/*
//  Author:  Armand Niculescu
//  Description:  Light weight images slideshow
//  http://www.scriptingmaster.com/javascript/commenting-JavaScript-scripts.asp
*/
slidePrefix = "slide-";
slideControlPrefix = "slide-control-";
slideHighlightClass = "highlight";
slidesContainerID = "slides";
slidesControlsID = "slides-controls";
slideDelay = 10000;
slideAnimationInterval = 20;
slideTransitionSteps = 10;

function setUpSlideShow() {
    // collect the slides and the controls
    slidesCollection = document.getElementById(slidesContainerID).children;
    slidesControllersCollection = document.getElementById(slidesControlsID).children;

    totalSlides = slidesCollection.length;

    if (totalSlides < 2) return;

    //go through all slides
    for (var i = 0; i < slidesCollection.length; i++) {
        // give IDs to slides and controls
        slidesCollection[i].id = slidePrefix + (i + 1);
        slidesControllersCollection[i].id = slideControlPrefix + (i + 1);

        // attach onclick handlers to controls, highlight the first control
        slidesControllersCollection[i].onclick = function () { clickSlide(this); };

        //hide all slides except the first
        if (i > 0)
            slidesCollection[i].style.display = "none";
        else
            slidesControllersCollection[i].className = slideHighlightClass;
    }

    // initialize vars
    slideTransStep = 0;
    transTimeout = 0;
    crtSlideIndex = 1;

    // show the next slide
    showSlide(2);
}

function showSlide(slideNo, immediate) {
    // don't do any action while a transition is in progress
    if (slideTransStep != 0 || slideNo == crtSlideIndex)
        return;

    clearTimeout(transTimeout);

    // get references to the current slide and to the one to be shown next
    nextSlideIndex = slideNo;
    crtSlide = document.getElementById(slidePrefix + crtSlideIndex);
    nextSlide = document.getElementById(slidePrefix + nextSlideIndex);
    slideTransStep = 0;

    // start the transition now upon request or after a delay (default)
    if (immediate == true)
        transSlide();
    else
        transTimeout = setTimeout("transSlide()", slideDelay);
}

function clickSlide(control) {
    showSlide(Number(control.id.substr(control.id.lastIndexOf("-") + 1)), true);
}



function transSlide() {
    // make sure the next slide is visible (albeit transparent)
    nextSlide.style.display = "block";

    // calculate opacity
    var opacity = slideTransStep / slideTransitionSteps;

    // fade out the current slide
    crtSlide.style.opacity = "" + (1 - opacity);
    crtSlide.style.filter = "alpha(opacity=" + (100 - opacity * 100) + ")";

    // fade in the next slide
    nextSlide.style.opacity = "" + opacity;
    nextSlide.style.filter = "alpha(opacity=" + (opacity * 100) + ")";

    // if not completed, do this step again after a short delay
    if (++slideTransStep <= slideTransitionSteps)
        transTimeout = setTimeout("transSlide()", slideAnimationInterval);
    else {
        // complete
        crtSlide.style.display = "none";
        transComplete();
    }
}

function transComplete() {
    slideTransStep = 0;
    crtSlideIndex = nextSlideIndex;

    // for IE filters, removing filters reenables cleartype
    if (nextSlide.style.removeAttribute)
        nextSlide.style.removeAttribute("filter");

    // show next slide
    showSlide((crtSlideIndex >= totalSlides) ? 1 : crtSlideIndex + 1);

    //unhighlight all controls
    for (var i = 0; i < slidesControllersCollection.length; i++)
        slidesControllersCollection[i].className = "";

    // highlight the control for the next slide
    document.getElementById("slide-control-" + crtSlideIndex).className = slideHighlightClass;
}