class RulesSettingsForm

class RulesSettingsForm extends ConfigFormBase {
    
    /**
     * {@inheritdoc}
     */
    public function getFormId() {
        return 'rules_settings_form';
    }
    
    /**
     * {@inheritdoc}
     */
    protected function getEditableConfigNames() {
        return [
            'rules.settings',
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildForm(array $form, FormStateInterface $form_state) {
        $config = $this->config('rules.settings');
        $form['#tree'] = TRUE;
        $form['system_log'] = [
            '#type' => 'fieldset',
            '#title' => $this->t('System logging'),
        ];
        $form['system_log']['log_level'] = [
            '#type' => 'radios',
            '#title' => $this->t('Evaluation errors log level'),
            '#options' => [
                LogLevel::WARNING => $this->t('Log all warnings and errors'),
                LogLevel::ERROR => $this->t('Log errors only'),
            ],
            '#default_value' => $config->get('system_log.log_level'),
            '#description' => $this->t('Evaluation errors are logged to the system database logger and all other registered loggers.'),
        ];
        $form['debug_log'] = [
            '#type' => 'fieldset',
            '#title' => $this->t('Debug logging'),
        ];
        $form['debug_log']['enabled'] = [
            '#type' => 'checkbox',
            '#title' => $this->t('Enable debug logging'),
            '#description' => $this->t('Show debug information on screen (in the HTML response). Debug information is only shown when rules are evaluated, and is visible for users having the permission %permission.', [
                '%permission' => Link::createFromRoute('View Rules debug log', 'user.admin_permissions', [], [
                    'fragment' => 'module-rules',
                ])->toString(),
            ]),
            '#default_value' => $config->get('debug_log.enabled'),
        ];
        $form['debug_log']['settings'] = [
            '#type' => 'fieldset',
            '#title' => $this->t('Settings'),
            '#states' => [
                // Hide the logging destination fields when the debug log is disabled.
'invisible' => [
                    'input[name="debug_log[enabled]"]' => [
                        'checked' => FALSE,
                    ],
                ],
            ],
        ];
        $form['debug_log']['settings']['system_debug'] = [
            '#type' => 'checkbox',
            '#title' => $this->t('Also log debug information to the system log'),
            '#description' => $this->t('Write a copy of the debug information to the system database log. This will be visible for users having the permission %permission.', [
                '%permission' => Link::createFromRoute('View site reports', 'user.admin_permissions', [], [
                    'fragment' => 'module-system',
                ])->toString(),
            ]),
            '#default_value' => $config->get('debug_log.system_debug'),
        ];
        $form['debug_log']['settings']['log_level'] = [
            '#type' => 'radios',
            '#title' => $this->t('Debug log level'),
            '#options' => [
                LogLevel::DEBUG => $this->t('Log everything'),
                LogLevel::WARNING => $this->t('Log warnings and errors only'),
                LogLevel::ERROR => $this->t('Log errors only'),
            ],
            '#default_value' => $config->get('debug_log.log_level'),
            '#description' => $this->t('Level of debug log messages shown on screen'),
        ];
        return parent::buildForm($form, $form_state);
    }
    
    /**
     * {@inheritdoc}
     */
    public function submitForm(array &$form, FormStateInterface $form_state) {
        $this->config('rules.settings')
            ->set('system_log.log_level', $form_state->getValue([
            'system_log',
            'log_level',
        ]))
            ->set('debug_log.enabled', $form_state->getValue([
            'debug_log',
            'enabled',
        ]))
            ->set('debug_log.system_debug', $form_state->getValue([
            'debug_log',
            'settings',
            'system_debug',
        ]))
            ->set('debug_log.log_level', $form_state->getValue([
            'debug_log',
            'settings',
            'log_level',
        ]))
            ->save();
        parent::submitForm($form, $form_state);
    }

}