private async Task DoLogin(Func <AuthenticationResult, Task> onSuccess)
{
_vm.LoggingIn();
var authenticationResult = await _authenticationService.Authenticate();
if (authenticationResult != null && !authenticationResult.IsError)
{
_user.Initialize(authenticationResult);
await onSuccess(authenticationResult);
}
else
{
_vm.AllowLogin();
}
}