class ConfigDeleteForm

class ConfigDeleteForm extends FormBase implements ConfirmFormInterface {
  
  /**
   * {@inheritdoc}
   */
  public function getFormId() {
    return 'devel_config_system_delete_form';
  }
  
  /**
   * {@inheritdoc}
   */
  public function buildForm(array $form, FormStateInterface $form_state, $config_name = '') {
    $config = $this->config($config_name);
    if ($config === FALSE || $config->isNew()) {
      $this->messenger()
        ->addError($this->t('Config @name does not exist in the system.', [
        '@name' => $config_name,
      ]));
      return;
    }
    $form['#title'] = $this->getQuestion();
    $form['#attributes']['class'][] = 'confirmation';
    $form['description'] = [
      '#markup' => $this->getDescription(),
    ];
    $form[$this->getFormName()] = [
      '#type' => 'hidden',
      '#value' => 1,
    ];
    // By default, render the form using theme_confirm_form().
    if (!isset($form['#theme'])) {
      $form['#theme'] = 'confirm_form';
    }
    $form['name'] = [
      '#type' => 'value',
      '#value' => $config_name,
    ];
    $form['actions'] = [
      '#type' => 'actions',
    ];
    $form['actions']['submit'] = [
      '#type' => 'submit',
      '#value' => $this->getConfirmText(),
      '#submit' => [
        [
          $this,
          'submitForm',
        ],
      ],
    ];
    $form['actions']['cancel'] = ConfirmFormHelper::buildCancelLink($this, $this->getRequest());
    return $form;
  }
  
  /**
   * {@inheritdoc}
   */
  public function submitForm(array &$form, FormStateInterface $form_state) {
    $config_name = $form_state->getValue('name');
    try {
      $this->configFactory()
        ->getEditable($config_name)
        ->delete();
      $this->messenger()
        ->addStatus($this->t('Configuration variable %variable was successfully deleted.', [
        '%variable' => $config_name,
      ]));
      $this->logger('devel')
        ->info('Configuration variable %variable was successfully deleted.', [
        '%variable' => $config_name,
      ]);
      $form_state->setRedirectUrl($this->getCancelUrl());
    } catch (\Exception $e) {
      $this->messenger()
        ->addError($e->getMessage());
      $this->logger('devel')
        ->error('Error deleting configuration variable %variable : %error.', [
        '%variable' => $config_name,
        '%error' => $e->getMessage(),
      ]);
    }
  }
  
  /**
   * {@inheritdoc}
   */
  public function getCancelUrl() {
    return Url::fromRoute('devel.configs_list');
  }
  
  /**
   * {@inheritdoc}
   */
  public function getQuestion() {
    return $this->t('Are you sure you want to delete this configuration?');
  }
  
  /**
   * {@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';
  }

}