public async Task <IActionResult> OnPostAsync(string returnUrl = null)
        {
            returnUrl = returnUrl ?? Url.Content("~/");

            if (ModelState.IsValid)
            {
                bool result;
                IConfigurationRoot configuration = new ConfigurationBuilder().SetBasePath(Directory.GetCurrentDirectory()).AddJsonFile("appsettings.json").Build();
                bool.TryParse(configuration.GetValue <string>("AppSettings:Settings:useADlogin"), out bool useADlogin);

                if (useADlogin && !string.IsNullOrEmpty(Input.Tenant)) // if tenant is null, then assume that it is system level login. Go to the ValidateLogin which is used for regular login process first
                {
                    result = await _signInManager.ADSigninAsync(Input.Tenant, Input.Password, Input.RememberMe);
                }
                else
                {
                    // This doesn't count login failures towards account lockout
                    // To enable password failures to trigger account lockout, set lockoutOnFailure: true
                    result = await _signInManager.PasswordSignInAsync(Input.Tenant, Input.Email, Input.Password, Input.RememberMe);
                }

                if (result)
                {
                    _logger.LogInformation("User logged in.");
                    return(LocalRedirect(returnUrl));
                }
                else
                {
                    ModelState.AddModelError(string.Empty, "Invalid login attempt.");
                    return(Page());
                }
            }

            // If we got this far, something failed, redisplay form
            return(Page());
        }