STM

import Control.Exception (setUncaughtExceptionHandler, handle, finally)

import Control.Monad (forM, forM_, filterM, liftM, unless)

import Maybe (fromMaybe)

import Data.List

import Miscutils

import HWProto

import Opts

acceptLoop :: Socket -> TChan ClientInfo -> IO ()

acceptLoop servSock acceptChan = do

	(cHandle, host, port) <- accept servSock

	cChan <- atomically newTChan

	forkIO $ clientLoop cHandle cChan

	atomically $ writeTChan acceptChan (ClientInfo cChan cHandle "" 0 "" False)

	hPutStrLn cHandle "CONNECTED\n"

	hFlush cHandle

	acceptLoop servSock acceptChan

listenLoop :: Handle -> [String] -> TChan [String] -> IO ()

listenLoop handle buf chan = do

	str <- hGetLine handle

	if str == "" then do

		atomically $ writeTChan chan buf

		listenLoop handle [] chan

		else

		listenLoop handle (buf ++ [str]) chan

clientLoop :: Handle -> TChan [String] -> IO ()

clientLoop handle chan =

	listenLoop handle [] chan

		`catch` (const $ clientOff >> return ())

	where clientOff = atomically $ writeTChan chan ["QUIT"] -- if the client disconnects, we perform as if it sent QUIT message

sendAnswers [] _ clients _ = return clients

sendAnswers ((handlesFunc, answer):answers) client clients rooms = do

	let recipients = handlesFunc client clients rooms

	unless (null recipients) $ putStrLn ("< " ++ (show answer))

	clHandles' <- forM recipients $

		\ch -> Control.Exception.handle (\e -> putStrLn (show e) >> hClose ch >> return []) $ -- cannot just remove

			do

			forM_ answer (\str -> hPutStrLn ch str)

			hPutStrLn ch ""

			hFlush ch

			if (not $ null answer) && (head answer == "BYE") then hClose ch >> return [ch] else return []

	let mclients = remove clients $ concat clHandles'

	sendAnswers answers client mclients rooms

	where

		remove list rmClHandles = deleteFirstsBy2t (\ a b -> (Miscutils.handle a) == b) list rmClHandles

mainLoop :: Socket -> TChan ClientInfo -> [ClientInfo] -> [RoomInfo] -> IO ()

mainLoop servSock acceptChan clients rooms = do

	r <- atomically $ (Left `fmap` readTChan acceptChan) `orElse` (Right `fmap` tselect clients)

	case r of

		Left ci -> do

			mainLoop servSock acceptChan (clients ++ [ci]) rooms

		Right (cmd, client) -> do

			putStrLn ("> " ++ show cmd)

			let (clientsFunc, roomsFunc, answers) = handleCmd client clients rooms $ cmd

			let mrooms = roomsFunc rooms

			let mclients = (clientsFunc clients)

			let mclient = fromMaybe client $ find (== client) mclients

			clientsIn <- sendAnswers answers mclient mclients mrooms

			mainLoop servSock acceptChan clientsIn mrooms

startServer serverSocket = do

	acceptChan <- atomically newTChan

	forkIO $ acceptLoop serverSocket acceptChan

	mainLoop serverSocket acceptChan [] []

main = withSocketsDo $ do

	startServer serverSocket `finally` sClose serverSocket