package us.tss3.blockparty.jukebox;

import java.security.SecureRandom;
import java.util.Map;
import java.util.UUID;
import java.util.concurrent.ConcurrentHashMap;

/**
 * Issues short-lived, easy-to-type numeric codes that link a web voting session back to a
 * specific logged-in player, without requiring any real account/password auth on the web
 * page. A code is only ever handed out via the in-game {@code /blockparty musicvote}
 * command, so possessing one proves you're the player who ran it (or someone they showed it
 * to) for as long as it's valid.
 */
public class VoteCodeManager {

    private record CodeEntry(UUID playerId, long expiresAtMs) {
    }

    private final Map<String, CodeEntry> codes = new ConcurrentHashMap<>();
    private final SecureRandom random = new SecureRandom();

    public String issueCode(UUID playerId, int ttlMinutes) {
        codes.values().removeIf(e -> e.playerId().equals(playerId));
        String code;
        do {
            code = String.valueOf(100000 + random.nextInt(900000));
        } while (codes.containsKey(code));
        codes.put(code, new CodeEntry(playerId, System.currentTimeMillis() + ttlMinutes * 60_000L));
        return code;
    }

    /** Resolves a code to the player who issued it, or null if unknown/expired. */
    public UUID resolve(String code) {
        if (code == null) {
            return null;
        }
        CodeEntry entry = codes.get(code);
        if (entry == null) {
            return null;
        }
        if (System.currentTimeMillis() > entry.expiresAtMs()) {
            codes.remove(code);
            return null;
        }
        return entry.playerId();
    }
}