class TimeInterval

class TimeInterval extends FieldPluginBase {
    
    /**
     * The date formatter service.
     *
     * @var \Drupal\Core\Datetime\DateFormatterInterface
     */
    protected $dateFormatter;
    
    /**
     * Constructs a TimeInterval plugin 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\Datetime\DateFormatterInterface $date_formatter
     *   The date formatter service.
     */
    public function __construct(array $configuration, $plugin_id, $plugin_definition, DateFormatterInterface $date_formatter) {
        $this->dateFormatter = $date_formatter;
        parent::__construct($configuration, $plugin_id, $plugin_definition);
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
        return new static($configuration, $plugin_id, $plugin_definition, $container->get('date.formatter'));
    }
    
    /**
     * {@inheritdoc}
     */
    protected function defineOptions() {
        $options = parent::defineOptions();
        $options['granularity'] = [
            'default' => 2,
        ];
        return $options;
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildOptionsForm(&$form, FormStateInterface $form_state) {
        parent::buildOptionsForm($form, $form_state);
        $form['granularity'] = [
            '#type' => 'textfield',
            '#title' => $this->t('Granularity'),
            '#description' => $this->t('How many different units to display in the string.'),
            '#default_value' => $this->options['granularity'],
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function render(ResultRow $values) {
        $value = $values->{$this->field_alias};
        return $this->dateFormatter
            ->formatInterval($value, isset($this->options['granularity']) ? $this->options['granularity'] : 2);
    }

}