server.js

require('dotenv').config();
const { authenticateWsConnection } = require('./controllers/authController');
const WebSocket = require('ws');
const {
  notifyClients,
  addSeat,
  removeSeat
} = require('./controllers/webSocketController');
const mongoose = require('mongoose');
const app = require('./app');
const http = require('http');

const port = process.env.PORT || 5000;

process.on('uncaughtException', err => {
  console.log('UNCAUGHT EXEPTION. App crashed...');
  console.log(err.name, err.message, err);

  process.exit(1);
});

const server = http.createServer(app);
server.listen(port, () => {
  console.log(`Listening on port ${port}`);
});

const wss = new WebSocket.Server({
  server,
  verifyClient: authenticateWsConnection,
  clientTracking: true
});

wss.broadcast = notifyClients;

const addSeatHandler = async (callbacks, data) => {
  const cancelCallback = await addSeat(data, function() {
    wss.broadcast({ event: 'seatRemoved', data });
  });
  console.log(cancelCallback);
  callbacks[`${data.line}_${data.seatNumber}`] = cancelCallback;
  wss.broadcast({ event: 'seatAdded', data });
};

wss.on('connection', (ws, req) => {
  console.log('Connection');
  const user = req.user;
  let callbacks = {};

  ws.on('message', async wsEvent => {
    const wsMessage = JSON.parse(wsEvent);
    const { event, data } = JSON.parse(wsMessage);
    data.user = user.id;

    switch (event) {
      case 'addSeat':
        await addSeatHandler(callbacks, data);
        break;

      case 'removeSeat':
        if (callbacks[`${data.line}_${data.seatNumber}`]) {
          clearTimeout(callbacks[`${data.line}_${data.seatNumber}`]);
          delete callbacks[`${data.line}_${data.seatNumber}`];
        }
        removeSeat(data);
        wss.broadcast({ event: 'seatRemoved', data });
        break;
    }
  });

  ws.on('close', (code, reason) => {
    console.log(`Disconnected`);
  });
});

//Db configuration
const db_connection_str = process.env.DB_URL.replace(
  '<username>',
  process.env.DB_USER
).replace('<password>', process.env.DB_PASSWORD);
mongoose.connect(
  db_connection_str,
  {
    useNewUrlParser: true,
    useFindAndModify: false,
    useUnifiedTopology: true
  },
  () => {
    console.log('Db connected');
  }
);

process.on('unhandledRejection', err => {
  console.log('UNHANDLED REJECTION. App crashed...');
  console.log(err.name, err.message);
  server.close(() => {
    process.exit(1);
  });
});