class FileUploadHandler

class FileUploadHandler {
    
    /**
     * The default extensions if none are provided.
     */
    const DEFAULT_EXTENSIONS = 'jpg jpeg gif png txt doc xls pdf ppt pps odt ods odp';
    
    /**
     * The file system service.
     *
     * @var \Drupal\Core\File\FileSystemInterface
     */
    protected $fileSystem;
    
    /**
     * The entity type manager.
     *
     * @var \Drupal\Core\Entity\EntityTypeManagerInterface
     */
    protected $entityTypeManager;
    
    /**
     * The stream wrapper manager.
     *
     * @var \Drupal\Core\StreamWrapper\StreamWrapperManagerInterface
     */
    protected $streamWrapperManager;
    
    /**
     * The event dispatcher.
     *
     * @var \Symfony\Component\EventDispatcher\EventDispatcherInterface
     */
    protected $eventDispatcher;
    
    /**
     * The current user.
     *
     * @var \Drupal\Core\Session\AccountInterface
     */
    protected $currentUser;
    
    /**
     * The MIME type guesser.
     *
     * @var \Symfony\Component\Mime\MimeTypeGuesserInterface
     */
    protected $mimeTypeGuesser;
    
    /**
     * The request stack.
     *
     * @var \Symfony\Component\HttpFoundation\RequestStack
     */
    protected $requestStack;
    
    /**
     * The file Repository.
     *
     * @var \Drupal\file\FileRepositoryInterface
     */
    protected $fileRepository;
    
    /**
     * The file validator.
     *
     * @var \Drupal\file\Validation\FileValidatorInterface
     */
    protected FileValidatorInterface $fileValidator;
    public function __construct(FileSystemInterface $fileSystem, EntityTypeManagerInterface $entityTypeManager, StreamWrapperManagerInterface $streamWrapperManager, EventDispatcherInterface $eventDispatcher, MimeTypeGuesserInterface $mimeTypeGuesser, AccountInterface $currentUser, RequestStack $requestStack, FileRepositoryInterface $fileRepository, FileValidatorInterface $file_validator, LockBackendInterface $lock, BasicRecursiveValidatorFactory $validatorFactory) {
        $this->fileSystem = $fileSystem;
        $this->entityTypeManager = $entityTypeManager;
        $this->streamWrapperManager = $streamWrapperManager;
        $this->eventDispatcher = $eventDispatcher;
        $this->mimeTypeGuesser = $mimeTypeGuesser;
        $this->currentUser = $currentUser;
        $this->requestStack = $requestStack;
        $this->fileRepository = $fileRepository;
        $this->fileValidator = $file_validator;
    }
    
    /**
     * Creates a file from an upload.
     *
     * @param \Drupal\file\Upload\UploadedFileInterface $uploadedFile
     *   The uploaded file object.
     * @param array $validators
     *   The validators to run against the uploaded file.
     * @param string $destination
     *   The destination directory.
     * @param \Drupal\Core\File\FileExists|int $fileExists
     *   The behavior when the destination file already exists.
     *
     * @return \Drupal\file\Upload\FileUploadResult
     *   The created file entity.
     *
     * @throws \Symfony\Component\HttpFoundation\File\Exception\FileException
     *    Thrown when a file upload error occurred and $throws is TRUE.
     * @throws \Drupal\Core\File\Exception\FileWriteException
     *    Thrown when there is an error moving the file and $throws is TRUE.
     * @throws \Drupal\Core\File\Exception\FileException
     *    Thrown when a file system error occurs and $throws is TRUE.
     * @throws \Drupal\file\Upload\FileValidationException
     *    Thrown when file validation fails and $throws is TRUE.
     * @throws \Drupal\Core\Lock\LockAcquiringException
     *   Thrown when a lock cannot be acquired.
     * @throws \ValueError
     *   Thrown if $fileExists is a legacy int and not a valid value.
     */
    public function handleFileUpload(UploadedFileInterface $uploadedFile, array $validators = [], string $destination = 'temporary://', $fileExists = FileExists::Replace) : FileUploadResult {
        if (!$fileExists instanceof FileExists) {
            // @phpstan-ignore-next-line
            $fileExists = FileExists::fromLegacyInt($fileExists, __METHOD__);
        }
        $result = new FileUploadResult();
        $violations = $uploadedFile->validate($this->validatorFactory
            ->createValidator());
        if (count($violations) > 0) {
            $result->addViolations($violations);
            return $result;
        }
        $originalName = $uploadedFile->getClientOriginalName();
        $extensions = $this->handleExtensionValidation($validators);
        // Assert that the destination contains a valid stream.
        $destinationScheme = $this->streamWrapperManager::getScheme($destination);
        if (!$this->streamWrapperManager
            ->isValidScheme($destinationScheme)) {
            throw new InvalidStreamWrapperException(sprintf('The file could not be uploaded because the destination "%s" is invalid.', $destination));
        }
        // A file URI may already have a trailing slash or look like "public://".
        if (!str_ends_with($destination, '/')) {
            $destination .= '/';
        }
        // Call an event to sanitize the filename and to attempt to address security
        // issues caused by common server setups.
        $event = new FileUploadSanitizeNameEvent($originalName, $extensions);
        $this->eventDispatcher
            ->dispatch($event);
        $filename = $event->getFilename();
        $mimeType = $this->mimeTypeGuesser
            ->guessMimeType($filename);
        $destinationFilename = $this->fileSystem
            ->getDestinationFilename($destination . $filename, $fileExists);
        if ($destinationFilename === FALSE) {
            throw new FileExistsException(sprintf('Destination file "%s" exists', $destinationFilename));
        }
        // Lock based on the prepared file URI.
        $lock_id = $this->generateLockId($destinationFilename);
        try {
            if (!$this->lock
                ->acquire($lock_id)) {
                throw new LockAcquiringException(sprintf('File "%s" is already locked for writing.', $destinationFilename));
            }
            $file = File::create([
                'uid' => $this->currentUser
                    ->id(),
                'status' => 0,
                'uri' => $uploadedFile->getRealPath(),
            ]);
            // This will be replaced later with a filename based on the destination.
            $file->setFilename($filename);
            $file->setMimeType($mimeType);
            $file->setSize($uploadedFile->getSize());
            // Add in our check of the file name length.
            $validators['FileNameLength'] = [];
            // Call the validation functions specified by this function's caller.
            $violations = $this->fileValidator
                ->validate($file, $validators);
            if (count($violations) > 0) {
                $result->addViolations($violations);
                return $result;
            }
            $file->setFileUri($destinationFilename);
            if (!$this->moveUploadedFile($uploadedFile, $file->getFileUri())) {
                throw new FileWriteException('File upload error. Could not move uploaded file.');
            }
            // Update the filename with any changes as a result of security or
            // renaming due to an existing file.
            $file->setFilename($this->fileSystem
                ->basename($file->getFileUri()));
            if ($fileExists === FileExists::Replace) {
                $existingFile = $this->fileRepository
                    ->loadByUri($file->getFileUri());
                if ($existingFile) {
                    $file->fid = $existingFile->id();
                    $file->setOriginalId($existingFile->id());
                }
            }
            $result->setOriginalFilename($originalName)
                ->setSanitizedFilename($filename)
                ->setFile($file);
            // If the filename has been modified, let the user know.
            if ($event->isSecurityRename()) {
                $result->setSecurityRename();
            }
            // Set the permissions on the new file.
            $this->fileSystem
                ->chmod($file->getFileUri());
            // We can now validate the file object itself before it's saved.
            $violations = $file->validate();
            if (count($violations) > 0) {
                $result->addViolations($violations);
                return $result;
            }
            // If we made it this far it's safe to record this file in the database.
            $file->save();
            // Allow an anonymous user who creates a non-public file to see it. See
            // \Drupal\file\FileAccessControlHandler::checkAccess().
            if ($this->currentUser
                ->isAnonymous() && $destinationScheme !== 'public') {
                $session = $this->requestStack
                    ->getCurrentRequest()
                    ->getSession();
                $allowed_temp_files = $session->get('anonymous_allowed_file_ids', []);
                $allowed_temp_files[$file->id()] = $file->id();
                $session->set('anonymous_allowed_file_ids', $allowed_temp_files);
            }
        } finally {
            $this->lock
                ->release($lock_id);
        }
        return $result;
    }
    
    /**
     * Move the uploaded file from the temporary path to the destination.
     *
     * @param \Drupal\file\Upload\UploadedFileInterface $uploadedFile
     *   The uploaded file.
     * @param string $uri
     *   The destination URI.
     *
     * @return bool
     *   Returns FALSE if moving failed.
     *
     * @see https://www.drupal.org/project/drupal/issues/2940383
     */
    protected function moveUploadedFile(UploadedFileInterface $uploadedFile, string $uri) : bool {
        if ($uploadedFile instanceof FormUploadedFile) {
            return $this->fileSystem
                ->moveUploadedFile($uploadedFile->getRealPath(), $uri);
        }
        // We use FileExists::Error) as the file location has already
        // been determined above in FileSystem::getDestinationFilename().
        return $this->fileSystem
            ->move($uploadedFile->getRealPath(), $uri, FileExists::Error);
    }
    
    /**
     * Gets the list of allowed extensions and updates the validators.
     *
     * This will add an extension validator to the list of validators if one is
     * not set.
     *
     * If the extension validator is set, but no extensions are specified, it
     * means all extensions are allowed, so the validator is removed from the list
     * of validators.
     *
     * @param array $validators
     *   The file validators in use.
     *
     * @return string
     *   The space delimited list of allowed file extensions.
     */
    protected function handleExtensionValidation(array &$validators) : string {
        // No validator was provided, so add one using the default list.
        // Build a default non-munged safe list for
        // \Drupal\system\EventSubscriber\SecurityFileUploadEventSubscriber::sanitizeName().
        if (!isset($validators['FileExtension'])) {
            $validators['FileExtension'] = [
                'extensions' => self::DEFAULT_EXTENSIONS,
            ];
            return self::DEFAULT_EXTENSIONS;
        }
        // Check if we want to allow all extensions.
        if (!isset($validators['FileExtension']['extensions'])) {
            // If 'FileExtension' is set and the list is empty then the caller wants
            // to allow any extension. In this case we have to remove the validator
            // or else it will reject all extensions.
            unset($validators['FileExtension']);
            return '';
        }
        return $validators['FileExtension']['extensions'];
    }
    
    /**
     * Generates a lock ID based on the file URI.
     */
    protected static function generateLockId(string $fileUri) : string {
        return 'file:upload:' . Crypt::hashBase64($fileUri);
    }

}