class LanguageListBuilder

class LanguageListBuilder extends DraggableListBuilder {
    
    /**
     * {@inheritdoc}
     */
    protected $entitiesKey = 'languages';
    
    /**
     * The language manager.
     *
     * @var \Drupal\Core\Language\LanguageManagerInterface
     */
    protected $languageManager;
    
    /**
     * The configuration factory.
     *
     * @var \Drupal\Core\Config\ConfigFactoryInterface
     */
    protected $configFactory;
    
    /**
     * The messenger.
     *
     * @var \Drupal\Core\Messenger\MessengerInterface
     */
    protected $messenger;
    
    /**
     * {@inheritdoc}
     */
    public static function createInstance(ContainerInterface $container, EntityTypeInterface $entity_type) {
        return new static($entity_type, $container->get('entity_type.manager')
            ->getStorage($entity_type->id()), $container->get('language_manager'), $container->get('config.factory'), $container->get('messenger'));
    }
    
    /**
     * Constructs a new LanguageListBuilder object.
     *
     * @param \Drupal\Core\Entity\EntityTypeInterface $entity_type
     *   The entity type definition.
     * @param \Drupal\Core\Entity\EntityStorageInterface $storage
     *   The entity storage handler class.
     * @param \Drupal\Core\Language\LanguageManagerInterface $language_manager
     *   The language manager.
     * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory
     *   The factory for configuration objects.
     * @param \Drupal\Core\Messenger\MessengerInterface $messenger
     *   The messenger.
     */
    public function __construct(EntityTypeInterface $entity_type, EntityStorageInterface $storage, LanguageManagerInterface $language_manager, ConfigFactoryInterface $config_factory, MessengerInterface $messenger) {
        parent::__construct($entity_type, $storage);
        $this->languageManager = $language_manager;
        $this->configFactory = $config_factory;
        $this->messenger = $messenger;
    }
    
    /**
     * {@inheritdoc}
     */
    public function load() {
        $entities = $this->storage
            ->loadByProperties([
            'locked' => FALSE,
        ]);
        // Sort the entities using the entity class's sort() method.
        // See \Drupal\Core\Config\Entity\ConfigEntityBase::sort().
        uasort($entities, [
            $this->entityType
                ->getClass(),
            'sort',
        ]);
        return $entities;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getFormId() {
        return 'language_admin_overview_form';
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildHeader() {
        $header = [
            'label' => $this->t('Name'),
            'default' => $this->t('Default'),
        ] + parent::buildHeader();
        return $header;
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildRow(EntityInterface $entity) {
        $row['label'] = $entity->label();
        $row['default'] = [
            '#type' => 'radio',
            '#parents' => [
                'site_default_language',
            ],
            '#title' => $this->t('Set @title as default', [
                '@title' => $entity->label(),
            ]),
            '#title_display' => 'invisible',
            '#return_value' => $entity->id(),
            '#id' => 'edit-site-default-language-' . $entity->id(),
        ];
        // Mark the right language as default in the form.
        if ($entity->id() == $this->languageManager
            ->getDefaultLanguage()
            ->getId()) {
            $row['default']['#default_value'] = $entity->id();
        }
        return $row + parent::buildRow($entity);
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildForm(array $form, FormStateInterface $form_state) {
        $form = parent::buildForm($form, $form_state);
        $form[$this->entitiesKey]['#languages'] = $this->entities;
        $form['actions']['submit']['#value'] = $this->t('Save configuration');
        return $form;
    }
    
    /**
     * {@inheritdoc}
     */
    public function validateForm(array &$form, FormStateInterface $form_state) {
        if (!isset($this->entities[$form_state->getValue('site_default_language')])) {
            $form_state->setErrorByName('site_default_language', $this->t('Selected default language no longer exists.'));
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function submitForm(array &$form, FormStateInterface $form_state) {
        parent::submitForm($form, $form_state);
        // Save the default language if changed.
        $new_id = $form_state->getValue('site_default_language');
        if ($new_id != $this->languageManager
            ->getDefaultLanguage()
            ->getId()) {
            $this->configFactory
                ->getEditable('system.site')
                ->set('default_langcode', $new_id)
                ->save();
            $this->languageManager
                ->reset();
        }
        if ($this->languageManager instanceof ConfigurableLanguageManagerInterface) {
            $this->languageManager
                ->updateLockedLanguageWeights();
        }
        $this->messenger
            ->addStatus($this->t('Configuration saved.'));
        // Force the redirection to the page with the language we have just
        // selected as default.
        $form_state->setRedirectUrl($this->entities[$new_id]
            ->toUrl('collection', [
            'language' => $this->entities[$new_id],
        ]));
    }

}