// JavaScript Document

	/*
	Script: XHR.js
	        Contains the basic XMLHttpRequest Class Wrapper.
	
	License:
	        MIT-style license.
	*/
	
	/*
	Class: XHR
	        Basic XMLHttpRequest Wrapper.
	
	Arguments:
	        options - an object with options names as keys. See options below.
	
	Options:
	        method - 'post' or 'get' - the protocol for the request; optional, defaults to 'post'.
	        async - boolean: asynchronous option; true uses asynchronous requests. Defaults to true.
	        onRequest - function to execute when the XHR request is fired.
	        onSuccess - function to execute when the XHR request completes.
	        onStateChange - function to execute when the state of the XMLHttpRequest changes.
	        onFailure - function to execute when the state of the XMLHttpRequest changes.
	        encoding - the encoding, defaults to utf-8.
	        autoCancel - cancels the already running request if another one is sent. defaults to false.
	        headers - accepts an object, that will be set to request headers.
	
	Properties:
	        running - true if the request is running.
	        response - object, text and xml as keys. You can access this property in the onSuccess event.
	
	Example:
	        >var myXHR = new XHR({method: 'get'}).send('http://site.com/requestHandler.php', 'name=john&lastname=dorian');
	*/
	
	var XHR = new Class({
	
	        options: {
	                method: 'post',
	                async: true,
	                onRequest: Class.empty,
	                onSuccess: Class.empty,
	                onFailure: Class.empty,
	                urlEncoded: true,
	                encoding: 'utf-8',
	                autoCancel: false,
	                headers: {}
	        },
	       
	        setTransport: function(){
	                this.transport = (window.XMLHttpRequest) ? new XMLHttpRequest() : (window.ie ? new ActiveXObject('Microsoft.XMLHTTP') : false);
	                return this;
	        },
	
	        initialize: function(options){
	                this.setTransport().setOptions(options);
	                this.options.isSuccess = this.options.isSuccess || this.isSuccess;
	                this.headers = {};
	                if (this.options.urlEncoded && this.options.method == 'post'){
	                        var encoding = (this.options.encoding) ? '; charset=' + this.options.encoding : '';
	                        this.setHeader('Content-type', 'application/x-www-form-urlencoded' + encoding);
	                }
	                if (this.options.initialize) this.options.initialize.call(this);
	        },
	
	        onStateChange: function(){
	                if (this.transport.readyState != 4 || !this.running) return;
	                this.running = false;
	                var status = 0;
					try {status = this.transport.status} catch(e){};
	                if (this.options.isSuccess.call(this, status)) this.onSuccess();
	                else this.onFailure();
	                this.transport.onreadystatechange = Class.empty;
	        },
	
	        isSuccess: function(status){
	                return ((status >= 200) && (status < 300));
	        },
	
	        onSuccess: function(){
	                this.response = {
	                        'text': this.transport.responseText,
	                        'xml': this.transport.responseXML
	                };
	                this.fireEvent('onSuccess', [this.response.text, this.response.xml]);
	                this.callChain();
	        },
		        onFailure: function(){
	                this.fireEvent('onFailure', this.transport);
	        },
	
	        /*
	        Property: setHeader
	                Add/modify an header for the request. It will not override headers from the options.
	
	        Example:
	                >var myAjax = new Ajax(url, {method: 'get', headers: {'X-Request': 'JSON'}});
	                >myAjax.setHeader('Last-Modified','Sat, 1 Jan 2005 05:00:00 GMT');
	        */
	
	        setHeader: function(name, value){
	                this.headers[name] = value;
	                return this;
        },
	
	        /*
	        Property: send
	                Opens the XHR connection and sends the data. Data has to be null or a string.
	
	        Example:
	                >var myXhr = new XHR({method: 'post'});
	                >myXhr.send(url, querystring);
	                >
	                >var syncXhr = new XHR({async: false, method: 'post'});
	                >syncXhr.send(url, null);
	                >
	        */
	
	        send: function(url, data){
	                if (this.options.autoCancel) this.cancel();
	                else if (this.running) return this;
	                this.running = true;
	                if (data && this.options.method == 'get') url = url + (url.contains('?') ? '&' : '?') + data, data = null;
	                this.transport.open(this.options.method, url, this.options.async);
	                this.transport.onreadystatechange = this.onStateChange.bind(this);
	                if ((this.options.method == 'post') && this.transport.overrideMimeType) this.setHeader('Connection', 'close');
	                $extend(this.headers, this.options.headers);
	                for (var type in this.headers) try {this.transport.setRequestHeader(type, this.headers[type]);} catch(e){};
	                this.fireEvent('onRequest');
	                this.transport.send($pick(data, null));
	                return this;
	        },
	
	        /*
	        Property: cancel
	                Cancels the running request. No effect if the request is not running.
	
	        Example:
	                >var myXhr = new XHR({method: 'get'}).send(url);
	                >myXhr.cancel();
	        */
	
	        cancel: function(){
	                if (!this.running) return this;
	                this.running = false;
	                this.transport.abort();
	                this.transport.onreadystatechange = Class.empty;
	                this.setTransport();
	                this.fireEvent('onCancel');
	                return this;
	        }
	
	});

	XHR.implement(new Chain, new Events, new Options);