// JScript File
// global flag
var isIE = false;

// global request and XML document objects
var req;
var currlevel;

// retrieve XML document (reusable generic function);
function loadXMLDoc(level,item) {
    var myurl = BaseUrl;

    currlevel = 0;    
    if (level > 0 && item > 0) {
        currlevel = level;
        myurl = myurl + "?section=" + Section + "&level=" + currlevel + "&item=" + item;
    }
    //alert("level: " + level + ", item: " + item + ", url: " + myurl);
         
    // branch for native XMLHttpRequest object
    if (window.XMLHttpRequest) {
        req = new XMLHttpRequest();
        req.onreadystatechange = processReqChange;
        req.open("GET", myurl, 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", myurl, 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) {
            clearList(currlevel);
            buildList(currlevel);
         } else {
            alert("There was a problem retrieving the XML data:\n" +
                req.statusText);
         }
    }
}

// empty select list content
function clearList(level) {
    var select;
    
    //alert("clearTopicList:level " + level);    
    switch(level) {
        case 0:
            select = document.getElementById("ctl00_contentMainLeft_ctlTaxonomyNavigator_ddlLevel1");  
            break;    
        case 1:
            select = document.getElementById("ctl00_contentMainLeft_ctlTaxonomyNavigator_ddlLevel2");  
            break;          
        case 2:
            select = document.getElementById("ctl00_contentMainLeft_ctlTaxonomyNavigator_ddlLevel3");  
            break;  
        case 3:
            select = document.getElementById("ctl00_contentMainLeft_ctlTaxonomyNavigator_ddlLevel4");  
            break;     
        case 4:
            select = document.getElementById("ctl00_contentMainLeft_ctlTaxonomyNavigator_ddlLevel5");  
            break;    
        case 5:
            select = document.getElementById("ctl00_contentMainLeft_ctlTaxonomyNavigator_ddlLevel6");  
            break;      
    }
   
    if (level >= 0)
    {   if (select != null)
        {
            while (select.length > 0) {
                select.remove(0);
            }
        }
    }
}

// fill select list with items from XML document returned from taxonomy service call
function buildList(level) {
    var select;
    
    //alert("buildTopicList:level " + level);
    switch(level) {
        case 0:
            select = document.getElementById("ctl00_contentMainLeft_ctlTaxonomyNavigator_ddlLevel1");  
            break;    
        case 1:
            select = document.getElementById("ctl00_contentMainLeft_ctlTaxonomyNavigator_ddlLevel2");  
            break;          
        case 2:
            select = document.getElementById("ctl00_contentMainLeft_ctlTaxonomyNavigator_ddlLevel3");  
            break;  
        case 3:
            select = document.getElementById("ctl00_contentMainLeft_ctlTaxonomyNavigator_ddlLevel4");  
            break;     
        case 4:
            select = document.getElementById("ctl00_contentMainLeft_ctlTaxonomyNavigator_ddlLevel5");  
            break;    
        case 5:
            select = document.getElementById("ctl00_contentMainLeft_ctlTaxonomyNavigator_ddlLevel6");  
            break;     
    }
        
    var items = req.responseXML.getElementsByTagName("item");
    // loop through <item> elements, and add each nested
    // <title> element to Topics select element
    if (select != null)
    {
        //alert("buildTopicList: adding options");
        for (var i = 0; i < items.length; i++) {
            appendToSelect(select, getElementTextNS("", "value", items[i], 0),
                document.createTextNode(getElementTextNS("", "name", items[i], 0)));
        }
    }
}

// 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);
}

// 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";
    }
}

function nullOptions(aMenu){
    aMenu.options.length=0;
}

function changeLevel(level){
    var select;
    
    //alert("changeLevel:level " + level);
    switch(level) {
        case 1:
            select = document.getElementById("ctl00_contentMainLeft_ctlTaxonomyNavigator_ddlLevel1");                    break;    
        case 2:
            select = document.getElementById("ctl00_contentMainLeft_ctlTaxonomyNavigator_ddlLevel2");  
            break;          
        case 3:
            select = document.getElementById("ctl00_contentMainLeft_ctlTaxonomyNavigator_ddlLevel3");  
            break;  
        case 4:
            select = document.getElementById("ctl00_contentMainLeft_ctlTaxonomyNavigator_ddlLevel4");  
            break;     
        case 5:
            select = document.getElementById("ctl00_contentMainLeft_ctlTaxonomyNavigator_ddlLevel5");  
            break;    
        case 6:
            select = document.getElementById("ctl00_contentMainLeft_ctlTaxonomyNavigator_ddlLevel6");  
            break;                                                             
    }
    
    with (select){
        //alert("changeLevel: calling loadXMLDoc");
        loadXMLDoc(level,select.options[select.selectedIndex].value);
    }  
}