using Microsoft.AspNetCore.Http;
using Microsoft.IdentityModel.Tokens;
using System.IdentityModel.Tokens.Jwt;
using System.Linq;
using System.Threading.Tasks;
using YLErp.Helpers;
using YLErp;
using System;

namespace YLErp.Web.Middleware
{
    /// <summary>
    /// Token续期中间件
    /// 用于在用户有操作时自动续期登录状态
    /// </summary>
    public class RefreshTokenMiddleware
    {
        private readonly RequestDelegate _next;
        // 续期阈值设为Token过期时间的20%，避免过于频繁的续期
        private static int RefreshThreshold => (int)(AuthHelper.ExpireInSeconds * 0.2);

        /// <summary>
        /// 构造函数
        /// </summary>
        /// <param name="next">下一个中间件</param>
        public RefreshTokenMiddleware(RequestDelegate next)
        {
            _next = next;
        }

        /// <summary>
        /// 处理请求
        /// </summary>
        /// <param name="context">HTTP上下文</param>
        public async Task InvokeAsync(HttpContext context)
        {
            // 检查是否有Access-Token
            if (context.Request.Cookies.TryGetValue("Access-Token", out var token))
            {
                try
                {
                    // 配置token验证参数
                    var validationParameters = new TokenValidationParameters
                    {
                        ValidateIssuerSigningKey = true,
                        ValidateIssuer = true,
                        ValidateAudience = true,
                        ValidateLifetime = true,
                        IssuerSigningKey = new SymmetricSecurityKey(Convert.FromBase64String(AuthHelper.JwtSecretKey)),
                        ValidIssuer = AuthHelper.JwtIssuer,
                        ValidAudience = AuthHelper.JwtAudience,
                        ClockSkew = TimeSpan.Zero // 不容忍时钟偏差
                    };

                    var tokenHandler = new JwtSecurityTokenHandler();
                    
                    // 验证并解析token
                    var principal = tokenHandler.ValidateToken(token, validationParameters, out var validatedToken);
                    var jwtToken = validatedToken as JwtSecurityToken;
                    
                    // 检查token是否接近过期
                    var expiration = jwtToken.ValidTo;
                    var timeUntilExpiry = expiration - DateTime.UtcNow;
                    
                    // 如果剩余时间少于阈值，自动续期
                    if (timeUntilExpiry.TotalSeconds < RefreshThreshold)
                    {
                        // 从token中获取用户信息
                        var userId = jwtToken.Claims.FirstOrDefault(c => c.Type == "userId")?.Value;
                        var userName = jwtToken.Claims.FirstOrDefault(c => c.Type == "account")?.Value;
                        var userToken = jwtToken.Claims.FirstOrDefault(c => c.Type == "uuid")?.Value;
                        
                        if (!string.IsNullOrEmpty(userId) && !string.IsNullOrEmpty(userName))
                        {
                            // 创建新的identity
                            var identity = UserManager.CreateIdentity(userId, userName, userToken);
                            
                            // 生成新的token
                            var newToken = AuthHelper.CreateJwtToken2(identity);
                            
                            // 更新cookie
                            context.Response.Cookies.Append("Access-Token", newToken, new CookieOptions
                            {
                                MaxAge = TimeSpan.FromSeconds(AuthHelper.ExpireInSeconds),
                                HttpOnly = true,
                                Secure = true,
                                SameSite = SameSiteMode.Strict
                            });
                            
                            context.Response.Cookies.Append("Access-Token-Encrypt", 
                                YLErp.Helpers.DataProtectHelper.Encrypt(newToken),
                                new CookieOptions
                                {
                                    HttpOnly = true,
                                    Secure = true,
                                    SameSite = SameSiteMode.Strict
                                });
                            
                            // 记录续期日志
                            Console.WriteLine($"Token refreshed for user: {userName}, new expiry: {DateTime.UtcNow.AddSeconds(AuthHelper.ExpireInSeconds)}");
                        }
                    }
                }
                catch (SecurityTokenExpiredException)
                {
                    // Token已过期，清除cookie
                    context.Response.Cookies.Delete("Access-Token");
                    context.Response.Cookies.Delete("Access-Token-Encrypt");
                    Console.WriteLine("Token expired, cookies cleared");
                }
                catch (SecurityTokenInvalidSignatureException)
                {
                    // Token签名无效，可能是被篡改
                    context.Response.Cookies.Delete("Access-Token");
                    context.Response.Cookies.Delete("Access-Token-Encrypt");
                    Console.WriteLine("Invalid token signature, cookies cleared");
                }
                catch (Exception ex)
                {
                    // 记录其他异常
                    Console.WriteLine($"Token refresh error: {ex.Message}");
                    // 继续处理请求，不影响正常流程
                }
            }

            // 处理后续请求
            await _next(context);
        }
    }
}