angular
  .module("rv.directives")
  .directive("bachParallax", function ($window, $document, $interval) {
    return {
      link: function (scope, element, attrs) {
        var sizeOffset;
        var offsetParent = element.offsetParent();
        var mobileInterval;

        function getElementPosition() {
          return {
            top: offsetParent.offset().top,
            height: offsetParent.outerHeight(),
          };
        }

        function getScrollPosition() {
          return {
            top: window.pageYOffset,
            height: window.innerHeight,
          };
        }

        function getVisibilityPercentage() {
          var elementPosition = getElementPosition();
          var scrollPosition = getScrollPosition();
          return (
            (scrollPosition.top +
              scrollPosition.height -
              elementPosition.top -
              15) /
            (elementPosition.height + scrollPosition.height)
          );
        }

        function setPosition() {
          var percentage = getVisibilityPercentage();

          if (percentage >= 0 && percentage <= 1) {
            TweenMax.to(element, 0.1, {
              y: percentage * 2 * sizeOffset - sizeOffset,
            });
          }
        }

        function initPosition() {
          var percentage = getVisibilityPercentage();

          if (percentage >= 0 && percentage <= 1) {
            TweenMax.set(element, {
              y: percentage * 2 * sizeOffset - sizeOffset,
            });
          }
        }

        function handleTouchstart() {
          $document.off("scroll", setPosition);
          setPosition();
        }

        function handleTouchmove() {
          setPosition();

          if (!mobileInterval) {
            mobileInterval = $interval(function () {
              setPosition();
            }, 40);
            $document.on("scroll", handleScrollStop);
          }
        }

        var handleScrollStop = _.debounce(function () {
          if (mobileInterval) {
            setPosition();
            $document.off("scroll", handleScrollStop);
            $interval.cancel(mobileInterval);
            mobileInterval = null;
          }
        }, 1000);

        function init(size) {
          sizeOffset = parseInt(size, 10);
          initPosition();

          if (sizeOffset) {
            scope.$watch(function () {
              return element.height();
            }, initPosition);

            $document.on("scroll", setPosition);
            $document.on("touchstart", handleTouchstart);
            $document.on("touchmove", handleTouchmove);
          }
        }

        init(attrs.bachParallax);
      },
    };
  });