index.js

const express = require('express');
const path = require('path');
const get = require('lodash/get');
const enableKafka = require('./backend/kafka/index');
const randomLogin = require('./backend/nicknames/generator');

const defaultPort = 8080;

function getPort() {
	return (
		process.argv
			.filter(a => a.startsWith('port'))
			.map(val => Number(val.split(/[ =]+/g)[1] || defaultPort))
			.pop() || defaultPort
	);
}

const port = getPort(); // should be possible to overide the port via console arg
const v = 11; // indicating app version from kubernetes logs

const app = express();
const server = require('http').Server(app);
const io = require('socket.io')(server);

app.use(express.static('build/public'));

app.get('/api', (req, res) => res.json(process.env)); // test rest api

// as we don't have separate persistance service (like redis) we have to introduce local state <- which is not good.
// With stateless services everything is simpler!
const set = new Set();

if (process.env.KAFKA_ENABLED === 'true') {
	const emitter = enableKafka(io);
	emitter.on('kafkaIncome', msg => {
		const data = get(JSON.parse(msg.value), 'packet.data', []);
		if (data[0] === 'userConnected') {
			set.add(data[1]);
		}
		if (data[0] === 'userDisconnected') {
			set.delete(data[1]);
		}
	});
}

function getUserName(socket) {
	const cookie = get(socket, 'handshake.headers.cookie', '');
	const check = cookie.split(/\s*;\s*/).find(c => c.startsWith('check'));
	if (!check) {
		return randomLogin();
	}

	const parts = check.split('^');
	if (!parts.length === 2) {
		return randomLogin();
	}

	const userData = parts[1].split('|');
	if (!userData.length === 4) {
		return randomLogin();
	}

	return `${decodeURIComponent(userData[1])}_${decodeURIComponent(userData[2])} (${userData[0]})`;
}

/** Chat Websocket logic is here */
const chat = io.of('/api/chat').on('connection', socket => {
	const nick = getUserName(socket);
	set.add(nick);
	socket.emit('message', { msg: `Welcome #${nick}`, currUserId: nick });
	socket.emit('activeUsers', Array.from(set));
	socket.broadcast.emit('message', { msg: `${nick} connected to the chat` });

	chat.emit('userConnected', nick);

	socket.on('message', msg => {
		console.log(`message: ${msg}`);

		const time = new Date();
		chat.emit('message', {
			msg,
			user: nick,
			time: `${time.getHours()}:${time.getMinutes()}`,
		});
	});

	socket.on('disconnect', () => {
		set.delete(nick);
		chat.emit('userDisconnected', nick);
		chat.emit('message', { msg: `~ ${nick} disconnected` });
		console.log('Client disconnected');
	});
});

app.get('*', (req, res) => {
	const fileDirectory = path.resolve(__dirname, '.', 'public/');

	res.sendFile('index.html', { root: fileDirectory });
});

/* Run the application */
server.listen(port, () => console.log('Chat server started...', { port, v }));