package netbase

import (
	"errors"
	"net/http"
	"sync"
	"time"

	"github.com/gorilla/websocket"
)

type Connection struct {
	wsConnect *websocket.Conn
	inChan    chan []byte
	outChan   chan []byte
	closeChan chan byte

	mutex    sync.Mutex // 对closeChan关闭上锁
	isClosed bool       // 防止closeChan被关闭多次
}

type CWebSocketServer struct {
	Connection
	bindurl string
}

func NewWebSocketServer(bindurl string) *CWebSocketServer {
	wss := new(CWebSocketServer)
	wss.bindurl = bindurl
	return wss
}

func (wss *CWebSocketServer) Start() {

	http.HandleFunc("/ws", wsHandler)
	go http.ListenAndServe(wss.bindurl, nil)
}

var (
	upgrader = websocket.Upgrader{
		// 允许跨域
		CheckOrigin: func(r *http.Request) bool {
			return true
		},
	}
)

func wsHandler(w http.ResponseWriter, r *http.Request) {
	//	w.Write([]byte("hello"))
	var (
		wsConn *websocket.Conn
		err    error
		conn   *Connection
		data   []byte
	)
	// 完成ws协议的握手操作
	// Upgrade:websocket
	if wsConn, err = upgrader.Upgrade(w, r, nil); err != nil {
		return
	}

	if conn, err = InitConnection(wsConn); err != nil {
		goto ERR
	}

	// 启动线程，不断发消息
	go func() {
		var (
			err error
		)
		for {
			if err = conn.WriteMessage([]byte("heartbeat")); err != nil {
				return
			}
			time.Sleep(1 * time.Second)
		}
	}()

	for {
		if data, err = conn.ReadMessage(); err != nil {
			goto ERR
		}
		if err = conn.WriteMessage(data); err != nil {
			goto ERR
		}
	}

ERR:
	conn.Close()

}

func InitConnection(wsConn *websocket.Conn) (conn *Connection, err error) {
	conn = &Connection{
		wsConnect: wsConn,
		inChan:    make(chan []byte, 1000),
		outChan:   make(chan []byte, 1000),
		closeChan: make(chan byte, 1),
	}
	// 启动读协程
	go conn.readLoop()
	// 启动写协程
	go conn.writeLoop()
	return
}

func (conn *Connection) ReadMessage() (data []byte, err error) {

	select {
	case data = <-conn.inChan:
	case <-conn.closeChan:
		err = errors.New("connection is closeed")
	}
	return
}

func (conn *Connection) WriteMessage(data []byte) (err error) {

	select {
	case conn.outChan <- data:
	case <-conn.closeChan:
		err = errors.New("connection is closeed")
	}
	return
}

func (conn *Connection) Close() {
	// 线程安全，可多次调用
	conn.wsConnect.Close()
	// 利用标记，让closeChan只关闭一次
	conn.mutex.Lock()
	if !conn.isClosed {
		close(conn.closeChan)
		conn.isClosed = true
	}
	conn.mutex.Unlock()
}

// 内部实现
func (conn *Connection) readLoop() {
	var (
		data []byte
		err  error
	)
	for {
		if _, data, err = conn.wsConnect.ReadMessage(); err != nil {
			goto ERR
		}
		//阻塞在这里，等待inChan有空闲位置
		select {
		case conn.inChan <- data:
		case <-conn.closeChan: // closeChan 感知 conn断开
			goto ERR
		}

	}

ERR:
	conn.Close()
}

func (conn *Connection) writeLoop() {
	var (
		data []byte
		err  error
	)

	for {
		select {
		case data = <-conn.outChan:
		case <-conn.closeChan:
			goto ERR
		}
		if err = conn.wsConnect.WriteMessage(websocket.TextMessage, data); err != nil {
			goto ERR
		}
	}

ERR:
	conn.Close()

}