networkmanager

using Unity.Entities;
using Unity.NetCode;
using Unity.Networking.Transport;
using UnityEngine;
using UnityEngine.SceneManagement;

public class NetworkManager : MonoBehaviour
{
    public static NetworkManager Instance { get; private set; }
    public ushort Port = 7979;
    [SerializeField] private string gameSceneName = "World";

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

    public void StartServer(bool anyIpv4 = false)
    {
        var endpoint = anyIpv4
            ? NetworkEndpoint.AnyIpv4.WithPort(Port)
            : NetworkEndpoint.LoopbackIpv4.WithPort(Port);

        CleanupOldWorlds();
        var serverWorld = ClientServerBootstrap.CreateServerWorld("ServerWorld");
        var clientWorld = ClientServerBootstrap.CreateClientWorld("ClientWorld");
        World.DefaultGameObjectInjectionWorld = clientWorld;
        ScriptBehaviourUpdateOrder.AppendWorldToCurrentPlayerLoop(serverWorld);
        ScriptBehaviourUpdateOrder.AppendWorldToCurrentPlayerLoop(clientWorld);

        // listen
        var serverDriver = serverWorld.EntityManager
            .CreateEntityQuery(typeof(NetworkStreamDriver))
            .GetSingletonRW<NetworkStreamDriver>();
        serverDriver.ValueRW.Listen(endpoint);

        // client always connects loopback for same‑machine play
        var clientDriver = clientWorld.EntityManager
            .CreateEntityQuery(typeof(NetworkStreamDriver))
            .GetSingletonRW<NetworkStreamDriver>();
        clientDriver.ValueRW.Connect(clientWorld.EntityManager,
            NetworkEndpoint.LoopbackIpv4.WithPort(Port));

        SceneManager.LoadScene(gameSceneName, LoadSceneMode.Single);

        Debug.Log($"Server listening on {(anyIpv4 ? GetLocalIp() : "127.0.0.1")}:{Port}");
    }

    public void JoinServer(string ip, ushort port)
    {
        CleanupOldWorlds();
        var clientWorld = ClientServerBootstrap.CreateClientWorld("ClientWorld");
        World.DefaultGameObjectInjectionWorld = clientWorld;
        ScriptBehaviourUpdateOrder.AppendWorldToCurrentPlayerLoop(clientWorld);

        var endpoint = NetworkEndpoint.Parse(ip, port);
        var clientDriver = clientWorld.EntityManager
            .CreateEntityQuery(typeof(NetworkStreamDriver))
            .GetSingletonRW<NetworkStreamDriver>();
        clientDriver.ValueRW.Connect(clientWorld.EntityManager, endpoint);

        SceneManager.LoadScene(gameSceneName, LoadSceneMode.Single);
    }

    private void CleanupOldWorlds()
    {
        for (int i = World.All.Count - 1; i >= 0; i--)
        {
            var w = World.All[i];
            if ((w.Flags & (WorldFlags.Game | WorldFlags.GameServer)) != 0)
                w.Dispose();
        }
    }
            string GetLocalIp()
        {
            foreach (var ip in System.Net.Dns.GetHostEntry(System.Net.Dns.GetHostName()).AddressList)
            {
                if (ip.AddressFamily == System.Net.Sockets.AddressFamily.InterNetwork)
                    return ip.ToString();
            }
            return "127.0.0.1";
        }


}