/**
 * @license
 * Copyright Google LLC All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.io/license
 */

import {ListKeyManager, ListKeyManagerOption} from './list-key-manager';

/**
 * This is the interface for focusable items (used by the FocusKeyManager).
 * Each item must know how to focus itself, whether or not it is currently disabled
 * and be able to supply it's label.
 */
export interface FocusableOption extends ListKeyManagerOption {
  /** Focuses the `FocusableOption`. */
  focus(): void;
}

export class FocusKeyManager<T> extends ListKeyManager<FocusableOption & T> {
  /**
   * This method sets the active item to the item at the specified index.
   * It also adds focuses the newly active item.
   */
  setActiveItem(index: number): void {
    super.setActiveItem(index);

    if (this.activeItem) {
      this.activeItem.focus();
    }
  }
}