class Language

class Language extends CKEditorPluginBase implements CKEditorPluginConfigurableInterface, CKEditorPluginCssInterface {
  
  /**
   * {@inheritdoc}
   */
  public function isInternal() {
    return TRUE;
  }
  
  /**
   * {@inheritdoc}
   */
  public function getFile() {
    // This plugin is already part of Drupal core's CKEditor build.
    return FALSE;
  }
  
  /**
   * {@inheritdoc}
   */
  public function getLibraries(Editor $editor) {
    return [
      'ckeditor/drupal.ckeditor.plugins.language',
    ];
  }
  
  /**
   * {@inheritdoc}
   */
  public function getConfig(Editor $editor) {
    $language_list = [];
    $config = [
      'language_list' => 'un',
    ];
    $settings = $editor->getSettings();
    if (isset($settings['plugins']['language'])) {
      $config = $settings['plugins']['language'];
    }
    $predefined_languages = $config['language_list'] === 'all' ? LanguageManager::getStandardLanguageList() : LanguageManager::getUnitedNationsLanguageList();
    // Generate the language_list setting as expected by the CKEditor Language
    // plugin, but key the values by the full language name so that we can sort
    // them later on.
    foreach ($predefined_languages as $langcode => $language) {
      $english_name = $language[0];
      $direction = empty($language[2]) ? NULL : $language[2];
      if ($direction === LanguageInterface::DIRECTION_RTL) {
        $language_list[$english_name] = $langcode . ':' . $english_name . ':rtl';
      }
      else {
        $language_list[$english_name] = $langcode . ':' . $english_name;
      }
    }
    // Sort on full language name.
    ksort($language_list);
    $config = [
      'language_list' => array_values($language_list),
    ];
    return $config;
  }
  
  /**
   * {@inheritdoc}
   */
  public function getButtons() {
    $label = $this->t('Language');
    return [
      'Language' => [
        'label' => $label,
        'image_alternative' => [
          '#type' => 'inline_template',
          '#template' => '<a href="#" class="cke-icon-only" role="button" title="{{ label }}" aria-label="{{ label }}"><span class="cke_button_icon cke_button__language_icon">{{ label }}</span></a>',
          '#context' => [
            'label' => $label,
          ],
        ],
      ],
    ];
  }
  
  /**
   * {@inheritdoc}
   */
  public function settingsForm(array $form, FormStateInterface $form_state, Editor $editor) {
    // Defaults.
    $config = [
      'language_list' => 'un',
    ];
    $settings = $editor->getSettings();
    if (isset($settings['plugins']['language'])) {
      $config = $settings['plugins']['language'];
    }
    $predefined_languages = LanguageManager::getStandardLanguageList();
    $form['language_list'] = [
      '#title' => $this->t('Language list'),
      '#title_display' => 'invisible',
      '#type' => 'select',
      '#options' => [
        'un' => $this->t("United Nations' official languages"),
        'all' => $this->t('All @count languages', [
          '@count' => count($predefined_languages),
        ]),
      ],
      '#default_value' => $config['language_list'],
      '#description' => $this->t('The list of languages to show in the language dropdown. The basic list will only show the <a href=":url">six official languages of the UN</a>. The extended list will show all @count languages that are available in Drupal.', [
        ':url' => 'https://www.un.org/en/sections/about-un/official-languages',
        '@count' => count($predefined_languages),
      ]),
      '#attached' => [
        'library' => [
          'ckeditor/drupal.ckeditor.language.admin',
        ],
      ],
    ];
    return $form;
  }
  
  /**
   * {@inheritdoc}
   */
  public function getCssFiles(Editor $editor) {
    return [
      $this->getModulePath('ckeditor') . '/css/plugins/language/ckeditor.language.css',
    ];
  }

}