var EventBus = {
    topics: {},

    subscribe: function (topic, listener) {
        // create the topic if not yet created
        if (!this.topics[topic]) this.topics[topic] = [];

        // add the listener
        this.topics[topic].push(listener);
    },

    publish: function (topic, data) {
        // return if the topic doesn't exist, or there are no listeners
        if (!this.topics[topic] || this.topics[topic].length < 1) return;

        // send the event to all listeners
        this.topics[topic].forEach(function (listener) {
            listener(data || {});
        });
    }
};

EventBus.subscribe('foo', alert);
EventBus.publish('foo', 'Hello World!');

(function() {
    var eventService = this.EventService = {};
    var _listeners = {};

    eventService.add = function (topic, func) {
        if (!func instanceof Function) {
            console.warn(topic + " must add a function.");
        }

        if (!_listeners[topic]) {
            _listeners[topic] = [];
        }
        _listeners[topic].push(func)
    };

    eventService.remove = function (topic, func) {
        if (_listeners[topic]) {
            var index = _listeners[topic].indexOf(func);

            if (index !== -1) {
                _listeners[topic].splice(index, 1);
            }
        }
    };

    eventService.fire = function (topic, data) {
        var listeners;

        if (typeof topic !== 'string') {
            console.warn('EventDispatcher', 'First params must be an event type (String)')
        } else if(_listeners[topic] == undefined)
            console.warn('EventDispatcher', 'No Event Register');
        else {
            _listeners[topic].forEach(function (func) {
                func(data);
            });
        }
    };

    return eventService;
}.call(this));