// declare a global XMLHTTP Request Object
var XmlHttpObj = false;

// create an instance of XMLHTTP Request Object, varies with browser type, try for IE first then Mozilla
function CreateXmlHttpObj()
{
	// try creating for IE (note: we don't know the user's browser type here, just attempting IE first.)
	try
	{
		XmlHttpObj = new ActiveXObject("Msxml2.XMLHTTP");
	}
	catch(e)
	{
		try
		{
			XmlHttpObj = new ActiveXObject("Microsoft.XMLHTTP");
		} 
		catch(e2)
		{
			XmlHttpObj = false;
		}
	}
	// if unable to create using IE specific code then try creating for Mozilla (FireFox) 
	if(!XmlHttpObj && typeof XMLHttpRequest != 'undefined')
	{
		XmlHttpObj = new XMLHttpRequest();
	}
}

// called from onChange or onClick event of the continent dropdown list
function countryListOnChange() 
{
    var countryList = document.getElementById("countryList");
    
    // get selected continent from dropdown list
    var selectedContinent = countryList.options[countryList.selectedIndex].value;
    
    // url of page that will send xml data back to client browser
    var requestUrl;
    // use the following line if using asp
    requestUrl = "geoselector/xml_data_provider2.php" + "?filter=" + encodeURIComponent(selectedContinent) + "&dummy=" + new Date().getTime();
    // use the following line if using php
    // requestUrl = "geoselector/xml_data_provider2.php" + "?filter=" + encodeURIComponent(selectedContinent) + "&dummy=" + new Date().getTime();
    
	CreateXmlHttpObj();
	
	// verify XmlHttpObj variable was successfully initialized
	if(XmlHttpObj)
	{
        // assign the StateChangeHandler function ( defined below in this file)
        // to be called when the state of the XmlHttpObj changes
        // receiving data back from the server is one such change
		XmlHttpObj.onreadystatechange = StateChangeHandler;
		
		// define the iteraction with the server -- true for as asynchronous.
		XmlHttpObj.open("GET", requestUrl,  true);
		
		// send request to server, null arg  when using "GET"
		XmlHttpObj.send(null);		
	}
}

// called from onChange or onClick event of the region dropdown list
function ClearRegionsOnChange() 
{
	var regionList = document.getElementById("regionList");
	var areaList = document.getElementById("areaList");
	
	// clear the region list 
	for (var count = regionList.options.length-1; count >-1; count--)
	{
		regionList.options[count] = null;
	}
	
	if (areaList.selectedIndex == 0)
	{
		optionItem = new Option("All", 0,  false, false);
		regionList.options[regionList.length] = optionItem;
	}
	
	else
	{
		optionItem = new Option("All", 0,  false, false);
		regionList.options[regionList.length] = optionItem;
		
		optionItem = new Option("North", "North",  false, false);
		regionList.options[regionList.length] = optionItem;
		
		optionItem = new Option("West", "West",  false, false);
		regionList.options[regionList.length] = optionItem;
		
		optionItem = new Option("Central", "Central",  false, false);
		regionList.options[regionList.length] = optionItem;
		
		optionItem = new Option("East", "East",  false, false);
		regionList.options[regionList.length] = optionItem;
		
		optionItem = new Option("South", "South",  false, false);
		regionList.options[regionList.length] = optionItem;
		
		regionList.selectedIndex = 0;
	}
}

// this function called when state of  XmlHttpObj changes
// we're interested in the state that indicates data has been
// received from the server
function StateChangeHandler()
{
	// state ==4 indicates receiving response data from server is completed
	if(XmlHttpObj.readyState == 4)
	{
		// To make sure valid response is received from the server, 200 means response received is OK
		if(XmlHttpObj.status == 200)
		{			
			PopulateareaList(XmlHttpObj.responseXML.documentElement);
		}
		else
		{
			alert("problem retrieving data from the server, status code: "  + XmlHttpObj.status);
		}
	}
}

// populate the contents of the country dropdown list
function PopulateareaList(countryNode)
{
    var areaList = document.getElementById("areaList");
	// clear the country list 
	for (var count = areaList.options.length-1; count >-1; count--)
	{
		areaList.options[count] = null;
	}
	
	var regionList = document.getElementById("regionList");
	//regionList.selectedIndex = 0;
	
	// clear the region list 
	for (var count = regionList.options.length-1; count >-1; count--)
	{
		regionList.options[count] = null;
	}
	
	optionItem = new Option("All", 0,  false, false);
	regionList.options[regionList.length] = optionItem;

	var countryNodes = countryNode.getElementsByTagName('country');
	var idValue;
	var textValue; 
	var optionItem;
	// populate the dropdown list with data from the xml doc
	if (countryNodes.length > 0)
	{
		optionItem = new Option("All", 0,  false, false);
		areaList.options[areaList.length] = optionItem;
		
		for (var count = 0; count < countryNodes.length; count++)
		{
			textValue = GetInnerText(countryNodes[count]);
			idValue = countryNodes[count].getAttribute("id");
			optionItem = new Option(textValue, textValue,  false, false);
			areaList.options[areaList.length] = optionItem;
		}
		
		
	}
	else
	{
		optionItem = new Option("All", 0,  false, false);
		areaList.options[areaList.length] = optionItem;
	}

}

// returns the node text value 
function GetInnerText (node)
{
	 return (node.textContent || node.innerText || node.text) ;
}