var slides = [];
var currentSlide = 0;
var slideShowTimer;

//set the slideshow up once all images have loaded
$(window).load(function(){
    slides = $("#presentation ul li");
    
    if(slides.length > 0){
        $(slides[0]).fadeIn(2000);
        
        $("a#slideshowAdvance, a#slideshowRewind").fadeTo(1, 0).css("display", "");
        
        //make the controls appear on hover over slideshow
        $("#presentation").hover(
            function () {
                $("a#slideshowAdvance, a#slideshowRewind").stop().fadeTo(250, .25);
            }, 
            function () {
                $("a#slideshowAdvance, a#slideshowRewind").stop().fadeTo(250, 0);
            }
        );
        $("a#slideshowAdvance, a#slideshowRewind").hover(
            function () {
                $(this).stop().fadeTo(250, .75);
            }, 
            function () {
                $(this).stop().fadeTo(250, .25);
            }
        );
    
        startSlideshow();
        
    }
});

//start the slideshow timer
function startSlideshow() {
    slideShowTimer = setInterval("advanceSlideshow();", 6500);
}

//stop the slideshow timer
function stopSlideshow() {
    clearTimeout(slideShowTimer);
}

//advance the slideshow 1 slide
function advanceSlideshow(){
    var nextSlide = 0;
    if( currentSlide < slides.length - 1) {
        nextSlide = currentSlide + 1;
    }

    $(slides[currentSlide]).fadeOut(1500);
    $(slides[nextSlide]).fadeIn(2000);
    currentSlide = nextSlide;
}

//rewind the slideshow 1 slide
function rewindSlideshow(){
    var prevSlide = slides.length - 1;
    if( currentSlide > 0) {
        prevSlide = currentSlide - 1;
    }

    $(slides[currentSlide]).fadeOut(1500);
    $(slides[prevSlide]).fadeIn(2000);
    currentSlide = prevSlide;
}