$(function() {

  $(".dropdown-toggle").on("mouseenter", function() {
    $(this).css("cursor", "pointer");
    var menu = $(this).parent().find(".dropdown-menu");

    if (!menu.is(":visible")) {
      menu.show();
    }
  });

  $(".dropdown-toggle").on("click", function() {
    var menu = $(this).parent().find(".dropdown-menu");

    if (menu.is(":visible")) {
      menu.hide();
      $(this).blur();
    } else {
      menu.show();
    }
  });

  $(".dropdown").on("mouseleave", function() {
    var menu = $(this).find(".dropdown-menu");
    $(this).blur();
    if (menu.is(":visible")) {
      menu.hide();
    }
  });

  var swapTimer = 5000; // must be >= 2500
  var maxImages = 15;
  var current = 2;

  // change background-image every swapTimer ms
  function nextBackground() {
    var nextImage = rand(1, maxImages);

    if (nextImage == current) {
      // no change
      if (nextImage > 1) {
        nextImage = rand(1, nextImage - 1);
      } else {
        nextImage = rand(nextImage + 1, maxImages);
      }
    }

    var image = "../images/bg/" + nextImage + ".jpg";

    $(".whole-screen").css("background-image", 'url("' + image + '")').animate({opacity: 1});

    current = nextImage;

    setTimeout(nextBackground, swapTimer);
  }

  setTimeout(nextBackground, swapTimer * 8);

  function rand(min, max) {
    return Math.floor(Math.random() * (max - min + 1) + min);
  }
});