// Ajax class

function Ajax(){
	this.req = null; // XMLHttpRequest object
	this.url = null; // url van php script
	this.method = null; // GET of POST
	this.async = true; // niet synchroon laden of niet
	this.status = null; // status van server
	this.statusText = ''; // status
	this.postData = null; // body, null voor GET, voor POST komt hierin de data
	this.readyState = null; // status van server
	this.responseText = null; // tekst van server
	this.responseXML = null; // XML van server
	this.handleResp = null; // functie die gegevens van server moet verwerker
	this.responseFormat = null; // 'text', 'xml', 'object', 'JSON'
	this.handleState = null;
	this.id = null;
	
	// maak XMLHttpRequest object
	this.init = function(){
		if (!this.req){
			try{
				// Try to create object for Firefox, Safari, IE7, etc.
				this.req = new XMLHttpRequest();
			}
			catch(e){
				try{
					// Try to create object for later versions of IE.
					this.req = new ActiveXObject('MSXML2.XMLHTTP');
				}
				catch(e){
					try{
						// Try to create object for early versions of IE.
						this.req = new ActiveXObject('Microsoft.XMLHTTP');
					}
					catch(e){
						// Could not create an XMLHttpRequest object.
						return false;
					}
				}
			}
		}
		return this.req;
	};
	
	// stuur request naar server
	this.doReq = function(){
		if (!this.init()) {
			alert('Could not create XMLHttpRequest object.');
			return;
		}
		this.req.open(this.method, this.url, this.async);
		var self = this; // Fix loss-of-scope in inner function
		// wacht op antwoord van server
		this.req.onreadystatechange = function(){
			var resp = null;
			if(self.req.readyState == 4){
				switch (self.responseFormat){
					case 'text':
						resp = self.req.responseText;
						break;
					case 'JSON':
						resp = new Array();
						eval('resp = ' + self.req.responseText);
						break;
					case 'xml':
						resp = self.req.responseXML;
						break;
					case 'object':
						resp = req;
						break;
					
				}
				if(self.handleState != null){
					self.handleState(self.id, true);
				}
				if(self.req.status >= 200 && self.req.status <= 299){
					self.handleResp(self.id, resp);
				}
				else{
					self.handleErr(resp);
				}
			}
			if(self.req.readyState > 0 && self.req.readyState < 4 && self.handleState != null){
				self.handleState(self.id, false);
			}	
		};
		this.req.setRequestHeader('X_USERAGENT', 'AjaxApplicatie');
		this.req.setRequestHeader('Cache-Control', 'no-cache');
		if(this.method == 'POST'){
			this.req.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
			this.req.setRequestHeader("Content-length", this.postData.length);
			this.req.setRequestHeader("Connection", "close");
		}
		this.req.send(this.postData);
	};
	
	
	
	// laat errors zien
	this.handleErr = function(){
		var errorWin;
		try{
			errorWin = window.open('', 'errorWin');
			errorWin.document.body.innerHTML = this.responseText;
		}
		catch(e){
			alert('De foutmelding kan niet getoond worden. Dit komt waarschijnlijk door de pop-up blocker van uw browser\n'
			+ 'Sta pop-ups toe om de volledige foutmelding te bekijken.\n'
			+ '\n'
			+ 'Statuscode: ' + this.req.status + '\n'
			+ 'Statusbeschrijving: ' + this.req.statusText);
		}
	};
	
	// reset XMLHttpRequest object
	this.abort = function(){
		if (this.req) {
			this.req.onreadystatechange = function(){};
			this.req.abort();
			this.req = null;
			this.handleState(this.id, true);
		}
	};
	
	// Request via GET methode
	this.doGet = function(id, url, data, hand, format, state){
		this.id = id;
		this.method = 'GET';
		this.url = url + '?' + data;
		/*for(key in data){
			this.url += key + '=' + data[key] + '&';
		}
		*/
		this.handleResp = hand;
		this.responseFormat = format;
		this.handleState = null || state;
		this.doReq();
	};
	
	// Request via POST methode
	this.doPost = function(id, url, data, hand, format, state){
		this.id = id;
		this.method = 'POST';
		this.url = url;
		this.postData = data;
		/*for(key in data){
			 += key + '=' + data[key] + '&';
		}
		*/
		this.handleResp = hand;
		this.responseFormat = format;
		this.handleState = null || state;
		this.doReq();
	};
}