using Fusion;
using Fusion.Sockets;
using System.Collections;
using System.Collections.Generic;
using System.Threading.Tasks;
using UnityEngine;
using UnityEngine.SceneManagement;
using TMPro;
using UnityEngine.UI;
using System.Linq;

public class FusionLauncher : MonoBehaviour, INetworkRunnerCallbacks
{
    [Header("Network Runner (Drag NOTHING here)")]
    public NetworkRunner runner;      // we'll create/destroy this at runtime

    [Header("Lobby UI")]
    public GameObject lobbyUI;
    public SessionListUIHandler sessionListUIHandler;
    public TMP_InputField lobbyNameInput;
    public Button createLobbyButton;
    public TextMeshProUGUI waitingText;

    [Header("Player Prefab")]
    public NetworkPrefabRef playerPrefab;

    private Coroutine refreshCoroutine;
    private int playerCount = 0;
    private const int maxPlayers = 2;
    private bool gameplayLoaded = false;
    private bool connectedToServer = false;

    void Awake()
    {
        // Ensure this launcher persists across loads
        if (FindObjectsOfType<FusionLauncher>().Length > 1)
        {
            Destroy(gameObject);
            return;
        }
        DontDestroyOnLoad(gameObject);
    }

    void Start()
    {
        // Kick off our dummy runner purely in client/browse mode:
        StartDummyRunner();

        // UI hookups
        if (lobbyNameInput != null) lobbyNameInput.onValueChanged.AddListener(OnLobbyNameChanged);
        OnLobbyNameChanged(lobbyNameInput.text);
        waitingText.gameObject.SetActive(false);

        // Start periodic lobby refresh once connected
        refreshCoroutine = StartCoroutine(AutoRefreshLobbyList());
    }

    void OnDestroy()
    {
        if (refreshCoroutine != null)
            StopCoroutine(refreshCoroutine);
    }

    IEnumerator AutoRefreshLobbyList()
    {
        while (true)
        {
            RefreshLobbyList();
            yield return new WaitForSeconds(5f);
        }
    }

    void OnLobbyNameChanged(string s)
    {
        createLobbyButton.interactable = !string.IsNullOrWhiteSpace(s) && s.Length <= 15;
    }

    // —————— DUMMY RUNNER ——————
    // Starts a runner in CLIENT mode so we can list sessions.
    async void StartDummyRunner()
    {
        // If already up & running, just bail.
        if (runner != null && runner.IsRunning)
            return;

        // Ensure any old runner is cleared
        await EnsureFreshRunner();

        // Start as CLIENT
        var result = await runner.StartGame(new StartGameArgs()
        {
            GameMode = GameMode.Client,
            SceneManager = runner.gameObject.AddComponent<NetworkSceneManagerDefault>()
        });

        if (result.Ok)
        {
            Debug.Log("✅ Browser runner connected (Client mode).");
            connectedToServer = true;
        }
        else if (result.ShutdownReason == ShutdownReason.GameNotFound)
        {
            Debug.Log("ℹ️ No lobbies yet—but browser runner is live.");
            connectedToServer = true;
        }
        else
        {
            Debug.LogError($"❌ Browser runner failed: {result.ShutdownReason}");
        }
    }

    // —————— RESET / CREATE FRESH RUNNER ——————
    private async Task EnsureFreshRunner()
    {
        // Reset flags
        playerCount = 0;
        gameplayLoaded = false;
        connectedToServer = false;

        // If an old runner exists & is running, shut it down & destroy its GO
        if (runner != null && runner.IsRunning)
        {
            await runner.Shutdown();
            Destroy(runner.gameObject);
        }

        // Stop auto-refresh while we rebuild
        if (refreshCoroutine != null)
        {
            StopCoroutine(refreshCoroutine);
            refreshCoroutine = null;
        }

        // Make brand-new runner GameObject
        var go = new GameObject("NetworkRunnerGO");
        DontDestroyOnLoad(go);                     // keep it alive across scenes

        runner = go.AddComponent<NetworkRunner>();
        runner.ProvideInput = true;
        runner.AddCallbacks(this);
    }

    // —————— CREATE LOBBY (Host) ——————
    public async void CreateLobby()
    {
        var name = lobbyNameInput.text.Trim();
        if (string.IsNullOrEmpty(name))
        {
            Debug.LogWarning("Empty lobby name!");
            return;
        }

        // Tear down browse runner & spawn a fresh one
        await EnsureFreshRunner();

        var sceneRef = SceneRef.FromIndex(SceneManager.GetActiveScene().buildIndex);
        var res = await runner.StartGame(new StartGameArgs()
        {
            GameMode = GameMode.Host,
            SessionName = name,
            PlayerCount = maxPlayers,
            Scene = sceneRef,
            SceneManager = runner.gameObject.AddComponent<NetworkSceneManagerDefault>()
        });

        if (res.Ok)
        {
            Debug.Log($"✔ Hosted Lobby '{name}'");
            lobbyUI.SetActive(false);
            waitingText.text = "Waiting for player 2…";
            waitingText.gameObject.SetActive(true);
        }
        else
        {
            Debug.LogError($"✖ Host failed: {res.ShutdownReason}");
        }
    }

    // —————— JOIN LOBBY (Client) ——————
    public async void JoinLobby(SessionInfo info)
    {
        // Tear down browse runner & spawn a fresh one
        await EnsureFreshRunner();

        var res = await runner.StartGame(new StartGameArgs()
        {
            GameMode = GameMode.Client,
            SessionName = info.Name,
            Scene = SceneRef.FromIndex(SceneManager.GetActiveScene().buildIndex),
            SceneManager = runner.gameObject.AddComponent<NetworkSceneManagerDefault>()
        });

        if (res.Ok)
        {
            Debug.Log($"✔ Joined Lobby '{info.Name}'");
            lobbyUI.SetActive(false);
            waitingText.text = "Waiting for host…";
            waitingText.gameObject.SetActive(true);
        }
        else
        {
            Debug.LogError($"✖ Join failed: {res.ShutdownReason}");
        }
    }

    // —————— REFRESH LOBBY LIST ——————
    public void RefreshLobbyList()
    {
        if (!connectedToServer) return;
        //sessionListUIHandler.ClearList();
        runner.JoinSessionLobby(SessionLobby.ClientServer);
    }

    // —————— FUSION CALLBACKS ——————
    public void OnConnectedToServer(NetworkRunner r)
    {
        connectedToServer = true;
        Debug.Log("✔ Connected to server; can refresh lobbies.");
        RefreshLobbyList();
    }

    public void OnSessionListUpdated(NetworkRunner runner, List<SessionInfo> sessionList)
    {
        // First thing, wipe out the old items every time
        sessionListUIHandler.ClearList();

        // If there really are no sessions, show your “no sessions” message
        if (sessionList.Count == 0)
        {
            sessionListUIHandler.ShowNoSessionsMessage();
            return;
        }

        // Otherwise re-populate
        foreach (var session in sessionList)
        {
            if (session.IsOpen && session.IsVisible && session.PlayerCount < session.MaxPlayers)
            {
                sessionListUIHandler.AddToList(session, JoinLobby);
            }
        }
    }

    public void OnPlayerJoined(NetworkRunner r, PlayerRef p)
    {
        playerCount++;
        // Only the host in Gameplay scene spawns cars
        //if (r.IsServer && SceneManager.GetActiveScene().name == "Gameplay")
        //{
        //    var pos = new Vector3(Random.Range(-5, 5), 0, Random.Range(-5, 5));
        //    r.Spawn(playerPrefab, pos, Quaternion.identity, p);
        //}


        // Only the host triggers scene‐load when 2 players are present
        if (r.IsServer && playerCount == maxPlayers && !gameplayLoaded)
        {
            gameplayLoaded = true;
            var scene = SceneRef.FromIndex(
                SceneUtility.GetBuildIndexByScenePath("Assets/Scenes/Gameplay.unity")
            );
            r.LoadScene(scene, LoadSceneMode.Single);
            waitingText.gameObject.SetActive(false);
        }
    }
    public void OnSceneLoadDone(NetworkRunner runner)
    {
        if (!runner.IsServer) return;

        // only run once per game start
        if (gameplayLoaded)
        {
            gameplayLoaded = false;

            // grab your provider
            var provider = FindObjectOfType<SpawnPointProvider>();
            if (provider == null || provider.spawnPoints == null || provider.spawnPoints.Length == 0)
            {
                Debug.LogError("No SpawnPointProvider or no spawnPoints assigned!");
                return;
            }

            // convert the IEnumerable to an array
            PlayerRef[] players = runner.ActivePlayers.ToArray();
            // pick the smaller of (number of players) vs (number of spawnPoints)
            int count = Mathf.Min(players.Length, provider.spawnPoints.Length);

            for (int i = 0; i < count; i++)
            {
                PlayerRef p = players[i];
                Transform sp = provider.spawnPoints[i];
                runner.Spawn(playerPrefab, sp.position, sp.rotation, p);
            }
        }
    }
    public void OnDisconnectedFromServer(NetworkRunner r, NetDisconnectReason reason) { }
    public void OnConnectRequest(NetworkRunner r, NetworkRunnerCallbackArgs.ConnectRequest req, byte[] tok) { }
    public void OnConnectFailed(NetworkRunner r, NetAddress addr, NetConnectFailedReason reason) { }
    public void OnUserSimulationMessage(NetworkRunner r, SimulationMessagePtr msg) { }
    public void OnShutdown(NetworkRunner r, ShutdownReason reason) { }
    public void OnPlayerLeft(NetworkRunner r, PlayerRef p) { }
    public void OnInput(NetworkRunner r, NetworkInput input) { }
    public void OnInputMissing(NetworkRunner r, PlayerRef p, NetworkInput input) { }
    public void OnObjectEnterAOI(NetworkRunner r, NetworkObject obj, PlayerRef p) { }
    public void OnObjectExitAOI(NetworkRunner r, NetworkObject obj, PlayerRef p) { }
    public void OnReliableDataReceived(NetworkRunner r, PlayerRef p, ReliableKey k, System.ArraySegment<byte> data) { }
    public void OnReliableDataProgress(NetworkRunner r, PlayerRef p, ReliableKey k, float prog) { }
    //public void OnSceneLoadDone(NetworkRunner r) { }
    public void OnSceneLoadStart(NetworkRunner r) { }
    public void OnHostMigration(NetworkRunner r, HostMigrationToken t) { }
    public void OnCustomAuthenticationResponse(NetworkRunner r, Dictionary<string, object> data) { }
}