package dev.wiing.gossip.server;

import dev.wiing.gossip.lib.models.SecretUser;
import dev.wiing.gossip.lib.models.User;

import java.security.SecureRandom;
import java.util.*;

public class Database {
    private final Map<Long, User> users = Collections.synchronizedMap(new HashMap<>());
    private final Map<byte[], User> usersBySecret = Collections.synchronizedMap(new HashMap<>());
    private final Set<String> usedUsernames = Collections.synchronizedSet(new HashSet<>());

    private Database() {

    }

    private static final Database instance = new Database();

    public static Database getInstance() {
        return instance;
    }

    public SecretUser registerUser(String username, char iconID) {
        SecureRandom random = new SecureRandom();

        byte[] secret = new byte[32];
        random.nextBytes(secret);

        long userID = random.nextLong();

        User user = new User(username, iconID, userID);

        users.put(userID, user);
        usersBySecret.put(secret, user);
        usedUsernames.add(username);

        System.out.println("Created user: " + username + " #" + Long.toUnsignedString(userID));

        return new SecretUser(username, iconID, userID, secret);
    }

    public User getUserByID(long uID) {
        return users.getOrDefault(uID, null);
    }

    public User getUserByUsername(String username) {
        return users.values().stream()
                .filter(user -> user.getUsername().equals(username))
                .findFirst()
                .orElse(null);
    }

    public User getUserBySecret(byte[] secret) {
        return usersBySecret.getOrDefault(secret, null);
    }

    public void removeUser(User user) {
        users.remove(user.getUserID());

        usersBySecret.entrySet().stream()
                .filter(userEntry -> userEntry.getValue().getUserID() == user.getUserID())
                .map(Map.Entry::getKey)
                .findFirst()
                .ifPresent(usersBySecret::remove);

        usedUsernames.remove(user.getUsername());
    }
}