Why Firebase is unable to get PlayGames AuthCode and pass it into its Credential?

Question

To begin with, I'm working on a Unity Game where I'm authenticating user when the game starts. My build environment is android. I'm using Firebase authentication for Google Play Games Services to authenticate user.

When the game starts in my android device or emulator, it is able to authenticate Play Games Services as well as able to connect with Firebase (I'm getting analytics data). However, when I pass the PlayGames AuthCode into Firebase.Auth Credentials, it stops executing the code (I've debug log for it). It does not throw any error in LogCat except

Firebase | server_auth_code

I tried searching web for different issues, but nothing. I checked my keys in player setting, firebase settings, OAuth 2.0 credentials on my Google API console and even check keys from my Google Play Console (which I'm not using at this stage). I have even checked my test users email addresses in Game Services and tried multiple google play games account. But issue still persist.

I'm using similar script in my other unity project where authentication works like a charm. I tried to use same script here and ended up with this issue: here. However, I solved it by removing all the packages and re-importing them into unity and changed my call functions in the script. Now, I'm stuck at this issue. Here is cs file:

using GooglePlayGames;
using GooglePlayGames.BasicApi;
using UnityEngine.SocialPlatforms;
using System.Threading.Tasks;

public class SetFirebase : MonoBehaviour
{
    string authCode;
    void Start()
    {
        PlayGamesClientConfiguration config = new PlayGamesClientConfiguration.Builder().
        RequestServerAuthCode(false /* Don't force refresh */).Build();

        PlayGamesPlatform.InitializeInstance(config);
        PlayGamesPlatform.Activate();
        Social.localUser.Authenticate((bool success) =>
        {
            if (success)
            {
                authCode = PlayGamesPlatform.Instance.GetServerAuthCode();
                Debug.Log("PlayGames successfully authenticated!");
                Debug.Log("AuthCode: " + authCode);
            }
            else
            {
                Debug.Log("PlayGames SignIn Failed");
            }
        });

        Firebase.FirebaseApp.CheckAndFixDependenciesAsync().ContinueWith(task =>
        {
            var dependencyStatus = task.Result;
            if (dependencyStatus == Firebase.DependencyStatus.Available)
            {
                Debug.Log("Firebase Ready!!!");
                RunFirebase();
            }
            else
            {
                Debug.LogError(System.String.Format("Could not resolve all Firebase dependencies: {0}", dependencyStatus));
            }
        });
    }    

    private void RunFirebase(){
        Firebase.Auth.FirebaseAuth auth = Firebase.Auth.FirebaseAuth.DefaultInstance;
        Debug.Log("init firebase auth ");

        Firebase.Auth.Credential credential = Firebase.Auth.PlayGamesAuthProvider.GetCredential(authCode);
        Debug.Log(" passed auth code ");

        auth.SignInWithCredentialAsync(credential).ContinueWith(task =>
        {
            if (task.IsCanceled)
            {
                Debug.LogError("SignInOnClick was canceled.");
                return;
            }
            if (task.IsFaulted)
            {
                Debug.LogError("SignInOnClick encountered an error: " + task.Exception);
                return;
            }
            Firebase.Auth.FirebaseUser newUser = task.Result;
            Debug.LogFormat("SignInOnClick: User signed in successfully: {0} ({1})", newUser.DisplayName, newUser.UserId);
        });    
    }
}

My LogCat executes everything till "init firebase auth" but does not execute "passed auth code" so I know there is some issue in passing the credentials. It also does not run anything inside auth.SignInWithCredentialAsync(credential).

Any help or suggestion would be highly appreciated. Thank you.

Answer 1

There are two things I may suggest:

1) Replace ContinueWith with ContinueWithOnMainThread. This is a Firebase Extension that will guarantee that your logic runs on the main Unity thread (which tends to resolve many Unity specific issues). I go into more detail about that here.

2) Your logic may have a race condition between the Authenticate callback and the CheckAndFixDependenciesAsync continuation. These will not necessarily run in the order that you see them in your logic.

If I were building this system, I might prefer using Coroutines and a custom yield instruction:

class Authenticate : CustomYieldInstruction
{
    private bool _keepWaiting = true;
    public override bool keepWaiting => _keepWaiting;

    public Authenticate(Social.ILocalUser user) {
        user.Authenticate((bool success)=>{
            /* old authentication code here */
            _keepWaiting = false;
        });
    }

}

Then in a coroutine have something like:

private IEnumerator InitializeCoroutine() {
    /* old authentication code */

    // I'm ignoring error checking for now, but it shouldn't be hard to figure in.
    // I'm mostly going from memory now anyway

    // start both authentication processes in parallel
    var authenticate = new Authenticate(Social.localUser);
    var firebaseDependenciesTask = FirebaseApp.CheckAndFixDependenciesAsync();

    // wait on social
    yield return authenticate;

    // wait on Firebase. If it finished in the meantime this should just fall through
    yield return new WaitUntil(()=>firebaseDependenciesTask.IsComplete);

    RunFirebase();
}

This way my logic looks roughly synchronous whilst still maintaining the asynchronosity (spell check claims that I made up that word) of the systems you're depending on and you avoid threading related issues that arise when using ContinueWith.

Let me know if that helps!

--Patrick