function toggleNavOff() {
  $$('a.nav-item').invoke('removeClassName','nav-item-hover');
}

function toggleNavOn(item) {
  toggleNavOff();
  $(item).addClassName('nav-item-hover');
}

function setOpacity(obj) {
  if (obj.xOpacity > .99) {
    obj.xOpacity = .99;
    return;
  }
  obj.setStyle({
    opacity: obj.xOpacity,
    MozOpacity: obj.xOpacity,
    filter: "alpha(opacity=" + (obj.xOpacity*100) + ")"
  });
}

function tweenImages(currentSlideIndex) {
  var slides = $$('.slide');
  currentSlideOpacity = slides[currentSlideIndex].xOpacity;
  nextSlideIndex = slides[currentSlideIndex + 1] ? currentSlideIndex + 1 : 0;  
  nextSlideOpacity = slides[nextSlideIndex].xOpacity;

  currentSlideOpacity -= .05; 
  nextSlideOpacity += .05;
  
  slides[nextSlideIndex].setStyle({display: 'block'});
  slides[currentSlideIndex].xOpacity = currentSlideOpacity;
  slides[nextSlideIndex].xOpacity = nextSlideOpacity;
  
  setOpacity(slides[currentSlideIndex]); 
  setOpacity(slides[nextSlideIndex]);
  
  if (currentSlideOpacity <= 0) {
    slides[currentSlideIndex].setStyle({display: "none"});
    currentSlideIndex = nextSlideIndex;
    setTimeout("tweenImages(" + currentSlideIndex + ")",1000);
  } else {
    setTimeout("tweenImages(" + currentSlideIndex + ")",50);
  }   
}
  
function runSlideShow() {
  var slides = $$('.slide');
  slides.each( function(slide) { slide.xOpacity = 0 });
  slides[0].setStyle({ display: 'block' });
  slides[0].xOpacity = .99;
  setTimeout("tweenImages(0)",1000);  
}

function showDress(style, aspect, palette) {
  var imageSource = "/images/original-product/" + style + "-" + aspect + ".jpg";
  var frontSource = "/images/original-product/" + style + "-front" + ".jpg";
  var backSource = "/images/original-product/" + style + "-back" + ".jpg";
 
  $('product-image').src = imageSource;
  $('product-text').innerHTML = $(style).innerHTML;
  if(aspect == 'back'){
      $('image-reverse').src = frontSource;
      $('image-reverse').attributes['onclick'].value = "showDress('" + style + "', 'front', '');";
  }else{
      $('image-reverse').src = backSource;
      $('image-reverse').attributes['onclick'].value = "showDress('" + style + "', 'back', '');";
  }
}

function showAlt(style, aspect) {
  var imageSource = "/images/original-product/" + style + "-" + aspect + ".jpg";
  var frontSource = "/images/original-product/" + style + "-front" + ".jpg";
  var backSource = "/images/original-product/" + style + "-back" + ".jpg";
  $('product-image').src = imageSource;
  if(aspect == 'back'){
      $('image-alt').src = frontSource;
      $('image-alt').attributes['onclick'].value = "showAlt('" + style + "', 'front');";
  }else{
      $('image-alt').src = backSource;
      $('image-alt').attributes['onclick'].value = "showAlt('" + style + "', 'back');";
  }
}

function changeLeftNav(navElement, replacementDiv){
  $('text-container').innerHTML = $(replacementDiv).innerHTML; 
  $$('a.left-nav-item').invoke('removeClassName','left-on');
  $(navElement).addClassName('left-on');
}