chat-server.js

"use strict";

// Optional. You will see this name in eg. 'ps' or 'top' command
process.title = 'node-chat';

// Port where we'll run the websocket server
const webSocketsServerPort = 1337;

// websocket and http servers
const webSocketServer = require('websocket').server;
const http = require('http');
const fs = require('fs');
const path = require('path');

/**
 * Global variables
 */
// latest 100 messages
var history = [ ];
// list of currently connected clients (users)
var clients = [ ];

/**
 * Helper function for escaping input strings
 */
function htmlEntities(str) {
    return String(str).replace(/&/g, '&amp;').replace(/</g, '&lt;')
                      .replace(/>/g, '&gt;').replace(/"/g, '&quot;');
}

function shuffle(array) {
    let counter = array.length;

    while (counter > 0) {
        const index = Math.floor(Math.random() * counter);
        counter--;
        const temp = array[counter];
        array[counter] = array[index];
        array[index] = temp;
    }

    return array;
}

// Array with some colors
var colors = shuffle([ 'red', 'green', 'blue', 'magenta', 'purple', 'plum', 'orange' ]);

/**
 * HTTP server
 */
var server = http.createServer(function(request, response) {
    // Only support two things, send frontend.html and chat-frontend.js
    let filePath = '.' + request.url;
    if (filePath == './') {
        filePath = './frontend.html';
    }

    let contentType = 'text/html';
    if (path.extname(filePath) == '.js') {
        contentType = 'text/javascript';
    }

    fs.readFile(filePath, function(error, content) {
        response.writeHead(200, { 'Content-Type' : contentType });
        response.end(content, 'utf-8');
    });
});

server.listen(webSocketsServerPort, function() {
    console.log((new Date()) + " Server is listening on port " + webSocketsServerPort);
});

/**
 * WebSocket server
 */
const wsServer = new webSocketServer({
    // WebSocket server is tied to a HTTP server. WebSocket request is just
    // an enhanced HTTP request. For more info http://tools.ietf.org/html/rfc6455#page-6
    httpServer: server
});

// This callback function is called every time someone
// tries to connect to the WebSocket server
wsServer.on('request', function(request) {
    console.log((new Date()) + ' Connection from origin ' + request.origin + '.');

    // accept connection - you should check 'request.origin' to make sure that
    // client is connecting from your website
    // (http://en.wikipedia.org/wiki/Same_origin_policy)
    const connection = request.accept(null, request.origin);
    // we need to know client index to remove them on 'close' event
    const index = clients.push(connection) - 1;
    let userName = false;
    let userColor = false;

    console.log((new Date()) + ' Connection accepted.');

    // send back chat history
    if (history.length > 0) {
        connection.sendUTF(JSON.stringify( { type: 'history', data: history} ));
    }

    // user sent some message
    connection.on('message', function(message) {
        if (message.type === 'utf8') { // accept only text
            if (userName === false) { // first message sent by user is their name
                // remember user name
                userName = htmlEntities(message.utf8Data);
                // get random color and send it back to the user
                userColor = colors.shift();
                connection.sendUTF(JSON.stringify({ type:'color', data: userColor }));
                console.log((new Date()) + ' User is known as: ' + userName
                            + ' with ' + userColor + ' color.');

            } else { // log and broadcast the message
                console.log((new Date()) + ' Received Message from '
                            + userName + ': ' + message.utf8Data);

                send_msg(message, userName, userColor);
            }
        }
    });

    // user disconnected
    connection.on('close', function(connection) {
        if (userName !== false && userColor !== false) {
            console.log((new Date()) + " Peer "
                + connection.remoteAddress + " disconnected.");
            // remove user from the list of connected clients
            clients.splice(index, 1);
            // push back user's color to be reused by another user
            colors.push(userColor);
            send_msg({ utf8Data: "*** disconnected from server ***" }, userName, userColor)
        }
    });

});

function send_msg(message, userName, userColor) {
    const obj = {
        time: (new Date()).getTime(),
        text: htmlEntities(message.utf8Data),
        author: userName,
        color: userColor
    };
    // we want to keep history of all sent messages
    history.push(obj);
    history = history.slice(-100);
    // broadcast message to all connected clients
    const json = JSON.stringify({ type: 'message', data: obj });
    for (var i = 0; i < clients.length; i++) {
        clients[i].sendUTF(json);
    }
}