/*	
	jQuery pub/sub plugin by Túbal Martín (http://margenn.com)

	Inspired by Peter Higgings plugin: https://github.com/phiggins42/bloody-jquery-plugins/blob/8ccf0da40b85fa4ecc30079c8650bac58f7a334c/pubsub.js
*/

(function($) {
	
	// The topics/subscriptions hash
	var topics = {};
	
	/**
	 * @description Publishes some data on a named topic.
	 * @param {String} topic The topic to publish.
	 * @param {Array} [args] The data to publish.			
	 * @returns {jQuery} returns jQuery object.
	 * @example
	 * $( "#sidebarWidget" ).publish( "/some/topic", [ "a", "b", "c" ] ); 
	 */
	$.fn.publish = function ( topic, args ) {	
		args = args || [],
		argsLength = args.length;
		
		if ( topics[topic] ) {
			this.each( function( i, obj ) {
				// Let's add a reference to the publisher object
				args[argsLength] = obj;
				$.each( topics[topic], function( j, aElem ) {
					aElem.callback.apply( aElem.object, args );
				});	
			});
		}
		
		return this;
	};
	
	
	/**
	 * @description Registers a callback on a named topic.
	 * @param {String} topic The topic to subscribe to.
	 * @param {Function} callback The handler. Anytime something is published on a subscribed 
	 * topic, the callback will be called with the published array as ordered arguments.			
	 * @returns {jQuery} returns jQuery object.
	 * @example
	 * $( "#header" ).subscribe( "/some/topic", function( a, b, c ) { // handle data } ); 
	 */
	$.fn.subscribe = function( topic, callback ) {
		topics[topic] = topics[topic] || [];
		
		this.each( function( i, obj ) {
			// Array.push() is way slower. See: http://jsperf.com/array-push-el-vs-array-array-length-el
			topics[topic][topics[topic].length] = { "object": obj, "callback": callback };
		});
		
		return this;	
	};
	
	
	/**
	 * @description Unregisters a previously registered callback for a named topic.
	 * @param {String} topic The topic to unsubscribe from.		
	 * @returns {jQuery} returns jQuery object.
	 * @example
	 * $( "#header" ).unsubscribe( "/some/topic" ); 
	 */
	$.fn.unsubscribe = function ( topic ) {
		
		if ( topics[topic] ) {
			this.each( function( i, obj ) {
				topics[topic] = $.grep( topics[topic], function( aElem, j ) {
					return ( obj !== aElem.object );
				});
			});
			
			if ( topics[topic].length === 0 ) {
				delete topics[topic];
			}
		}
		
		return this;	
	};
	
}(jQuery));