NonInventPurchasingSystem/CPRNIMS.WebApps/Common/Middleware/TokenRefreshMiddleware.cs

using CPRNIMS.Infrastructure.Helper;
using Microsoft.AspNetCore.Mvc;
using Newtonsoft.Json;
using System.IdentityModel.Tokens.Jwt;

namespace CPRNIMS.WebApps.Common.Middleware
{
    public class TokenRefreshMiddleware
    {
        private readonly RequestDelegate _next;

        public TokenRefreshMiddleware(RequestDelegate next)
        {
            _next = next;
        }

        public async Task InvokeAsync(
            HttpContext context,
            IHttpClientFactory httpClientFactory)
        {
            var accessToken = context.Session.GetString("AccessToken");

            if (!string.IsNullOrEmpty(accessToken) &&
                IsTokenExpiringSoon(accessToken))
            {
                var client = httpClientFactory.CreateClient($"AuthApi{"Account/RefreshToken"}");

                var response = await client.PostAsync("RefreshToken", null);

                if (response.IsSuccessStatusCode)
                {
                    var json = await response.Content.ReadAsStringAsync();
                    var tokenResult = JsonConvert.DeserializeObject<TokenResult>(json);

                    context.Session.SetString("AccessToken", tokenResult.AccessToken);
                }
                else
                {
                    // refresh token invalid → force logout
                    context.Session.Clear();
                    context.Response.Redirect("/Home/Logout");
                    return;
                }
            }

            await _next(context);
        }

        private static bool IsTokenExpiringSoon(string token, int thresholdMinutes = 2)
        {
            var jwt = new JwtSecurityTokenHandler().ReadJwtToken(token);
            return DateTime.UtcNow >= jwt.ValidTo.AddMinutes(-thresholdMinutes);
        }
        public class TokenResult
        {
            public string? AccessToken { get; set; }
            public DateTime Expiration { get; set; }
        }

    }

}