class LinkBase

abstract class LinkBase extends FieldPluginBase {
    use RedirectDestinationTrait;
    use EntityTranslationRenderTrait;
    
    /**
     * The access manager service.
     *
     * @var \Drupal\Core\Access\AccessManagerInterface
     */
    protected $accessManager;
    
    /**
     * Current user object.
     *
     * @var \Drupal\Core\Session\AccountInterface
     */
    protected $currentUser;
    
    /**
     * The language manager.
     *
     * @var \Drupal\Core\Language\LanguageManagerInterface
     */
    protected $languageManager;
    
    /**
     * The entity type manager.
     *
     * @var \Drupal\Core\Entity\EntityTypeManagerInterface
     */
    protected $entityTypeManager;
    
    /**
     * The entity repository.
     *
     * @var \Drupal\Core\Entity\EntityRepositoryInterface
     */
    protected $entityRepository;
    
    /**
     * Constructs a LinkBase 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\Core\Access\AccessManagerInterface $access_manager
     *   The access manager.
     * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
     *   The entity type manager.
     * @param \Drupal\Core\Entity\EntityRepositoryInterface $entity_repository
     *   The entity repository.
     * @param \Drupal\Core\Language\LanguageManagerInterface $language_manager
     *   The language manager.
     */
    public function __construct(array $configuration, $plugin_id, $plugin_definition, AccessManagerInterface $access_manager, EntityTypeManagerInterface $entity_type_manager, EntityRepositoryInterface $entity_repository, LanguageManagerInterface $language_manager) {
        parent::__construct($configuration, $plugin_id, $plugin_definition);
        $this->accessManager = $access_manager;
        $this->entityTypeManager = $entity_type_manager;
        $this->entityRepository = $entity_repository;
        $this->languageManager = $language_manager;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
        return new static($configuration, $plugin_id, $plugin_definition, $container->get('access_manager'), $container->get('entity_type.manager'), $container->get('entity.repository'), $container->get('language_manager'));
    }
    
    /**
     * Gets the current active user.
     *
     * @todo https://www.drupal.org/node/2105123 put this method in
     *   \Drupal\Core\Plugin\PluginBase instead.
     *
     * @return \Drupal\Core\Session\AccountInterface
     *   The current user.
     */
    protected function currentUser() {
        if (!$this->currentUser) {
            $this->currentUser = \Drupal::currentUser();
        }
        return $this->currentUser;
    }
    
    /**
     * {@inheritdoc}
     */
    protected function defineOptions() {
        $options = parent::defineOptions();
        $options['text'] = [
            'default' => $this->getDefaultLabel(),
        ];
        return $options;
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildOptionsForm(&$form, FormStateInterface $form_state) {
        $form['text'] = [
            '#type' => 'textfield',
            '#title' => $this->t('Text to display'),
            '#default_value' => $this->options['text'],
        ];
        parent::buildOptionsForm($form, $form_state);
        // The path is set by ::renderLink() so we do not allow to set it.
        $form['alter'] += [
            'path' => [],
            'query' => [],
            'external' => [],
        ];
        $form['alter']['path'] += [
            '#access' => FALSE,
        ];
        $form['alter']['query'] += [
            '#access' => FALSE,
        ];
        $form['alter']['external'] += [
            '#access' => FALSE,
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function usesGroupBy() {
        return FALSE;
    }
    
    /**
     * {@inheritdoc}
     */
    public function query() {
        if ($this->languageManager
            ->isMultilingual()) {
            $this->getEntityTranslationRenderer()
                ->query($this->query, $this->relationship);
        }
        $this->addAdditionalFields();
    }
    
    /**
     * {@inheritdoc}
     */
    public function render(ResultRow $row) {
        $access = $this->checkUrlAccess($row);
        if ($access) {
            $build = [
                '#markup' => $access->isAllowed() ? $this->renderLink($row) : '',
            ];
            BubbleableMetadata::createFromObject($access)->applyTo($build);
            return $build;
        }
        return '';
    }
    
    /**
     * Checks access to the link route.
     *
     * @param \Drupal\views\ResultRow $row
     *   A view result row.
     *
     * @return \Drupal\Core\Access\AccessResultInterface|null
     *   The access result, or NULL if the URI elements of the link doesn't exist.
     */
    protected function checkUrlAccess(ResultRow $row) {
        if ($url = $this->getUrlInfo($row)) {
            return $this->accessManager
                ->checkNamedRoute($url->getRouteName(), $url->getRouteParameters(), $this->currentUser(), TRUE);
        }
    }
    
    /**
     * Returns the URI elements of the link.
     *
     * @param \Drupal\views\ResultRow $row
     *   A view result row.
     *
     * @return \Drupal\Core\Url|null
     *   The URI elements of the link.
     */
    protected abstract function getUrlInfo(ResultRow $row);
    
    /**
     * Prepares the link to view an entity.
     *
     * @param \Drupal\views\ResultRow $row
     *   A view result row.
     *
     * @return string
     *   Returns a string for the link text.
     */
    protected function renderLink(ResultRow $row) {
        $this->options['alter']['make_link'] = TRUE;
        $this->options['alter']['url'] = $this->getUrlInfo($row);
        $text = !empty($this->options['text']) ? $this->sanitizeValue($this->options['text']) : $this->getDefaultLabel();
        $this->addLangcode($row);
        return $text;
    }
    
    /**
     * Adds language information to the options.
     *
     * @param \Drupal\views\ResultRow $row
     *   A view result row.
     */
    protected function addLangcode(ResultRow $row) {
        $entity = $this->getEntity($row);
        if ($entity && $this->languageManager
            ->isMultilingual()) {
            $this->options['alter']['language'] = $this->getEntityTranslationByRelationship($entity, $row)
                ->language();
        }
    }
    
    /**
     * Returns the default label for this link.
     *
     * @return \Drupal\Core\StringTranslation\TranslatableMarkup
     *   The default link label.
     */
    protected function getDefaultLabel() {
        return $this->t('link');
    }
    
    /**
     * {@inheritdoc}
     */
    protected function getEntityTypeId() {
        return $this->getEntityType();
    }
    
    /**
     * {@inheritdoc}
     */
    protected function getEntityTypeManager() {
        return $this->entityTypeManager;
    }
    
    /**
     * {@inheritdoc}
     */
    protected function getEntityRepository() {
        return $this->entityRepository;
    }
    
    /**
     * {@inheritdoc}
     */
    protected function getLanguageManager() {
        return $this->languageManager;
    }
    
    /**
     * {@inheritdoc}
     */
    protected function getView() {
        return $this->view;
    }

}