{-# LANGUAGE CPP, ScopedTypeVariables #-}

module Main where

import Network

import IO

import System.IO

import Control.Concurrent

import Control.Concurrent.STM

import Control.Exception (handle, finally, Exception, IOException)

import Control.Monad

import Maybe (fromMaybe, isJust, fromJust)

import Data.List

import Miscutils

import HWProto

import Opts

import Data.Time

#if !defined(mingw32_HOST_OS)

import System.Posix

#endif

data Messages =

	Accept ClientInfo

	| ClientMessage ([String], ClientInfo)

	| CoreMessage [String]

	| TimerTick

messagesLoop :: TChan [String] -> IO()

messagesLoop messagesChan = forever $ do

	threadDelay (25 * 10^6) -- 25 seconds

	atomically $ writeTChan messagesChan ["PING"]

timerLoop :: TChan [String] -> IO()

timerLoop messagesChan = forever $ do

	threadDelay (60 * 10^6) -- 60 seconds

	atomically $ writeTChan messagesChan ["MINUTELY"]

socketCloseLoop :: TChan Handle -> IO()

socketCloseLoop closingChan = forever $ do

	h <- atomically $ readTChan closingChan

	Control.Exception.handle (\(_ :: IOException) -> putStrLn "error on hClose") $ hClose h

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

acceptLoop servSock acceptChan =

	Control.Exception.handle (\(_ :: IOException) -> putStrLn "exception on connect" >> acceptLoop servSock acceptChan) $

	do

	(cHandle, host, _) <- accept servSock

	currentTime <- getCurrentTime

	putStrLn $ (show currentTime) ++ " new client: " ++ host

	cChan <- atomically newTChan

	forkIO $ clientLoop cHandle cChan

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

	atomically $ writeTChan cChan ["ASKME"]

	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` (\e -> (clientOff $ show e) >> return ())

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

sendAnswers _ [] _ clients _ = return clients

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

	let recipients = handlesFunc client clients rooms

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

	when (head answer == "NICK") $ putStrLn (show answer)

	clHandles' <- forM recipients $

		\ch -> Control.Exception.handle

			(\(e :: IOException) -> if head answer == "BYE" then

					return [ch]

				else

					atomically $ writeTChan (chan $ fromJust $ clientByHandle ch clients) ["QUIT", show e] >> return []  -- cannot just remove

			) $

			do

			forM_ answer (\str -> hPutStrLn ch str)

			hPutStrLn ch ""

			hFlush ch

			if head answer == "BYE" then return [ch] else return []

	let outHandles = concat clHandles'

	unless (null outHandles) $ putStrLn ((show $ length outHandles) ++ " / " ++ (show $ length clients) ++ " : " ++ (show answer))

	-- strange, but this seems to be a bad idea to manually close these handles as it causes hangs

	mapM_ (\ch -> atomically $ writeTChan closingChan ch) outHandles

	let mclients = remove clients outHandles

	sendAnswers closingChan answers client mclients rooms

	where

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

reactCmd :: ServerInfo -> TChan Handle -> [String] -> ClientInfo -> [ClientInfo] -> [RoomInfo] -> IO ([ClientInfo], [RoomInfo])

reactCmd serverInfo closingChan cmd client clients rooms = do

	--putStrLn ("> " ++ show cmd)

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

	let mrooms = roomsFunc rooms

	let mclients = (clientsFunc clients)

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

	let answers = map (\x -> x serverInfo) answerFuncs

	clientsIn <- sendAnswers closingChan answers mclient mclients mrooms

	mapM_ (\cl -> atomically $ writeTChan (chan cl) ["QUIT", "Kicked"]) $ filter forceQuit $ clientsIn

	return (clientsIn, mrooms)

mainLoop :: ServerInfo -> TChan ClientInfo -> TChan [String] -> TChan Handle -> [ClientInfo] -> [RoomInfo] -> IO ()

mainLoop serverInfo acceptChan messagesChan closingChan clients rooms = do

	r <- atomically $

		(Accept `fmap` readTChan acceptChan) `orElse`

		(ClientMessage `fmap` tselect clients) `orElse`

		(CoreMessage `fmap` readTChan messagesChan)

	case r of

		Accept ci -> do

			let sameHostClients = filter (\cl -> host ci == host cl) clients

			let haveJustConnected = not $ null $ filter (\cl -> connectTime ci `diffUTCTime` connectTime cl <= 25) sameHostClients

			when haveJustConnected $ do

				atomically $ do

					writeTChan (chan ci) ["QUIT", "Reconnected too fast"]

			currentTime <- getCurrentTime

			let newServerInfo = serverInfo{

					loginsNumber = loginsNumber serverInfo + 1,

					lastHourUsers = currentTime : lastHourUsers serverInfo

					}

			mainLoop newServerInfo acceptChan messagesChan closingChan (clients ++ [ci]) rooms

		ClientMessage (cmd, client) -> do

			(clientsIn, mrooms) <- reactCmd serverInfo closingChan cmd client clients rooms

			let hadRooms = (not $ null rooms) && (null mrooms)

				in unless ((not $ isDedicated serverInfo) && ((null clientsIn) || hadRooms)) $

					mainLoop serverInfo acceptChan messagesChan closingChan clientsIn mrooms

		CoreMessage msg -> case msg of

			["PING"] ->

				if not $ null $ clients then

					do

					let client = head clients -- don't care

					(clientsIn, mrooms) <- reactCmd serverInfo closingChan msg client clients rooms

					mainLoop serverInfo acceptChan messagesChan closingChan clientsIn mrooms

				else

					mainLoop serverInfo acceptChan messagesChan closingChan clients rooms

			["MINUTELY"] -> do

				currentTime <- getCurrentTime

				let newServerInfo = serverInfo{

						lastHourUsers = filter (\t -> currentTime `diffUTCTime` t < 3600) $ lastHourUsers serverInfo

						}

				mainLoop newServerInfo acceptChan messagesChan closingChan clients rooms

startServer :: ServerInfo -> Socket -> IO()

startServer serverInfo serverSocket = do

	acceptChan <- atomically newTChan

	forkIO $ acceptLoop serverSocket acceptChan

	messagesChan <- atomically newTChan

	forkIO $ messagesLoop messagesChan

	forkIO $ timerLoop messagesChan

	closingChan <- atomically newTChan

	forkIO $ socketCloseLoop closingChan

	mainLoop serverInfo acceptChan messagesChan closingChan [] []

main = withSocketsDo $ do

#if !defined(mingw32_HOST_OS)

	installHandler sigPIPE Ignore Nothing;

#endif

	serverInfo <- getOpts $ newServerInfo

	putStrLn $ "Listening on port " ++ show (listenPort serverInfo)

	serverSocket <- listenOn $ PortNumber (listenPort serverInfo)

	startServer serverInfo serverSocket `finally` sClose serverSocket