package logic

//websocket连接
import (
	"bytes"
	"encoding/hex"
	"encoding/json"
	"errors"
	"fusenapi/constants"
	"fusenapi/utils/auth"
	"fusenapi/utils/basic"
	"fusenapi/utils/encryption_decryption"
	"fusenapi/utils/websocket_data"
	"net/http"
	"strings"
	"sync"
	"time"

	"github.com/google/uuid"
	"github.com/gorilla/websocket"

	"context"

	"fusenapi/server/websocket/internal/svc"

	"github.com/zeromicro/go-zero/core/logx"
)

type DataTransferLogic struct {
	logx.Logger
	ctx    context.Context
	svcCtx *svc.ServiceContext
}

func NewDataTransferLogic(ctx context.Context, svcCtx *svc.ServiceContext) *DataTransferLogic {
	return &DataTransferLogic{
		Logger: logx.WithContext(ctx),
		ctx:    ctx,
		svcCtx: svcCtx,
	}
}

var (
	//临时对象缓存池
	buffPool = sync.Pool{
		New: func() interface{} {
			return bytes.Buffer{}
		},
	}
	//升级websocket
	upgrader = websocket.Upgrader{
		//最大可读取大小 1M
		ReadBufferSize: 1024,
		//最大可写大小 1M
		WriteBufferSize: 1024,
		//握手超时时间15s
		HandshakeTimeout: time.Second * 15,
		//允许跨域
		CheckOrigin: func(r *http.Request) bool {
			return true
		},
		//写的缓冲队列
		WriteBufferPool: &buffPool,
		//是否支持压缩
		EnableCompression: false,
	}
	//websocket连接存储
	mapConnPool = sync.Map{}
	//每个websocket连接入口缓冲队列长度
	websocketInChanLen = 1000
	//每个websocket连接出口缓冲队列长度
	websocketOutChanLen = 1000
	//渲染任务调度（添加任务/删除任务/修改任务属性）缓冲队列长度（该队列用于避免map并发读写冲突）
	renderImageTaskCtlChanLen = 500
	//渲染任务缓冲队列长度
	renderChanLen = 500
)

// 每个连接的连接基本属性
type wsConnectItem struct {
	conn                 *websocket.Conn      //websocket的连接(基本属性)
	userAgent            string               //用户代理头信息(基本属性，用于重连标识验证因素之一)
	logic                *DataTransferLogic   //logic(基本属性，用于获取上下文，配置或者操作数据库)
	closeChan            chan struct{}        //ws连接关闭chan(基本属性)
	isClose              bool                 //是否已经关闭(基本属性)
	uniqueId             string               //ws连接唯一标识(基本属性)
	inChan               chan []byte          //接受消息缓冲队列(基本属性)
	outChan              chan []byte          //要发送回客户端的消息缓冲队列(基本属性)
	mutex                sync.Mutex           //互斥锁(基本属性)
	userId               int64                //用户id(基本属性)
	guestId              int64                //游客id(基本属性)
	extendRenderProperty extendRenderProperty //扩展云渲染属性(扩展属性)
}

// 请求建立连接，升级websocket协议
func (l *DataTransferLogic) DataTransfer(w http.ResponseWriter, r *http.Request) {
	//把子协议携带的token设置到标准token头信息中
	token := r.Header.Get("Sec-Websocket-Protocol")
	//有token是正常用户，无则是白板用户，也可以连接
	if token != "" {
		r.Header.Set("Authorization", "Bearer "+token)
		//设置Sec-Websocket-Protocol
		upgrader.Subprotocols = []string{token}
	}
	//判断下是否火狐浏览器(获取浏览器第一条消息返回有收不到的bug需要延迟1秒)
	userAgent := r.Header.Get("User-Agent")
	//是否火狐浏览器
	isFirefoxBrowser := false
	if strings.Contains(userAgent, "Firefox") {
		isFirefoxBrowser = true
	}
	//升级websocket
	conn, err := upgrader.Upgrade(w, r, nil)
	if err != nil {
		logx.Error("http upgrade websocket err:", err)
		return
	}
	//鉴权不成功后断开
	var (
		userInfo *auth.UserInfo
		isAuth   bool
	)
	isAuth, userInfo = l.checkAuth(r)
	if !isAuth {
		//未授权响应消息
		l.unAuthResponse(conn, isFirefoxBrowser)
		conn.Close()
		return
	}
	//设置连接
	ws, err := l.setConnPool(conn, userInfo, isFirefoxBrowser, userAgent)
	if err != nil {
		conn.Close()
		return
	}
	//循环读客户端信息
	go ws.acceptBrowserMessage()
	//消费出口数据并发送浏览器端
	go ws.consumeOutChanData()
	//消费入口数据
	go ws.consumeInChanData()
	//操作连接中渲染任务的增加/删除
	go ws.operationRenderTask()
	//消费渲染缓冲队列
	go ws.consumeRenderImageData()
	//心跳
	ws.heartbeat()
}

// 设置连接
func (l *DataTransferLogic) setConnPool(conn *websocket.Conn, userInfo *auth.UserInfo, isFirefoxBrowser bool, userAgent string) (wsConnectItem, error) {
	//生成连接唯一标识（失败重试10次）
	uniqueId, err := l.getUniqueId(userInfo, userAgent, 10)
	if err != nil {
		//发送获取唯一标识失败的消息
		l.sendGetUniqueIdErrResponse(conn)
		return wsConnectItem{}, err
	}
	ws := wsConnectItem{
		conn:      conn,
		userAgent: userAgent,
		logic:     l,
		closeChan: make(chan struct{}, 1),
		isClose:   false,
		uniqueId:  uniqueId,
		inChan:    make(chan []byte, websocketInChanLen),
		outChan:   make(chan []byte, websocketOutChanLen),
		mutex:     sync.Mutex{},
		userId:    userInfo.UserId,
		guestId:   userInfo.GuestId,
		extendRenderProperty: extendRenderProperty{
			renderImageTask:        make(map[string]*renderTask),
			renderImageTaskCtlChan: make(chan renderImageControlChanItem, renderImageTaskCtlChanLen),
			renderChan:             make(chan []byte, renderChanLen),
		},
	}
	//保存连接
	mapConnPool.Store(uniqueId, ws)
	if isFirefoxBrowser {
		time.Sleep(time.Second * 1) //兼容下火狐(直接发回去收不到第一条消息：有待研究)
	}
	ws.sendToOutChan(ws.respondDataFormat(constants.WEBSOCKET_CONNECT_SUCCESS, uniqueId))
	return ws, nil
}

// 获取唯一id
func (l *DataTransferLogic) getUniqueId(userInfo *auth.UserInfo, userAgent string, retryTimes int) (uniqueId string, err error) {
	if retryTimes < 0 {
		return "", errors.New("failed to get unique id")
	}
	//后面拼接上用户id
	uniqueId = hex.EncodeToString([]byte(uuid.New().String())) + getUserJoinPart(userInfo.UserId, userInfo.GuestId, userAgent)
	//存在则从新获取
	if _, ok := mapConnPool.Load(uniqueId); ok {
		uniqueId, err = l.getUniqueId(userInfo, userAgent, retryTimes-1)
		if err != nil {
			return "", err
		}
	}
	//加密
	uniqueId, err = encryption_decryption.CBCEncrypt(uniqueId)
	if err != nil {
		return "", err
	}
	return uniqueId, nil
}

// 鉴权
func (l *DataTransferLogic) checkAuth(r *http.Request) (isAuth bool, userInfo *auth.UserInfo) {
	// 解析JWT token,并对空用户进行判断
	userInfo, err := basic.ParseJwtToken(r, l.svcCtx)
	if err != nil {
		return false, nil
	}
	//白板用户
	return true, userInfo
}

// 鉴权失败通知
func (l *DataTransferLogic) unAuthResponse(conn *websocket.Conn, isFirefoxBrowser bool) {
	rsp := websocket_data.DataTransferData{
		T: constants.WEBSOCKET_UNAUTH,
		D: nil,
	}
	b, _ := json.Marshal(rsp)
	if isFirefoxBrowser {
		time.Sleep(time.Second * 1) //兼容下火狐(直接发回去收不到第一条消息：有待研究)
	}
	//先发一条正常信息
	_ = conn.WriteMessage(websocket.TextMessage, b)
	//发送关闭信息
	_ = conn.WriteMessage(websocket.CloseMessage, nil)
}

// 获取唯一标识失败通知
func (l *DataTransferLogic) sendGetUniqueIdErrResponse(conn *websocket.Conn) {
	time.Sleep(time.Second * 1) //兼容下火狐(直接发回去收不到第一条消息：有待研究)
	rsp := websocket_data.DataTransferData{
		T: constants.WEBSOCKET_GEN_UNIQUE_ID_ERR,
		D: "err to gen unique id ",
	}
	b, _ := json.Marshal(rsp)
	//先发一条正常信息
	_ = conn.WriteMessage(websocket.TextMessage, b)
	//发送关闭信息
	_ = conn.WriteMessage(websocket.CloseMessage, nil)
}

// 心跳检测
func (w *wsConnectItem) heartbeat() {
	tick := time.Tick(time.Second * 5)
	for {
		select {
		case <-w.closeChan:
			return
		case <-tick:
			//发送心跳信息
			if err := w.conn.WriteMessage(websocket.PongMessage, nil); err != nil {
				logx.Error("发送心跳信息异常，关闭连接:", w.uniqueId, err)
				w.close()
				return
			}
		}
	}
}

// 关闭websocket连接
func (w *wsConnectItem) close() {
	w.mutex.Lock()
	defer w.mutex.Unlock()
	logx.Info("###websocket:", w.uniqueId, "  uid:", w.userId, "  gid:", w.guestId, " is closing....")
	//发送关闭信息
	_ = w.conn.WriteMessage(websocket.CloseMessage, nil)
	w.conn.Close()
	mapConnPool.Delete(w.uniqueId)
	if !w.isClose {
		w.isClose = true
		close(w.closeChan)
	}
	logx.Info("###websocket:", w.uniqueId, "  uid:", w.userId, "  gid:", w.guestId, " is closed")
}

// 读取出口缓冲队列数据输出返回给浏览器端
func (w *wsConnectItem) consumeOutChanData() {
	defer func() {
		if err := recover(); err != nil {
			logx.Error("write loop panic:", err)
		}
	}()
	for {
		select {
		case <-w.closeChan: //如果关闭了
			return
		case data := <-w.outChan:
			if err := w.conn.WriteMessage(websocket.TextMessage, data); err != nil {
				logx.Error("websocket write loop err:", err)
				w.close()
				return
			}
		}
	}
}

// 消费websocket入口数据池中的数据
func (w *wsConnectItem) consumeInChanData() {
	defer func() {
		if err := recover(); err != nil {
			logx.Error("send loop panic:", err)
		}
	}()
	for {
		select {
		case <-w.closeChan:
			return
		case data := <-w.inChan:
			//对不同消息类型分发处理
			w.allocationProcessing(data)
		}
	}
}

// 接受浏览器端发来的消息并写入入口缓冲队列
func (w *wsConnectItem) acceptBrowserMessage() {
	defer func() {
		if err := recover(); err != nil {
			logx.Error("read loop panic:", err)
		}
	}()
	for {
		select {
		case <-w.closeChan: //如果关闭了
			return
		default: //收取消息
			msgType, data, err := w.conn.ReadMessage()
			if err != nil {
				logx.Error("接受信息错误:", err)
				//关闭连接
				w.close()
				return
			}
			//ping/pong/close的消息不处理
			if msgType != websocket.PingMessage && msgType != websocket.PongMessage && msgType != websocket.CloseMessage {
				w.sendToInChan(data)
			}
		}
	}
}

// 把要传递给客户端的数据放入出口缓冲队列
func (w *wsConnectItem) sendToOutChan(data []byte) {
	select {
	case <-w.closeChan:
		return
	case w.outChan <- data:
		return
	case <-time.After(time.Millisecond * 200): //阻塞超过200ms丢弃
		logx.Error("failed to send to out chan,time expired,data:", string(data))
		return
	}
}

// 发送接受到的消息到入口缓冲队列中
func (w *wsConnectItem) sendToInChan(data []byte) {
	select {
	case <-w.closeChan: //关闭了
		return
	case w.inChan <- data:
		return
	case <-time.After(time.Millisecond * 200): //200豪秒超时丢弃，说明超过消费速度了
		w.sendToOutChan(w.respondDataFormat(constants.WEBSOCKET_INCOME_CACHE_QUEUE_OVERFLOW, "send message is too frequent,the message is ignore by system:"+string(data)))
		return
	}
}

// 格式化为websocket标准返回格式
func (w *wsConnectItem) respondDataFormat(msgType constants.Websocket, data interface{}) []byte {
	d := websocket_data.DataTransferData{
		T: msgType,
		D: data,
	}
	b, _ := json.Marshal(d)
	return b
}

// 处理入口缓冲队列中不同类型的数据（分发处理）
func (w *wsConnectItem) allocationProcessing(data []byte) {
	var parseInfo websocket_data.DataTransferData
	if err := json.Unmarshal(data, &parseInfo); err != nil {
		w.incomeDataFormatErrResponse("invalid format of income message:" + string(data))
		logx.Error("invalid format of websocket message:", err)
		return
	}
	d, _ := json.Marshal(parseInfo.D)
	//获取工厂实例
	processor := w.newAllocationProcessor(parseInfo.T)
	if processor == nil {
		logx.Error("未知消息类型:", string(data))
		return
	}
	//执行工厂方法
	processor.allocationMessage(w, d)
}