class File

class File extends FieldPluginBase {
    
    /**
     * The file URL generator.
     *
     * @var \Drupal\Core\File\FileUrlGeneratorInterface
     */
    protected $fileUrlGenerator;
    
    /**
     * Constructs a File 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\File\FileUrlGeneratorInterface $file_url_generator
     *   The file URL generator.
     */
    public function __construct(array $configuration, $plugin_id, $plugin_definition, FileUrlGeneratorInterface $file_url_generator) {
        parent::__construct($configuration, $plugin_id, $plugin_definition);
        $this->fileUrlGenerator = $file_url_generator;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
        return new static($configuration, $plugin_id, $plugin_definition, $container->get('file_url_generator'));
    }
    
    /**
     * {@inheritdoc}
     */
    public function init(ViewExecutable $view, DisplayPluginBase $display, ?array &$options = NULL) {
        parent::init($view, $display, $options);
        if (!empty($options['link_to_file'])) {
            $this->additional_fields['uri'] = 'uri';
        }
    }
    
    /**
     * {@inheritdoc}
     */
    protected function defineOptions() {
        $options = parent::defineOptions();
        $options['link_to_file'] = [
            'default' => FALSE,
        ];
        return $options;
    }
    
    /**
     * Provide link to file option.
     */
    public function buildOptionsForm(&$form, FormStateInterface $form_state) {
        $form['link_to_file'] = [
            '#title' => $this->t('Link this field to download the file'),
            '#description' => $this->t("Enable to override this field's links."),
            '#type' => 'checkbox',
            '#default_value' => !empty($this->options['link_to_file']),
        ];
        parent::buildOptionsForm($form, $form_state);
    }
    
    /**
     * Prepares link to the file.
     *
     * @param string $data
     *   The XSS safe string for the link text.
     * @param \Drupal\views\ResultRow $values
     *   The values retrieved from a single row of a view's query result.
     *
     * @return string
     *   Returns a string for the link text.
     */
    protected function renderLink($data, ResultRow $values) {
        if (!empty($this->options['link_to_file']) && $data !== NULL && $data !== '') {
            $this->options['alter']['make_link'] = TRUE;
            $this->options['alter']['url'] = $this->fileUrlGenerator
                ->generate($this->getValue($values, 'uri'));
        }
        return $data;
    }
    
    /**
     * {@inheritdoc}
     */
    public function render(ResultRow $values) {
        $value = $this->getValue($values);
        return $this->renderLink($this->sanitizeValue($value), $values);
    }

}