var currentSection = "home-pane"; // The default loaded section on the page
var tabTag = "-tab";
var paneTag = "-pane";

// Scroll the page manually to the position of element "link", passed to us.

function ScrollSection(link, scrollArea, offset)
{

        // Store the last section, and update the current section

        if (currentSection == link) {
                return;
        }
        lastSection = currentSection;
        currentSection = link;

        // Change the section highlight.
        // Extract the root section name, and use that to change the background image to 'top', revealing the alt. state

    sectionTab = currentSection.split("-")[0] + tabTag;
    document.getElementById(sectionTab).className = 'TabbedPanelsTabSelected';
    if (lastSection) {
           lastTab = lastSection.split("-")[0] + tabTag;
           document.getElementById(lastTab).className = "TabbedPanelsTab";
        }

        // Get the element we want to scroll, get the position of the element to scroll to

        theScroll = document.getElementById(scrollArea);
        position = findElementPos(document.getElementById(link));

        // Get the position of the offset div -- the div at the far left.
        // This is the amount we compensate for when scrolling

        if (offset != "") {
                offsetPos = findElementPos(document.getElementById(offset));
                position[0] = position[0] - offsetPos[0];
        }


        scrollStart(theScroll, theScroll.scrollLeft, position[0], "horiz");
        // return false;
}
function ScrollArrow(direction, toolbar, scrollArea, offset) {

        toolbarElem = document.getElementById(toolbar);
        toolbarNames = new Array();

        // Find all the <li> elements in the toolbar, and extract their id's into an array.

        if (toolbarElem.hasChildNodes())
        {
                var children = toolbarElem.childNodes;
                for (var i = 0; i < children.length; i++)
                {
                        if (toolbarElem.childNodes[i].tagName == "LI") {
                                toolbarNames.push(toolbarElem.childNodes[i].id.split("-")[0]);
                        }
                }
        }

        // Now iterate through our array of tab names, find matches, and determine where to go.

        for (var i = 0; i < toolbarNames.length; i++) {
                if (toolbarNames[i] == currentSection.split("-")[0]) {
                        if (direction == "left") {
                                if (i - 1 < 0) {
                                        gotoTab = toolbarNames[toolbarNames.length - 1];
                                } else {
                                        gotoTab = toolbarNames[i - 1];
                                }
                        } else {
                                if ((i + 1) > (toolbarNames.length - 1)) {
                                        gotoTab = toolbarNames[0];
                                } else {
                                        gotoTab = toolbarNames[i + 1];
                                }
                        }
                }
        }

        // Go to the section name!

        ScrollSection(gotoTab+paneTag, scrollArea, offset);

}
var scrollanim = {time:0, begin:0, change:0.0, duration:0.0, element:null, timer:null};

function scrollStart(elem, start, end, direction)
{
        //console.log("scrollStart from "+start+" to "+end+" in direction "+direction);

        if (scrollanim.timer != null) {
                clearInterval(scrollanim.timer);
                scrollanim.timer = null;
        }
        scrollanim.time = 0;
        scrollanim.begin = start;
        scrollanim.change = end - start;
        scrollanim.duration = 25;
        scrollanim.element = elem;

        if (direction == "horiz") {
                scrollanim.timer = setInterval("scrollHorizAnim();", 15);
        }
        else {
                scrollanim.timer = setInterval("scrollVertAnim();", 15);
        }
}

function scrollVertAnim()
{
        if (scrollanim.time > scrollanim.duration) {
                clearInterval(scrollanim.timer);
                scrollanim.timer = null;
        }
        else {
                move = sineInOut(scrollanim.time, scrollanim.begin, scrollanim.change, scrollanim.duration);
                scrollanim.element.scrollTop = move;
                scrollanim.time++;
        }
}

function scrollHorizAnim()
{
        if (scrollanim.time > scrollanim.duration) {
                clearInterval(scrollanim.timer);
                scrollanim.timer = null;
        }
        else {
                move = sineInOut(scrollanim.time, scrollanim.begin, scrollanim.change, scrollanim.duration);
                scrollanim.element.scrollLeft = move;
                scrollanim.time++;
        }
}
function findElementPos(elemFind)
{
        var elemX = 0;
        var elemY = 0;
        do {
                elemX += elemFind.offsetLeft;
                elemY += elemFind.offsetTop;
        } while ( elemFind = elemFind.offsetParent )

        //console.log("Found element "+elemFind+" at "+elemY+"/"+elemX);

        return Array(elemX, elemY);
}
function sineInOut(t, b, c, d)
{
        return -c/2 * (Math.cos(Math.PI*t/d) - 1) + b;
}