Certified/app/Http/Controllers/SharedCertificateController.php

<?php

namespace App\Http\Controllers;

use App\Models\Certificate;
use Illuminate\Support\Facades\Storage;
use Symfony\Component\HttpFoundation\StreamedResponse;

class SharedCertificateController extends Controller
{
    /**
     * Stream a certificate to an external recipient via a temporary signed
     * URL. The 'signed' middleware is the authorization here, so this runs
     * unauthenticated (the global scope no-ops without a logged-in user).
     */
    public function __invoke(Certificate $certificate): StreamedResponse
    {
        abort_unless(filled($certificate->file_path) && Storage::disk('local')->exists($certificate->file_path), 404);

        return Storage::disk('local')->download(
            $certificate->file_path,
            $certificate->title.'.'.pathinfo($certificate->file_path, PATHINFO_EXTENSION),
        );
    }
}