{-# LANGUAGE ScopedTypeVariables, OverloadedStrings #-}

module ClientIO where

import qualified Control.Exception as Exception

import Control.Concurrent.Chan

import Control.Concurrent

import Control.Monad

import Network

import Network.Socket.ByteString

import qualified Data.ByteString.Char8 as B

----------------

import CoreTypes

import RoomsAndClients

import Utils

pDelim :: B.ByteString

pDelim = B.pack "\n\n"

bs2Packets :: B.ByteString -> ([[B.ByteString]], B.ByteString)

bs2Packets = unfoldrE extractPackets

    where

    extractPackets :: B.ByteString -> Either B.ByteString ([B.ByteString], B.ByteString)

    extractPackets buf =

        let buf' = until (not . B.isPrefixOf pDelim) (B.drop 2) buf in

            let (bsPacket, bufTail) = B.breakSubstring pDelim buf' in

                if B.null bufTail then

                    Left bsPacket

                    else

                    if B.null bsPacket then 

                        Left bufTail

                        else

                        Right (B.splitWith (== '\n') bsPacket, bufTail)

listenLoop :: Socket -> Chan CoreMessage -> ClientIndex -> IO ()

listenLoop sock chan ci = recieveWithBufferLoop B.empty

    where

        recieveWithBufferLoop recvBuf = do

            recvBS <- recv sock 4096

            unless (B.null recvBS) $ do

                let (packets, newrecvBuf) = bs2Packets $ B.append recvBuf recvBS

                forM_ packets sendPacket

                recieveWithBufferLoop newrecvBuf

        sendPacket packet = writeChan chan $ ClientMessage (ci, packet)

clientRecvLoop :: Socket -> Chan CoreMessage -> ClientIndex -> IO ()

clientRecvLoop s chan ci =

    do

        msg <- (listenLoop s chan ci >> return "Connection closed") `catch` (return . B.pack . show)

        clientOff msg

    `Exception.finally`

        remove

    where

        clientOff msg = writeChan chan $ ClientMessage (ci, ["QUIT", msg])

        remove = writeChan chan $ Remove ci

clientSendLoop :: Socket -> ThreadId -> Chan CoreMessage -> Chan [B.ByteString] -> ClientIndex -> IO ()

clientSendLoop s tId cChan chan ci = do

    answer <- readChan chan

    Exception.handle

        (\(e :: Exception.IOException) -> unless (isQuit answer) $ sendQuit e) $

            sendAll s $ B.unlines answer `B.append` B.singleton '\n'

    if isQuit answer then

        do

        Exception.handle (\(_ :: Exception.IOException) -> putStrLn "error on sClose") $ sClose s

        Exception.throwTo tId ShutdownThreadException

        else

        clientSendLoop s tId cChan chan ci

    where

        sendQuit e = do

            print e

            writeChan cChan $ ClientMessage (ci, ["QUIT", B.pack $ show e])

        isQuit ("BYE":_) = True

        isQuit _ = False