// global flag
var isIE = false;

// global request and XML document objects
var req;

var sText = ""
var iNews = 0
var index = 0

// retrieve XML document (reusable generic function);
// parameter is URL string (relative or complete) to
// an .xml file whose Content-Type is a valid XML
// type, such as text/xml; XML source must be from
// same domain as HTML file
function loadXMLDoc(url) {
    // branch for native XMLHttpRequest object
    if (window.XMLHttpRequest) {
        req = new XMLHttpRequest();
        req.onreadystatechange = processReqChange;
        req.open("GET", url, true);
		
        req.send(null);
    // branch for IE/Windows ActiveX version
    } else if (window.ActiveXObject) {
        isIE = true;
        req = new ActiveXObject("Microsoft.XMLHTTP");
        if (req) {
            req.onreadystatechange = processReqChange;
            req.open("GET", url, true);
            req.send();
        }
    }
}

// handle onreadystatechange event of req object
function processReqChange() {
    // only if req shows "loaded"
    if (req.readyState == 4) {
        // only if "OK"
        if (req.status == 200) {
			
            GetNewsSource();
         } else {
            alert("There was a problem retrieving the XML data:\n" +
                req.statusText);
         }
    }
}

// invoked by "Category" select element change;
// loads chosen XML document, clears Topics select
// element, loads new items into Topics select element
function loadDoc(evt) {
    // equalize W3C/IE event models to get event object
	
    evt = (evt) ? evt : ((window.event) ? window.event : null);
    if (evt) {
        // equalize W3C/IE models to get event target reference
        var elem = (evt.target) ? evt.target : ((evt.srcElement) ? evt.srcElement : null);
       
		//if (elem) {
            try {
               // if (elem.selectedIndex > 0) {
					
                    loadXMLDoc("http://www.world-nuclear-news.org/rss.xml");
                //}	
            }
            catch(e) {
                var msg = (typeof e == "string") ? e : ((e.message) ? e.message : "Unknown Error");
                alert("Unable to get XML data:\n" + msg);
                return;
            }
        //}
    }
}

// retrieve text of an XML document element, including
// elements using namespaces
function getElementTextNS(prefix, local, parentElem, index) {
    var result = "";
    if (prefix && isIE) {
        // IE/Windows way of handling namespaces
        result = parentElem.getElementsByTagName(prefix + ":" + local)[index];
    } else {
        // the namespace versions of this method 
        // (getElementsByTagNameNS()) operate
        // differently in Safari and Mozilla, but both
        // return value with just local name, provided 
        // there aren't conflicts with non-namespace element
        // names
        result = parentElem.getElementsByTagName(local)[index];
    }
    if (result) {
        // get text, accounting for possible
        // whitespace (carriage return) text nodes 
        if (result.childNodes.length > 1) {
            return result.childNodes[1].nodeValue;
        } else {
            return result.firstChild.nodeValue;    		
        }
    } else {
        return "n/a";
    }
}

// fill Topics select list with items from
// the current XML document
function GetNewsSource() {
   //var select = document.getElementById("topics");
    var items = req.responseXML.getElementsByTagName("item");
	
	
	var iMax = items.length
	
	//sText = items.item(iNews).getElementsByTagName("title").item(0).text
	
	//myTicker.href = items.item(iNews).getElementsByTagName("link").item(0).text
	
	sText = getElementTextNS("", "title", items[iNews], 0)
	//alert("text: " + sText)
	myTicker.href = getElementTextNS("", "link", items[iNews], 0)
	//alert("text: " + myTicker.href)
	
	ticker()
	iNews+=1
	if(iNews==iMax){
		iNews=0
	}
	window.setTimeout("GetNewsSource()", (90*sText.length +4000))
}

function ticker(){
	index+=1
	//alert("myTicker ")
	var cursor = (index == sText.length) ? " " : "_"

	//alert("myTicker ")
	myTicker.innerHTML = sText.substring(0,index) + cursor
	
	//alert("myTicker: " + myTicker.innerText)
	if(index<sText.length){
		window.setTimeout("ticker()",90)
	}
	else{
		index=0
	}
}