// Scroll: Setup Scrolling Stuff

var currentSection = "why_hire-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 = "active";
    if (lastSection) {
        lastTab = lastSection.split("-")[0] + tabTag;
        document.getElementById(lastTab).className = "inactive";
    }
    
    // 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;
}

// Scroll the page using the arrows

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);

}

//
// Animated Scroll Functions
// Scrolls are synchronous -- only one at a time.
//

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;
}