class LocaleTranslation

class LocaleTranslation extends QueueWorkerBase implements ContainerFactoryPluginInterface {
    
    /**
     * The module handler.
     *
     * @var \Drupal\Core\Extension\ModuleHandlerInterface
     */
    protected $moduleHandler;
    
    /**
     * The queue object.
     *
     * @var \Drupal\Core\Queue\QueueInterface
     */
    protected $queue;
    
    /**
     * Constructs a new LocaleTranslation 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 array $plugin_definition
     *   The plugin implementation definition.
     * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
     *   The module handler.
     * @param \Drupal\Core\Queue\QueueInterface $queue
     *   The queue object.
     */
    public function __construct(array $configuration, $plugin_id, array $plugin_definition, ModuleHandlerInterface $module_handler, QueueInterface $queue) {
        parent::__construct($configuration, $plugin_id, $plugin_definition);
        $this->moduleHandler = $module_handler;
        $this->queue = $queue;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
        return new static($configuration, $plugin_id, $plugin_definition, $container->get('module_handler'), $container->get('queue')
            ->get('locale_translation', TRUE));
    }
    
    /**
     * {@inheritdoc}
     *
     * The translation update functions executed here are batch operations which
     * are also used in translation update batches. The batch functions may need
     * to be executed multiple times to complete their task, typically this is the
     * translation import function. When a batch function is not finished, a new
     * queue task is created and added to the end of the queue. The batch context
     * data is needed to continue the batch task is stored in the queue with the
     * queue data.
     */
    public function processItem($data) {
        $this->moduleHandler
            ->loadInclude('locale', 'batch.inc');
        list($function, $args) = $data;
        // We execute batch operation functions here to check, download and import
        // the translation files. Batch functions use a context variable as last
        // argument which is passed by reference. When a batch operation is called
        // for the first time a default batch context is created. When called
        // iterative (usually the batch import function) the batch context is passed
        // through via the queue and is part of the $data.
        $last = count($args) - 1;
        if (!is_array($args[$last]) || !isset($args[$last]['finished'])) {
            $batch_context = [
                'sandbox' => [],
                'results' => [],
                'finished' => 1,
                'message' => '',
            ];
        }
        else {
            $batch_context = $args[$last];
            unset($args[$last]);
        }
        $args = array_merge($args, [
            &$batch_context,
        ]);
        // Call the batch operation function.
        call_user_func_array($function, $args);
        // If the batch operation is not finished we create a new queue task to
        // continue the task. This is typically the translation import task.
        if ($batch_context['finished'] < 1) {
            unset($batch_context['strings']);
            $this->queue
                ->createItem([
                $function,
                $args,
            ]);
        }
    }

}