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';
    }

}