namespace Dpz.Core.Service.RepositoryServiceImpl;

/// <summary>
/// 密码哈希服务实现
/// 使用BCrypt作为新版本密码哈希算法，同时兼容旧版本MD5密码
/// </summary>
public class PasswordHashService : IPasswordHashService
{
    private const int DefaultWorkFactor = 12;

    /// <summary>
    /// 使用BCrypt对密码进行哈希（新版本）
    /// </summary>
    /// <param name="password">原始密码</param>
    /// <param name="workFactor">工作因子（默认12）</param>
    /// <returns>BCrypt哈希字符串</returns>
    public string HashPasswordBCrypt(string password, int workFactor = DefaultWorkFactor)
    {
        if (string.IsNullOrWhiteSpace(password))
        {
            throw new ArgumentException("密码不能为空", nameof(password));
        }

        if (workFactor is < 4 or > 31)
        {
            throw new ArgumentException("工作因子必须在4-31之间", nameof(workFactor));
        }
        return BCrypt.Net.BCrypt.HashPassword(password, workFactor);
    }

    /// <summary>
    /// 使用MD5对密码进行哈希（旧版本兼容）
    /// </summary>
    /// <param name="account">用户账号</param>
    /// <param name="password">原始密码</param>
    /// <returns>MD5哈希后的密码</returns>
    public string HashPasswordMD5(string account, string password)
    {
        if (string.IsNullOrWhiteSpace(account))
        {
            throw new ArgumentException("账号不能为空", nameof(account));
        }
        if (string.IsNullOrWhiteSpace(password))
        {
            throw new ArgumentException("密码不能为空", nameof(password));
        }

        var combinedString = account + password;
        return combinedString.GenerateMd5();
    }

    /// <summary>
    /// 验证BCrypt密码（新版本）
    /// </summary>
    /// <param name="password">输入的密码</param>
    /// <param name="hashedPassword">存储的BCrypt哈希</param>
    /// <returns>密码是否正确</returns>
    public bool VerifyPasswordBCrypt(string password, string hashedPassword)
    {
        if (string.IsNullOrWhiteSpace(password) || string.IsNullOrWhiteSpace(hashedPassword))
        {
            return false;
        }

        try
        {
            return BCrypt.Net.BCrypt.Verify(password, hashedPassword);
        }
        catch
        {
            return false;
        }
    }

    /// <summary>
    /// 验证MD5密码（旧版本兼容）
    /// </summary>
    /// <param name="account">用户账号</param>
    /// <param name="password">输入的密码</param>
    /// <param name="storedHash">存储的MD5哈希</param>
    /// <returns>密码是否正确</returns>
    public bool VerifyPasswordMD5(string account, string password, string storedHash)
    {
        if (
            string.IsNullOrWhiteSpace(account)
            || string.IsNullOrWhiteSpace(password)
            || string.IsNullOrWhiteSpace(storedHash)
        )
        {
            return false;
        }

        var expectedHash = HashPasswordMD5(account, password);
        return expectedHash.Equals(storedHash, StringComparison.Ordinal);
    }

    /// <summary>
    /// 智能验证密码（自动识别BCrypt或MD5）
    /// </summary>
    /// <param name="account">用户账号</param>
    /// <param name="password">输入的密码</param>
    /// <param name="storedHash">存储的密码哈希</param>
    /// <returns>密码是否正确</returns>
    public bool VerifyPassword(string account, string password, string storedHash)
    {
        if (string.IsNullOrWhiteSpace(password) || string.IsNullOrWhiteSpace(storedHash))
        {
            return false;
        }

        // 如果是BCrypt格式，使用BCrypt验证
        if (IsBCryptHash(storedHash))
        {
            return VerifyPasswordBCrypt(password, storedHash);
        }

        // 否则使用MD5验证（兼容旧版本）
        return VerifyPasswordMD5(account, password, storedHash);
    }

    /// <summary>
    /// 生成新版本密码哈希（BCrypt）
    /// </summary>
    /// <param name="password">原始密码</param>
    /// <returns>BCrypt哈希字符串</returns>
    public string CreatePasswordHash(string password)
    {
        return HashPasswordBCrypt(password);
    }

    /// <summary>
    /// 检查密码哈希是否为BCrypt格式（新版本）
    /// </summary>
    /// <param name="hashedPassword">密码哈希</param>
    /// <returns>是否为BCrypt格式</returns>
    public bool IsBCryptHash(string? hashedPassword)
    {
        if (string.IsNullOrWhiteSpace(hashedPassword))
        {
            return false;
        }

        // BCrypt哈希格式：$2a$, $2b$, $2x$, $2y$ 开头
        return hashedPassword.StartsWith("$2a$")
            || hashedPassword.StartsWith("$2b$")
            || hashedPassword.StartsWith("$2x$")
            || hashedPassword.StartsWith("$2y$");
    }

    /// <summary>
    /// 检查密码是否使用了新版本算法（BCrypt）
    /// </summary>
    /// <param name="hashedPassword">密码哈希</param>
    /// <returns>是否为新版本密码</returns>
    public bool IsNewVersionPassword(string? hashedPassword)
    {
        return IsBCryptHash(hashedPassword);
    }
}