class FileFormHooks

class FileFormHooks {
  use StringTranslationTrait;
  public function __construct(protected ConfigFactoryInterface $configFactory) {
  }
  
  /**
   * Implements hook_form_FORM_ID_alter().
   *
   * Injects the file sanitization options into /admin/config/media/file-system.
   *
   * These settings are enforced during upload by the FileEventSubscriber that
   * listens to the FileUploadSanitizeNameEvent event.
   *
   * @see \Drupal\system\Form\FileSystemForm
   * @see \Drupal\Core\File\Event\FileUploadSanitizeNameEvent
   * @see \Drupal\file\EventSubscriber\FileEventSubscriber
   */
  public function formSystemFileSystemSettingsAlter(array &$form, FormStateInterface $form_state) : void {
    $config = $this->configFactory
      ->get('file.settings');
    $form['filename_sanitization'] = [
      '#type' => 'details',
      '#title' => $this->t('Sanitize filenames'),
      '#description' => $this->t('These settings only apply to new files as they are uploaded. Changes here do not affect existing file names.'),
      '#open' => TRUE,
      '#tree' => TRUE,
    ];
    $form['filename_sanitization']['replacement_character'] = [
      '#type' => 'select',
      '#title' => $this->t('Replacement character'),
      '#default_value' => $config->get('filename_sanitization.replacement_character'),
      '#options' => [
        '-' => $this->t('Dash (-)'),
        '_' => $this->t('Underscore (_)'),
      ],
      '#description' => $this->t('Used when replacing whitespace, replacing non-alphanumeric characters or transliterating unknown characters.'),
    ];
    $form['filename_sanitization']['transliterate'] = [
      '#type' => 'checkbox',
      '#title' => $this->t('Transliterate'),
      '#default_value' => $config->get('filename_sanitization.transliterate'),
      '#description' => $this->t('Transliteration replaces any characters that are not alphanumeric, underscores, periods or hyphens with the replacement character. It ensures filenames only contain ASCII characters. It is recommended to keep transliteration enabled.'),
    ];
    $form['filename_sanitization']['replace_whitespace'] = [
      '#type' => 'checkbox',
      '#title' => $this->t('Replace whitespace with the replacement character'),
      '#default_value' => $config->get('filename_sanitization.replace_whitespace'),
    ];
    $form['filename_sanitization']['replace_non_alphanumeric'] = [
      '#type' => 'checkbox',
      '#title' => $this->t('Replace non-alphanumeric characters with the replacement character'),
      '#default_value' => $config->get('filename_sanitization.replace_non_alphanumeric'),
      '#description' => $this->t('Alphanumeric characters, dots <span aria-hidden="true">(.)</span>, underscores <span aria-hidden="true">(_)</span> and dashes <span aria-hidden="true">(-)</span> are preserved.'),
    ];
    $form['filename_sanitization']['deduplicate_separators'] = [
      '#type' => 'checkbox',
      '#title' => $this->t('Replace sequences of dots, underscores and/or dashes with the replacement character'),
      '#default_value' => $config->get('filename_sanitization.deduplicate_separators'),
    ];
    $form['filename_sanitization']['lowercase'] = [
      '#type' => 'checkbox',
      '#title' => $this->t('Convert to lowercase'),
      '#default_value' => $config->get('filename_sanitization.lowercase'),
    ];
    $form['#submit'][] = [
      FileFormHooks::class,
      'settingsSubmit',
    ];
  }
  
  /**
   * Form submission handler for file system settings form.
   *
   * @todo change this to a non-static method when
   *   https://www.drupal.org/project/drupal/issues/3536726 is in.
   */
  public static function settingsSubmit(array &$form, FormStateInterface $form_state) : void {
    $config = \Drupal::service(ConfigFactoryInterface::class)->getEditable('file.settings')
      ->set('filename_sanitization', $form_state->getValue('filename_sanitization'));
    $config->save();
  }

}