class ConfigEditor

class ConfigEditor extends FormBase {
  
  /**
   * Logger service.
   */
  protected LoggerInterface $logger;
  
  /**
   * The dumper service.
   */
  protected DevelDumperManagerInterface $dumper;
  
  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container) : static {
    $instance = parent::create($container);
    $instance->messenger = $container->get('messenger');
    $instance->logger = $container->get('logger.channel.devel');
    $instance->configFactory = $container->get('config.factory');
    $instance->requestStack = $container->get('request_stack');
    $instance->stringTranslation = $container->get('string_translation');
    $instance->dumper = $container->get('devel.dumper');
    return $instance;
  }
  
  /**
   * {@inheritdoc}
   */
  public function getFormId() : string {
    return 'devel_config_system_edit_form';
  }
  
  /**
   * {@inheritdoc}
   */
  public function buildForm(array $form, FormStateInterface $form_state, $config_name = '') : array {
    $config = $this->configFactory
      ->get($config_name);
    if ($config->isNew()) {
      $this->messenger
        ->addError($this->t('Config @name does not exist in the system.', [
        '@name' => $config_name,
      ]));
      return $form;
    }
    $data = $config->getOriginal();
    if (empty($data)) {
      $this->messenger
        ->addWarning($this->t('Config @name exists but has no data.', [
        '@name' => $config_name,
      ]));
      return $form;
    }
    try {
      $output = Yaml::encode($data);
    } catch (InvalidDataTypeException $e) {
      $this->messenger
        ->addError($this->t('Invalid data detected for @name : %error', [
        '@name' => $config_name,
        '%error' => $e->getMessage(),
      ]));
      return $form;
    }
    $form['current'] = [
      '#type' => 'details',
      '#title' => $this->t('Current value for %variable', [
        '%variable' => $config_name,
      ]),
      '#attributes' => [
        'class' => [
          'container-inline',
        ],
      ],
    ];
    $form['current']['value'] = [
      '#type' => 'item',
      '#markup' => $this->dumper
        ->dumpOrExport(input: $output, plugin_id: 'default'),
    ];
    $form['name'] = [
      '#type' => 'value',
      '#value' => $config_name,
    ];
    $form['new'] = [
      '#type' => 'textarea',
      '#title' => $this->t('New value'),
      '#default_value' => $output,
      '#rows' => 24,
      '#required' => TRUE,
    ];
    $form['actions'] = [
      '#type' => 'actions',
    ];
    $form['actions']['submit'] = [
      '#type' => 'submit',
      '#value' => $this->t('Save'),
    ];
    $form['actions']['cancel'] = [
      '#type' => 'link',
      '#title' => $this->t('Cancel'),
      '#url' => $this->buildCancelLinkUrl(),
    ];
    $form['actions']['delete'] = [
      '#type' => 'link',
      '#title' => $this->t('Delete'),
      '#url' => Url::fromRoute('devel.config_delete', [
        'config_name' => $config_name,
      ]),
      '#attributes' => [
        'class' => [
          'button',
          'button--danger',
        ],
      ],
    ];
    return $form;
  }
  
  /**
   * {@inheritdoc}
   */
  public function validateForm(array &$form, FormStateInterface $form_state) : void {
    $value = $form_state->getValue('new');
    // Try to parse the new provided value.
    try {
      $parsed_value = Yaml::decode($value);
      // Config::setData needs array for the new configuration and
      // a simple string is valid YAML for any reason.
      if (is_array($parsed_value)) {
        $form_state->setValue('parsed_value', $parsed_value);
      }
      else {
        $form_state->setErrorByName('new', $this->t('Invalid input'));
      }
    } catch (InvalidDataTypeException $e) {
      $form_state->setErrorByName('new', $this->t('Invalid input: %error', [
        '%error' => $e->getMessage(),
      ]));
    }
  }
  
  /**
   * {@inheritdoc}
   */
  public function submitForm(array &$form, FormStateInterface $form_state) : void {
    $values = $form_state->getValues();
    try {
      $this->configFactory
        ->getEditable($values['name'])
        ->setData($values['parsed_value'])
        ->save();
      $this->messenger
        ->addMessage($this->t('Configuration variable %variable was successfully saved.', [
        '%variable' => $values['name'],
      ]));
      $this->logger
        ->info('Configuration variable %variable was successfully saved.', [
        '%variable' => $values['name'],
      ]);
      $form_state->setRedirectUrl(Url::fromRoute('devel.configs_list'));
    } catch (\Exception $e) {
      $this->messenger
        ->addError($e->getMessage());
      $this->logger
        ->error('Error saving configuration variable %variable : %error.', [
        '%variable' => $values['name'],
        '%error' => $e->getMessage(),
      ]);
    }
  }
  
  /**
   * Builds the cancel link url for the form.
   *
   * @return \Drupal\Core\Url
   *   Cancel url
   */
  private function buildCancelLinkUrl() : Url {
    $query = $this->requestStack
      ->getCurrentRequest()->query;
    if ($query->has('destination')) {
      $options = UrlHelper::parse($query->get('destination'));
      return Url::fromUserInput('/' . ltrim((string) $options['path'], '/'), $options);
    }
    return Url::fromRoute('devel.configs_list');
  }

}