Psr7Middlewares\Middleware\LanguageNegotiator::__invoke PHP Метод

    public function __invoke(ServerRequestInterface $request, ResponseInterface $response, callable $next)
    {
        $language = null;
        $uri = $request->getUri();
        //Use path
        if ($this->usePath) {
            $path = ltrim($uri->getPath(), '/');
            $dirs = explode('/', $path, 2);
            $first = strtolower(array_shift($dirs));
            if (!empty($first) && in_array($first, $this->languages, true)) {
                $language = $first;
                //remove the language in the path
                $request = $request->withUri($uri->withPath('/' . array_shift($dirs)));
            }
        }
        //Use http headers
        if ($language === null) {
            $language = $this->negotiateHeader($request->getHeaderLine('Accept-Language'), new Negotiator(), $this->languages);
            if (empty($language)) {
                $language = isset($this->languages[0]) ? $this->languages[0] : '';
            }
            //Redirect to a path with the language
            if ($this->redirectStatus !== false && $this->usePath) {
                $path = Utils\Helpers::joinPath($language, $uri->getPath());
                return $this->getRedirectResponse($request, $uri->withPath($path), $response);
            }
        }
        $response = $next(self::setAttribute($request, self::KEY, $language), $response->withHeader('Content-Language', $language));
        if (!$response->hasHeader('Content-Language')) {
            $response = $response->withHeader('Content-Language', $language);
        }
        return $response;
    }