{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE ScopedTypeVariables #-}

module Network.QUIC.Client.Reader (
    readerClient,
    recvClient,
    ConnectionControl (..),
    controlConnection,
    clientSocket,
) where

import Control.Concurrent
import qualified Control.Exception as E
import Data.List (intersect)
import Network.Socket (Socket, close, getSocketName)
import qualified Network.Socket.ByteString as NSB

import Network.QUIC.Connection
import Network.QUIC.Connector
import Network.QUIC.Crypto
import Network.QUIC.Exception
import Network.QUIC.Imports
import Network.QUIC.Packet
import Network.QUIC.Parameters
import Network.QUIC.Qlog
import Network.QUIC.Recovery
import Network.QUIC.Socket
import Network.QUIC.Types

-- | readerClient dies when the socket is closed.
readerClient :: Socket -> Connection -> IO ()
readerClient s0 conn = handleLogUnit logAction $ do
    wait
    loop
  where
    wait = do
        bound <- E.handle (throughAsync (return False)) $ do
            _ <- getSocketName s0
            return True
        unless bound $ do
            yield
            wait
    loop = do
        ito <- readMinIdleTimeout conn
        mbs <-
            timeout ito "readeClient" $
                NSB.recvMsg s0 2048 2048 0 -- fixme
        case mbs of
            Nothing -> close s0
            Just (peersa, bs, cmsgs, _) -> do
                setPeerInfo conn $ PeerInfo peersa cmsgs
                now <- getTimeMicrosecond
                let quicBit = greaseQuicBit $ getMyParameters conn
                pkts <- decodePackets bs (not quicBit)
                mapM_ (putQ now) pkts
                loop
    logAction msg = connDebugLog conn ("debug: readerClient: " <> msg)
    putQ _ (PacketIB BrokenPacket _) = return ()
    putQ t (PacketIV pkt@(VersionNegotiationPacket dCID sCID peerVers)) = do
        qlogReceived conn pkt t
        myVerInfo <- getVersionInfo conn
        let myVer = chosenVersion myVerInfo
            myVers0 = otherVersions myVerInfo
        -- ignoring VN if the original version is included.
        when (myVer `notElem` peerVers && Negotiation `notElem` peerVers) $ do
            ok <- checkCIDs conn dCID (Left sCID)
            let myVers = filter (not . isGreasingVersion) myVers0
                nextVerInfo = case myVers `intersect` peerVers of
                    vers@(ver : _) | ok -> VersionInfo ver vers
                    _ -> brokenVersionInfo
            E.throwTo (mainThreadId conn) $ VerNego nextVerInfo
    putQ t (PacketIC pkt lvl siz) = writeRecvQ (connRecvQ conn) $ mkReceivedPacket pkt t siz lvl
    putQ t (PacketIR pkt@(RetryPacket ver dCID sCID token ex)) = do
        qlogReceived conn pkt t
        ok <- checkCIDs conn dCID ex
        when ok $ do
            resetPeerCID conn sCID
            setPeerAuthCIDs conn $ \auth -> auth{retrySrcCID = Just sCID}
            initializeCoder conn InitialLevel $ initialSecrets ver sCID
            setToken conn token
            setRetried conn True
            releaseByRetry (connLDCC conn) >>= mapM_ put
      where
        put ppkt = putOutput conn $ OutRetrans ppkt

checkCIDs :: Connection -> CID -> Either CID (ByteString, ByteString) -> IO Bool
checkCIDs conn dCID (Left sCID) = do
    localCID <- getMyCID conn
    remoteCID <- getPeerCID conn
    return (dCID == localCID && sCID == remoteCID)
checkCIDs conn dCID (Right (pseudo0, tag)) = do
    localCID <- getMyCID conn
    remoteCID <- getPeerCID conn
    ver <- getVersion conn
    let ok = calculateIntegrityTag ver remoteCID pseudo0 == tag
    return (dCID == localCID && ok)

recvClient :: RecvQ -> IO ReceivedPacket
recvClient = readRecvQ

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

-- | How to control a connection.
data ConnectionControl
    = ChangeServerCID
    | ChangeClientCID
    | NATRebinding
    | ActiveMigration
    deriving (Eq, Show)

controlConnection :: Connection -> ConnectionControl -> IO Bool
controlConnection conn typ
    | isClient conn = do
        waitEstablished conn
        controlConnection' conn typ
    | otherwise = return False

controlConnection' :: Connection -> ConnectionControl -> IO Bool
controlConnection' conn ChangeServerCID = do
    mn <- timeout (Microseconds 1000000) "controlConnection' 1" $ waitPeerCID conn -- fixme
    case mn of
        Nothing -> return False
        Just (CIDInfo n _ _) -> do
            sendFrames conn RTT1Level [RetireConnectionID n]
            return True
controlConnection' conn ChangeClientCID = do
    cidInfo <- getNewMyCID conn
    x <- (+ 1) <$> getMyCIDSeqNum conn
    sendFrames conn RTT1Level [NewConnectionID cidInfo x]
    return True
controlConnection' conn NATRebinding = do
    rebind conn $ Microseconds 5000 -- nearly 0
    return True
controlConnection' conn ActiveMigration = do
    mn <- timeout (Microseconds 1000000) "controlConnection' 2" $ waitPeerCID conn -- fixme
    case mn of
        Nothing -> return False
        mcidinfo -> do
            rebind conn $ Microseconds 5000000
            validatePath conn mcidinfo
            return True

rebind :: Connection -> Microseconds -> IO ()
rebind conn microseconds = do
    PeerInfo peersa _ <- getPeerInfo conn
    newSock <- natRebinding peersa
    oldSock <- setSocket conn newSock
    let reader = readerClient newSock conn
    forkIO reader >>= addReader conn
    fire conn microseconds $ close oldSock