/* ========================================================================
* Bootstrap: scrollspy.js v3.3.2
* http://getbootstrap.com/javascript/#scrollspy
* ========================================================================
* Copyright 2011-2015 Twitter, Inc.
* Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
* ======================================================================== */

/**
 * Customized by iissnan & Ivan.Nginx
 *
 * - Add a `clear.bs.scrollspy` event.
 * - Esacpe targets selector.
 * - Refactored with eslint-config-theme-next style.
 */

/* global NexT */

(function($) {
  'use strict';

  // SCROLLSPY CLASS DEFINITION
  // ==========================
  function ScrollSpy(element, options) {
    this.$body          = $(document.body);
    this.$scrollElement = $(element).is(document.body) ? $(window) : $(element);
    this.options        = $.extend({}, ScrollSpy.DEFAULTS, options);
    this.selector       = (this.options.target || '') + ' .nav li > a';
    this.offsets        = [];
    this.targets        = [];
    this.activeTarget   = null;
    this.scrollHeight   = 0;

    this.$scrollElement.on('scroll.bs.scrollspy', $.proxy(this.process, this));
    this.refresh();
    this.process();
  }

  ScrollSpy.VERSION  = '3.3.2';

  ScrollSpy.DEFAULTS = {
    offset: 10
  };

  ScrollSpy.prototype.getScrollHeight = function() {
    return this.$scrollElement[0].scrollHeight || Math.max(this.$body[0].scrollHeight, document.documentElement.scrollHeight);
  };

  ScrollSpy.prototype.refresh = function() {
    var that          = this;
    var offsetMethod  = 'offset';
    var offsetBase    = 0;

    this.offsets      = [];
    this.targets      = [];
    this.scrollHeight = this.getScrollHeight();

    if (!$.isWindow(this.$scrollElement[0])) {
      offsetMethod = 'position';
      offsetBase   = this.$scrollElement.scrollTop();
    }

    this.$body
      .find(this.selector)
      .map(function() {
        var $el   = $(this);
        var href  = $el.data('target') || $el.attr('href');
        var $href = /^#./.test(href) && $(NexT.utils.escapeSelector(href)); // Need to escape selector.

        return ($href
          && $href.length
          && $href.is(':visible')
          && [[$href[offsetMethod]().top + offsetBase, href]]) || null;
      })
      .sort(function(a, b) {
        return a[0] - b[0];
      })
      .each(function() {
        that.offsets.push(this[0]);
        that.targets.push(this[1]);
      });


  };

  ScrollSpy.prototype.process = function() {
    var scrollTop    = this.$scrollElement.scrollTop() + this.options.offset;
    var scrollHeight = this.getScrollHeight();
    var maxScroll    = this.options.offset + scrollHeight - this.$scrollElement.height();
    var offsets      = this.offsets;
    var targets      = this.targets;
    var activeTarget = this.activeTarget;
    var i;

    if (this.scrollHeight !== scrollHeight) {
      this.refresh();
    }

    if (scrollTop >= maxScroll) {
      return activeTarget !== (i = targets[targets.length - 1]) && this.activate(i);
    }

    if (activeTarget && scrollTop < offsets[0]) {
      $(this.selector).trigger('clear.bs.scrollspy'); // Add a custom event.
      this.activeTarget = null;
      return this.clear();
    }

    for (i = offsets.length; i--;) {
      activeTarget !== targets[i]
        && scrollTop >= offsets[i]
        && (!offsets[i + 1] || scrollTop <= offsets[i + 1])
        && this.activate(targets[i]);
    }
  };

  ScrollSpy.prototype.activate = function(target) {
    this.activeTarget = target;

    this.clear();

    var selector = this.selector
      + '[data-target="' + target + '"],'
      + this.selector + '[href="' + target + '"]';

    var active = $(selector)
      .parents('li')
      .addClass('active');

    if (active.parent('.dropdown-menu').length) {
      active = active
        .closest('li.dropdown')
        .addClass('active');
    }

    active.trigger('activate.bs.scrollspy');
  };

  ScrollSpy.prototype.clear = function() {
    $(this.selector)
      .parentsUntil(this.options.target, '.active')
      .removeClass('active');
  };

  // SCROLLSPY PLUGIN DEFINITION
  // ===========================
  function Plugin(option) {
    return this.each(function() {
      var $this   = $(this);
      var data    = $this.data('bs.scrollspy');
      var options = typeof option === 'object' && option;

      if (!data) $this.data('bs.scrollspy', data = new ScrollSpy(this, options));
      if (typeof option === 'string') data[option]();
    });
  }

  var old = $.fn.scrollspy;

  $.fn.scrollspy             = Plugin;
  $.fn.scrollspy.Constructor = ScrollSpy;

  // SCROLLSPY NO CONFLICT
  // =====================
  $.fn.scrollspy.noConflict = function() {
    $.fn.scrollspy = old;
    return this;
  };

  // SCROLLSPY DATA-API
  // ==================
  $(window).on('load.bs.scrollspy.data-api', function() {
    $('[data-spy="scroll"]').each(function() {
      var $spy = $(this);
      Plugin.call($spy, $spy.data());
    });
  });

}(jQuery));