/* ***********************************************************************
 * Class to create Flickr-API REST calls. 
 * See http://www.flickr.com/services/api/ for supported
 * methods, params and returns.
 * 1. 	You need a valid API-Key 
 * 		(http://www.flickr.com/services/apps/create/apply/)
 * 2.	This class is supported on 
 *  	- Internet Explorer 8+
 *  	- Firefox 3.1+
 *  	- Safari 4+
 *  	- Chrome 3+
 *  	- Opera 10.5+
 * 		If you're using an older browser, include the json2.js library
 * 		(https://github.com/douglascrockford/JSON-js/blob/master/json2.js)
 * 3.	This class only supports JSON-response-format
 * 4.	This class doesn's support authentication and methods which
 * 		require user authorization.
 * 
 * CONSTRUCTOR(apiKey):
 * Parameters:		apiKey:
 * 					Your valid API key
 * 
 * METHODS:
 * 	Api(method, callback, params, cparams):
 *  Creates a async request for given method with given params.
 * 	Parameters:		method:
 * 					Name of the Flickr-API-REST method as STRING.
 * 					callback:
 * 					Function to call after response. Should take minimum 
 * 					one parameter as API-Response as JS-Object, 
 * 					2. optional parameter = cparams (callback-params)
 * 					params:
 * 					API-method parameters as Object
 * 					cparams (optional). Additional parameters for call-
 * 					back function.
 * 	Return:			VOID
 * 
 *  Api_S(method, callback)
 *  Creates a sync request for given method with given params.
 *  Parameters:		See Flickr.Api-method
 *  Return:			API-Response as JS-Object.
 * 
 * //////////////// EXAMPLE /////////////////
 * 	var f = new Flickr("[MyApiKey]");
 * 	f.Api(
 * 		"flickr.photos.search",
 * 		function(resp){
 *	 		if(resp.stat != "fail"){
 * 				alert("Number of photos: " + resp.photos.total);} 
 * 			}else{
 *				alert("API-error: " + resp.message); 
 * 			}
 * 		},
 * 		{user_id: "[MyFlickrUserId]"}
 *  );
 * 
 * **********************************************************************/
function Flickr(apiKey){
	if(!apiKey){throw "InvalidApiKeyProvided";}
	this.key = apiKey;
	this.Api = function(method, callback, params, cparams){
 
		var xhttp = new XMLHttpRequest();
		xhttp.open('GET', this.createUrl(method, params), true);
		xhttp.onreadystatechange = function(){
			if(xhttp.readyState == 4){
				callback(JSON.parse(xhttp.responseText), cparams);
			}
		}
		xhttp.send(null);
	}
	this.Api_S = function(method, params){
		var xhttp = new XMLHttpRequest();
		xhttp.open('GET', this.createUrl(method, params), false);
		xhttp.send(null);
		return JSON.parse(xhttp.responseText);
	}
	this.createUrl = function(method, params){
		var url = 
			"http://api.flickr.com/services/rest/?method=" + method + 
			"&api_key=" + this.key + 
			"&format=json" +
			"&nojsoncallback=1";
		if(params){
			for(var p in params){
				url += "&" + p + "=" + params[p];
			}
		}
		return url;
	}
}