<!– @license Copyright © 2015 The Polymer Project Authors. All rights reserved. This code may only be used under the BSD style license found at polymer.github.io/LICENSE.txt The complete set of authors may be found at polymer.github.io/AUTHORS.txt The complete set of contributors may be found at polymer.github.io/CONTRIBUTORS.txt Code distributed by Google as part of the polymer project is also subject to an additional IP rights grant found at polymer.github.io/PATENTS.txt –>

<link rel=“import” href=“../polymer/polymer.html”>

<script>

/**
 * @param {!Function} selectCallback
 * @constructor
 */
Polymer.IronSelection = function(selectCallback) {
  this.selection = [];
  this.selectCallback = selectCallback;
};

Polymer.IronSelection.prototype = {

  /**
   * Retrieves the selected item(s).
   *
   * @method get
   * @returns Returns the selected item(s). If the multi property is true,
   * `get` will return an array, otherwise it will return
   * the selected item or undefined if there is no selection.
   */
  get: function() {
    return this.multi ? this.selection.slice() : this.selection[0];
  },

  /**
   * Clears all the selection except the ones indicated.
   *
   * @method clear
   * @param {Array} excludes items to be excluded.
   */
  clear: function(excludes) {
    this.selection.slice().forEach(function(item) {
      if (!excludes || excludes.indexOf(item) < 0) {
        this.setItemSelected(item, false);
      }
    }, this);
  },

  /**
   * Indicates if a given item is selected.
   *
   * @method isSelected
   * @param {*} item The item whose selection state should be checked.
   * @returns Returns true if `item` is selected.
   */
  isSelected: function(item) {
    return this.selection.indexOf(item) >= 0;
  },

  /**
   * Sets the selection state for a given item to either selected or deselected.
   *
   * @method setItemSelected
   * @param {*} item The item to select.
   * @param {boolean} isSelected True for selected, false for deselected.
   */
  setItemSelected: function(item, isSelected) {
    if (item != null) {
      if (isSelected !== this.isSelected(item)) {
        // proceed to update selection only if requested state differs from current
        if (isSelected) {
          this.selection.push(item);
        } else {
          var i = this.selection.indexOf(item);
          if (i >= 0) {
            this.selection.splice(i, 1);
          }
        }
        if (this.selectCallback) {
          this.selectCallback(item, isSelected);
        }
      }
    }
  },

  /**
   * Sets the selection state for a given item. If the `multi` property
   * is true, then the selected state of `item` will be toggled; otherwise
   * the `item` will be selected.
   *
   * @method select
   * @param {*} item The item to select.
   */
  select: function(item) {
    if (this.multi) {
      this.toggle(item);
    } else if (this.get() !== item) {
      this.setItemSelected(this.get(), false);
      this.setItemSelected(item, true);
    }
  },

  /**
   * Toggles the selection state for `item`.
   *
   * @method toggle
   * @param {*} item The item to toggle.
   */
  toggle: function(item) {
    this.setItemSelected(item, !this.isSelected(item));
  }

};

</script>