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

* Bootstrap: affix.js v3.1.0
* http://getbootstrap.com/javascript/#affix
* ========================================================================
* Copyright 2011-2014 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 = $.extend({}, Affix.DEFAULTS, options)
  this.$window = $(window)
    .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      =
  this.unpin        =
  this.pinnedOffset = null

  this.checkPosition()
}

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

Affix.DEFAULTS = {
  offset: 0
}

Affix.prototype.getPinnedOffset = function () {
  if (this.pinnedOffset) return this.pinnedOffset
  this.$element.removeClass(Affix.RESET).addClass('affix')
  var scrollTop = this.$window.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 scrollHeight = $(document).height()
  var scrollTop    = this.$window.scrollTop()
  var position     = this.$element.offset()
  var offset       = this.options.offset
  var offsetTop    = offset.top
  var offsetBottom = offset.bottom

  if (this.affixed == 'top') position.top += scrollTop

  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.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
  if (this.unpin) 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.$element
    .removeClass(Affix.RESET)
    .addClass(affixType)
    .trigger($.Event(affixType.replace('affix', 'affixed')))

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

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

var old = $.fn.affix

$.fn.affix = function (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]()
  })
}

$.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) data.offset.bottom = data.offsetBottom
    if (data.offsetTop)    data.offset.top    = data.offsetTop

    $spy.affix(data)
  })
})

}(jQuery);