/** @license
 * RequireJS plugin for async dependency load like JSONP and Google Maps
 * Author: Miller Medeiros
 * Version: 0.1.2 (2014/02/24)
 * Released under the MIT license
 */
define(function(){

	var DEFAULT_PARAM_NAME = 'callback',
		_uid = 0;

	function injectScript(src){
		var s, t;
		s = document.createElement('script'); s.type = 'text/javascript'; s.async = true; s.src = src;
		t = document.getElementsByTagName('script')[0]; t.parentNode.insertBefore(s,t);
	}

	function formatUrl(name, id){
		var paramRegex = /!(.+)/,
			url = name.replace(paramRegex, ''),
			param = (paramRegex.test(name))? name.replace(/.+!/, '') : DEFAULT_PARAM_NAME;
		url += (url.indexOf('?') < 0)? '?' : '&';
		return url + param +'='+ id;
	}

	function uid() {
		_uid += 1;
		return '__async_req_'+ _uid +'__';
	}

	return{
		load : function(name, req, onLoad, config){
			if(config.isBuild){
				onLoad(null); //avoid errors on the optimizer
			}else{
				var id = uid();
				//create a global variable that stores onLoad so callback
				//function can define new module after async load
				window[id] = onLoad;
				injectScript(formatUrl(req.toUrl(name), id));
			}
		}
	};
});