stream trading events from Luno.com

stream.js

var WebsocketClient = require('websocket').client,
    colors = require('colors'),
    sprintf = require('sprintf-js').sprintf;

var ws = new WebsocketClient();
var asks = bids = {};

var now = function () {
    var date = new Date();
    return sprintf("%02d:%02d:%02d", date.getHours(), date.getMinutes(), date.getSeconds());
}

ws.on('connect', function (conn) {
    console.log('connection established.');
    conn.on('message', function (msg) {
        var data = JSON.parse(msg.utf8Data);
        if (data == "") return;
        if (data.trade_updates) {
            data.trade_updates.forEach(function (trade) {
                var price = trade.order_id in asks ? asks[trade.order_id].price : bids[trade.order_id].price;
                console.log(sprintf("%16s %-15s %11s %15s %10s", "TRADE".white, trade.order_id, trade.base, price, now()));
            });
        }
        if (data.create_update) {
            if (data.create_update.type == "BID") {
                bids[data.create_update.order_id] = {price: data.create_update.price, volume: data.create_update.volume};
                console.log(sprintf("%16s %-15s %11s %15s %10s", colors.green(data.create_update.type), data.create_update.order_id, data.create_update.volume, data.create_update.price, now()));
            } else {
                bids[data.create_update.order_id] = {price: data.create_update.price, volume: data.create_update.volume};
                console.log(sprintf("%16s %-15s %11s %15s %10s", colors.yellow(data.create_update.type), data.create_update.order_id, data.create_update.volume, data.create_update.price, now()));
            }
        }
        if (data.delete_update) {
            if (data.delete_update.order_id in asks) {
                console.log(sprintf("%16s %-15s %11s %15s %10s", "DELETE".red, data.delete_update.order_id, asks[data.delete_update.order_id].volume, asks[data.delete_update.order_id].price, now()));
                delete asks[data.delete_update.order_id];
            } else if (data.delete_update.order_id in bids) {
                console.log(sprintf("%16s %-15s %11s %15s %10s", "DELETE".red, data.delete_update.order_id, bids[data.delete_update.order_id].volume, bids[data.delete_update.order_id].price, now()));
                delete bids[data.delete_update.order_id];
            } else {
                console.log(sprintf("%16s %-15s %10s", "DELETE".red, data.delete_update.order_id, now()));
            }
        }
        if (data.asks) {
            asks = {};
            data.asks.forEach(function (ask) {
                asks[ask.id] = {price: ask.price, volume: ask.volume};
            });
        }
        if (data.bids) {
            bids = {};
            data.bids.forEach(function (bid) {
                bids[bid.id] = {price: bid.price, volume: bid.volume};
            });
        }
    });
    conn.on('close', function () {
        console.log('connected closed.');
    });
    conn.on('error', function (err) {
        console.log('err:', err.toString());
    });
    conn.sendUTF('');
});

var options = ['NGN', 'ZAR', 'IDR', 'MYR', 'SGD'];

if (process.argv.length < 3 || options.indexOf(process.argv[2]) == -1) {
    console.log('usage:', process.argv[1], '(' + options.join('|') + ')');
    process.exit(9);
}

ws.connect('wss://ws.bitx.co/XBT' + options.find(function (item) { return item == process.argv[2]; }));