{-# LANGUAGE ScopedTypeVariables, OverloadedStrings, Rank2Types #-}

module ClientIO where

import qualified Control.Exception as Exception

import Control.Monad.State

import Control.Concurrent.Chan

import Control.Concurrent

import Network

import Network.Socket.ByteString

import qualified Data.ByteString.Char8 as B

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

import CoreTypes

import RoomsAndClients

pDelim :: B.ByteString

pDelim = "\n\n"

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

bs2Packets = runState takePacks

takePacks :: State B.ByteString [[B.ByteString]]

takePacks

  = do modify (until (not . B.isPrefixOf pDelim) (B.drop 2))

       packet <- state $ B.breakSubstring pDelim

       buf <- get

       if B.null buf then put packet >> return [] else

        if B.null packet then  return [] else

         do packets <- takePacks

            return (B.splitWith (== '\n') packet : packets)

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 -> Chan [B.ByteString] -> ClientIndex -> (forall a. IO a -> IO a) -> IO ()

clientRecvLoop s chan clChan ci restore =

    (myThreadId >>=

    \t -> (restore $ forkIO (clientSendLoop s t clChan ci) >>

        listenLoop s chan ci >> return "Connection closed")

        `Exception.catch` (\(e :: ShutdownThreadException) -> return . B.pack . show $ e)

        `Exception.catch` (\(e :: Exception.IOException) -> return . B.pack . show $ e)

        `Exception.catch` (\(e :: Exception.SomeException) -> return . B.pack . show $ e)

        >>= clientOff) `Exception.finally` remove

    where

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

        remove = do

            clientOff "Client is in some weird state"

            writeChan chan $ Remove ci

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

clientSendLoop s tId chan ci = do

    answer <- readChan chan

    when (isQuit answer) $

        killReciever . B.unpack $ quitMessage answer

    Exception.handle

            sendAll s $ B.unlines answer `B.snoc` '\n'

    if isQuit answer then

        else

        clientSendLoop s tId chan ci

    where

        killReciever = Exception.throwTo tId . ShutdownThreadException

        quitMessage ["BYE"] = "bye"

        quitMessage ("BYE":msg:_) = msg

        quitMessage _ = error "quitMessage"

        isQuit ("BYE":_) = True

        isQuit _ = False