package net

import (
	"bytes"
	"context"
	"encoding/hex"
	"fmt"
	"io"
	"net"
	"sync"
	"sync/atomic"
	"time"
)

// MSG_CMD_HELLO 控制链路主动链接参头  16byte
var MSG_CMD_HELLO, _ = hex.DecodeString("B6121127AF7ECDA1")
var MSG_CMD_HELLO_REPLY, _ = hex.DecodeString("B6121127AF7ECDA2")

// MSG_NEW_CONN_HELLO 交链路主动连接头 16byte
var MSG_NEW_CONN_HELLO, _ = hex.DecodeString("B6121127AF7ECDFF")

type NatServer struct {
	sync.RWMutex
	cmdTCPConn   net.Conn
	listenTcp    net.Listener
	listenUDP    *net.UDPConn
	Addr         string
	Port         int
	lastTCPHeart int64
	lastUDPHeart int64
	Passwd       string
	DialTimeout  int64
	UDPTimeout   int64
	running      int32
	tcpConnPool  chan net.Conn
	stopCtx      context.Context
	stopFn       context.CancelFunc
}

func (n *NatServer) Run() error {
	if n.running != 0 {
		return fmt.Errorf("Server Already Run")
	}
	n.stopCtx, n.stopFn = context.WithCancel(context.Background())
	return nil
}

func (n *NatServer) cmdTcploop(conn net.Conn) error {
	var header = make([]byte, 16)
	for {
		c, err := conn.Read(header)
		if err != nil {
			//todo
		}
		if c != 16 {

		}
	}
}

func (n *NatServer) runTcpListen() error {
	atomic.AddInt32(&n.running, 1)
	defer atomic.AddInt32(&n.running, -1)
	listener, err := net.Listen("tcp", n.Addr)
	if err != nil {
		return err
	}
	n.listenTcp = listener
	for {
		conn, err := listener.Accept()
		if err != nil {
			continue
		}
		headedr := make([]byte, 16)
		conn.SetReadDeadline(time.Now().Add(time.Millisecond * 700))
		c, err := conn.Read(headedr)
		if err == nil && c == 16 {
			if bytes.Equal(headedr, MSG_CMD_HELLO) {
				if n.cmdTCPConn != nil {
					n.cmdTCPConn.Close()
				}
				n.cmdTCPConn = conn
				conn.Write(MSG_CMD_HELLO_REPLY)
				//
			}
		}
		io.ReadFull(conn, headedr)
	}
}