class Config

class Config extends DestinationBase implements ContainerFactoryPluginInterface, DependentPluginInterface {
  use DependencyTrait;
  
  /**
   * The config object.
   *
   * @var \Drupal\Core\Config\Config
   */
  protected $config;
  
  /**
   * The language manager.
   *
   * @var \Drupal\Core\Language\LanguageManagerInterface
   */
  protected $language_manager;
  
  /**
   * Constructs a Config destination object.
   *
   * @param array $configuration
   *   A configuration array containing information about the plugin instance.
   * @param string $plugin_id
   *   The plugin ID for the plugin instance.
   * @param mixed $plugin_definition
   *   The plugin implementation definition.
   * @param \Drupal\migrate\Plugin\MigrationInterface $migration
   *   The migration entity.
   * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory
   *   The configuration factory.
   * @param \Drupal\Core\Language\LanguageManagerInterface $language_manager
   *   The language manager.
   */
  public function __construct(array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration, ConfigFactoryInterface $config_factory, LanguageManagerInterface $language_manager) {
    parent::__construct($configuration, $plugin_id, $plugin_definition, $migration);
    $this->config = $config_factory->getEditable($configuration['config_name']);
    $this->language_manager = $language_manager;
    if ($this->isTranslationDestination()) {
      $this->supportsRollback = TRUE;
    }
  }
  
  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration = NULL) {
    return new static($configuration, $plugin_id, $plugin_definition, $migration, $container->get('config.factory'), $container->get('language_manager'));
  }
  
  /**
   * {@inheritdoc}
   */
  public function import(Row $row, array $old_destination_id_values = []) {
    if ($this->isTranslationDestination()) {
      $this->config = $this->language_manager
        ->getLanguageConfigOverride($row->getDestinationProperty('langcode'), $this->config
        ->getName());
    }
    foreach ($row->getRawDestination() as $key => $value) {
      if (isset($value) || !empty($this->configuration['store null'])) {
        $this->config
          ->set(str_replace(Row::PROPERTY_SEPARATOR, '.', $key), $value);
      }
    }
    $this->config
      ->save();
    $ids[] = $this->config
      ->getName();
    if ($this->isTranslationDestination()) {
      $ids[] = $row->getDestinationProperty('langcode');
    }
    return $ids;
  }
  
  /**
   * {@inheritdoc}
   */
  public function fields() {
    // @todo Dynamically fetch fields using Config Schema API.
  }
  
  /**
   * {@inheritdoc}
   */
  public function getIds() {
    $ids['config_name']['type'] = 'string';
    if ($this->isTranslationDestination()) {
      $ids['langcode']['type'] = 'string';
    }
    return $ids;
  }
  
  /**
   * {@inheritdoc}
   */
  public function calculateDependencies() {
    $provider = explode('.', $this->config
      ->getName(), 2)[0];
    $this->addDependency('module', $provider);
    return $this->dependencies;
  }
  
  /**
   * Get whether this destination is for translations.
   *
   * @return bool
   *   Whether this destination is for translations.
   */
  protected function isTranslationDestination() {
    return !empty($this->configuration['translations']);
  }
  
  /**
   * {@inheritdoc}
   */
  public function rollback(array $destination_identifier) {
    if ($this->isTranslationDestination()) {
      $language = $destination_identifier['langcode'];
      $config = $this->language_manager
        ->getLanguageConfigOverride($language, $this->config
        ->getName());
      $config->delete();
    }
  }
  
  /**
   * {@inheritdoc}
   */
  public function getDestinationModule() {
    if (!empty($this->configuration['destination_module'])) {
      return $this->configuration['destination_module'];
    }
    if (!empty($this->pluginDefinition['destination_module'])) {
      return $this->pluginDefinition['destination_module'];
    }
    // Config translations require the config_translation module so set the
    // migration provider to 'config_translation'. The corresponding non
    // translated configuration is expected to be handled in a separate
    // migration.
    if (isset($this->configuration['translations'])) {
      return 'config_translation';
    }
    // Get the module handling this configuration object from the config_name,
    // which is of the form <module_name>.<configuration object name>
    return !empty($this->configuration['config_name']) ? explode('.', $this->configuration['config_name'], 2)[0] : NULL;
  }

}