using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
#if UNITY_ANDROID && !UNITY_EDITOR
using Firebase.Extensions;
using Firebase.Messaging;
#endif

/// <summary>
/// Android FCM registration for the player client. The Editor and dedicated server builds do not talk to Firebase.
/// </summary>
public class PushNotificationService : MonoBehaviour
{
    public const string BroadcastTopic = "kk_broadcast";
    public const string ChannelId = "support";

    public static PushNotificationService instance { get; private set; }

    static string _pendingTicketId;

    readonly List<Action> _mainThread = new List<Action>();
    readonly object _mainLock = new object();

#if UNITY_ANDROID && !UNITY_EDITOR
    const string RegisteredFidKey = "WalkInvest.SupportPushFid";
    const string RegisteredUserKey = "WalkInvest.SupportPushUserId";
    const string PostNotificationsPermission = "android.permission.POST_NOTIFICATIONS";
    const float UnregisterTimeoutSeconds = 5f;

    string _fid;
    string _lastRegisteredFid;
    int _lastRegisteredUserId;
    bool _sessionReady;
    bool _registerQueued;
    bool _registerInFlight;
    bool _topicSubscribed;
    bool _subscribeInFlight;
    bool _firebaseReady;
    Firebase.FirebaseApp _firebaseApp;
#endif

    public static void EnsureCreated()
    {
#if UNITY_ANDROID && !UNITY_EDITOR
        if (instance != null)
            return;
        var go = new GameObject(nameof(PushNotificationService));
        go.AddComponent<PushNotificationService>();
#endif
    }

    public static void OnGameSessionReady()
    {
#if UNITY_ANDROID && !UNITY_EDITOR
        EnsureCreated();
        if (instance == null)
            return;
        instance._sessionReady = true;
        instance.RequestRegister();
#endif
    }

    /// <summary>
    /// Deletes this install on the admin API, then runs <paramref name="next"/>.
    /// A failed or timed-out delete still continues.
    /// </summary>
    public static void UnregisterThen(Action next)
    {
#if UNITY_ANDROID && !UNITY_EDITOR
        if (instance != null && instance.CanUnregister)
        {
            instance.StartCoroutine(instance.UnregisterAndContinue(next));
            return;
        }
        if (instance != null)
            instance.ForgetLocalRegistration();
#endif
        next?.Invoke();
    }

    public static string ConsumePendingTicket()
    {
        string ticketId = _pendingTicketId;
        _pendingTicketId = null;
        return ticketId;
    }

    void Awake()
    {
        if (instance != null && instance != this)
        {
            Destroy(gameObject);
            return;
        }

        instance = this;
        DontDestroyOnLoad(gameObject);
#if UNITY_ANDROID && !UNITY_EDITOR
        _lastRegisteredFid = PlayerPrefs.GetString(RegisteredFidKey, "");
        _lastRegisteredUserId = PlayerPrefs.GetInt(RegisteredUserKey, 0);
        InitializeFirebase();
#endif
    }

    void OnDestroy()
    {
        if (instance == this)
            instance = null;
#if UNITY_ANDROID && !UNITY_EDITOR
        if (_firebaseReady)
        {
            FirebaseMessaging.RegistrationReceived -= OnRegistrationReceived;
            FirebaseMessaging.MessageReceived -= OnMessageReceived;
        }
#endif
    }

    void Update()
    {
        Action[] batch = null;
        lock (_mainLock)
        {
            if (_mainThread.Count == 0)
                return;
            batch = _mainThread.ToArray();
            _mainThread.Clear();
        }

        for (int i = 0; i < batch.Length; i++)
            batch[i]?.Invoke();
    }

#if UNITY_ANDROID && !UNITY_EDITOR
    bool CanUnregister
    {
        get { return _sessionReady && !string.IsNullOrEmpty(_fid) && SupportClient.IsSignedIn; }
    }

    void InitializeFirebase()
    {
        Firebase.FirebaseApp.CheckAndFixDependenciesAsync().ContinueWithOnMainThread(task =>
        {
            if (instance != this)
                return;
            if (task.IsFaulted || task.IsCanceled)
            {
                Logger.Log("Firebase dependency check failed.");
                return;
            }

            var status = task.Result;
            if (status != Firebase.DependencyStatus.Available)
            {
                Logger.Log("Firebase dependencies unavailable: " + status);
                return;
            }

            _firebaseApp = Firebase.FirebaseApp.DefaultInstance;
            if (_firebaseApp == null)
            {
                Logger.Log("Firebase app missing.");
                return;
            }
            _firebaseReady = true;
            EnsureNotificationChannel();
            RequestNotificationPermission();
            FirebaseMessaging.RegistrationReceived += OnRegistrationReceived;
            FirebaseMessaging.MessageReceived += OnMessageReceived;
            FirebaseMessaging.RegisterAsync().ContinueWithOnMainThread(register =>
            {
                if (instance != this)
                    return;
                if (register.IsFaulted)
                    Logger.Log("FCM register failed: " + register.Exception.GetBaseException().Message);
            });
        });
    }

    void OnRegistrationReceived(object sender, RegistrationReceivedEventArgs args)
    {
        string fid = args != null ? args.InstallationId : null;
        RunOnMain(() => HandleRegistration(fid));
    }

    void OnMessageReceived(object sender, MessageReceivedEventArgs args)
    {
        string type = null;
        string ticketId = null;
        if (args != null && args.Message != null && args.Message.Data != null)
        {
            args.Message.Data.TryGetValue("type", out type);
            args.Message.Data.TryGetValue("ticketId", out ticketId);
        }

        string typeCopy = type;
        string ticketCopy = ticketId;
        RunOnMain(() => HandleMessage(typeCopy, ticketCopy));
    }

    void HandleRegistration(string fid)
    {
        if (string.IsNullOrEmpty(fid))
            return;

        if (fid != _fid)
        {
            _topicSubscribed = false;
            _subscribeInFlight = false;
        }
        _fid = fid;
        if (!_topicSubscribed && !_subscribeInFlight)
        {
            _subscribeInFlight = true;
            StartCoroutine(SubscribeBroadcast());
        }
        RequestRegister();
    }

    void HandleMessage(string type, string ticketId)
    {
        if (!string.Equals(type, "support_reply", StringComparison.Ordinal))
            return;
        if (string.IsNullOrEmpty(ticketId))
            return;

        CustomerSupportCanvas canvas = CustomerSupportCanvas.instance;
        if (canvas != null && canvas.isActiveAndEnabled)
            canvas.OpenFromNotification(ticketId);
        else
            _pendingTicketId = ticketId;
    }

    IEnumerator SubscribeBroadcast()
    {
        var task = FirebaseMessaging.SubscribeAsync(BroadcastTopic);
        while (!task.IsCompleted)
            yield return null;

        _subscribeInFlight = false;
        if (task.IsFaulted || task.IsCanceled)
        {
            Logger.Log("FCM topic subscribe failed.");
            yield break;
        }

        _topicSubscribed = true;
    }

    void RequestRegister()
    {
        if (!_sessionReady || string.IsNullOrEmpty(_fid))
            return;

        _registerQueued = true;
        if (!_registerInFlight)
            StartCoroutine(RegisterLoop());
    }

    IEnumerator RegisterLoop()
    {
        _registerInFlight = true;
        while (_registerQueued && _sessionReady)
        {
            _registerQueued = false;
            yield return RegisterDeviceBody();
        }
        _registerInFlight = false;
    }

    IEnumerator RegisterDeviceBody()
    {
        if (!_sessionReady || string.IsNullOrEmpty(_fid))
            yield break;

        if (!SupportClient.IsSignedIn)
        {
            string username = LoginManager.SessionUsername;
            string password = LoginManager.SessionPassword;
            if (string.IsNullOrEmpty(username) || string.IsNullOrEmpty(password))
            {
                Logger.Log("Push registration skipped: support session is not available.");
                yield break;
            }

            SupportCallResult<SupportLoginResponse> login = null;
            yield return SupportClient.Login(username, password, r => login = r);
            if (!_sessionReady)
                yield break;
            if (login == null || !login.ok)
            {
                Logger.Log("Push registration skipped: support login failed.");
                yield break;
            }
        }

        int userId = SupportClient.UserId;
        if (_fid == _lastRegisteredFid && userId != 0 && userId == _lastRegisteredUserId)
            yield break;

        string fid = _fid;
        SupportCallResult<SupportDeviceResponse> result = null;
        yield return SupportClient.RegisterDevice(fid, "android", r => result = r);
        if (!_sessionReady || fid != _fid)
            yield break;
        if (result == null || !result.ok)
        {
            Logger.Log("Push registration failed: " + (result != null ? result.error : "no result"));
            yield break;
        }

        _lastRegisteredFid = fid;
        _lastRegisteredUserId = SupportClient.UserId;
        PlayerPrefs.SetString(RegisteredFidKey, _lastRegisteredFid ?? "");
        PlayerPrefs.SetInt(RegisteredUserKey, _lastRegisteredUserId);
        PlayerPrefs.Save();
    }

    IEnumerator UnregisterAndContinue(Action next)
    {
        _sessionReady = false;
        bool done = false;
        StartCoroutine(FinishUnregister(_fid, () => done = true));
        float start = Time.unscaledTime;
        while (!done && Time.unscaledTime - start < UnregisterTimeoutSeconds)
            yield return null;

        if (!done)
            Logger.Log("Push unregister timed out.");

        ForgetLocalRegistration();
        next?.Invoke();
    }

    IEnumerator FinishUnregister(string fid, Action done)
    {
        SupportCallResult<SupportDeviceResponse> result = null;
        yield return SupportClient.UnregisterDevice(fid, r => result = r);
        if (result == null || !result.ok)
            Logger.Log("Push unregister failed: " + (result != null ? result.error : "no result"));
        done?.Invoke();
    }

    void ForgetLocalRegistration()
    {
        _lastRegisteredFid = null;
        _lastRegisteredUserId = 0;
        PlayerPrefs.DeleteKey(RegisteredFidKey);
        PlayerPrefs.DeleteKey(RegisteredUserKey);
        PlayerPrefs.Save();
    }

    void RunOnMain(Action action)
    {
        if (action == null)
            return;
        lock (_mainLock)
            _mainThread.Add(action);
    }

    static void RequestNotificationPermission()
    {
        try
        {
            using (var version = new AndroidJavaClass("android.os.Build$VERSION"))
            {
                if (version.GetStatic<int>("SDK_INT") < 33)
                    return;
            }

            if (!UnityEngine.Android.Permission.HasUserAuthorizedPermission(PostNotificationsPermission))
                UnityEngine.Android.Permission.RequestUserPermission(PostNotificationsPermission);
        }
        catch (Exception e)
        {
            Logger.Log("Notification permission request failed: " + e.Message);
        }
    }

    static void EnsureNotificationChannel()
    {
        try
        {
            using (var version = new AndroidJavaClass("android.os.Build$VERSION"))
            {
                if (version.GetStatic<int>("SDK_INT") < 26)
                    return;
            }

            using (var unityPlayer = new AndroidJavaClass("com.unity3d.player.UnityPlayer"))
            using (var activity = unityPlayer.GetStatic<AndroidJavaObject>("currentActivity"))
            using (var channel = new AndroidJavaObject("android.app.NotificationChannel", ChannelId, "Support", 4))
            using (var manager = activity.Call<AndroidJavaObject>("getSystemService", "notification"))
            {
                channel.Call("setDescription", "Support replies and announcements");
                manager.Call("createNotificationChannel", channel);
            }
        }
        catch (Exception e)
        {
            Logger.Log("Notification channel setup failed: " + e.Message);
        }
    }
#endif
}