var Request = Class.create({
	initialize: function(opts){
		this.required = new Array();
		this.callOnFinish = new Array();
		Object.extend(this, opts || {});
		if (!this.id || String(this.id).length == 0){
			this.id = Request.generateID();
			this._forget_on_load = true;
		}
	},
	id: "",
	static: false,
	src: "",
	url: function(){
		return this.src + (typeof(this.params) == "undefined" ? "" : "?" + this.params);
	},
	useServerCall: false,
	usePrototype: true,
	loaded: false,
	onFinish: function(){},
	onSuccess: function(){
		this.loaded = true;
		if (typeof this.onFinish == "function") this.onFinish(this);
		this.callOnFinish.invoke("call", this);
		this.callOnFinish.clear();
	},
	onFailure: function(sMessage, nErrorCode){
		if (Object.isFunction(this.onException)) this.onException(sMessage, nErrorCode);
		else alert("Failed to load " + this.url() + ".\n" + sMessage);
	},
	onLoadingStarted: function(){
		if (Object.isFunction(this.src)) this.src = this.src();
		switch (typeof this.params){
			case "function": this.params = this.params(); break;
			case "object": this.params = URLSerializeVS(this.params); break;
		}
	},
	load: function(){
		if (Object.isFunction(this.action)){
			this.action();
			this.onSuccess();
			return;
		}
		this.onLoadingStarted();
		if (this.useServerCall)
			new ServerCall(this.src, this.params || "", {
				onSuccess: function(oPacket){
					this.result = oPacket.Data();
					this.onSuccess();
				}.bind(this),
				onException: this.onFailure.bind(this)
			});
		else if (this.usePrototype)
			new Ajax.Request(this.url(), {
				method: "get",
				onSuccess: function(transport){
					this.transport = transport;
					this.onSuccess();
				}.bind(this),
				onFailure: this.onFailure.bind(this)
			});
		else
			new AjaxRequest("get", this.src, this.params || "", {
				onSuccess: function(transport){
					this.transport = transport.oTransport_;
					this.onSuccess();
				}.bind(this),
				onException: this.onFailure.bind(this)
			});
	},
	AddCallOnFinish: function(func){
		if (Object.isFunction(func)) this.callOnFinish.push(func);
	},
	IsLoaded: function(){ return this.loaded; },
	GetResponseText: function(){ return this.transport.responseText; },
	GetResponseXML: function(){ return this.transport.responseXML; },
	GetResult: function(){ return this.result || {}; }
});

Request.counter = 0;
Request.generateID = function(){
	return "__request__" + (Request.counter++);
};

var RequestLoader = Class.create({
	initialize: function(){
		this.requests = {};
	},

	addRequest: function(request){
		if (!(request instanceof Request)) request = new Request(request);
		this.requests[request.id] = request;
		request.AddCallOnFinish(this.refresh.bind(this));
		request.loader = this;
		if (request.static){
			request.static = false;
			request.started = true;
			if (!GRequestLoader.RequestExists(request.id)) GRequestLoader.addRequest({ "id": request.id, "src": request.src });
			var static_request = GRequestLoader.GetRequest(request.id);
			var complete_request = function(){
				request.transport = static_request.transport;
				request.onSuccess();
			}
			if (static_request.IsLoaded()) complete_request();
			else static_request.AddCallOnFinish(complete_request);
		}else{
			request.started = false;
			this.startRequest(request);
		}
		return request;
	},

	AddRequest: function(request){ return this.addRequest(request); },

	refresh: function(){
		for (requestID in this.requests){
			var request = this.requests[requestID];
			if (request.loaded && request._forget_on_load) delete this.requests[requestID];
			else this.startRequest(request);
		}
	},

	startRequest: function(request){
		if (request.started) return;
		if ($A(request.required).collect(function(requestID){
			if (!this.requests[requestID]) return false;
			return (this.requests[requestID].loaded);
		}, this).all()){
			request.started = true;
			request.load();
		}
	},

	clear: function(requestIDs){
		if (typeof(requestIDs) == "undefined"){
			LogE("Warning: clearing ALL requests");
			this.requests = {};
			return;
		}
		$A(requestIDs).each(function(requestID){
			if (!delete this.requests[requestID]) LogE("Cannot delete request \"" + requestID + "\"");
			else LogL("requests[\"" + requestID + "\"] deleted");
		}, this);
	},

	ClearRequests: function(array){
		if (!Object.isArray(array)) return;
		return this.clear(array);
	},

	RequestExists: function(requestID){
		return !Object.isUndefined(this.requests[requestID]);
	},

	getRequestNames: function(){
		return $H(this.requests).keys();
	},

	GetRequest: function(id){ return this.requests[id]; },

	IsLoaded: function(id){ return this.RequestExists(id) && this.GetRequest(id).IsLoaded(); },

	GetRequestStatuses: function(){
		var result = {};
		this.getRequestNames().each(function(id){
			result[id] = this.requests[id].IsLoaded();
		}.bind(this));
		return result;
	}
});

RequestLoader.SerializeStructure = URLSerializeVS;

var GRequestLoader = new RequestLoader();