class LocaleSettingsForm

locale.routing.yml in drupal/core/modules/locale/locale.routing.yml

drupal/core/modules/locale/locale.routing.yml

class LocaleSettingsForm extends SystemConfigFormBase {

  /**
   * Implements \Drupal\Core\Form\FormInterface::getFormID().
   */
  public function getFormID() {
    return 'locale_translate_settings';
  }

  /**
   * Implements \Drupal\Core\Form\FormInterface::buildForm().
   */
  public function buildForm(array $form, array &$form_state) {
    $config = $this->configFactory
      ->get('locale.settings');
    $form['update_interval_days'] = array(
      '#type' => 'radios',
      '#title' => t('Check for updates'),
      '#default_value' => $config
        ->get('translation.update_interval_days'),
      '#options' => array(
        '0' => t('Never (manually)'),
        '1' => t('Daily'),
        '7' => t('Weekly'),
      ),
      '#description' => t('Select how frequently you want to check for new interface translations for your currently installed modules and themes. <a href="@url">Check updates now</a>.', array(
        '@url' => url('admin/reports/translations/check'),
      )),
    );
    $form['check_disabled_modules'] = array(
      '#type' => 'checkbox',
      '#title' => t('Check for updates of disabled modules and themes'),
      '#default_value' => $config
        ->get('translation.check_disabled_modules'),
    );
    if ($directory = config('locale.settings')
      ->get('translation.path')) {
      $description = t('Translation files are stored locally in the  %path directory. You can change this directory on the <a href="@url">File system</a> configuration page.', array(
        '%path' => $directory,
        '@url' => url('admin/config/media/file-system'),
      ));
    }
    else {
      $description = t('Translation files will not be stored locally. Change the Interface translation directory on the <a href="@url">File system configuration</a> page.', array(
        '@url' => url('admin/config/media/file-system'),
      ));
    }
    $form['#translation_directory'] = $directory;
    $form['use_source'] = array(
      '#type' => 'radios',
      '#title' => t('Translation source'),
      '#default_value' => $config
        ->get('translation.use_source'),
      '#options' => array(
        LOCALE_TRANSLATION_USE_SOURCE_REMOTE_AND_LOCAL => t('Drupal translation server and local files'),
        LOCALE_TRANSLATION_USE_SOURCE_LOCAL => t('Local files only'),
      ),
      '#description' => t('The source of translation files for automatic interface translation.') . ' ' . $description,
    );
    if ($config
      ->get('translation.overwrite_not_customized') == FALSE) {
      $default = LOCALE_TRANSLATION_OVERWRITE_NONE;
    }
    elseif ($config
      ->get('translation.overwrite_customized') == TRUE) {
      $default = LOCALE_TRANSLATION_OVERWRITE_ALL;
    }
    else {
      $default = LOCALE_TRANSLATION_OVERWRITE_NON_CUSTOMIZED;
    }
    $form['overwrite'] = array(
      '#type' => 'radios',
      '#title' => t('Import behaviour'),
      '#default_value' => $default,
      '#options' => array(
        LOCALE_TRANSLATION_OVERWRITE_NONE => t("Don't overwrite existing translations."),
        LOCALE_TRANSLATION_OVERWRITE_NON_CUSTOMIZED => t('Only overwrite imported translations, customized translations are kept.'),
        LOCALE_TRANSLATION_OVERWRITE_ALL => t('Overwrite existing translations.'),
      ),
      '#description' => t('How to treat existing translations when automatically updating the interface translations.'),
    );
    return parent::buildForm($form, $form_state);
  }

  /**
   * Implements \Drupal\Core\Form\FormInterface::validateForm().
   */
  public function validateForm(array &$form, array &$form_state) {
    parent::validateForm($form, $form_state);
    if (empty($form['#translation_directory']) && $form_state['values']['use_source'] == LOCALE_TRANSLATION_USE_SOURCE_LOCAL) {
      form_set_error('use_source', t('You have selected local translation source, but no <a href="@url">Interface translation directory</a> was configured.', array(
        '@url' => url('admin/config/media/file-system'),
      )));
    }
  }

  /**
   * Implements \Drupal\Core\Form\FormInterface::submitForm().
   */
  public function submitForm(array &$form, array &$form_state) {
    $values = $form_state['values'];
    $config = $this->configFactory
      ->get('locale.settings');
    $config
      ->set('translation.update_interval_days', $values['update_interval_days'])
      ->save();
    $config
      ->set('translation.use_source', $values['use_source'])
      ->save();
    switch ($values['overwrite']) {
      case LOCALE_TRANSLATION_OVERWRITE_ALL:
        $config
          ->set('translation.overwrite_customized', TRUE)
          ->set('translation.overwrite_not_customized', TRUE);
        break;
      case LOCALE_TRANSLATION_OVERWRITE_NON_CUSTOMIZED:
        $config
          ->set('translation.overwrite_customized', FALSE)
          ->set('translation.overwrite_not_customized', TRUE);
        break;
      case LOCALE_TRANSLATION_OVERWRITE_NONE:
        $config
          ->set('translation.overwrite_customized', FALSE)
          ->set('translation.overwrite_not_customized', FALSE);
        break;
    }
    $config
      ->set('translation.check_disabled_modules', $values['check_disabled_modules'])
      ->save();

    // Invalidate the cached translation status when the configuration setting of
    // 'use_source' and 'check_disabled_modules' change.
    if ($form['use_source']['#default_value'] != $form_state['values']['use_source'] || $form['check_disabled_modules']['#default_value'] != $form_state['values']['check_disabled_modules']) {
      locale_translation_clear_status();
    }
    parent::submitForm($form, $form_state);
  }

}