interface LanguageNegotiationMethodInterface

interface LanguageNegotiationMethodInterface {
    
    /**
     * Injects the language manager.
     *
     * @param \Drupal\language\ConfigurableLanguageManagerInterface $language_manager
     *   The language manager to be used to retrieve the language list and the
     *   already negotiated languages.
     */
    public function setLanguageManager(ConfigurableLanguageManagerInterface $language_manager);
    
    /**
     * Injects the configuration factory.
     *
     * @param \Drupal\Core\Config\ConfigFactoryInterface $config
     *   The configuration factory.
     */
    public function setConfig(ConfigFactoryInterface $config);
    
    /**
     * Injects the current user.
     *
     * @param \Drupal\Core\Session\AccountInterface $current_user
     *   The current active user.
     */
    public function setCurrentUser(AccountInterface $current_user);
    
    /**
     * Performs language negotiation.
     *
     * @param \Symfony\Component\HttpFoundation\Request $request
     *   (optional) The current request. Defaults to NULL if it has not been
     *   initialized yet.
     *
     * @return string|null|false
     *   A valid language code if the negotiation was successful and either NULL
     *    or FALSE otherwise.
     *
     * @todo Determine whether string|false or string|null should be the
     *   normalized result across all implementations and update the @return and
     *   its comment accordingly.
     *
     * @see https://www.drupal.org/node/3329952
     */
    public function getLangcode(Request $request = NULL);
    
    /**
     * Notifies the plugin that the language code it returned has been accepted.
     *
     * @param \Drupal\Core\Language\LanguageInterface $language
     *   The accepted language.
     */
    public function persist(LanguageInterface $language);

}