AzuraCast/src/Middleware/RemoveSlashes.php

<?php

namespace App\Middleware;

use GuzzleHttp\Psr7\Response;
use Psr\Http\Message\ResponseInterface;
use Psr\Http\Message\ServerRequestInterface;
use Psr\Http\Server\MiddlewareInterface;
use Psr\Http\Server\RequestHandlerInterface;

/**
 * Remove trailing slash from all URLs when routing.
 */
class RemoveSlashes implements MiddlewareInterface
{
    /**
     * @param ServerRequestInterface $request
     * @param RequestHandlerInterface $handler
     */
    public function process(ServerRequestInterface $request, RequestHandlerInterface $handler): ResponseInterface
    {
        $uri = $request->getUri();
        $path = $uri->getPath();

        if ($path !== '/' && substr($path, -1) === '/') {
            // permanently redirect paths with a trailing slash
            // to their non-trailing counterpart
            $uri = $uri->withPath(substr($path, 0, -1));

            /** @var ResponseInterface $response */
            $response = new Response(308);

            return $response->withHeader('Location', (string)$uri);
        }

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