const express = require('express');
const webSocketStream = require('websocket-stream/stream');
const expressWebSocket = require('express-ws');
 const { v4: uuidv4 } = require('uuid')

 // 客户端连接管理
const rtspConnectionsCache={}

// 代理客户端管理
const proxyAgentCache={}

/**
 * 创建网络服务器
 */
function createServer() {
    const app = express();
    expressWebSocket(app, null, {
        perMessageDeflate: true
    });

    // web rtsp request url
    app.ws('/rtsp/', handlerRtsp);
    // proxy agent client connect
    app.ws('/proxy/', handlerProxy);

    // push server stream
    app.ws('/push/', handlerPush);

    app.get('/', (req, response) => {
        response.send('rtsp proxy');
    });

    var server = app.listen(8100,'0.0.0.0', () => {
     const host =server.address().address
     const port =server.address().port
     console.log('started at http://%s:%s',host,port);
    });
}

/**
 * 处理请求连接
 * @param {*} ws 
 * @param {*} req 
 */
function handlerRtsp(ws, req){
    const stream = webSocketStream(ws, {
        binary: true,
        browserBufferTimeout: 1000000
   }, {
        browserBufferTimeout: 1000000
   });

   const rtsp = new Buffer(req.query.url, 'base64').toString();


   console.log('handler rtsp request')
   const connectId = uuidv4()
   rtspConnectionsCache[connectId]=stream

   stream.on('close',()=>{
     console.log('close rtsp connect for:',connectId,rtsp)
      rtspConnectionsCache[connectId]=undefined
   })

   console.log('rtsp connect add cahced')

   const proxyId = req.query.proxyId

   const proxyClientStream =proxyAgentCache[proxyId]
   if(!proxyClientStream){
     ws.close()
   }

   const msg={
     action:'connected',
     connectId,
     payload:{
          rtsp
     }
   }

   console.log('send msg',msg)
   proxyClientStream.write(JSON.stringify(msg))
}

/**
 * 处理网络连接
 * @param {*} ws 
 * @param {*} req 
 */
function handlerProxy(ws,req){
     const stream = webSocketStream(ws, {
          binary: false,
     });

     const proxyId = req.query.proxyId 
     proxyAgentCache[proxyId]=stream
     console.log('add proxy agent into cache proxyId:',proxyId)

     stream.on('close',()=>{
          // 移除proxy id 
          console.log('remove proxyId from cache:',proxyId)
          proxyAgentCache[proxyId]=undefined
     })
}

/**
 * handle push rtsp stream
 * @param {*} ws 
 * @param {*} req 
 */
function handlerPush(ws,req){

     console.log('received push data')
     const stream = webSocketStream(ws, {
          binary: true,
          browserBufferTimeout: 1000000
     }, {
          browserBufferTimeout: 1000000
     });

     const connectId = req.query.connectId
     const connectStream = rtspConnectionsCache[connectId]

     console.log("pipe to connectId",connectId)

     if(!connectStream){
          ws.close()
     }

     connectStream.on('close',()=>{
          console.log('close rtsp push stream')
          stream.end()
     })
     connectStream.on('error',()=>{
          console.log('close rtsp push stream')
          ws.close()
     })
     stream.pipe(connectStream)
}


createServer()