using Firebase;
using Firebase.Auth;
using Firebase.Firestore;
using System;
using System.Threading.Tasks;
using UnityEngine;

namespace BulletHellTemplate
{
    /// <summary>
    /// Handles Firebase-specific authentication, storing the authenticated user,
    /// and delegating data loading to FirebaseManager.
    /// </summary>
    public class FirebaseAuthManager : MonoBehaviour
    {
        [Tooltip("Singleton instance for global access.")]
        public static FirebaseAuthManager Singleton;

        private bool instanceInitialized;
        private FirebaseAuth firebaseAuth;
        private FirebaseFirestore firebaseFirestore;
        private FirebaseUser currentUser;

        private void Awake()
        {
            if (Singleton == null)
            {
                Singleton = this;
                DontDestroyOnLoad(gameObject);
            }
            else
            {
                Destroy(gameObject);
            }
        }

        /// <summary>
        /// Indicates if this FirebaseAuthManager was successfully initialized.
        /// </summary>
        /// <returns>True if initialized, false otherwise.</returns>
        public bool IsInitialized()
        {
            return instanceInitialized;
        }

        /// <summary>
        /// Initializes FirebaseAuthManager with the provided FirebaseAuth and FirebaseFirestore instances.
        /// </summary>
        /// <param name="auth">FirebaseAuth instance.</param>
        /// <param name="firestore">FirebaseFirestore instance.</param>
        public void InitializeAuthBackend(FirebaseAuth auth, FirebaseFirestore firestore)
        {
            firebaseAuth = auth;
            firebaseFirestore = firestore;
            currentUser = firebaseAuth.CurrentUser;
            instanceInitialized = true;
        }

        /// <summary>
        /// Returns the current FirebaseUser, or null if none is logged in.
        /// </summary>
        public FirebaseUser GetCurrentUser()
        {
            return currentUser;
        }

        /// <summary>
        /// Logs in a user with email and password using FirebaseAuth.
        /// </summary>
        /// <param name="email">The user's email.</param>
        /// <param name="password">The user's password.</param>
        public async Task LoginWithEmailAsync(string email, string password)
        {
            if (!instanceInitialized)
            {
                throw new Exception("FirebaseAuthManager not initialized.");
            }
            await firebaseAuth.SignInWithEmailAndPasswordAsync(email, password);
            currentUser = firebaseAuth.CurrentUser;
        }

        /// <summary>
        /// Logs in a user anonymously using FirebaseAuth.
        /// </summary>
        public async Task LoginAnonymouslyAsync()
        {
            if (!instanceInitialized)
            {
                throw new Exception("FirebaseAuthManager not initialized.");
            }
            await firebaseAuth.SignInAnonymouslyAsync();
            currentUser = firebaseAuth.CurrentUser;
        }

        /// <summary>
        /// Creates a new user account with the specified email and password.
        /// </summary>
        /// <param name="email">User's email.</param>
        /// <param name="password">User's password.</param>
        public async Task CreateAccountAsync(string email, string password)
        {
            if (!instanceInitialized)
            {
                throw new Exception("FirebaseAuthManager not initialized.");
            }
            await firebaseAuth.CreateUserWithEmailAndPasswordAsync(email, password);
            currentUser = firebaseAuth.CurrentUser;
        }

        /// <summary>
        /// Calls FirebaseManager to load and synchronize the current user's data from Firestore.
        /// Returns a message describing the load result.
        /// </summary>
        public async Task<string> LoadPlayerDataAsync()
        {
            if (!instanceInitialized)
            {
                return "FirebaseAuthManager is not initialized.";
            }
            if (currentUser == null)
            {
                return "No user is currently logged in.";
            }

            string userId = currentUser.UserId;
            return await FirebaseManager.Singleton.LoadAndSyncPlayerData(userId);
        }
    }
}