Snaparazzi/Assets/Scripts/FirebaseInitializer.cs

using Firebase;
using System.Collections;
using UnityEngine;
using System;

public class FirebaseInitializer : MonoBehaviour
{
    public Action onFirebaseReady;
    public static FirebaseInitializer Instance;

    void Awake()
    {
        Instance = this;
    }

    // Start is called before the first frame update
    IEnumerable Start()
    {
        FirebaseApp.CheckAndFixDependenciesAsync().ContinueWith(task =>
        {
            var dependencyStatus = task.Result;
            if (dependencyStatus == DependencyStatus.Available)
            {
                // Create and hold a reference to your FirebaseApp,
                // where app is a Firebase.FirebaseApp property of your application class.
                var app = FirebaseApp.DefaultInstance;
                Authenticate();

                // Set a flag here to indicate whether Firebase is ready to use by your app.
            }
            else
            {
                Debug.LogError($"Could not resolve all Firebase dependencies: {dependencyStatus}");
            }
        });

        yield return Application.RequestUserAuthorization(UserAuthorization.WebCam);
    }

    // Update is called once per frame
    void Authenticate()
    {
        Firebase.Auth.FirebaseAuth auth = Firebase.Auth.FirebaseAuth.DefaultInstance;

        auth.SignInAnonymouslyAsync().ContinueWith(task =>
        {
            if (task.IsCanceled)
            {
                Debug.LogError("SignInAnonymouslyAsync was canceled.");
                return;
            }
            if (task.IsFaulted)
            {
                Debug.LogError("SignInAnonymouslyAsync encountered an error: " + task.Exception);
                return;
            }

            Firebase.Auth.AuthResult result = task.Result;
            Debug.Log($"User signed in successfully: {result.User.UserId}");

            onFirebaseReady?.Invoke();
        });
    }
}