class WorkspaceActivateForm

class WorkspaceActivateForm extends EntityConfirmFormBase implements WorkspaceFormInterface {
  
  /**
   * The workspace entity.
   *
   * @var \Drupal\workspaces\WorkspaceInterface
   */
  protected $entity;
  
  /**
   * The workspace replication manager.
   *
   * @var \Drupal\workspaces\WorkspaceManagerInterface
   */
  protected $workspaceManager;
  
  /**
   * The messenger service.
   *
   * @var \Drupal\Core\Messenger\MessengerInterface
   */
  protected $messenger;
  
  /**
   * Constructs a new WorkspaceActivateForm.
   *
   * @param \Drupal\workspaces\WorkspaceManagerInterface $workspace_manager
   *   The workspace manager.
   * @param \Drupal\Core\Messenger\MessengerInterface $messenger
   *   The messenger service.
   */
  public function __construct(WorkspaceManagerInterface $workspace_manager, MessengerInterface $messenger) {
    $this->workspaceManager = $workspace_manager;
    $this->messenger = $messenger;
  }
  
  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container) {
    return new static($container->get('workspaces.manager'), $container->get('messenger'));
  }
  
  /**
   * {@inheritdoc}
   */
  public function getQuestion() {
    return $this->t('Would you like to activate the %workspace workspace?', [
      '%workspace' => $this->entity
        ->label(),
    ]);
  }
  
  /**
   * {@inheritdoc}
   */
  public function getDescription() {
    return $this->t('Activate the %workspace workspace.', [
      '%workspace' => $this->entity
        ->label(),
    ]);
  }
  
  /**
   * {@inheritdoc}
   */
  public function getCancelUrl() {
    return $this->entity
      ->toUrl('collection');
  }
  
  /**
   * {@inheritdoc}
   */
  public function buildForm(array $form, FormStateInterface $form_state) {
    $form = parent::buildForm($form, $form_state);
    // Content entity forms do not use the parent's #after_build callback.
    unset($form['#after_build']);
    return $form;
  }
  
  /**
   * {@inheritdoc}
   */
  public function actions(array $form, FormStateInterface $form_state) {
    $actions = parent::actions($form, $form_state);
    $actions['cancel']['#attributes']['class'][] = 'dialog-cancel';
    return $actions;
  }
  
  /**
   * {@inheritdoc}
   */
  public function submitForm(array &$form, FormStateInterface $form_state) {
    try {
      $this->workspaceManager
        ->setActiveWorkspace($this->entity);
      $this->messenger
        ->addMessage($this->t('%workspace_label is now the active workspace.', [
        '%workspace_label' => $this->entity
          ->label(),
      ]));
    } catch (WorkspaceAccessException $e) {
      $this->messenger
        ->addError($this->t('You do not have access to activate the %workspace_label workspace.', [
        '%workspace_label' => $this->entity
          ->label(),
      ]));
    }
    // Redirect to the workspace manage page by default.
    if (!$this->getRequest()->query
      ->has('destination')) {
      $form_state->setRedirectUrl($this->entity
        ->toUrl());
    }
  }
  
  /**
   * Checks access for the workspace activate form.
   *
   * @param \Drupal\Core\Routing\RouteMatchInterface $route_match
   *   The route match.
   *
   * @return \Drupal\Core\Access\AccessResult
   *   The access result.
   */
  public function checkAccess(RouteMatchInterface $route_match) {
    /** @var \Drupal\workspaces\WorkspaceInterface $workspace */
    $workspace = $route_match->getParameter('workspace');
    $active_workspace = $this->workspaceManager
      ->getActiveWorkspace();
    $access = AccessResult::allowedIf(!$active_workspace || $active_workspace && $active_workspace->id() != $workspace->id())
      ->addCacheableDependency($workspace);
    return $access;
  }

}