// global flag
var isIE = false;

// global request and XML document objects
var req;
var objName;
// 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,dObj) {	
    // branch for native XMLHttpRequest object
   //alert(dObj);
   if(dObj!=undefined)
{
	   objName = dObj;
   }else{
      objName = "subcategory_code";
   }
    if (window.XMLHttpRequest) {
        req = new XMLHttpRequest();
		req.onreadystatechange = processReqChange;
        req.open("POST", 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("POST", url, true);
           req.send();
        }
    }
}

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


// 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";
    }*/
	return parentElem;
}


// add item to select element the less
// elegant, but compatible way.
function appendToSelect(select, value, content) {
    var opt;
    opt = document.createElement("option");
    opt.value = value;
	opt.appendChild(content);
    select.appendChild(opt);
}


// 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(elem.options[elem.selectedIndex].value);
                }	
            }
            catch(e) {
                var msg = (typeof e == "string") ? e : ((e.message) ? e.message : "Unknown Error");
                alert("Unable to get XML data:\n" + msg);
                return;
            }
        }
    }
}

// empty Topics select list content
function clearTopicList(objName) {
	var select = document.getElementById(objName);
    while (select.length > 0) {
        select.remove(0);
    }
}

// fill Topics select list with items from
// the current XML document
function buildTopicList(objName) {
	//alert("heres");
	var select = document.getElementById(objName);
    //var items = req.responseXML.getElementsByTagName("item");
	var str = req.responseText;
	//alert(str);
	//var str =  str.substr(0,str.length-4);
	var arr ;
	if (""!=str){
		arr= str.split(";");
	}
	//alert(arr.length);
	for (var i = 0; i < arr.length; i++) {
		//alert(arr[i]);
		var valueandcontent = arr[i].split(":");
		//alert(valueandcontent[0]);
		//alert(valueandcontent[1]);
        appendToSelect(select, valueandcontent[0],document.createTextNode(getElementTextNS("", "title", valueandcontent[1], 0)));
    }

    // loop through <item> elements, and add each nested
    // <title> element to Topics select element
    /*for (var i = 0; i < items.length; i++) {
        appendToSelect(select, i,
            document.createTextNode(getElementTextNS("", "title", items[i], 0)));
    }*/
    // clear detail display
    //document.getElementById("details").innerHTML = "";
}

// display details retrieved from XML document
function showDetail(evt) {
    evt = (evt) ? evt : ((window.event) ? window.event : null);
    var item, content, div;
    if (evt) {
        var select = (evt.target) ? evt.target : ((evt.srcElement) ? evt.srcElement : null);
        if (select && select.options.length > 1) {
            // copy <content:encoded> element text for
            // the selected item
            item = req.responseXML.getElementsByTagName("item")[select.value];
            content = getElementTextNS("content", "encoded", item, 0);
            div = document.getElementById("details");
            div.innerHTML = "";
            // blast new HTML content into "details" <div>
            div.innerHTML = content;
        }
    }
}