前端全栈之路--使用Node.js与React仿微信的视频IM应用

/**
 * @File   : koa-websocket.js
 * @Author : Richard Hsueh <xiaowei.hsueh@gmail.com> (https://www.gistop.com/)
 * @Link   : http://www.gistop.com/
 * @Date   : 2018-7-1 16:31:26
 */
const url = require('url');
const https = require('https');
const compose = require('koa-compose');
const co = require('co');
const ws = require('ws');

const WebSocketServer = ws.Server;
const debug = require('debug')('koa:websockets');

function KoaWebSocketServer(app) {
  this.app = app;
  this.middleware = [];
}

KoaWebSocketServer.prototype.listen = function listen(options) {
  this.server = new WebSocketServer(options);
  this.server.on('connection', this.onConnection.bind(this));
};

KoaWebSocketServer.prototype.onConnection = function onConnection(socket, req) {
  debug('Connection received');
  socket.on('error', err => {
    debug('Error occurred:', err);
  });
  const fn = co.wrap(compose(this.middleware));

  const context = this.app.createContext(req);
  context.websocket = socket;
  context.path = url.parse(req.url).pathname;

  fn(context).catch(err => {
    debug(err);
  });
};

KoaWebSocketServer.prototype.use = function use(fn) {
  this.middleware.push(fn);
  return this;
};

module.exports = function middleware(app, wsOptions, httpsOptions) {
  const oldListen = app.listen;
  app.listen = function listen(...args) {
    debug('Attaching server...');
    if (typeof httpsOptions === 'object') {
      const httpsServer = https.createServer(httpsOptions, app.callback());
      app.server = httpsServer.listen(...args);
    } else {
      app.server = oldListen.apply(app, args);
    }
    const options = { server: app.server };
    if (wsOptions) {
      Object.keys(wsOptions).forEach(key => {
        if (Object.prototype.hasOwnProperty.call(wsOptions, key)) {
          options[key] = wsOptions[key];
        }
      });
    }
    app.ws.listen(options);
    return app.server;
  };
  app.ws = new KoaWebSocketServer(app);
  return app;
};

const RTC_MESSAGE_TYPE = {
  CANDIDATE: 'new-ice-candidate',
  HANG_UP: 'hang-up',
  VIDEO_OFFER: 'video-offer',
  VIDEO_ANSWER: 'video-answer',
  INVITE_OFFER: 'invite-offer',
  INVITE_ACCEPT: 'invite-accept',
  INVITE_REFUSE: 'invite-refuse',
  INVITE_CANCEL: 'invite-cancel'
};

websocket.get('/wechat/:token', async(ctx, next) => {
  const { token } = ctx.params;
  const { secret } = configs;
  const user = await verify(token, secret, { ignoreExpiration: true });
  ctx.mongo = mongo;
  // 已经登录通过难
  if (user) {
    const { phone } = user;
    sockets.set(phone, ctx.websocket);
    await sendInitialData(ctx, user);
    ctx.websocket.on('message', message => {
      try {
        const msg = JSON.parse(message);
        const { type } = msg;
        const { payload } = msg;
        const { to } = payload;
        switch (type) {
          case 'candidate':
            sendCandidate(ctx, user, msg);
            break;
          case 'wechat/saveMessage':
            sendMessage(ctx, user, msg);
            break;
          case RTC_MESSAGE_TYPE.CANDIDATE:
          case RTC_MESSAGE_TYPE.HANG_UP:
          case RTC_MESSAGE_TYPE.VIDEO_OFFER:
          case RTC_MESSAGE_TYPE.VIDEO_ANSWER:
          case RTC_MESSAGE_TYPE.INVITE_ACCEPT:
          case RTC_MESSAGE_TYPE.INVITE_CANCEL:
          case RTC_MESSAGE_TYPE.INVITE_OFFER:
          case RTC_MESSAGE_TYPE.INVITE_REFUSE:
            sendMessageToClient(to, message);
            break;
          default:
            break;
        }
      } catch (e) {
        console.error(e);
      }
    });
    ctx.websocket.on('close', () => {
      sockets.delete(phone);
    });
  } else {
    // 未登录的情况直接关闭socket链接
    ctx.websocket.close();
  }
  await next();
});

/**
 * 保存离线消息
 * @param {object} ctx 上下文
 * @param {object} user 当前会话用户
 * @param {object} msg 消息对象
 */
const saveOfflineMessage = async(ctx, user, msg) => {
  const now = new Date();
  const { payload } = msg;
  const { to, content, from, timestamp } = payload;
  const { phone } = user;
  const conversationModel = new ConversationModel(ctx);
  const selector = {
    phone: to
  };
  const prefix = `conversation.${phone}`;
  const document = {
    $set: {
      [`${prefix}.timestamp`]: now.getTime()
    },
    $inc: {
      [`${prefix}.newCount`]: 1
    },
    $addToSet: {
      [`${prefix}.items`]: {
        content,
        to,
        from,
        timestamp
      }
    }
  };
  const options = {
    upsert: true
  };
  const p = conversationModel.update(selector, document, options);
  p.then(() => {
    console.log('保存离线消息成功！');
  }).catch(error => {
    console.log('保存离线消息失败！');
    console.error(error);
  });
};

/**
 * 发送初始化数据
 * @param {Application} ctx 上下文对象
 */
const sendInitialData = async(ctx, user) => {
  const userModel = new UserModel(ctx, user);
  const conversations = await userModel.getConversationList();
  if (conversations) {
    ctx.websocket.send(JSON.stringify({
      type: 'wechat/saveConversation',
      payload: {
        conversations
      }
    }));
  }
  const contacts = await userModel.getContactList();
  ctx.websocket.send(JSON.stringify({
    type: 'wechat/save',
    payload: {
      contacts
    }
  }));
};