private function loginFacebookCanvas():Promise {
    function retryLogin():Promise {
        return FacebookManager.Instance.login()
        .except(function(reason:*):Promise{
            Log.warning("fbauth", "Unable to connect to Facebook, retrying in 3...\n\t$(reason)", {reason:reason});
            return Promise.WallClockDelay(3)
            .then(function(_:*):Promise{
                return retryLogin();
            });
        });
    }

    return FacebookManager.Instance.queryProfile()
    .then(function(profile: FacebookOwnProfile): Promise {
        if (!profile) {
            return retryLogin();
        }
        return Promise.Resolve(profile);
    }, function(reason:*):Promise{
        return retryLogin();
    })
    .then(getUserFromFBProfile)
    .except(function(reason:Object):Promise{
        Log.warning("fbauth", "Facebook authorization failed: $(reason)", {reason : reason});
        return Promise.Reject("fbauth login failed");
    });
}

private function getUserFromFBProfile(profile:FacebookOwnProfile):Promise{
    if ( !profile ){
        return Promise.Reject("no fb profile");
    }

    Log.trace("fbauth", "Authenticating with a Facebook signed request for uid=$(uid)...", { uid:profile.uid } );

    return Promise.Repeat(
        function():Promise{
            return Promise.WithTimeout(model.authService.loginWithFBSignedRequest(profile.signedRequest), 15);
        },
        3
    )
    .then(function(login:LoginResult):UserState {
        Log.trace("fbauth", "Authenticated as Facebook user, with player uid=$(uid). Fetching save game...", { uid:login.uid } );

        var user:UserState = UserState.FromLoginResult(model, login);
        user.defaultProfile = UserProfile.FromFB(profile);
        return user;
    });
}