var isIE = false;
var req;

function loadXMLDoc(url) {
    if (window.XMLHttpRequest) {
        req = new XMLHttpRequest();
        req.onreadystatechange = processReqChange;
        req.open("GET", url, true);
        req.send(null);
    } else if (window.ActiveXObject) {
        isIE = true;
        req = new ActiveXObject("Microsoft.XMLHTTP");
        if (req) {
            req.onreadystatechange = processReqChange;
            req.open("GET", url, true);
            req.send();
        }
    }
}

function processReqChange() {
    if (req.readyState == 4) {
        if (req.status == 200) {
            clearTopicList();
            buildTopicList();
         } else {
            alert("There was a problem retrieving the XML data:\n" +
                req.statusText);
         }
    }
}

function loadDoc(evt) {
    evt = (evt) ? evt : ((window.event) ? window.event : null);
    if (evt) {
        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;
            }
        }
    }
}

function getElementTextNS(prefix, local, parentElem, index) {
    var result = "";
    if (prefix && isIE) {
        result = parentElem.getElementsByTagName(prefix + ":" + local)[index];
    } else {
        result = parentElem.getElementsByTagName(local)[index];
    }
    if (result) {
        if (result.childNodes.length > 1) {
            return result.childNodes[1].nodeValue;
        } else {
            return result.firstChild.nodeValue;    		
        }
    } else {
        return "";
    }
}

function clearTopicList() {
    var select = document.getElementById("category");
    while (select.length > 0) {
        select.remove(0);
    }
}

function appendToSelect(select, value, content) {
    var opt;
    opt = document.createElement("option");
    opt.value = value;
    opt.appendChild(content);
    select.appendChild(opt);
}

function buildTopicList() {
    var select = document.getElementById("category");
    var items = req.responseXML.getElementsByTagName("item");
    for (var i = 0; i < items.length; i++) {
        appendToSelect(select, i,
            document.createTextNode(getElementTextNS("", "catname", items[i], 0)));
    }
    document.getElementById("details").innerHTML = "";
}

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) {
            selected = select.value;
            item = req.responseXML.getElementsByTagName("item")[selected];
            item2 = req.responseXML.getElementsByTagName("item")[selected];
            content = getElementTextNS("", "link", item, 0);
            destname = getElementTextNS("", "destination", item2, 0);
            if(content != '')
               window.location='/' + content + '/' + destname + '/';
        }
    }
}