define([

'jquery',
'./utils'

], function ($, Utils) {

function Results ($element, options, dataAdapter) {
  this.$element = $element;
  this.data = dataAdapter;
  this.options = options;

  Results.__super__.constructor.call(this);
}

Utils.Extend(Results, Utils.Observable);

Results.prototype.render = function () {
  var $results = $(
    '<ul class="select2-results__options" role="tree"></ul>'
  );

  if (this.options.get('multiple')) {
    $results.attr('aria-multiselectable', 'true');
  }

  this.$results = $results;

  return $results;
};

Results.prototype.clear = function () {
  this.$results.empty();
};

Results.prototype.displayMessage = function (params) {
  var escapeMarkup = this.options.get('escapeMarkup');

  this.clear();
  this.hideLoading();

  var $message = $(
    '<li role="treeitem" aria-live="assertive"' +
    ' class="select2-results__option"></li>'
  );

  var message = this.options.get('translations').get(params.message);

  $message.append(
    escapeMarkup(
      message(params.args)
    )
  );

  $message[0].className += ' select2-results__message';

  this.$results.append($message);
};

Results.prototype.hideMessages = function () {
  this.$results.find('.select2-results__message').remove();
};

Results.prototype.append = function (data) {
  this.hideLoading();

  var $options = [];

  if (data.results == null || data.results.length === 0) {
    if (this.$results.children().length === 0) {
      this.trigger('results:message', {
        message: 'noResults'
      });
    }

    return;
  }

  data.results = this.sort(data.results);

  for (var d = 0; d < data.results.length; d++) {
    var item = data.results[d];

    var $option = this.option(item);

    $options.push($option);
  }

  this.$results.append($options);
};

Results.prototype.position = function ($results, $dropdown) {
  var $resultsContainer = $dropdown.find('.select2-results');
  $resultsContainer.append($results);
};

Results.prototype.sort = function (data) {
  var sorter = this.options.get('sorter');

  return sorter(data);
};

Results.prototype.highlightFirstItem = function () {
  var $options = this.$results
    .find('.select2-results__option[aria-selected]');

  var $selected = $options.filter('[aria-selected=true]');

  // Check if there are any selected options
  if ($selected.length > 0) {
    // If there are selected options, highlight the first
    $selected.first().trigger('mouseenter');
  } else {
    // If there are no selected options, highlight the first option
    // in the dropdown
    $options.first().trigger('mouseenter');
  }

  this.ensureHighlightVisible();
};

Results.prototype.setClasses = function () {
  var self = this;

  this.data.current(function (selected) {
    var selectedIds = $.map(selected, function (s) {
      return s.id.toString();
    });

    var $options = self.$results
      .find('.select2-results__option[aria-selected]');

    $options.each(function () {
      var $option = $(this);

      var item = $.data(this, 'data');

      // id needs to be converted to a string when comparing
      var id = '' + item.id;

      if ((item.element != null && item.element.selected) ||
          (item.element == null && $.inArray(id, selectedIds) > -1)) {
        $option.attr('aria-selected', 'true');
      } else {
        $option.attr('aria-selected', 'false');
      }
    });

  });
};

Results.prototype.showLoading = function (params) {
  this.hideLoading();

  var loadingMore = this.options.get('translations').get('searching');

  var loading = {
    disabled: true,
    loading: true,
    text: loadingMore(params)
  };
  var $loading = this.option(loading);
  $loading.className += ' loading-results';

  this.$results.prepend($loading);
};

Results.prototype.hideLoading = function () {
  this.$results.find('.loading-results').remove();
};

Results.prototype.option = function (data) {
  var option = document.createElement('li');
  option.className = 'select2-results__option';

  var attrs = {
    'role': 'treeitem',
    'aria-selected': 'false'
  };

  if (data.disabled) {
    delete attrs['aria-selected'];
    attrs['aria-disabled'] = 'true';
  }

  if (data.id == null) {
    delete attrs['aria-selected'];
  }

  if (data._resultId != null) {
    option.id = data._resultId;
  }

  if (data.title) {
    option.title = data.title;
  }

  if (data.children) {
    attrs.role = 'group';
    attrs['aria-label'] = data.text;
    delete attrs['aria-selected'];
  }

  for (var attr in attrs) {
    var val = attrs[attr];

    option.setAttribute(attr, val);
  }

  if (data.children) {
    var $option = $(option);

    var label = document.createElement('strong');
    label.className = 'select2-results__group';

    var $label = $(label);
    this.template(data, label);

    var $children = [];

    for (var c = 0; c < data.children.length; c++) {
      var child = data.children[c];

      var $child = this.option(child);

      $children.push($child);
    }

    var $childrenContainer = $('<ul></ul>', {
      'class': 'select2-results__options select2-results__options--nested'
    });

    $childrenContainer.append($children);

    $option.append(label);
    $option.append($childrenContainer);
  } else {
    this.template(data, option);
  }

  $.data(option, 'data', data);

  return option;
};

Results.prototype.bind = function (container, $container) {
  var self = this;

  var id = container.id + '-results';

  this.$results.attr('id', id);

  container.on('results:all', function (params) {
    self.clear();
    self.append(params.data);

    if (container.isOpen()) {
      self.setClasses();
      self.highlightFirstItem();
    }
  });

  container.on('results:append', function (params) {
    self.append(params.data);

    if (container.isOpen()) {
      self.setClasses();
    }
  });

  container.on('query', function (params) {
    self.hideMessages();
    self.showLoading(params);
  });

  container.on('select', function () {
    if (!container.isOpen()) {
      return;
    }

    self.setClasses();
    self.highlightFirstItem();
  });

  container.on('unselect', function () {
    if (!container.isOpen()) {
      return;
    }

    self.setClasses();
    self.highlightFirstItem();
  });

  container.on('open', function () {
    // When the dropdown is open, aria-expended="true"
    self.$results.attr('aria-expanded', 'true');
    self.$results.attr('aria-hidden', 'false');

    self.setClasses();
    self.ensureHighlightVisible();
  });

  container.on('close', function () {
    // When the dropdown is closed, aria-expended="false"
    self.$results.attr('aria-expanded', 'false');
    self.$results.attr('aria-hidden', 'true');
    self.$results.removeAttr('aria-activedescendant');
  });

  container.on('results:toggle', function () {
    var $highlighted = self.getHighlightedResults();

    if ($highlighted.length === 0) {
      return;
    }

    $highlighted.trigger('mouseup');
  });

  container.on('results:select', function () {
    var $highlighted = self.getHighlightedResults();

    if ($highlighted.length === 0) {
      return;
    }

    var data = $highlighted.data('data');

    if ($highlighted.attr('aria-selected') == 'true') {
      self.trigger('close', {});
    } else {
      self.trigger('select', {
        data: data
      });
    }
  });

  container.on('results:previous', function () {
    var $highlighted = self.getHighlightedResults();

    var $options = self.$results.find('[aria-selected]');

    var currentIndex = $options.index($highlighted);

    // If we are already at te top, don't move further
    if (currentIndex === 0) {
      return;
    }

    var nextIndex = currentIndex - 1;

    // If none are highlighted, highlight the first
    if ($highlighted.length === 0) {
      nextIndex = 0;
    }

    var $next = $options.eq(nextIndex);

    $next.trigger('mouseenter');

    var currentOffset = self.$results.offset().top;
    var nextTop = $next.offset().top;
    var nextOffset = self.$results.scrollTop() + (nextTop - currentOffset);

    if (nextIndex === 0) {
      self.$results.scrollTop(0);
    } else if (nextTop - currentOffset < 0) {
      self.$results.scrollTop(nextOffset);
    }
  });

  container.on('results:next', function () {
    var $highlighted = self.getHighlightedResults();

    var $options = self.$results.find('[aria-selected]');

    var currentIndex = $options.index($highlighted);

    var nextIndex = currentIndex + 1;

    // If we are at the last option, stay there
    if (nextIndex >= $options.length) {
      return;
    }

    var $next = $options.eq(nextIndex);

    $next.trigger('mouseenter');

    var currentOffset = self.$results.offset().top +
      self.$results.outerHeight(false);
    var nextBottom = $next.offset().top + $next.outerHeight(false);
    var nextOffset = self.$results.scrollTop() + nextBottom - currentOffset;

    if (nextIndex === 0) {
      self.$results.scrollTop(0);
    } else if (nextBottom > currentOffset) {
      self.$results.scrollTop(nextOffset);
    }
  });

  container.on('results:focus', function (params) {
    params.element.addClass('select2-results__option--highlighted');
  });

  container.on('results:message', function (params) {
    self.displayMessage(params);
  });

  if ($.fn.mousewheel) {
    this.$results.on('mousewheel', function (e) {
      var top = self.$results.scrollTop();

      var bottom = self.$results.get(0).scrollHeight - top + e.deltaY;

      var isAtTop = e.deltaY > 0 && top - e.deltaY <= 0;
      var isAtBottom = e.deltaY < 0 && bottom <= self.$results.height();

      if (isAtTop) {
        self.$results.scrollTop(0);

        e.preventDefault();
        e.stopPropagation();
      } else if (isAtBottom) {
        self.$results.scrollTop(
          self.$results.get(0).scrollHeight - self.$results.height()
        );

        e.preventDefault();
        e.stopPropagation();
      }
    });
  }

  this.$results.on('mouseup', '.select2-results__option[aria-selected]',
    function (evt) {
    var $this = $(this);

    var data = $this.data('data');

    if ($this.attr('aria-selected') === 'true') {
      if (self.options.get('multiple')) {
        self.trigger('unselect', {
          originalEvent: evt,
          data: data
        });
      } else {
        self.trigger('close', {});
      }

      return;
    }

    self.trigger('select', {
      originalEvent: evt,
      data: data
    });
  });

  this.$results.on('mouseenter', '.select2-results__option[aria-selected]',
    function (evt) {
    var data = $(this).data('data');

    self.getHighlightedResults()
        .removeClass('select2-results__option--highlighted');

    self.trigger('results:focus', {
      data: data,
      element: $(this)
    });
  });
};

Results.prototype.getHighlightedResults = function () {
  var $highlighted = this.$results
  .find('.select2-results__option--highlighted');

  return $highlighted;
};

Results.prototype.destroy = function () {
  this.$results.remove();
};

Results.prototype.ensureHighlightVisible = function () {
  var $highlighted = this.getHighlightedResults();

  if ($highlighted.length === 0) {
    return;
  }

  var $options = this.$results.find('[aria-selected]');

  var currentIndex = $options.index($highlighted);

  var currentOffset = this.$results.offset().top;
  var nextTop = $highlighted.offset().top;
  var nextOffset = this.$results.scrollTop() + (nextTop - currentOffset);

  var offsetDelta = nextTop - currentOffset;
  nextOffset -= $highlighted.outerHeight(false) * 2;

  if (currentIndex <= 2) {
    this.$results.scrollTop(0);
  } else if (offsetDelta > this.$results.outerHeight() || offsetDelta < 0) {
    this.$results.scrollTop(nextOffset);
  }
};

Results.prototype.template = function (result, container) {
  var template = this.options.get('templateResult');
  var escapeMarkup = this.options.get('escapeMarkup');

  var content = template(result, container);

  if (content == null) {
    container.style.display = 'none';
  } else if (typeof content === 'string') {
    container.innerHTML = escapeMarkup(content);
  } else {
    $(container).append(content);
  }
};

return Results;

});