/*!
Deck JS - deck.navigation
Copyright (c) 2011-2014 Caleb Troughton
Dual licensed under the MIT license.
https://github.com/imakewebthings/deck.js/blob/master/MIT-license.txt
*/

/*
This module adds clickable previous and next links to the deck.
*/
(function($, undefined) {
  var $document = $(document);

  /* Updates link hrefs, and disabled states if last/first slide */
  var updateButtons = function(event, from, to) {
    var options = $.deck('getOptions');
    var lastIndex = $.deck('getSlides').length - 1;
    var $prevSlide = $.deck('getSlide', to - 1);
    var $nextSlide = $.deck('getSlide', to + 1);
    var hrefBase = window.location.href.replace(/#.*/, '');
    var prevId = $prevSlide ? $prevSlide.attr('id') : undefined;
    var nextId = $nextSlide ? $nextSlide.attr('id') : undefined;
    var $prevButton = $(options.selectors.previousLink);
    var $nextButton = $(options.selectors.nextLink);

    $prevButton.toggleClass(options.classes.navDisabled, to === 0);
    $prevButton.attr('aria-disabled', to === 0);
    $prevButton.attr('href', hrefBase + '#' + (prevId ? prevId : ''));
    $nextButton.toggleClass(options.classes.navDisabled, to === lastIndex);
    $nextButton.attr('aria-disabled', to === lastIndex);
    $nextButton.attr('href', hrefBase + '#' + (nextId ? nextId : ''));
  };

  /*
  Extends defaults/options.

  options.classes.navDisabled
    This class is added to a navigation link when that action is disabled.
    It is added to the previous link when on the first slide, and to the
    next link when on the last slide.

  options.selectors.nextLink
    The elements that match this selector will move the deck to the next
    slide when clicked.

  options.selectors.previousLink
    The elements that match this selector will move to deck to the previous
    slide when clicked.
  */
  $.extend(true, $.deck.defaults, {
    classes: {
      navDisabled: 'deck-nav-disabled'
    },

    selectors: {
      nextLink: '.deck-next-link',
      previousLink: '.deck-prev-link'
    }
  });

  $document.bind('deck.init', function() {
    var options = $.deck('getOptions');
    var slides = $.deck('getSlides');
    var $current = $.deck('getSlide');
    var $prevButton = $(options.selectors.previousLink);
    var $nextButton = $(options.selectors.nextLink);
    var index;

    // Setup prev/next link events
    $prevButton.unbind('click.decknavigation');
    $prevButton.bind('click.decknavigation', function(event) {
      $.deck('prev');
      event.preventDefault();
    });

    $nextButton.unbind('click.decknavigation');
    $nextButton.bind('click.decknavigation', function(event) {
      $.deck('next');
      event.preventDefault();
    });

    // Find where we started in the deck and set initial states
    $.each(slides, function(i, $slide) {
      if ($slide === $current) {
        index = i;
        return false;
      }
    });
    updateButtons(null, index, index);
  });

  $document.bind('deck.change', updateButtons);
})(jQuery);