package de.w665.testing.service;

import org.springframework.stereotype.Service;

import java.security.SecureRandom;
import java.util.Base64;
import java.util.Map;
import java.util.Optional;
import java.util.concurrent.ConcurrentHashMap;

@Service
public class TokenService {
    private final Map<String, String> tokenToUser = new ConcurrentHashMap<>();
    private final SecureRandom random = new SecureRandom();

    public String createTokenForUsername(String username) {
        String token = generateToken();
        tokenToUser.put(token, username);
        return token;
    }

    public Optional<String> resolveUsername(String token) {
        return Optional.ofNullable(tokenToUser.get(token));
    }

    public void invalidate(String token) {
        tokenToUser.remove(token);
    }

    private String generateToken() {
        byte[] bytes = new byte[32];
        random.nextBytes(bytes);
        return Base64.getUrlEncoder().withoutPadding().encodeToString(bytes);
    }
}