engelsystem/src/Middleware/SetLocale.php

<?php

namespace Engelsystem\Middleware;

use Engelsystem\Helpers\Translation\Translator;
use Psr\Http\Message\ResponseInterface;
use Psr\Http\Message\ServerRequestInterface;
use Psr\Http\Server\MiddlewareInterface;
use Psr\Http\Server\RequestHandlerInterface;
use Symfony\Component\HttpFoundation\Session\Session;

class SetLocale implements MiddlewareInterface
{
    /** @var Translator */
    protected $translator;

    /** @var Session */
    protected $session;

    /**
     * @param Translator $translator
     * @param Session    $session
     */
    public function __construct(Translator $translator, Session $session)
    {
        $this->translator = $translator;
        $this->session = $session;
    }

    /**
     * Process an incoming server request and setting the locale if required
     *
     * @param ServerRequestInterface  $request
     * @param RequestHandlerInterface $handler
     * @return ResponseInterface
     */
    public function process(ServerRequestInterface $request, RequestHandlerInterface $handler): ResponseInterface
    {
        $query = $request->getQueryParams();
        if (isset($query['set-locale']) && $this->translator->hasLocale($query['set-locale'])) {
            $locale = $query['set-locale'];

            $this->translator->setLocale($locale);
            $this->session->set('locale', $locale);
        }

        return $handler->handle($request);
    }
}