class FileUpload

class FileUpload {
    use EntityValidationTrait;
    use FileUploadLocationTrait;
    use FileValidatorSettingsTrait;
    public function __construct(AccountInterface $currentUser, EntityFieldManagerInterface $fieldManager, FileUploadHandler $fileUploadHandler, HttpKernelInterface $httpKernel, InputStreamFileWriterInterface $inputStreamFileWriter, FileSystemInterface $fileSystem) {
    }
    
    /**
     * Handles JSON:API file upload requests.
     *
     * @param \Symfony\Component\HttpFoundation\Request $request
     *   The HTTP request object.
     * @param \Drupal\jsonapi\ResourceType\ResourceType $resource_type
     *   The JSON:API resource type for the current request.
     * @param string $file_field_name
     *   The file field for which the file is to be uploaded.
     * @param \Drupal\Core\Entity\FieldableEntityInterface $entity
     *   The entity for which the file is to be uploaded.
     *
     * @return \Drupal\jsonapi\ResourceResponse
     *   The response object.
     *
     * @throws \Symfony\Component\HttpKernel\Exception\UnprocessableEntityHttpException
     *   Thrown when there are validation errors.
     * @throws \Drupal\Core\Entity\EntityStorageException
     *   Thrown if the upload's target resource could not be saved.
     * @throws \Exception
     *   Thrown if an exception occurs during a subrequest to fetch the newly
     *   created file entity.
     */
    public function handleFileUploadForExistingResource(Request $request, ResourceType $resource_type, string $file_field_name, FieldableEntityInterface $entity) : Response {
        $result = $this->handleFileUploadForResource($request, $resource_type, $file_field_name, $entity);
        $file = $result->getFile();
        if ($resource_type->getFieldByInternalName($file_field_name)
            ->hasOne()) {
            $entity->{$file_field_name} = $file;
        }
        else {
            $entity->get($file_field_name)
                ->appendItem($file);
        }
        static::validate($entity, [
            $file_field_name,
        ]);
        $entity->save();
        $route_parameters = [
            'entity' => $entity->uuid(),
        ];
        $route_name = sprintf('jsonapi.%s.%s.related', $resource_type->getTypeName(), $resource_type->getPublicName($file_field_name));
        $related_url = Url::fromRoute($route_name, $route_parameters)->toString(TRUE);
        $request = Request::create($related_url->getGeneratedUrl(), 'GET', [], $request->cookies
            ->all(), [], $request->server
            ->all());
        return $this->httpKernel
            ->handle($request, HttpKernelInterface::SUB_REQUEST);
    }
    
    /**
     * Handles JSON:API file upload requests.
     *
     * @param \Symfony\Component\HttpFoundation\Request $request
     *   The HTTP request object.
     * @param \Drupal\jsonapi\ResourceType\ResourceType $resource_type
     *   The JSON:API resource type for the current request.
     * @param string $file_field_name
     *   The file field for which the file is to be uploaded.
     *
     * @return \Drupal\jsonapi\ResourceResponse
     *   The response object.
     *
     * @throws \Symfony\Component\HttpKernel\Exception\UnprocessableEntityHttpException
     *   Thrown when there are validation errors.
     */
    public function handleFileUploadForNewResource(Request $request, ResourceType $resource_type, string $file_field_name) : ResourceResponse {
        $result = $this->handleFileUploadForResource($request, $resource_type, $file_field_name);
        $file = $result->getFile();
        // @todo Remove line below in favor of commented line in https://www.drupal.org/project/drupal/issues/2878463.
        $self_link = new Link(new CacheableMetadata(), Url::fromRoute('jsonapi.file--file.individual', [
            'entity' => $file->uuid(),
        ]), 'self');
        
        /* $self_link = new Link(new CacheableMetadata(), $this->entity->toUrl('jsonapi'), ['self']); */
        $links = new LinkCollection([
            'self' => $self_link,
        ]);
        $relatable_resource_types = $resource_type->getRelatableResourceTypesByField($resource_type->getPublicName($file_field_name));
        $file_resource_type = reset($relatable_resource_types);
        $resource_object = ResourceObject::createFromEntity($file_resource_type, $file);
        return new ResourceResponse(new JsonApiDocumentTopLevel(new ResourceObjectData([
            $resource_object,
        ], 1), new NullIncludedData(), $links), 201, []);
    }
    
    /**
     * Handles JSON:API file upload requests.
     *
     * @param \Symfony\Component\HttpFoundation\Request $request
     *   The HTTP request object.
     * @param \Drupal\jsonapi\ResourceType\ResourceType $resource_type
     *   The JSON:API resource type for the current request.
     * @param string $file_field_name
     *   The file field for which the file is to be uploaded.
     * @param \Drupal\Core\Entity\FieldableEntityInterface|null $entity
     *   (optional) The entity for which the file is to be uploaded.
     *
     * @return \Drupal\file\Upload\FileUploadResult
     *   The file upload result.
     */
    protected function handleFileUploadForResource(Request $request, ResourceType $resource_type, string $file_field_name, ?FieldableEntityInterface $entity = NULL) : FileUploadResult {
        $file_field_name = $resource_type->getInternalName($file_field_name);
        $field_definition = $this->validateAndLoadFieldDefinition($resource_type->getEntityTypeId(), $resource_type->getBundle(), $file_field_name);
        static::ensureFileUploadAccess($this->currentUser, $field_definition, $entity);
        $filename = ContentDispositionFilenameParser::parseFilename($request);
        $tempPath = $this->inputStreamFileWriter
            ->writeStreamToFile();
        $uploadedFile = new InputStreamUploadedFile($filename, $filename, $tempPath, @filesize($tempPath));
        $settings = $field_definition->getSettings();
        $validators = $this->getFileUploadValidators($settings);
        if (!array_key_exists('FileExtension', $validators) && $settings['file_extensions'] === '') {
            // An empty string means 'all file extensions' but the FileUploadHandler
            // needs the FileExtension entry to be present and empty in order for this
            // to be respected. An empty array means 'all file extensions'.
            // @see \Drupal\file\Upload\FileUploadHandler::handleExtensionValidation
            $validators['FileExtension'] = [];
        }
        $destination = $this->getUploadLocation($field_definition);
        // Check the destination file path is writable.
        if (!$this->fileSystem
            ->prepareDirectory($destination, FileSystemInterface::CREATE_DIRECTORY)) {
            throw new HttpException(500, 'Destination file path is not writable');
        }
        try {
            $result = $this->fileUploadHandler
                ->handleFileUpload($uploadedFile, $validators, $destination, FileExists::Rename, FALSE);
        } catch (LockAcquiringException $e) {
            throw new HttpException(503, $e->getMessage(), NULL, [
                'Retry-After' => 1,
            ]);
        } catch (UploadException $e) {
            throw new HttpException(500, 'Input file data could not be read', $e);
        } catch (CannotWriteFileException $e) {
            throw new HttpException(500, 'Temporary file data could not be written', $e);
        } catch (NoFileException $e) {
            throw new HttpException(500, 'Temporary file could not be opened', $e);
        } catch (FileExistsException $e) {
            throw new HttpException(500, $e->getMessage(), $e);
        } catch (FileException) {
            throw new HttpException(500, 'Temporary file could not be moved to file location');
        }
        if ($result->hasViolations()) {
            $message = "Unprocessable Entity: file validation failed.\n";
            $message .= implode("\n", array_map(function (ConstraintViolationInterface $violation) {
                return PlainTextOutput::renderFromHtml($violation->getMessage());
            }, (array) $result->getViolations()
                ->getIterator()));
            throw new UnprocessableEntityHttpException($message);
        }
        return $result;
    }
    
    /**
     * Checks if the current user has access to upload the file.
     *
     * @param \Drupal\Core\Session\AccountInterface $account
     *   The account for which file upload access should be checked.
     * @param \Drupal\Core\Field\FieldDefinitionInterface $field_definition
     *   The field definition for which to get validators.
     * @param \Drupal\Core\Entity\EntityInterface $entity
     *   (optional) The entity to which the file is to be uploaded, if it exists.
     *   If the entity does not exist and it is not given, create access to the
     *   entity the file is attached to will be checked.
     *
     * @return \Drupal\Core\Access\AccessResultInterface
     *   The file upload access result.
     */
    public static function checkFileUploadAccess(AccountInterface $account, FieldDefinitionInterface $field_definition, ?EntityInterface $entity = NULL) {
        assert(is_null($entity) || $field_definition->getTargetEntityTypeId() === $entity->getEntityTypeId() && (is_null($field_definition->getTargetBundle()) || $field_definition->getTargetBundle() === $entity->bundle()));
        $entity_type_manager = \Drupal::entityTypeManager();
        $entity_access_control_handler = $entity_type_manager->getAccessControlHandler($field_definition->getTargetEntityTypeId());
        $bundle = $entity_type_manager->getDefinition($field_definition->getTargetEntityTypeId())
            ->hasKey('bundle') ? $field_definition->getTargetBundle() : NULL;
        $entity_access_result = $entity ? $entity_access_control_handler->access($entity, 'update', $account, TRUE) : $entity_access_control_handler->createAccess($bundle, $account, [], TRUE);
        $field_access_result = $entity_access_control_handler->fieldAccess('edit', $field_definition, NULL, NULL, TRUE);
        return $entity_access_result->andIf($field_access_result);
    }
    
    /**
     * Ensures that the given account is allowed to upload a file.
     *
     * @param \Drupal\Core\Session\AccountInterface $account
     *   The account for which access should be checked.
     * @param \Drupal\Core\Field\FieldDefinitionInterface $field_definition
     *   The field for which the file is to be uploaded.
     * @param \Drupal\Core\Entity\FieldableEntityInterface|null $entity
     *   The entity, if one exists, for which the file is to be uploaded.
     */
    protected static function ensureFileUploadAccess(AccountInterface $account, FieldDefinitionInterface $field_definition, ?FieldableEntityInterface $entity = NULL) {
        $access_result = $entity ? static::checkFileUploadAccess($account, $field_definition, $entity) : static::checkFileUploadAccess($account, $field_definition);
        if (!$access_result->isAllowed()) {
            $reason = 'The current user is not permitted to upload a file for this field.';
            if ($access_result instanceof AccessResultReasonInterface) {
                $reason .= ' ' . $access_result->getReason();
            }
            throw new AccessDeniedHttpException($reason);
        }
    }
    
    /**
     * Validates and loads a field definition instance.
     *
     * @param string $entity_type_id
     *   The entity type ID the field is attached to.
     * @param string $bundle
     *   The bundle the field is attached to.
     * @param string $field_name
     *   The field name.
     *
     * @return \Drupal\Core\Field\FieldDefinitionInterface
     *   The field definition.
     *
     * @throws \Symfony\Component\HttpKernel\Exception\NotFoundHttpException
     *   Thrown when the field does not exist.
     * @throws \Symfony\Component\HttpFoundation\File\Exception\AccessDeniedException
     *   Thrown when the target type of the field is not a file, or the current
     *   user does not have 'edit' access for the field.
     */
    protected function validateAndLoadFieldDefinition($entity_type_id, $bundle, $field_name) {
        $field_definitions = $this->fieldManager
            ->getFieldDefinitions($entity_type_id, $bundle);
        if (!isset($field_definitions[$field_name])) {
            throw new NotFoundHttpException(sprintf('Field "%s" does not exist.', $field_name));
        }
        
        /** @var \Drupal\Core\Field\FieldDefinitionInterface $field_definition */
        $field_definition = $field_definitions[$field_name];
        if ($field_definition->getSetting('target_type') !== 'file') {
            throw new AccessDeniedException(sprintf('"%s" is not a file field', $field_name));
        }
        return $field_definition;
    }

}