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

* Bootstrap: affix.js v3.3.4
* http://getbootstrap.com/javascript/#affix
* ========================================================================
* Copyright 2011-2015 Twitter, Inc.
* Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
* ======================================================================== */

+function ($) {

'use strict';

// AFFIX CLASS DEFINITION
// ======================

var Affix = function (element, options) {
  this.options = $.extend({}, Affix.DEFAULTS, options)

  this.$target = $(this.options.target)
    .on('scroll.bs.affix.data-api', $.proxy(this.checkPosition, this))
    .on('click.bs.affix.data-api',  $.proxy(this.checkPositionWithEventLoop, this))

  this.$element     = $(element)
  this.affixed      = null
  this.unpin        = null
  this.pinnedOffset = null

  this.checkPosition()
}

Affix.VERSION  = '3.3.4'

Affix.RESET    = 'affix affix-top affix-bottom'

Affix.DEFAULTS = {
  offset: 0,
  target: window
}

Affix.prototype.getState = function (scrollHeight, height, offsetTop, offsetBottom) {
  var scrollTop    = this.$target.scrollTop()
  var position     = this.$element.offset()
  var targetHeight = this.$target.height()

  if (offsetTop != null && this.affixed == 'top') return scrollTop < offsetTop ? 'top' : false

  if (this.affixed == 'bottom') {
    if (offsetTop != null) return (scrollTop + this.unpin <= position.top) ? false : 'bottom'
    return (scrollTop + targetHeight <= scrollHeight - offsetBottom) ? false : 'bottom'
  }

  var initializing   = this.affixed == null
  var colliderTop    = initializing ? scrollTop : position.top
  var colliderHeight = initializing ? targetHeight : height

  if (offsetTop != null && scrollTop <= offsetTop) return 'top'
  if (offsetBottom != null && (colliderTop + colliderHeight >= scrollHeight - offsetBottom)) return 'bottom'

  return false
}

Affix.prototype.getPinnedOffset = function () {
  if (this.pinnedOffset) return this.pinnedOffset
  this.$element.removeClass(Affix.RESET).addClass('affix')
  var scrollTop = this.$target.scrollTop()
  var position  = this.$element.offset()
  return (this.pinnedOffset = position.top - scrollTop)
}

Affix.prototype.checkPositionWithEventLoop = function () {
  setTimeout($.proxy(this.checkPosition, this), 1)
}

Affix.prototype.checkPosition = function () {
  if (!this.$element.is(':visible')) return

  var height       = this.$element.height()
  var offset       = this.options.offset
  var offsetTop    = offset.top
  var offsetBottom = offset.bottom
  var scrollHeight = $(document.body).height()

  if (typeof offset != 'object')         offsetBottom = offsetTop = offset
  if (typeof offsetTop == 'function')    offsetTop    = offset.top(this.$element)
  if (typeof offsetBottom == 'function') offsetBottom = offset.bottom(this.$element)

  var affix = this.getState(scrollHeight, height, offsetTop, offsetBottom)

  if (this.affixed != affix) {
    if (this.unpin != null) this.$element.css('top', '')

    var affixType = 'affix' + (affix ? '-' + affix : '')
    var e         = $.Event(affixType + '.bs.affix')

    this.$element.trigger(e)

    if (e.isDefaultPrevented()) return

    this.affixed = affix
    this.unpin = affix == 'bottom' ? this.getPinnedOffset() : null

    this.$element
      .removeClass(Affix.RESET)
      .addClass(affixType)
      .trigger(affixType.replace('affix', 'affixed') + '.bs.affix')
  }

  if (affix == 'bottom') {
    this.$element.offset({
      top: scrollHeight - height - offsetBottom
    })
  }
}

// AFFIX PLUGIN DEFINITION
// =======================

function Plugin(option) {
  return this.each(function () {
    var $this   = $(this)
    var data    = $this.data('bs.affix')
    var options = typeof option == 'object' && option

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

var old = $.fn.affix

$.fn.affix             = Plugin
$.fn.affix.Constructor = Affix

// 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)
    var data = $spy.data()

    data.offset = data.offset || {}

    if (data.offsetBottom != null) data.offset.bottom = data.offsetBottom
    if (data.offsetTop    != null) data.offset.top    = data.offsetTop

    Plugin.call($spy, data)
  })
})

}(jQuery);