class FileSize

class FileSize extends FieldPluginBase {
    
    /**
     * {@inheritdoc}
     */
    protected function defineOptions() {
        $options = parent::defineOptions();
        $options['file_size_display'] = [
            'default' => 'formatted',
        ];
        return $options;
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildOptionsForm(&$form, FormStateInterface $form_state) {
        parent::buildOptionsForm($form, $form_state);
        $form['file_size_display'] = [
            '#title' => $this->t('File size display'),
            '#type' => 'select',
            '#options' => [
                'formatted' => $this->t('Formatted (in KB or MB)'),
                'bytes' => $this->t('Raw bytes'),
            ],
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function render(ResultRow $values) {
        $value = $this->getValue($values);
        if ($value) {
            switch ($this->options['file_size_display']) {
                case 'bytes':
                    return $value;
                case 'formatted':
                default:
                    return ByteSizeMarkup::create((int) $value);
            }
        }
        else {
            return '';
        }
    }

}