public class LayoutModelAttribute : ActionFilterAttribute
    {
        private readonly IViewModelFactory _viewModelFactory;

        public LayoutModelAttribute(IViewModelFactory viewModelFactory)
        {
            _viewModelFactory = viewModelFactory;
        }

        public override void OnActionExecuting(ActionExecutingContext filterContext)
        {
            var controller = filterContext.Controller as BaseController;
            if (controller != null)
            {
                (controller).Context = _viewModelFactory.Create<SharedContext>();
            }

            base.OnActionExecuting(filterContext);
        }

        public override void OnResultExecuting(ResultExecutingContext filterContext)
        {
            var viewModel = filterContext.Controller.ViewData.Model;
            var controller = filterContext.Controller as BaseController;

            var model = viewModel as LayoutViewModel;
            
            if (model != null)
            {
                (model).Context = controller != null && controller.Context != null ? controller.Context : _viewModelFactory.Create<SharedContext>();
            }

            base.OnResultExecuting(filterContext);
        }
    }

    public class ViewModelFactory : IViewModelFactory
    {
        private readonly IUserProvider _userService;
        private readonly IMessageSenderRepository _userMessageService;

        public ViewModelFactory(IUserProvider userService, IMessageSenderRepository userMessageService)
        {
            _userService = userService;
            _userMessageService = userMessageService;
        }

        public T Create<T>() where T : SharedContext, new()
        {
            var model = new T();
            Set(model);

            return model;
        }

        public void Set<T>(T model) where T : SharedContext, new()
        {
            User user = _userService.User;



            model.CurrentUser = user;
            model.UnreadMessageCount = _userMessageService.UnreadMessageCount(user.Id);
        }
    }

    public interface IViewModelFactory
    {
        T Create<T>() where T : SharedContext, new();
        void Set<T>(T model) where T : SharedContext, new();
    }