//Global XMLHTTP Request object
var XmlHttp;


//Creating and setting the instance of appropriate XMLHTTP Request object to a “XmlHttp” variable  
function CreateXmlHttp()
{
	//Creating object of XMLHTTP in IE
	try
	{
		XmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
	}
	catch(e)
	{
		try
		{
			XmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
		} 
		catch(oc)
		{
			XmlHttp = null;
		}
	}
	//Creating object of XMLHTTP in Mozilla and Safari 
	if(!XmlHttp && typeof XMLHttpRequest != "undefined") 
	{
		XmlHttp = new XMLHttpRequest();
	}
}

//Gets called when country combo box selection changes
function CountryListOnChange() 
{
	var countryList = document.getElementById("provincias");

	//Getting the selected country from country combo box.
	var selectedCountry = countryList.options[countryList.selectedIndex].value;
	if(selectedCountry!=0)
	{
	
	// URL to get states for a given country
	var requestUrl = AjaxServerPageName + "?provincia=" + encodeURIComponent(selectedCountry);
	CreateXmlHttp();
	
	// If browser supports XMLHTTPRequest object
	if(XmlHttp)
	{
		//Setting the event handler for the response
		XmlHttp.onreadystatechange = HandleResponse;
		
		//Initializes the request object with GET (METHOD of posting), 
		//Request URL and sets the request as asynchronous.
		XmlHttp.open("GET", requestUrl,  true);
		
		//Sends the request to server
		XmlHttp.send(null);		
	}
	}else //borramos el combo de poblaciones
		{
			    var stateList = document.getElementById("poblacion");
				//Clears the state combo box contents.
				for (var count = stateList.options.length-1; count >-1; count--)
				{
					stateList.options[count] = null;
				}
				var optionItem;
				optionItem = new Option( '(Todas)', 0,  false, false);
				stateList.options[stateList.length] = optionItem;
		}
}


//Called when response comes back from server
function HandleResponse()
{
	// To make sure receiving response data from server is completed
	if(XmlHttp.readyState == 4)
	{
		// To make sure valid response is received from the server, 200 means response received is OK
		if(XmlHttp.status == 200)
		{			
			ClearAndSetStateListItems(XmlHttp.responseXML.documentElement);
		}
		else
		{
			alert('Error al solicitar datos al servidor. Codigo Error: XmlHttp.Status:' + XmlHttp.status);
		}
	}
}

//Clears the contents of state combo box and adds the states of currently selected country
function ClearAndSetStateListItems(countryNode)
{
    var stateList = document.getElementById("poblacion");
	//Clears the state combo box contents.
	for (var count = stateList.options.length-1; count >-1; count--)
	{
		stateList.options[count] = null;
	}

	var stateNodes = countryNode.getElementsByTagName('DESCRIPCION');
	var idNodes = countryNode.getElementsByTagName('ID_POBLACION');
	var textValue;
	var idValue; 
	var optionItem;
	//Insertamos la opción 'Todas'.
	//if (stateNodes.length==0){
	optionItem = new Option( '(Todas)', 0,  false, false);
	stateList.options[stateList.length] = optionItem;
	//}
	//Rellenamos el combo con los datos recibidos.
	for (var count = 0; count < stateNodes.length; count++)
	{
   		textValue = GetInnerText(stateNodes[count]);
   		idValue = GetInnerText(idNodes[count]);
		optionItem = new Option( textValue, idValue,  false, false);
		stateList.options[stateList.length] = optionItem;
	}
}

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