public async Task <IActionResult> Index(InputModelLogin model)
        {
            _model = model;
            if (ModelState.IsValid)
            {
                var result = await _user.UserLoginAsync(model);

                if (result.Succeeded)
                {
                    return(Redirect("/Principal/Principal"));
                }
                else
                {
                    _model.ErrorMessage = "Correo o contraseña inválidos.";
                    return(Redirect("/"));
                }
            }
            else
            {
                foreach (var modelState in ModelState.Values)
                {
                    foreach (var error in modelState.Errors)
                    {
                        _model.ErrorMessage = error.ErrorMessage;
                    }
                }
                return(Redirect("/"));
            }
        }