using System;
using System.Collections.Concurrent;
using System.Security.Cryptography;
using System.Text;

namespace Gott.Services;

public class AuthService
{
    private readonly ConcurrentDictionary<string, string> _tokens = new(); // token -> userId

    public string HashPassword(string password)
    {
        var bytes = SHA256.HashData(Encoding.UTF8.GetBytes(password));
        return Convert.ToHexStringLower(bytes);
    }

    public bool VerifyPassword(string password, string hash)
    {
        return HashPassword(password) == hash;
    }

    public string CreateToken(string userId)
    {
        var token = Convert.ToHexStringLower(RandomNumberGenerator.GetBytes(32));
        _tokens[token] = userId;
        return token;
    }

    public string ValidateToken(string token)
    {
        if (string.IsNullOrEmpty(token)) return null;
        return _tokens.TryGetValue(token, out var userId) ? userId : null;
    }

    public void RevokeToken(string token)
    {
        if (!string.IsNullOrEmpty(token))
            _tokens.TryRemove(token, out _);
    }
}