class FieldLayoutHooks

class FieldLayoutHooks {
  use StringTranslationTrait;
  
  /**
   * Implements hook_help().
   */
  public function help($route_name, RouteMatchInterface $route_match) : ?string {
    switch ($route_name) {
      case 'help.page.field_layout':
        $output = '<h2>' . $this->t('About') . '</h2>';
        $output .= '<p>' . $this->t('The Field Layout module allows you to arrange fields into regions on forms and displays of entities such as nodes and users.') . '</p>';
        $output .= '<p>' . $this->t('For more information, see the <a href=":field-layout-documentation">online documentation for the Field Layout module</a>.', [
          ':field-layout-documentation' => 'https://www.drupal.org/documentation/modules/field_layout',
        ]) . '</p>';
        return $output;
    }
    return NULL;
  }
  
  /**
   * Implements hook_entity_type_alter().
   */
  public function entityTypeAlter(array &$entity_types) : void {
    /** @var \Drupal\Core\Entity\EntityTypeInterface[] $entity_types */
    $entity_types['entity_view_display']->setClass(FieldLayoutEntityViewDisplay::class);
    $entity_types['entity_form_display']->setClass(FieldLayoutEntityFormDisplay::class);
    // The form classes are only needed when Field UI is installed.
    if (\Drupal::moduleHandler()->moduleExists('field_ui')) {
      $entity_types['entity_view_display']->setFormClass('edit', FieldLayoutEntityViewDisplayEditForm::class);
      $entity_types['entity_form_display']->setFormClass('edit', FieldLayoutEntityFormDisplayEditForm::class);
    }
  }
  
  /**
   * Implements hook_entity_view_alter().
   */
  public function entityViewAlter(array &$build, EntityInterface $entity, EntityViewDisplayInterface $display) : void {
    if ($display instanceof EntityDisplayWithLayoutInterface) {
      \Drupal::classResolver(FieldLayoutBuilder::class)->buildView($build, $display);
    }
  }
  
  /**
   * Implements hook_form_alter().
   */
  public function formAlter(&$form, FormStateInterface $form_state, $form_id) : void {
    $form_object = $form_state->getFormObject();
    if ($form_object instanceof ContentEntityFormInterface && $display = $form_object->getFormDisplay($form_state)) {
      if ($display instanceof EntityDisplayWithLayoutInterface) {
        \Drupal::classResolver(FieldLayoutBuilder::class)->buildForm($form, $display);
      }
    }
  }
  
  /**
   * Implements hook_modules_installed().
   */
  public function modulesInstalled($modules, bool $is_syncing) : void {
    if (!in_array('layout_builder', $modules)) {
      return;
    }
    $display_changed = FALSE;
    $displays = LayoutBuilderEntityViewDisplay::loadMultiple();
    /** @var \Drupal\layout_builder\Entity\LayoutEntityDisplayInterface[] $displays */
    foreach ($displays as $display) {
      // Create the first section from any existing Field Layout settings.
      $field_layout = $display->getThirdPartySettings('field_layout');
      if (isset($field_layout['id'])) {
        $field_layout += [
          'settings' => [],
        ];
        $display->enableLayoutBuilder()
          ->appendSection(new Section($field_layout['id'], $field_layout['settings']))
          ->save();
        $display_changed = TRUE;
      }
      // Clear the rendered cache to ensure the new layout builder flow is used.
      // While in many cases the above change will not affect the rendered
      // output, the cacheability metadata will have changed and should be
      // processed to prepare for future changes.
      if ($display_changed) {
        Cache::invalidateTags([
          'rendered',
        ]);
      }
    }
  }

}