// script to display latest article from XML file
// display in element articleinfo

// global var
var isIE = false;
var arttitle="none";
var artcontent="";
var artlink="";
var req=false;

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

// 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();
        }
    }
}

// loads chosen XML document
function loadDoc() {
	try {
		loadXMLDoc("/cooper-matthews-articles.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 buildTopicList() {
    var items = req.responseXML.getElementsByTagName("item");
    // loop through item elements, and add each nested
    // title element to Topics select element
    for (var i = 0; i < 1; i++) {
        arttitle=getElementTextNS("", "title", items[i], 0);
        artcontent = getElementTextNS("","description", items[i], 0).substring(0,160)+'...';
        artlink = getElementTextNS("","link", items[i], 0);
		var link = document.createElement('a');
		var newBold = document.createElement("b");
		var newText = document.createTextNode(arttitle);
		newBold.appendChild(newText);
		link.appendChild(newBold);
		link.setAttribute('href', artlink);
		var newBr = document.createElement("br");
		var newBr2 = document.createElement("br");
		var description = document.createElement("i");
		var newText2 = document.createTextNode(artcontent);
		description.appendChild(newBr2);
		description.appendChild(newText2);
		var newText3 = document.createTextNode(arttitle);
		var spanq = document.getElementById("articleinfo");
		var throwaway = spanq.appendChild(link);
		throwaway = spanq.appendChild(description);
	}
}

loadDoc();