/* ==========================================================

 * bootstrap-affix.js v2.3.1

 * http://twitter.github.com/bootstrap/javascript.html#affix

 * ==========================================================

 * Copyright 2012 Twitter, Inc.

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 * http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 * ========================================================== */

!function ($) {

  "use strict"; // jshint ;_;

 /* AFFIX CLASS DEFINITION

  * ====================== */

  var Affix = function (element, options) {

    this.options = $.extend({}, $.fn.affix.defaults, options)

    this.$window = $(window)

      .on('scroll.affix.data-api', $.proxy(this.checkPosition, this))

      .on('click.affix.data-api',  $.proxy(function () { setTimeout($.proxy(this.checkPosition, this), 1) }, this))

    this.$element = $(element)

    this.checkPosition()

  }

  Affix.prototype.checkPosition = function () {

    if (!this.$element.is(':visible')) return

    var scrollHeight = $(document).height()

      , scrollTop = this.$window.scrollTop()

      , position = this.$element.offset()

      , offset = this.options.offset

      , offsetBottom = offset.bottom

      , offsetTop = offset.top

      , reset = 'affix affix-top affix-bottom'

      , affix

    if (typeof offset != 'object') offsetBottom = offsetTop = offset

    if (typeof offsetTop == 'function') offsetTop = offset.top()

    if (typeof offsetBottom == 'function') offsetBottom = offset.bottom()

    affix = this.unpin != null && (scrollTop + this.unpin <= position.top) ?

      false    : offsetBottom != null && (position.top + this.$element.height() >= scrollHeight - offsetBottom) ?

      'bottom' : offsetTop != null && scrollTop <= offsetTop ?

      'top'    : false

    if (this.affixed === affix) return

    this.affixed = affix

    this.unpin = affix == 'bottom' ? position.top - scrollTop : null

    this.$element.removeClass(reset).addClass('affix' + (affix ? '-' + affix : ''))

  }

 /* AFFIX PLUGIN DEFINITION

  * ======================= */

  var old = $.fn.affix

  $.fn.affix = function (option) {

    return this.each(function () {

      var $this = $(this)

        , data = $this.data('affix')

        , options = typeof option == 'object' && option

      if (!data) $this.data('affix', (data = new Affix(this, options)))

      if (typeof option == 'string') data[option]()

    })

  }

  $.fn.affix.Constructor = Affix

  $.fn.affix.defaults = {

    offset: 0

  }

 /* AFFIX NO CONFLICT

  * ================= */

  $.fn.affix.noConflict = function () {

    $.fn.affix = old

    return this

  }

 /* AFFIX DATA-API

  * ============== */

  $(window).on('load', function () {

    $('[data-spy="affix"]').each(function () {

      var $spy = $(this)

        , data = $spy.data()

      data.offset = data.offset || {}

      data.offsetBottom && (data.offset.bottom = data.offsetBottom)

      data.offsetTop && (data.offset.top = data.offsetTop)

      $spy.affix(data)

    })

  })

}(window.jQuery);