class ConfigImportForm

class ConfigImportForm extends FormBase {
    
    /**
     * The configuration storage.
     *
     * @var \Drupal\Core\Config\StorageInterface
     */
    protected $configStorage;
    
    /**
     * The file system service.
     *
     * @var \Drupal\Core\File\FileSystemInterface
     */
    protected $fileSystem;
    
    /**
     * The settings object.
     *
     * @var \Drupal\Core\Site\Settings
     */
    protected $settings;
    
    /**
     * Constructs a new ConfigImportForm.
     *
     * @param \Drupal\Core\Config\StorageInterface $config_storage
     *   The configuration storage.
     * @param \Drupal\Core\File\FileSystemInterface $file_system
     *   The file system service.
     * @param \Drupal\Core\Site\Settings $settings
     *   The settings object.
     */
    public function __construct(StorageInterface $config_storage, FileSystemInterface $file_system, Settings $settings) {
        $this->configStorage = $config_storage;
        $this->fileSystem = $file_system;
        $this->settings = $settings;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container) {
        return new static($container->get('config.storage.sync'), $container->get('file_system'), $container->get('settings'));
    }
    
    /**
     * {@inheritdoc}
     */
    public function getFormId() {
        return 'config_import_form';
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildForm(array $form, FormStateInterface $form_state) {
        $directory = $this->settings
            ->get('config_sync_directory');
        $directory_is_writable = is_writable($directory);
        if (!$directory_is_writable) {
            $this->messenger()
                ->addError($this->t('The directory %directory is not writable.', [
                '%directory' => $directory,
            ]));
        }
        $form['import_tarball'] = [
            '#type' => 'file',
            '#title' => $this->t('Configuration archive'),
            '#description' => $this->t('Allowed types: @extensions.', [
                '@extensions' => 'tar.gz tgz tar.bz2',
            ]),
        ];
        $form['submit'] = [
            '#type' => 'submit',
            '#value' => $this->t('Upload'),
            '#disabled' => !$directory_is_writable,
        ];
        return $form;
    }
    
    /**
     * {@inheritdoc}
     */
    public function validateForm(array &$form, FormStateInterface $form_state) {
        $all_files = $this->getRequest()->files
            ->get('files', []);
        if (!empty($all_files['import_tarball'])) {
            $file_upload = $all_files['import_tarball'];
            if ($file_upload->isValid()) {
                $form_state->setValue('import_tarball', $file_upload->getRealPath());
                return;
            }
        }
        $form_state->setErrorByName('import_tarball', $this->t('The file could not be uploaded.'));
    }
    
    /**
     * {@inheritdoc}
     */
    public function submitForm(array &$form, FormStateInterface $form_state) {
        if ($path = $form_state->getValue('import_tarball')) {
            $this->configStorage
                ->deleteAll();
            try {
                $archiver = new ArchiveTar($path, 'gz');
                $files = [];
                foreach ($archiver->listContent() as $file) {
                    $files[] = $file['filename'];
                }
                $archiver->extractList($files, $this->settings
                    ->get('config_sync_directory'), '', FALSE, FALSE);
                $this->messenger()
                    ->addStatus($this->t('Your configuration files were successfully uploaded and are ready for import.'));
                $form_state->setRedirect('config.sync');
            } catch (\Exception $e) {
                $this->messenger()
                    ->addError($this->t('Could not extract the contents of the tar file. The error message is <em>@message</em>', [
                    '@message' => $e->getMessage(),
                ]));
            }
            $this->fileSystem
                ->unlink($path);
        }
    }

}