define([
  'jquery',
  '../keys',
  '../utils'
], function ($, KEYS, Utils) {
  function AllowClear () { }

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

    decorated.call(this, container, $container);

    if (this.placeholder == null) {
      if (this.options.get('debug') && window.console && console.error) {
        console.error(
          'Select2: The `allowClear` option should be used in combination ' +
          'with the `placeholder` option.'
        );
      }
    }

    this.$selection.on('mousedown', '.select2-selection__clear',
      function (evt) {
        self._handleClear(evt);
    });

    container.on('keypress', function (evt) {
      self._handleKeyboardClear(evt, container);
    });
  };

  AllowClear.prototype._handleClear = function (_, evt) {
    // Ignore the event if it is disabled
    if (this.isDisabled()) {
      return;
    }

    var $clear = this.$selection.find('.select2-selection__clear');

    // Ignore the event if nothing has been selected
    if ($clear.length === 0) {
      return;
    }

    evt.stopPropagation();

    var data = Utils.GetData($clear[0], 'data');

    var previousVal = this.$element.val();
    this.$element.val(this.placeholder.id);

    var unselectData = {
      data: data
    };
    this.trigger('clear', unselectData);
    if (unselectData.prevented) {
      this.$element.val(previousVal);
      return;
    }

    for (var d = 0; d < data.length; d++) {
      unselectData = {
        data: data[d]
      };

      // Trigger the `unselect` event, so people can prevent it from being
      // cleared.
      this.trigger('unselect', unselectData);

      // If the event was prevented, don't clear it out.
      if (unselectData.prevented) {
        this.$element.val(previousVal);
        return;
      }
    }

    this.$element.trigger('input').trigger('change');

    this.trigger('toggle', {});
  };

  AllowClear.prototype._handleKeyboardClear = function (_, evt, container) {
    if (container.isOpen()) {
      return;
    }

    if (evt.which == KEYS.DELETE || evt.which == KEYS.BACKSPACE) {
      this._handleClear(evt);
    }
  };

  AllowClear.prototype.update = function (decorated, data) {
    decorated.call(this, data);

    this.$selection.find('.select2-selection__clear').remove();
    this.$selection[0].classList.remove('select2-selection--clearable');

    if (this.$selection.find('.select2-selection__placeholder').length > 0 ||
        data.length === 0) {
      return;
    }

    var selectionId = this.$selection.find('.select2-selection__rendered')
      .attr('id');

    var removeAll = this.options.get('translations').get('removeAllItems');

    var $remove = $(
      '<button type="button" class="select2-selection__clear" tabindex="-1">' +
        '<span aria-hidden="true">&times;</span>' +
      '</button>'
    );
    $remove.attr('title', removeAll());
    $remove.attr('aria-label', removeAll());
    $remove.attr('aria-describedby', selectionId);
    Utils.StoreData($remove[0], 'data', data);

    this.$selection.prepend($remove);
    this.$selection[0].classList.add('select2-selection--clearable');
  };

  return AllowClear;
});
