class ConfirmFormBase

abstract class ConfirmFormBase extends FormBase implements ConfirmFormInterface {
    
    /**
     * {@inheritdoc}
     */
    public function getDescription() {
        return $this->t('This action cannot be undone.');
    }
    
    /**
     * {@inheritdoc}
     */
    public function getConfirmText() {
        return $this->t('Confirm');
    }
    
    /**
     * {@inheritdoc}
     */
    public function getCancelText() {
        return $this->t('Cancel');
    }
    
    /**
     * {@inheritdoc}
     */
    public function getFormName() {
        return 'confirm';
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildForm(array $form, FormStateInterface $form_state) {
        $form['#title'] = $this->getQuestion();
        $form['#attributes']['class'][] = 'confirmation';
        $form['description'] = [
            '#markup' => $this->getDescription(),
        ];
        $form[$this->getFormName()] = [
            '#type' => 'hidden',
            '#value' => 1,
        ];
        $form['actions'] = [
            '#type' => 'actions',
        ];
        $form['actions']['submit'] = [
            '#type' => 'submit',
            '#value' => $this->getConfirmText(),
            '#button_type' => 'primary',
        ];
        $form['actions']['cancel'] = ConfirmFormHelper::buildCancelLink($this, $this->getRequest());
        // By default, render the form using theme_confirm_form().
        if (!isset($form['#theme'])) {
            $form['#theme'] = 'confirm_form';
        }
        return $form;
    }

}