DesktopRedirectAttribute.cs

using Microsoft.AspNetCore.Mvc.Filters;
using Wangkanai.Detection.Services;

namespace Mobile_Redirection_Subfolder
{
    public class DesktopRedirectAttribute : ActionFilterAttribute
    {
        public override void OnActionExecuting(ActionExecutingContext filterContext)
        {
            var path = filterContext.HttpContext.Request.Path.ToString();
            if (!IsMobile())
            {
                path = path.Contains("/mobile/") ? path.Substring(7) : path;
                filterContext.HttpContext.Response.Redirect(path);
            }

            bool IsMobile()
            {
                var service = (DetectionService)filterContext.HttpContext.RequestServices.GetService(typeof(IDetectionService));
                var deviceType = service.Device.Type;
                return deviceType == Wangkanai.Detection.Models.Device.Mobile;
            }
        }
    }
}