class MigrateStub

class MigrateStub implements MigrateStubInterface {
    
    /**
     * The migration plugin manager.
     *
     * @var \Drupal\migrate\Plugin\MigrationPluginManagerInterface
     */
    protected $migrationPluginManager;
    
    /**
     * Constructs a MigrationStub object.
     *
     * @param \Drupal\migrate\Plugin\MigrationPluginManagerInterface $migration_plugin_manager
     *   The migration plugin manager.
     */
    public function __construct(MigrationPluginManagerInterface $migration_plugin_manager) {
        $this->migrationPluginManager = $migration_plugin_manager;
    }
    
    /**
     * Creates a stub.
     *
     * @param string $migration_id
     *   The migration to stub.
     * @param array $source_ids
     *   An array of source ids.
     * @param array $default_values
     *   (optional) An array of default values to add to the stub.
     * @param bool $key_by_destination_ids
     *   (optional) NULL or TRUE to force indexing of the return array by
     *   destination id keys (default), or FALSE to return the raw return value of
     *   the destination plugin's ::import() method. The return value from
     *   MigrateDestinationInterface::import() is very poorly defined as "The
     *   entity ID or an indication of success". In practice, the mapping systems
     *   expect and all destination plugins return an array of destination
     *   identifiers. Unfortunately these arrays are inconsistently keyed. The
     *   core destination plugins return a numerically indexed array of
     *   destination identifiers, but several contrib destinations return an array
     *   of identifiers indexed by the destination keys. This method will
     *   generally index all return arrays for consistency and to provide as much
     *   information as possible, but this parameter is added for backwards
     *   compatibility to allow accessing the original array.
     *
     * @return array|false
     *   An array of destination ids for the new stub, keyed by destination id
     *   key, or false if the stub failed.
     *
     * @throws \Drupal\Component\Plugin\Exception\PluginException
     * @throws \Drupal\Component\Plugin\Exception\PluginNotFoundException
     * @throws \Drupal\migrate\MigrateException
     */
    public function createStub($migration_id, array $source_ids, array $default_values = [], $key_by_destination_ids = NULL) {
        $migrations = $this->migrationPluginManager
            ->createInstances([
            $migration_id,
        ]);
        if (!$migrations) {
            throw new PluginNotFoundException($migration_id);
        }
        if (count($migrations) !== 1) {
            throw new \LogicException(sprintf('Cannot stub derivable migration "%s".  You must specify the id of a specific derivative to stub.', $migration_id));
        }
        $migration = reset($migrations);
        $source_id_keys = array_keys($migration->getSourcePlugin()
            ->getIds());
        if (count($source_id_keys) !== count($source_ids)) {
            throw new \InvalidArgumentException('Expected and provided source id counts do not match.');
        }
        if (array_keys($source_ids) === range(0, count($source_ids) - 1)) {
            $source_ids = array_combine($source_id_keys, $source_ids);
        }
        $stub = $this->doCreateStub($migration, $source_ids, $default_values);
        // If the return from ::import is numerically indexed, and we aren't
        // requesting the raw return value, index it associatively using the
        // destination id keys.
        if ($key_by_destination_ids !== FALSE && array_keys($stub) === range(0, count($stub) - 1)) {
            $stub = array_combine(array_keys($migration->getDestinationPlugin()
                ->getIds()), $stub);
        }
        return $stub;
    }
    
    /**
     * Creates a stub.
     *
     * @param \Drupal\migrate\Plugin\MigrationInterface $migration
     *   The migration to use to create the stub.
     * @param array $source_ids
     *   The source ids to map to the stub.
     * @param array $default_values
     *   (optional) An array of values to include in the stub.
     *
     * @return array|bool
     *   An array of destination ids for the stub.
     *
     * @throws \Drupal\migrate\MigrateException
     */
    protected function doCreateStub(MigrationInterface $migration, array $source_ids, array $default_values = []) {
        $destination = $migration->getDestinationPlugin(TRUE);
        $process = $migration->getProcess();
        $id_map = $migration->getIdMap();
        $migrate_executable = new MigrateExecutable($migration);
        $row = new Row($source_ids + $migration->getSourceConfiguration(), $migration->getSourcePlugin()
            ->getIds(), TRUE);
        $migrate_executable->processRow($row, $process);
        foreach ($default_values as $key => $value) {
            $row->setDestinationProperty($key, $value);
        }
        $destination_ids = [];
        try {
            $destination_ids = $destination->import($row);
        } catch (\Exception $e) {
            $id_map->saveMessage($row->getSourceIdValues(), $e->getMessage());
        }
        if ($destination_ids) {
            $id_map->saveIdMapping($row, $destination_ids, MigrateIdMapInterface::STATUS_NEEDS_UPDATE);
            return $destination_ids;
        }
        return FALSE;
    }

}