/*
	File: ASXML.js
	Author: Peter Foran
	Purpose: The ASXML() function acts as a wrapper for all AJAX functionality on the site
*/
function ASXML() {

	var xmlHttpRequest;
	var callbackCode;
	var handle = -1;
	var self = this;
	var isAsync = true;

	this.getHandle = function() {
		return self.handle;
	}

	this.setHandle = function(newHandle) {
		self.handle = newHandle;
	}

	// public functions
	this.xmlResponse = function() {
		return self.xmlHttpRequest.responseXML;
	}

	this.textResponse = function() {
		return self.xmlHttpRequest.responseText;
	} 

	this.statusCode = function() {
		return self.xmlHttpRequest.status;
	}

	this.statusText = function() {
		return self.xmlHttpRequest.statusText;
	} 

	this.setCallback = function(callback) {
		self.callbackCode = callback;
	}

	this.getCallback = function()	{
		return self.callbackCode;
	}

	this.getXML = function(url)	{
		self.xmlHttpRequest = getBrowserHTTPRequest(); // get request object
		self.xmlHttpRequest.onreadystatechange = readyStateChange;
		self.xmlHttpRequest.open("GET", url, isAsync);
		self.xmlHttpRequest.send(null);
	}

	this.postXML = function(url,postData) {
		self.xmlHttpRequest = getBrowserHTTPRequest(); // get request object
		self.xmlHttpRequest.onreadystatechange = readyStateChange;
		self.xmlHttpRequest.open("POST", url, self.isAsync);
		self.xmlHttpRequest.setRequestHeader("Content-Type","application/x-www-form-urlencoded"); 
		self.xmlHttpRequest.send(postData);
	}

	// private functions
	var getBrowserHTTPRequest = function () {
		var httpRequestAccess = null;

		if(window.XMLHttpRequest) // is a moz / IE7 browser
		{
			httpRequestAccess = new XMLHttpRequest();
		}
		else if(window.ActiveXObject) // is a IE4,5,6 browser
		{
			httpRequestAccess = new ActiveXObject("Microsoft.XMLHTTP");
		}

		return httpRequestAccess;
	} 

	var readyStateChange = function () {
		var HTTP_REQUEST_UNINITIALISED = 0;
		var HTTP_REQUEST_LOADING = 1;
		var HTTP_REQUEST_LOADED = 2;
		var HTTP_REQUEST_INTERACTIVE = 3;
		var HTTP_REQUEST_COMPLETE = 4;
		var REQUEST_STATUS_OK = 200;
		var REQUEST_STATUS_NOTFOUND = 404;

		if(self.xmlHttpRequest)	{
			if (self.xmlHttpRequest.readyState == HTTP_REQUEST_COMPLETE) {
				if(self.callbackCode)	{
					self.callbackCode(self.xmlHttpRequest.status == REQUEST_STATUS_OK); //send true back, if the doc loaded ok, false otherwise
				}
			}
		}
	}
	/*==================================*/
	/*Function: clearDDL()				*/
	/*Purpose: clears a dropdownlist	*/
	/*==================================*/
	this.clearDDL = function(ddlID, startTxt, startVal) {

		//clear out dropdownlist
		_ddl = document.getElementById(ddlID);
		while (_ddl.childNodes.length >0){
			_ddl.removeChild(_ddl.childNodes[0]);
		}

		//insert initial value
		var o = document.createElement("Option");
		o.innerHTML = startTxt;
		o.value = startVal;
		_ddl.appendChild(o);
	}
	/*==================================================*/
	/*Function: populateDDL()							*/
	/*Purpose: clears and repopulates a dropdownlist	*/
	/*==================================================*/
	this.populateDDL = function(ddlID, nodes, startTxt, startVal) {

		//clear out dropdownlist
		this.clearDDL(ddlID,startTxt,startVal);

		//populate the dropdown
		for(var i = 0; i < nodes.length; i++) {
			var op=document.createElement("option");
			var v,t;

			if( document.implementation.hasFeature("XPath", "3.0") ) {
				v = nodes[i].selectSingleNode("value/text()").nodeValue;
				t = nodes[i].selectSingleNode("name/text()").nodeValue;}//Mozilla browser (requires mozxpath.js file)
			else
				{v = nodes[i].selectSingleNode("value").text;
				 t = nodes[i].selectSingleNode("name").text;}//IE browser

			op.value = v;
			op.innerHTML = t;
			_ddl.appendChild(op);
		}
	}
}