<?php

declare(strict_types=1);

namespace App\Security;

use Symfony\Component\Security\Core\Authentication\Token\TokenInterface;
use Symfony\Component\Security\Core\Authorization\Voter\CacheableVoterInterface;
use Symfony\Component\Security\Core\Authorization\Voter\VoterInterface;

class AuthenticationVoter implements CacheableVoterInterface
{
    public function supportsAttribute(string $attribute): bool
    {
        return \in_array($attribute, [
            'IS_AUTHENTICATED_NOT',
        ], true);
    }

    public function supportsType(string $subjectType): bool
    {
        return 'null' === $subjectType;
    }

    public function vote(TokenInterface $token, $subject, array $attributes): int
    {
        \assert(null === $subject);
        $vote = VoterInterface::ACCESS_ABSTAIN;
        $user = $token->getUser();

        foreach ($attributes as $attr) {
            if ($attr !== 'IS_AUTHENTICATED_NOT') continue;

            $vote = VoterInterface::ACCESS_DENIED;

            if (null === $user) return VoterInterface::ACCESS_GRANTED;
        }

        return $vote;
    }
}

<?php

declare(strict_types=1);

namespace App\Controller;

use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\Security\Core\Security;

class LoginController
{
    #[Route('/sign-in')]
    public function signIn(Request $request, Security $security): Response
    {
        if ($security->isGranted('IS_AUTHENTICATED_NOT')) {
            return new Response('Login');
        }

        return new Response('Only logged out users can login.');
    }
}