using Microsoft.IdentityModel.Tokens;
using QYZH.InteractiveMagazine.Models.Settings;
using System.IdentityModel.Tokens.Jwt;
using System.Security.Claims;
using System.Text;

namespace QYZH.InteractiveMagazine.Infrastructure.Auth;

/// <summary>
/// JWT工具类
/// </summary>
public static class JwtHelper
{
    public const string AdminTokenKeyPrefix = "InteractiveMagazine:AdminAuth:Token";
    public const string WeChatTokenKeyPrefix = "InteractiveMagazine:WeChatAuth:Token";

    /// <summary>
    /// 生成JWT令牌（管理端 / 单用户场景）
    /// </summary>
    /// <param name="userId">用户ID</param>
    /// <param name="userName">用户名</param>
    /// <param name="settings">JWT配置</param>
    /// <returns>JWT令牌字符串</returns>
    public static string GenerateToken(long userId, string userName, JwtSettings settings)
    {
        var claims = new[]
        {
            new Claim(JwtRegisteredClaimNames.Sub, userId.ToString()),
            new Claim(JwtRegisteredClaimNames.Name, userName),
            new Claim(JwtRegisteredClaimNames.Jti, Guid.NewGuid().ToString()),
            new Claim(ClaimTypes.NameIdentifier, userId.ToString()),
            new Claim(ClaimTypes.Name, userName)
        };

        return BuildToken(claims, settings);
    }

    /// <summary>
    /// 生成JWT令牌（小程序场景，同时携带 WxUserId 和 UserId）
    /// </summary>
    /// <param name="wxUserId">微信用户ID（WxUser.Id）</param>
    /// <param name="userId">当前激活用户ID（Users.Id，无用户时为 0）</param>
    /// <param name="userName">用户名</param>
    /// <param name="settings">JWT配置</param>
    /// <returns>JWT令牌字符串</returns>
    public static string GenerateToken(long wxUserId, long userId, string userName, JwtSettings settings)
    {
        var claims = new[]
        {
            new Claim(JwtRegisteredClaimNames.Sub, userId.ToString()),
            new Claim(JwtRegisteredClaimNames.Name, userName),
            new Claim(JwtRegisteredClaimNames.Jti, Guid.NewGuid().ToString()),
            new Claim(ClaimTypes.NameIdentifier, userId.ToString()),
            new Claim(ClaimTypes.Name, userName),
            new Claim(WxUserIdClaimType, wxUserId.ToString())
        };

        return BuildToken(claims, settings);
    }

    /// <summary>
    /// 自定义 Claim 类型：WxUserId
    /// </summary>
    public const string WxUserIdClaimType = "WxUserId";

    public static string BuildAdminTokenKey(string userId)
    {
        return $"{AdminTokenKeyPrefix}:{userId}";
    }

    public static string BuildWeChatTokenKey(string wxUserId, string userId)
    {
        return $"{WeChatTokenKeyPrefix}:{wxUserId}:{userId}";
    }

    public static string BuildWeChatTokenKey(long wxUserId, long userId)
    {
        return BuildWeChatTokenKey(wxUserId.ToString(), userId.ToString());
    }

    private static string BuildToken(Claim[] claims, JwtSettings settings)
    {
        var key = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(settings.SecretKey!));
        var credentials = new SigningCredentials(key, SecurityAlgorithms.HmacSha256);

        var token = new JwtSecurityToken(
            issuer: settings.Issuer,
            audience: settings.Audience,
            claims: claims,
            expires: DateTime.Now.AddDays(settings.JwtTokenExpiryDays),
            signingCredentials: credentials
        );

        return new JwtSecurityTokenHandler().WriteToken(token);
    }

    /// <summary>
    /// 获取Token过期时间
    /// </summary>
    /// <param name="token">JWT令牌</param>
    /// <returns>过期时间</returns>
    public static DateTime? GetTokenExpiry(string token)
    {
        var tokenHandler = new JwtSecurityTokenHandler();
        if (tokenHandler.ReadToken(token) is JwtSecurityToken jwtToken)
        {
            return jwtToken.ValidTo;
        }
        return null;
    }

    /// <summary>
    /// 从Token中获取用户ID
    /// </summary>
    /// <param name="token">JWT令牌</param>
    /// <returns>用户ID</returns>
    public static long? GetUserIdFromToken(string token)
    {
        var tokenHandler = new JwtSecurityTokenHandler();
        if (tokenHandler.ReadToken(token) is JwtSecurityToken jwtToken)
        {
            var userIdClaim = GetClaim(jwtToken, ClaimTypes.NameIdentifier, JwtRegisteredClaimNames.NameId, JwtRegisteredClaimNames.Sub);
            if (long.TryParse(userIdClaim?.Value, out long userId))
            {
                return userId;
            }
        }
        return null;
    }

    /// <summary>
    /// 从Token中获取微信用户ID（WxUserId）
    /// </summary>
    /// <param name="token">JWT令牌</param>
    /// <returns>WxUserId</returns>
    public static long? GetWxUserIdFromToken(string token)
    {
        var tokenHandler = new JwtSecurityTokenHandler();
        if (tokenHandler.ReadToken(token) is JwtSecurityToken jwtToken)
        {
            var wxUserIdClaim = jwtToken.Claims.FirstOrDefault(c => c.Type == WxUserIdClaimType);
            if (long.TryParse(wxUserIdClaim?.Value, out long wxUserId))
            {
                return wxUserId;
            }
        }
        return null;
    }

    /// <summary>
    /// 从Token中获取用户名
    /// </summary>
    /// <param name="token">JWT令牌</param>
    /// <returns>用户名</returns>
    public static string GetUserNameFromToken(string token)
    {
        var tokenHandler = new JwtSecurityTokenHandler();
        if (tokenHandler.ReadToken(token) is JwtSecurityToken jwtToken)
        {
            return GetClaim(jwtToken, ClaimTypes.Name, JwtRegisteredClaimNames.UniqueName, JwtRegisteredClaimNames.Name)?.Value ?? string.Empty;
        }
        return string.Empty;
    }

    private static Claim? GetClaim(JwtSecurityToken jwtToken, params string[] claimTypes)
    {
        return jwtToken.Claims.FirstOrDefault(c => claimTypes.Contains(c.Type));
    }
}