// loop for reading messages from frpc after control connection is established
func msgReader(cli *client.ProxyClient, c *conn.Conn, msgSendChan chan interface{}) error {
	// for heartbeat
	var heartbeatTimeout bool = false
	timer := time.AfterFunc(time.Duration(client.HeartBeatTimeout)*time.Second, func() {
		heartbeatTimeout = true
		c.Close()
		log.Error("ProxyName [%s], heartbeatRes from frps timeout", cli.Name)
	})
	defer timer.Stop()

	for {
		buf, err := c.ReadLine()
		if err == io.EOF || c == nil || c.IsClosed() {
			c.Close()
			log.Warn("ProxyName [%s], frps close this control conn!", cli.Name)
			var delayTime time.Duration = 1

			// loop until reconnect to frps
			for {
				log.Info("ProxyName [%s], try to reconnect to frps [%s:%d]...", cli.Name, client.ServerAddr, client.ServerPort)
				c, err = loginToServer(cli)
				if err == nil {
					close(msgSendChan)
					msgSendChan = make(chan interface{}, 1024)
					go heartbeatSender(c, msgSendChan)
					go msgSender(cli, c, msgSendChan)
					break
				}

				if delayTime < 60 {
					delayTime = delayTime * 2
				}
				time.Sleep(delayTime * time.Second)
			}
			continue
		} else if err != nil {
			log.Warn("ProxyName [%s], read from frps error: %v", cli.Name, err)
			continue
		}

		ctlRes := &msg.ControlRes{}
		if err := json.Unmarshal([]byte(buf), &ctlRes); err != nil {
			log.Warn("ProxyName [%s], parse msg from frps error: %v : %s", cli.Name, err, buf)
			continue
		}

		switch ctlRes.Type {
		case consts.HeartbeatRes:
			log.Debug("ProxyName [%s], receive heartbeat response", cli.Name)
			timer.Reset(time.Duration(client.HeartBeatTimeout) * time.Second)
		case consts.NoticeUserConn:
			log.Debug("ProxyName [%s], new user connection", cli.Name)
			// join local and remote connections, async
			go cli.StartTunnel(client.ServerAddr, client.ServerPort)
		default:
			log.Warn("ProxyName [%s}, unsupport msgType [%d]", cli.Name, ctlRes.Type)
		}
	}
	return nil
}

func echoWorker(c *conn.Conn) {
	for {
		buff, err := c.ReadLine()
		if err == io.EOF {
			break
		}
		if err != nil {
			fmt.Printf("echo server read error: %v\n", err)
			return
		}

		c.Write(buff)
	}
}

// loop for sending messages from channel to frpc
func msgSender(s *server.ProxyServer, c *conn.Conn, msgSendChan chan interface{}) {
	for {
		msg, ok := <-msgSendChan
		if !ok {
			break
		}

		buf, _ := json.Marshal(msg)
		err := c.Write(string(buf) + "\n")
		if err != nil {
			log.Warn("ProxyName [%s], write to client error, proxy exit", s.Name)
			s.Close()
			break
		}
	}
}

func heartbeatSender(c *conn.Conn, msgSendChan chan interface{}) {
	heartbeatReq := &msg.ControlReq{
		Type: consts.HeartbeatReq,
	}
	log.Info("Start to send heartbeat to frps")
	for {
		time.Sleep(time.Duration(client.HeartBeatInterval) * time.Second)
		if c != nil && !c.IsClosed() {
			log.Debug("Send heartbeat to server")
			msgSendChan <- heartbeatReq
		} else {
			break
		}
	}
	log.Debug("Heartbeat goroutine exit")
}

// loop for reading messages from frpc after control connection is established
func msgReader(s *server.ProxyServer, c *conn.Conn, msgSendChan chan interface{}) error {
	// for heartbeat
	var heartbeatTimeout bool = false
	timer := time.AfterFunc(time.Duration(server.HeartBeatTimeout)*time.Second, func() {
		heartbeatTimeout = true
		s.Close()
		log.Error("ProxyName [%s], client heartbeat timeout", s.Name)
	})
	defer timer.Stop()

	for {
		buf, err := c.ReadLine()
		if err != nil {
			if err == io.EOF {
				log.Warn("ProxyName [%s], client is dead!", s.Name)
				return err
			} else if c == nil || c.IsClosed() {
				log.Warn("ProxyName [%s], client connection is closed", s.Name)
				return err
			}
			log.Warn("ProxyName [%s], read error: %v", s.Name, err)
			continue
		}

		cliReq := &msg.ControlReq{}
		if err := json.Unmarshal([]byte(buf), &cliReq); err != nil {
			log.Warn("ProxyName [%s], parse msg from frpc error: %v : %s", s.Name, err, buf)
			continue
		}

		switch cliReq.Type {
		case consts.HeartbeatReq:
			log.Debug("ProxyName [%s], get heartbeat", s.Name)
			timer.Reset(time.Duration(server.HeartBeatTimeout) * time.Second)
			heartbeatRes := &msg.ControlRes{
				Type: consts.HeartbeatRes,
			}
			msgSendChan <- heartbeatRes
		default:
			log.Warn("ProxyName [%s}, unsupport msgType [%d]", s.Name, cliReq.Type)
		}
	}
	return nil
}

func (v *VhostMuxer) handle(c *conn.Conn) {
	if err := c.SetDeadline(time.Now().Add(v.timeout)); err != nil {
		return
	}

	sConn, name, err := v.vhostFunc(c)
	if err != nil {
		return
	}

	name = strings.ToLower(name)
	l, ok := v.getListener(name)
	if !ok {
		return
	}

	if err = sConn.SetDeadline(time.Time{}); err != nil {
		return
	}
	c.TcpConn = sConn

	l.accept <- c
}

// connection from every client and server
func controlWorker(c *conn.Conn) {
	// if login message type is NewWorkConn, don't close this connection
	var closeFlag bool = true
	var s *server.ProxyServer
	defer func() {
		if closeFlag {
			c.Close()
			if s != nil {
				s.Close()
			}
		}
	}()

	// get login message
	buf, err := c.ReadLine()
	if err != nil {
		log.Warn("Read error, %v", err)
		return
	}
	log.Debug("Get msg from frpc: %s", buf)

	cliReq := &msg.ControlReq{}
	if err := json.Unmarshal([]byte(buf), &cliReq); err != nil {
		log.Warn("Parse msg from frpc error: %v : %s", err, buf)
		return
	}

	// login when type is NewCtlConn or NewWorkConn
	ret, info := doLogin(cliReq, c)
	s, ok := server.ProxyServers[cliReq.ProxyName]
	if !ok {
		log.Warn("ProxyName [%s] is not exist", cliReq.ProxyName)
		return
	}
	// if login type is NewWorkConn, nothing will be send to frpc
	if cliReq.Type != consts.NewWorkConn {
		cliRes := &msg.ControlRes{
			Type: consts.NewCtlConnRes,
			Code: ret,
			Msg:  info,
		}
		byteBuf, _ := json.Marshal(cliRes)
		err = c.Write(string(byteBuf) + "\n")
		if err != nil {
			log.Warn("ProxyName [%s], write to client error, proxy exit", s.Name)
			time.Sleep(1 * time.Second)
			return
		}
	} else {
		closeFlag = false
		return
	}

	// if login failed, just return
	if ret > 0 {
		return
	}

	// create a channel for sending messages
	msgSendChan := make(chan interface{}, 1024)
	go msgSender(s, c, msgSendChan)
	go noticeUserConn(s, msgSendChan)

	// loop for reading control messages from frpc and deal with different types
	msgReader(s, c, msgSendChan)

	close(msgSendChan)
	log.Info("ProxyName [%s], I'm dead!", s.Name)
	return
}

// start listening for user conns
func (p *ProxyServer) Start(c *conn.Conn) (err error) {
	p.CtlConn = c
	p.Init()
	if p.Type == "tcp" {
		l, err := conn.Listen(p.BindAddr, p.ListenPort)
		if err != nil {
			return err
		}
		p.listeners = append(p.listeners, l)
	} else if p.Type == "http" {
		for _, domain := range p.CustomDomains {
			l, err := VhostMuxer.Listen(domain)
			if err != nil {
				return err
			}
			p.listeners = append(p.listeners, l)
		}
	}

	p.Lock()
	p.Status = consts.Working
	p.Unlock()

	// start a goroutine for every listener to accept user connection
	for _, listener := range p.listeners {
		go func(l Listener) {
			for {
				// block
				// if listener is closed, err returned
				c, err := l.Accept()
				if err != nil {
					log.Info("ProxyName [%s], listener is closed", p.Name)
					return
				}
				log.Debug("ProxyName [%s], get one new user conn [%s]", p.Name, c.GetRemoteAddr())

				if p.Status != consts.Working {
					log.Debug("ProxyName [%s] is not working, new user conn close", p.Name)
					c.Close()
					return
				}

				// start another goroutine for join two conns from frpc and user
				go func() {
					workConn, err := p.getWorkConn()
					if err != nil {
						return
					}

					userConn := c
					// msg will transfer to another without modifying
					// l means local, r means remote
					log.Debug("Join two connections, (l[%s] r[%s]) (l[%s] r[%s])", workConn.GetLocalAddr(), workConn.GetRemoteAddr(),
						userConn.GetLocalAddr(), userConn.GetRemoteAddr())

					if p.UseEncryption {
						go conn.JoinMore(userConn, workConn, p.AuthToken)
					} else {
						go conn.Join(userConn, workConn)
					}
				}()
			}
		}(listener)
	}
	return nil
}