jQuery(document).ready(function() {
  initGallery();
});

var images = 0;
var currentImage = 1;
var shiftImage;
var nextButton;
var backButton;
function initGallery() {

  var imageGallery = jQuery("#imageGallery");
  if (imageGallery.length > 0) {
    nextButton = jQuery("#imageGalleryBtnNext div");
    backButton = jQuery("#imageGalleryBtnBack div");
    images = imageGallery.children().length;
    shiftImage = imageGallery.children(":first").clone();
    imageGallery.prepend(shiftImage);
    imageGallery = jQuery("#imageGallery");
    toggleGalleryArrows();
    nextButton.click(function() {
      currentImage++;
      toggleGalleryArrows();
      shiftImage.attr("src", imageGallery.children()[currentImage].src);
    });

    backButton.click(function() {
      currentImage--;
      toggleGalleryArrows();
      shiftImage.attr("src", imageGallery.children()[currentImage].src);
    });
  }
}

function toggleGalleryArrows() {
  if (images > 1) {
    if (currentImage === 1) {
      backButton.css("display", "none");
      nextButton.css("display", "block");
    } else if (currentImage === images) {
      backButton.css("display", "block");
      nextButton.css("display", "none");
    } else {
      backButton.css("display", "block");
      nextButton.css("display", "block");
    }
  } else {
    backButton.css("display", "none");
    nextButton.css("display", "none");
  }
  jQuery("#imageGalleryPaging").html(currentImage + " / " + images);
}