class EntityTypeInfo

class EntityTypeInfo implements ContainerInjectionInterface {
    public function __construct(WorkspaceInformationInterface $workspaceInfo) {
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container) {
        return new static($container->get('workspaces.information'));
    }
    
    /**
     * Adds workspace support info to eligible entity types.
     *
     * @param \Drupal\Core\Entity\EntityTypeInterface[] $entity_types
     *   An associative array of all entity type definitions, keyed by the entity
     *   type name. Passed by reference.
     *
     * @see hook_entity_type_build()
     */
    public function entityTypeBuild(array &$entity_types) {
        foreach ($entity_types as $entity_type) {
            if ($entity_type->hasHandlerClass('workspace')) {
                continue;
            }
            // Revisionable and publishable entity types are always supported.
            if ($entity_type->entityClassImplements(EntityPublishedInterface::class) && $entity_type->isRevisionable()) {
                $entity_type->setHandlerClass('workspace', DefaultWorkspaceHandler::class);
                // Support for custom blocks has to be determined on a per-entity
                // basis.
                if ($entity_type->id() === 'block_content') {
                    $entity_type->setHandlerClass('workspace', BlockContentWorkspaceHandler::class);
                }
            }
            // Internal entity types are allowed to perform CRUD operations inside a
            // workspace.
            if ($entity_type->isInternal()) {
                $entity_type->setHandlerClass('workspace', IgnoredWorkspaceHandler::class);
            }
        }
    }
    
    /**
     * Adds Workspace configuration to appropriate entity types.
     *
     * @param \Drupal\Core\Entity\EntityTypeInterface[] $entity_types
     *   An array of entity types.
     *
     * @see hook_entity_type_alter()
     */
    public function entityTypeAlter(array &$entity_types) {
        foreach ($entity_types as $entity_type) {
            if (!$this->workspaceInfo
                ->isEntityTypeSupported($entity_type)) {
                continue;
            }
            // Workspace-support status has been declared in the "build" phase, now we
            // can use that information and add additional configuration in the
            // "alter" phase.
            $entity_type->addConstraint('EntityWorkspaceConflict');
            $entity_type->setRevisionMetadataKey('workspace', 'workspace');
            // Non-default workspaces display the active revision on the canonical
            // route of an entity, so the latest version route is no longer needed.
            $link_templates = $entity_type->get('links');
            unset($link_templates['latest-version']);
            $entity_type->set('links', $link_templates);
        }
    }
    
    /**
     * Alters field plugin definitions.
     *
     * @param array[] $definitions
     *   An array of field plugin definitions.
     *
     * @see hook_field_info_alter()
     */
    public function fieldInfoAlter(&$definitions) {
        if (isset($definitions['entity_reference'])) {
            $definitions['entity_reference']['constraints']['EntityReferenceSupportedNewEntities'] = [];
        }
        // Allow path aliases to be changed in workspace-specific pending revisions.
        if (isset($definitions['path'])) {
            unset($definitions['path']['constraints']['PathAlias']);
        }
    }
    
    /**
     * Provides custom base field definitions for a content entity type.
     *
     * @param \Drupal\Core\Entity\EntityTypeInterface $entity_type
     *   The entity type definition.
     *
     * @return \Drupal\Core\Field\FieldDefinitionInterface[]
     *   An array of field definitions, keyed by field name.
     *
     * @see hook_entity_base_field_info()
     */
    public function entityBaseFieldInfo(EntityTypeInterface $entity_type) {
        if ($this->workspaceInfo
            ->isEntityTypeSupported($entity_type)) {
            $field_name = $entity_type->getRevisionMetadataKey('workspace');
            $fields[$field_name] = BaseFieldDefinition::create('entity_reference')->setLabel(new TranslatableMarkup('Workspace'))
                ->setDescription(new TranslatableMarkup('Indicates the workspace that this revision belongs to.'))
                ->setSetting('target_type', 'workspace')
                ->setInternal(TRUE)
                ->setTranslatable(FALSE)
                ->setRevisionable(TRUE);
            return $fields;
        }
    }

}