import { ICommand } from '../../baseframework/ICommand';
import { SubscriptionEvent } from '../../utils/SubscriptionEvent';

/**
 * Represents a command which must be executed without parameters.
 *
 * @export
 * @class SimpleDelegateCommand
 * @implements {ICommand}
 * @wType Microsoft.Practices.Prism.Commands.DelegateCommand
 */
export class SimpleDelegateCommand implements ICommand {
  /**
   * Event trigerred when `CanExecute` changes its value.
   *
   * @type {SubscriptionEvent<any>}
   * @memberof SimpleDelegateCommand
   */
  CanExecuteChanged: SubscriptionEvent<any> = new SubscriptionEvent();

  /**
   * Event triguerred when `IsActive` changes its value.
   *
   * @type {SubscriptionEvent<any>}
   * @memberof SimpleDelegateCommand
   */
  IsActiveChanged: SubscriptionEvent<any> = new SubscriptionEvent();

  /**
   * Stored the value of `IsActive`.
   *
   * @private
   * @memberof SimpleDelegateCommand
   */
  private isActive = true;

  /**
   * Creates an instance of SimpleDelegateCommand.
   *
   * @param {() => void} f The function to call when the command is executed.
   * @param {(() => boolean)} [canExecute] The function to determine if the command can be executed.
   * @memberof SimpleDelegateCommand
   */
  constructor(private f: () => void, private canExecute?: () => boolean) {}

  /**
   * The active status of the command.
   *
   * @type {boolean}
   * @memberof SimpleDelegateCommand
   */
  get IsActive(): boolean {
    return this.isActive;
  }

  set IsActive(value: boolean) {
    if (this.isActive !== value) {
      this.isActive = value;
      this.IsActiveChanged.fire([this, {}]);
    }
  }

  /**
   * Query if the command can be executed.
   *
   * @return {*}  {boolean}
   * @memberof SimpleDelegateCommand
   */
  CanExecute(): boolean {
    return this.canExecute?.() ?? true;
  }

  /**
   * Executes the command if it can be executed.
   *
   * @memberof SimpleDelegateCommand
   */
  Execute(): void {
    if (this.CanExecute()) {
      this.f();
    }
  }

  /**
   * Alerts that `CanExecute()` has changed its value.
   *
   * @memberof SimpleDelegateCommand
   */
  RaiseCanExecuteChanged() {
    this.CanExecuteChanged?.fire([]);
  }
}