class ReactionRuleEditForm

class ReactionRuleEditForm extends RulesComponentFormBase {
    
    /**
     * The Rules event plugin manager.
     *
     * @var \Drupal\rules\Core\RulesEventManager
     */
    protected $eventManager;
    
    /**
     * The RulesUI handler of the currently active UI.
     *
     * @var \Drupal\rules\Ui\RulesUiConfigHandler
     */
    protected $rulesUiHandler;
    
    /**
     * Constructs a new object of this class.
     *
     * @param \Drupal\rules\Engine\ExpressionManagerInterface $expression_manager
     *   The expression manager.
     * @param \Drupal\rules\Core\RulesEventManager $event_manager
     *   The event plugin manager.
     */
    public function __construct(ExpressionManagerInterface $expression_manager, RulesEventManager $event_manager) {
        parent::__construct($expression_manager);
        $this->eventManager = $event_manager;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container) {
        return new static($container->get('plugin.manager.rules_expression'), $container->get('plugin.manager.rules_event'));
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildForm(array $form, FormStateInterface $form_state, RulesUiConfigHandler $rules_ui_handler = NULL) {
        // Overridden so that we can receive further route parameters.
        $this->rulesUiHandler = $rules_ui_handler;
        return parent::buildForm($form, $form_state);
    }
    
    /**
     * {@inheritdoc}
     */
    protected function prepareEntity() {
        parent::prepareEntity();
        // Replace the config entity with the latest entity from temp store, so any
        // interim changes are picked up.
        $this->entity = $this->rulesUiHandler
            ->getConfig();
    }
    
    /**
     * {@inheritdoc}
     */
    public function form(array $form, FormStateInterface $form_state) {
        $form['events'] = [
            '#type' => 'container',
            '#attributes' => [
                'class' => [
                    'edit-events',
                ],
            ],
        ];
        $form['events']['table'] = [
            '#theme' => 'table',
            '#header' => [
                $this->t('Events'),
                $this->t('Operations'),
            ],
            '#empty' => $this->t('None'),
        ];
        foreach ($this->entity
            ->getEventNames() as $key => $event_name) {
            $event_definition = $this->eventManager
                ->getDefinition($event_name);
            $form['events']['table']['#rows'][$key]['element'] = [
                'data' => [
                    '#type' => 'item',
                    '#plain_text' => $event_definition['label'],
                    '#suffix' => '<div class="description">' . $this->t('Machine name: @name', [
                        '@name' => $event_name,
                    ]) . '</div>',
                ],
            ];
            // Provide a delete button ONLY IF there is more than one event.
            if (count($this->entity
                ->getEventNames()) > 1) {
                $form['events']['table']['#rows'][$key]['operations'] = [
                    'data' => [
                        '#type' => 'operations',
                        '#links' => [
                            'delete' => [
                                'title' => $this->t('Delete'),
                                'url' => $this->rulesUiHandler
                                    ->getUrlFromRoute('event.delete', [
                                    'id' => $event_name,
                                ]),
                            ],
                        ],
                    ],
                ];
            }
            else {
                $form['events']['table']['#rows'][$key]['element']['colspan'] = 2;
            }
        }
        // Put action buttons in the table footer.
        $links['add-event'] = [
            '#theme' => 'menu_local_action',
            '#link' => [
                'title' => $this->t('Add event'),
                'url' => $this->rulesUiHandler
                    ->getUrlFromRoute('event.add', []),
            ],
        ];
        $form['events']['table']['#footer'][] = [
            [
                'data' => [
                    '#prefix' => '<ul class="action-links">',
                    'local-action-links' => $links,
                    '#suffix' => '</ul>',
                ],
                'colspan' => 2,
            ],
        ];
        // CSS to make form easier to use. Load this at end so we can override
        // styles added by #theme table.
        $form['#attached']['library'][] = 'rules/rules_ui.styles';
        $form = $this->rulesUiHandler
            ->getForm()
            ->buildForm($form, $form_state);
        return parent::form($form, $form_state);
    }
    
    /**
     * {@inheritdoc}
     */
    public function validateForm(array &$form, FormStateInterface $form_state) {
        parent::validateForm($form, $form_state);
        $this->rulesUiHandler
            ->getForm()
            ->validateForm($form, $form_state);
    }
    
    /**
     * {@inheritdoc}
     */
    protected function actions(array $form, FormStateInterface $form_state) {
        $actions = parent::actions($form, $form_state);
        $actions['submit']['#value'] = $this->t('Save');
        $actions['cancel'] = [
            '#type' => 'submit',
            '#limit_validation_errors' => [
                [
                    'locked',
                ],
            ],
            '#value' => $this->t('Cancel'),
            '#submit' => [
                '::cancel',
            ],
        ];
        return $actions;
    }
    
    /**
     * {@inheritdoc}
     */
    public function save(array $form, FormStateInterface $form_state) {
        $this->rulesUiHandler
            ->getForm()
            ->submitForm($form, $form_state);
        $component = $this->rulesUiHandler
            ->getComponent();
        $this->entity
            ->updateFromComponent($component);
        // Persist changes by saving the entity.
        parent::save($form, $form_state);
        // Remove the temporarily stored component; it has been persisted now.
        $this->rulesUiHandler
            ->clearTemporaryStorage();
        $this->messenger()
            ->addMessage($this->t('Reaction rule %label has been updated.', [
            '%label' => $this->entity
                ->label(),
        ]));
    }
    
    /**
     * Form submission handler for the 'cancel' action.
     */
    public function cancel(array $form, FormStateInterface $form_state) {
        $this->rulesUiHandler
            ->clearTemporaryStorage();
        $this->messenger()
            ->addMessage($this->t('Canceled.'));
        $form_state->setRedirect('entity.rules_reaction_rule.collection');
    }
    
    /**
     * Title callback: also display the rule label.
     */
    public function getTitle($rules_reaction_rule) {
        return $this->t('Edit reaction rule "@label"', [
            '@label' => $rules_reaction_rule->label(),
        ]);
    }

}