function NewsScroller() {
    if (window.NewsScrollerInstance != null) {
        window.alert("Only one NewsScroller control is allowed on a page.");
        return;
    }
    window.NewsScrollerInstance = this;
    this.LoadXML = NewsScroller_LoadXML;
    this.AddNewsItem = NewsScroller_AddNewsItem;
    this.Clear = NewsScroller_Clear;
    this.StartScrolling = NewsScroller_StartScrolling;
    this.StopScrolling = NewsScroller_StopScrolling;
    this.Render = NewsScroller_Render;

    // public properties
    this.className = "";
    this.itemNormalClassName = "";

    this.scrollRate = 25;
    this.scrollStep = 1;
    this.scrollPause = 2000;

    // internal use
    this.RenderChildren = NewsScroller_RenderChildren;

    this.renderedControl = "";
    this.itemsText = new Array();
    this.itemsLink = new Array();
    this.itemCount = 0;

    this.scrollEnabled = false;
}

function NewsScroller_LoadXML(sXmlID) {
    this.Clear();
    var xDoc = sXmlID;
    var xItems = xDoc.selectNodes("/Items/Item");
    for (var iNode = 0; iNode < xItems.length; iNode++) {
        var xItem = xItems[iNode];
        var xText = xItem.selectSingleNode("Text");
        var xLink = xItem.selectSingleNode("Link");
        this.AddNewsItem(xText.text, xLink.text);
    }
    var elmControl = document.getElementById(this.renderedControl);
    this.RenderChildren(this.renderedControl);
}

function NewsScroller_AddNewsItem(strText, strLink) {
    strText = replace(strText, '[', '<');
    strText = replace(strText, ']', '>');
    this.itemsText[this.itemCount] = strText;
    this.itemsLink[this.itemCount] = strLink;
    this.itemCount++;
}

function NewsScroller_Clear() {
    this.StopScrolling();
    var elmControl = document.getElementById(this.renderedControl);
    while (elmControl.childNodes.length > 0)
        elmControl.removeChild(elmControl.childNodes[0]);
    this.itemsText = new Array();
    this.itemsLink = new Array();
    this.itemCount = 0;
}

function NewsScroller_StartScrolling() {
    if (this.itemCount > 0) {
        var sControlName = this.renderedControl;
        if (sControlName == null) {
            window.alert("You must render a control before you can start scrolling it.");
            return;
        }
        var elmControl = document.getElementById(sControlName);
        var elmItem0 = document.getElementById("floatingNews0");
        if (this.itemCount > 1) {
            var elmItem1 = document.getElementById(sControlName + "1");
            this.cySeparator = (elmItem1.offsetTop - elmItem0.offsetTop) - elmItem0.offsetHeight;
        } else {
            this.cySeparator = 0;
        }

        if (this.ScrollTimerID == null)
            this.ScrollTimerID = window.setInterval(NewsScroller_ScrollNews, this.scrollRate);
    }
}

function NewsScroller_StopScrolling() {
    window.clearInterval(this.ScrollTimerID);
    this.ScrollTimerID = null;
}

function NewsScroller_Render(sControlID) {
    if (sControlID.length == 0) {
        window.alert("You must provide a unique ID for the rendered control.");
        return;
    }
    var elmControl = document.getElementById(sControlID);
    if (elmControl != null) {
        window.alert("A NewsScroller with this ID has already been rendered. Please use a unique ID.");
        return;
    }
    this.renderedControl = sControlID;

    // <DIV>
    document.write("<div");
    document.write(" id=\"" + sControlID + "\"");
    document.write(" class=\"" + this.className + "\"");
    document.write(" style=\"position: relative; width: 100%; height: 100%; \"");
    document.write(">");

    // </DIV>
    document.write("</div>");

    this.RenderChildren(sControlID);

    var dtNow = new Date();
    var dtResume = new Date(dtNow.getFullYear(), dtNow.getMonth(), dtNow.getDate(), dtNow.getHours(), dtNow.getMinutes(), dtNow.getSeconds(), this.scrollPause);
    elmControl = document.getElementById(sControlID);
    elmControl.ResumeDateTime = dtResume;
}

// Supporting functions
function NewsScroller_RenderChildren() {
    var sControlID = this.renderedControl;
    elmControl = document.getElementById(sControlID);

    // <DIV>
    elmDiv = document.createElement("div");
    elmDiv.style.position = "relative";
    elmDiv.style.left = "0px";
    elmDiv.style.top = "0px";
    elmDiv.style.width = "100%";
    elmDiv.style.height = "100%";
    elmDiv.style.overflow = "hidden";
    elmControl.appendChild(elmDiv);

    for (var nItem = 0; nItem < this.itemCount; nItem++) {
        var sItemName = sControlID + nItem.toString();

        var elmP = document.createElement("div");
        elmP.id = sItemName;
        elmP.style.position = "relative";
        elmP.style.top = "0px";
        elmP.style.width = "100%";
        elmP.style.paddingBottom = "10px";
        elmP.className = this.itemNormalClassName;
        elmDiv.appendChild(elmP);

        var elmA = document.createElement("a");
        elmA.className = this.itemNormalClassName;
        elmA.href = this.itemsLink[nItem];
        elmA.innerHTML = this.itemsText[nItem];
        elmP.appendChild(elmA);
    }
}

function NewsScroller_ScrollNews() {
    var ns = window.NewsScrollerInstance;
    var sControlName = ns.renderedControl;
    if (sControlName.length == 0) {
        //window.alert ("Do not call ScrollNews directly. Use the Start method of the NewsScroller object.");
        //window.status = 'Do not call ScrollNews directly. Use the Start method of the NewsScroller object.';
        return;
    }

    var elmControl = document.getElementById(sControlName);
    if (new Date() >= elmControl.ResumeDateTime) {
        // see whether any item is about to reach the top,
        for (var nItem = 0; nItem < ns.itemCount; nItem++) {
            var sItemName = sControlName + nItem.toString();
            var elmItem = document.getElementById(sItemName);
            var elTop = Number(String(elmItem.style.top).substr(0, String(elmItem.style.top).length - 2))
            elmItem.style.top = (elTop - ns.scrollStep) + "px";

            if ((elmItem.offsetTop > 0) && ((elmItem.offsetTop - ns.scrollStep) <= 0)) {
                // the top of this item has reached the top of the control, pause for # seconds
                var dtNow = new Date();
                var dtResume = new Date(dtNow.getFullYear(), dtNow.getMonth(), dtNow.getDate(), dtNow.getHours(), dtNow.getMinutes(), dtNow.getSeconds(), ns.scrollPause);
                elmControl.ResumeDateTime = dtResume;
            }
        }

        //check if the item at the top should be put to the bottom
        for (var nItem = 0; nItem < ns.itemCount; nItem++) {
            var sItemName = sControlName + nItem.toString();
            var elmItem = document.getElementById(sItemName);
            if (elmItem.offsetTop < (0 - elmItem.offsetHeight)) {
                var elmLast = document.getElementById(sControlName + (ns.itemCount - 1));
                elmItem.style.top = (elmLast.offsetTop + elmLast.offsetHeight) + "px";
            }
        }

    }
}

function replace(string, text, by) {
    var strLength = string.length, txtLength = text.length;
    if ((strLength == 0) || (txtLength == 0)) return string;

    var i = string.indexOf(text);
    if ((!i) && (text != string.substring(0, txtLength))) return string;
    if (i == -1) return string;

    var newstr = string.substring(0, i) + by;

    if (i + txtLength < strLength)
        newstr += replace(string.substring(i + txtLength, strLength), text, by);

    return newstr;
}