! function($, window, document, undefined) {
  $.fn.extend({
    scrollspy: function(options) {
      var defaults = {
        namespace: "scrollspy",
        activeClass: "active",
        animate: !1,
        duration: 1e3,
        offset: 0,
        container: window,
        replaceState: !1
      };
      options = $.extend({}, defaults, options);
      var add = function(ex1, ex2) {
          return parseInt(ex1, 10) + parseInt(ex2, 10)
        },
        findElements = function(links) {
          for (var elements = [], i = 0; i < links.length; i++) {
            var link = links[i],
              hash = $(link).attr("href"),
              element = $(hash);
            if (element.length > 0) {
              var top = Math.floor(element.offset().top),
                bottom = top + Math.floor(element.outerHeight());
              elements.push({
                element: element,
                hash: hash,
                top: top,
                bottom: bottom
              })
            }
          }
          return elements
        },
        findLink = function(links, hash) {
          for (var i = 0; i < links.length; i++) {
            var link = $(links[i]);
            if (link.attr("href") === hash) return link
          }
        },
        resetClasses = function(links) {
          for (var i = 0; i < links.length; i++) $(links[i]).parent().removeClass(options.activeClass)
        },
        scrollArea = "";
      return this.each(function() {
        for (var element = this, container = $(options.container), links = $(element).find("a"), i = 0; i < links.length; i++) {
          var link = links[i];
          $(link).on("click", function(e) {
            var target = $(this).attr("href"),
              $target = $(target);
            if ($target.length > 0) {
              var top = add($target.offset().top, options.offset);
              options.animate ? $("html, body").animate({
                scrollTop: top
              }, options.duration) : window.scrollTo(0, top), e.preventDefault()
            }
          })
        }
        resetClasses(links);
        var elements = findElements(links),
          trackChanged = function() {
            for (var link, position = {
                top: add($(this).scrollTop(), Math.abs(options.offset)),
                left: $(this).scrollLeft()
              }, i = 0; i < elements.length; i++) {
              var current = elements[i];
              if (position.top >= current.top && position.top < current.bottom) {
                var hash = current.hash;
                if (link = findLink(links, hash)) {
                  options.onChange && scrollArea !== hash && (options.onChange(current.element, $(element), position), scrollArea = hash), options.replaceState && history.replaceState({}, "", "/" + hash), resetClasses(links), link.parent().addClass(options.activeClass);
                  break
                }
              }
            }!link && "exit" !== scrollArea && options.onExit && (options.onExit($(element), position), resetClasses(links), scrollArea = "exit", options.replaceState && history.replaceState({}, "", "/"))
          };
        container.bind("scroll." + options.namespace, function() {
          trackChanged()
        }), $(document).ready(function(e) {
          trackChanged()
        })
      })
    }
  })
}(jQuery, window, document);