/*
 * Solo - A small and beautiful blogging system written in Java.
 * Copyright (c) 2010-2019, b3log.org & hacpai.com
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

!function ($) {

  "use strict"; // jshint ;_;


 /* SCROLLSPY CLASS DEFINITION
  * ========================== */

  function ScrollSpy(element, options) {
    var process = $.proxy(this.process, this)
      , $element = $(element).is('body') ? $(window) : $(element)
      , href
    this.options = $.extend({}, $.fn.scrollspy.defaults, options)
    this.$scrollElement = $element.on('scroll.scroll-spy.data-api', process)
    this.selector = (this.options.target
      || ((href = $(element).attr('href')) && href.replace(/.*(?=#[^\s]+$)/, '')) //strip for ie7
      || '') + ' .nav li > a'
    this.$body = $('body')
    this.refresh()
    this.process()
  }

  ScrollSpy.prototype = {

      constructor: ScrollSpy

    , refresh: function () {
        var self = this
          , $targets

        this.offsets = $([])
        this.targets = $([])

        $targets = this.$body
          .find(this.selector)
          .map(function () {
            var $el = $(this)
              , href = $el.data('target') || $el.attr('href')
              , $href = /^#\w/.test(href) && $(href)
            return ( $href
              && $href.length
              && [[ $href.position().top, href ]] ) || null
          })
          .sort(function (a, b) { return a[0] - b[0] })
          .each(function () {
            self.offsets.push(this[0])
            self.targets.push(this[1])
          })
      }

    , process: function () {
        var scrollTop = this.$scrollElement.scrollTop() + this.options.offset
          , scrollHeight = this.$scrollElement[0].scrollHeight || this.$body[0].scrollHeight
          , maxScroll = scrollHeight - this.$scrollElement.height()
          , offsets = this.offsets
          , targets = this.targets
          , activeTarget = this.activeTarget
          , i

        if (scrollTop >= maxScroll) {
          return activeTarget != (i = targets.last()[0])
            && this.activate ( i )
        }

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

    , activate: function (target) {
        var active
          , selector

        this.activeTarget = target

        $(this.selector)
          .parent('.active')
          .removeClass('active')

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

        active = $(selector)
          .parent('li')
          .addClass('active')

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

        active.trigger('activate')
      }

  }


 /* SCROLLSPY PLUGIN DEFINITION
  * =========================== */

  $.fn.scrollspy = function (option) {
    return this.each(function () {
      var $this = $(this)
        , data = $this.data('scrollspy')
        , options = typeof option == 'object' && option
      if (!data) $this.data('scrollspy', (data = new ScrollSpy(this, options)))
      if (typeof option == 'string') data[option]()
    })
  }

  $.fn.scrollspy.Constructor = ScrollSpy

  $.fn.scrollspy.defaults = {
    offset: 10
  }


 /* SCROLLSPY DATA-API
  * ================== */

  $(window).on('load', function () {
    $('[data-spy="scroll"]').each(function () {
      var $spy = $(this)
      $spy.scrollspy($spy.data())
    })
  })

}(window.jQuery);