/**
 * Wrapper class around AJAX functionality.
 */



function Ajax(listener) {

	/**
	 * An instance of XMLHttpRequest (or microsofts activeX object)
	 */
	this.xmlHttpRequest = undefined;

	/**
	 * An instance of Function that is listening for a return and accepts 1 single parameter, this xmlHttpRequest object
	 */
	this.listener = listener;

	/**
	 * Initialise the XMLHttpRequest object
	 *
	 * @return XmlHttpRequest
	 */
	this.initialise = function() {
		// check if the mozilla XMLHttpRequest object is defined
		if (window.XMLHttpRequest) {
			// create the object for mozilla
			try {
				this.xmlHttpRequest = new XMLHttpRequest();
				//if (this.xmlHttpRequest.overrideMimeType) {
				//	this.xmlHttpRequest.overrideMimeType("text/xml");
				//}
			} catch (e) {
				throw e;
			}
		// check if MS ActiveXObject is defined
		} else if (window.ActiveXObject) {
			// create the newer object for IE
			try {
				// try the new IE version first
				this.xmlHttpRequest = new ActiveXObject("Msxml2.XMLHTTP");
			} catch (e) {
				try {
					// try using the old IE version
					this.xmlHttpRequest = new ActiveXObject("Microsoft.XMLHTTP");
				} catch (e2) {
					throw e2;
				}
			}
		} else {
			throw "Browser does not support Ajax.";
		}
	}

	/**
	 * Send an HTTP GET request
	 */
	this.get = function(url) {
		var request = this.xmlHttpRequest;
		var listener = this.listener;
		request.onreadystatechange = function(evt) {
			if (request.readyState == 4 && request.status == 200) {
				listener(request);
			}
		}
		request.open("GET", url, true);
		request.send("");
	}


	/**
	 * Send an HTTP POST request
	 */
	this.post = function(url, queryString) {
		var request = this.xmlHttpRequest;
		request.open("POST", url, true);
		request.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
		var listener = this.listener;
		request.onreadystatechange = function() {
			if (request.readyState == 4) {
				listener(request);
			}
		}
		request.send(queryString);
	}

	/**
	 * Sets the function object that is listening for a return
	 *
	 */
	this.setListener = function(listener) {
		this.listener = listener;
	}


	this.initialise();

}