/*	Script: jsonp.js
		Creates a Json request using a script tag include and handles the callbacks for you.
		
		Dependencies:
		Mootools - <Moo.js>, <Array.js>, <String.js>, <Function.js>, <Utility.js>, <Element.js>, <Common.js>
		
		Author:
		Aaron Newton <aaron [dot] newton [at] cnet [dot] com>
		
		Class: JsonP
		Creates a Json request using a script tag include and handles the callbacks for you.
		
		Arguments:
			url - the url to get the json data
			options - an object with key/value options
		
		Options:
			onComplete - (optional) function to execute when the data returns; it will be passed the data
			callBackKey - (string) the key in the url that the server uses to wrap the Json results. 
					So, for example, if you used "callBackKey: 'callback'" then the server is expecting
					something like http://..../?q=search+term&callback=myFunction
					defaults to "callback". This must be defined correctly.
			queryString - (string, optional) additional query string values to append to the url
			data - (object, optional) additional key/value data to append to the url
		
		Example:
			(start code)
				new JsonP('http://api.cnet.com/restApi/v1.0/techProductSearch', {
					data: {
						partTag: 'mtvo',
						iod: 'hlPrice',
						iewType: 'json',
						results: '100',
						query: 'ipod'
					},
					onComplete: myFunction.bind(someObject)
				}).request();
			(end)

		The above example would generate this url:
			(start code)
				http://api.cnet.com/restApi/v1.0/techProductSearch?partTag=mtvo&iod=hlPrice&viewType=json&results=100&query=ipod&callback=JsonP.requestors[0].handleResults&
			(end)

		It would embed this script tag (in the head of the document) and, when it loaded, execute the "myFunction"
		callback defined.
	*/
var JsonP = new Class({
	options: {
		onComplete: Class.empty,
		callBackKey: "callback",
		queryString: "",
		data: {}
	},
	initialize: function(url, options){
		this.setOptions(options);
		this.url = this.makeUrl(url);
		this.fired = false;
	},
	/*	Property: request
		Executes the Json request.
	*/
	request: function(){
		var dl = (window.ie)?50:0; //for some reason, IE needs a moment here...
		(function(){
			this.script = new Asset.javascript(this.url);
			this.fired = true;
		}.bind(this)).delay(dl);
	},
	makeUrl: function(url){
		var index = JsonP.requestors.push(this) - 1;
		var separator = (url.test('\\?'))?'&':'?';
		var jurl = url + separator + this.options.callBackKey + "=JsonP.requestors[" +
				index+"].handleResults";
		if(this.options.queryString) jurl += "&"+this.options.queryString;
		jurl += "&"+Object.toQueryString(this.options.data);
		return jurl;
	},
	handleResults: function(data){
		this.fireEvent('onComplete', data);
		this.script.remove();
	}
});
JsonP.requestors = [];
JsonP.implement(new Options);
JsonP.implement(new Events);