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;
    }

}