/**
 * Magellan module.
 * @module foundation.magellan
 */
!function(Foundation, $) {
  'use strict';

  /**
   * Creates a new instance of Magellan.
   * @class
   * @fires Magellan#init
   * @param {Object} element - jQuery object to add the trigger to.
   * @param {Object} options - Overrides to the default plugin settings.
   */
  function Magellan(element, options) {
    this.$element = element;
    this.options  = $.extend({}, Magellan.defaults, this.$element.data(), options);

    this._init();

    Foundation.registerPlugin(this, 'Magellan');
  }

  /**
   * Default settings for plugin
   */
  Magellan.defaults = {
    /**
     * Amount of time, in ms, the animated scrolling should take between locations.
     * @option
     * @example 500
     */
    animationDuration: 500,
    /**
     * Animation style to use when scrolling between locations.
     * @option
     * @example 'ease-in-out'
     */
    animationEasing: 'linear',
    /**
     * Number of pixels to use as a marker for location changes.
     * @option
     * @example 50
     */
    threshold: 50,
    /**
     * Class applied to the active locations link on the magellan container.
     * @option
     * @example 'active'
     */
    activeClass: 'active',
    /**
     * Allows the script to manipulate the url of the current page, and if supported, alter the history.
     * @option
     * @example true
     */
    deepLinking: false,
    /**
     * Number of pixels to offset the scroll of the page on item click if using a sticky nav bar.
     * @option
     * @example 25
     */
    barOffset: 0
  };

  /**
   * Initializes the Magellan plugin and calls functions to get equalizer functioning on load.
   * @private
   */
  Magellan.prototype._init = function() {
    var id = this.$element[0].id || Foundation.GetYoDigits(6, 'magellan'),
        _this = this;
    this.$targets = $('[data-magellan-target]');
    this.$links = this.$element.find('a');
    this.$element.attr({
      'data-resize': id,
      'data-scroll': id,
      'id': id
    });
    this.$active = $();
    this.scrollPos = parseInt(window.pageYOffset, 10);

    this._events();
  };
  /**
   * Calculates an array of pixel values that are the demarcation lines between locations on the page.
   * Can be invoked if new elements are added or the size of a location changes.
   * @function
   */
  Magellan.prototype.calcPoints = function(){
    var _this = this,
        body = document.body,
        html = document.documentElement;

    this.points = [];
    this.winHeight = Math.round(Math.max(window.innerHeight, html.clientHeight));
    this.docHeight = Math.round(Math.max(body.scrollHeight, body.offsetHeight, html.clientHeight, html.scrollHeight, html.offsetHeight));

    this.$targets.each(function(){
      var $tar = $(this),
          pt = Math.round($tar.offset().top - _this.options.threshold);
      $tar.targetPoint = pt;
      _this.points.push(pt);
    });
  };
  /**
   * Initializes events for Magellan.
   * @private
   */
  Magellan.prototype._events = function() {
    var _this = this,
        $body = $('html, body'),
        opts = {
          duration: _this.options.animationDuration,
          easing:   _this.options.animationEasing
        };

    $(window).one('load', function(){
      _this.calcPoints();
      _this._updateActive();
    });

    this.$element.on({
      'resizeme.zf.trigger': this.reflow.bind(this),
      'scrollme.zf.trigger': this._updateActive.bind(this)
    }).on('click.zf.magellan', 'a[href^="#"]', function(e) {
        e.preventDefault();
        var arrival   = this.getAttribute('href'),
            scrollPos = $(arrival).offset().top - _this.options.threshold / 2 - _this.options.barOffset;

        // requestAnimationFrame is disabled for this plugin currently
        // Foundation.Move(_this.options.animationDuration, $body, function(){
          $body.stop(true).animate({
            scrollTop: scrollPos
          }, opts);
        });
      // });
  };
  /**
   * Calls necessary functions to update Magellan upon DOM change
   * @function
   */
  Magellan.prototype.reflow = function(){
    this.calcPoints();
    this._updateActive();
  };
  /**
   * Updates the visibility of an active location link, and updates the url hash for the page, if deepLinking enabled.
   * @private
   * @function
   * @fires Magellan#update
   */
  Magellan.prototype._updateActive = function(/*evt, elem, scrollPos*/){
    var winPos = /*scrollPos ||*/ parseInt(window.pageYOffset, 10),
        curIdx;

    if(winPos + this.winHeight === this.docHeight){ curIdx = this.points.length - 1; }
    else if(winPos < this.points[0]){ curIdx = 0; }
    else{
      var isDown = this.scrollPos < winPos,
          _this = this,
          curVisible = this.points.filter(function(p, i){
            return isDown ? p <= winPos : p - _this.options.threshold <= winPos;//&& winPos >= _this.points[i -1] - _this.options.threshold;
          });
      curIdx = curVisible.length ? curVisible.length - 1 : 0;
    }

    this.$active.removeClass(this.options.activeClass);
    this.$active = this.$links.eq(curIdx).addClass(this.options.activeClass);

    if(this.options.deepLinking){
      var hash = this.$active[0].getAttribute('href');
      if(window.history.pushState){
        window.history.pushState(null, null, hash);
      }else{
        window.location.hash = hash;
      }
    }

    this.scrollPos = winPos;
    /**
     * Fires when magellan is finished updating to the new active element.
     * @event Magellan#update
     */
    this.$element.trigger('update.zf.magellan', [this.$active]);
  };
  /**
   * Destroys an instance of Magellan and resets the url of the window.
   * @function
   */
  Magellan.prototype.destroy = function(){
    this.$element.off('.zf.trigger .zf.magellan')
        .find('.' + this.options.activeClass).removeClass(this.options.activeClass);

    if(this.options.deepLinking){
      var hash = this.$active[0].getAttribute('href');
      window.location.hash.replace(hash, '');
    }

    Foundation.unregisterPlugin(this);
  };
  Foundation.plugin(Magellan, 'Magellan');

  // Exports for AMD/Browserify
  if (typeof module !== 'undefined' && typeof module.exports !== 'undefined')
    module.exports = Magellan;
  if (typeof define === 'function')
    define(['foundation'], function() {
      return Magellan;
    });

}(Foundation, jQuery);