GoakeFlax/Source/Game/GameMode/NetworkManager.cs

using System;
using System.Collections.Generic;
using System.Linq;
using FlaxEditor;
using FlaxEngine;
using FlaxEngine.Assertions;
using FlaxEngine.Networking;
using Console = Game.Console;

namespace Game;

[AttributeUsage(AttributeTargets.Class)]
public class NetworkPredictedAttribute : Attribute
{
}

// TODO: insert code to update variables with this attribute?
// rename to NetworkReplicatedAttribute?
[AttributeUsage(AttributeTargets.Class)]
public class NetworkedAttribute : Attribute
{
}

// NetworkMulticastAttribute: calls methods marked with this in all clients

public enum NetworkMessageType : byte
{
    Handshake = 1,
    Message
}


public static partial class NetworkManager
{
    public delegate bool OnMessageDecl(ref NetworkEvent networkEvent);
    public delegate bool OnClientConnectingDecl(NetworkConnection sender);
    public delegate void OnClientConnectedDecl(NetworkConnection sender);

    private static bool initialized;

    public static NetworkPeer server;
    public static NetworkPeer client;

    private static readonly ushort ServerPort = 59183;
    private static string ServerAddress;
    private static readonly ushort MTU = 1500;
    private static readonly ushort MaximumClients = 32;

    private static List<OnMessageDecl> OnClientMessageDelegates = new(3);
    private static List<OnClientConnectingDecl> OnClientConnectingDelegates = new(3);
    private static List<OnClientConnectedDecl> OnClientConnectedDelegates = new(3);
    private static List<OnMessageDecl> OnServerMessageDelegates = new(3);
    private static List<OnClientConnectingDecl> OnServerConnectingDelegates = new(3);
    private static List<OnClientConnectedDecl> OnServerConnectedDelegates = new(3);

    public static void RegisterClientCallbacks(OnMessageDecl onMessage, OnClientConnectingDecl onClientConnecting, OnClientConnectedDecl onClientConnected)
    {
        Assert.IsTrue(!OnClientMessageDelegates.Contains(onMessage));
        OnClientMessageDelegates.Add(onMessage);

        if (onClientConnecting != null)
        {
            Assert.IsTrue(!OnClientConnectingDelegates.Contains(onClientConnecting));
            OnClientConnectingDelegates.Add(onClientConnecting);
        }
        if (onClientConnected != null)
        {
            Assert.IsTrue(!OnClientConnectedDelegates.Contains(onClientConnected));
            OnClientConnectedDelegates.Add(onClientConnected);
        }
    }
    public static void UnregisterClientCallbacks(OnMessageDecl onMessage, OnClientConnectingDecl onClientConnecting, OnClientConnectedDecl onClientConnected)
    {
        Assert.IsTrue(OnClientMessageDelegates.Contains(onMessage));
        OnClientMessageDelegates.Remove(onMessage);

        if (onClientConnecting != null)
        {
            Assert.IsTrue(OnClientConnectingDelegates.Contains(onClientConnecting));
            OnClientConnectingDelegates.Remove(onClientConnecting);
        }
        if (onClientConnected != null)
        {
            Assert.IsTrue(OnClientConnectedDelegates.Contains(onClientConnected));
            OnClientConnectedDelegates.Remove(onClientConnected);
        }
    }

    public static void RegisterServerCallbacks(OnMessageDecl onMessage, OnClientConnectingDecl onClientConnecting, OnClientConnectedDecl onClientConnected)
    {
        Assert.IsTrue(!OnServerMessageDelegates.Contains(onMessage));
        OnServerMessageDelegates.Add(onMessage);

        if (onClientConnecting != null)
        {
            Assert.IsTrue(!OnServerConnectingDelegates.Contains(onClientConnecting));
            OnServerConnectingDelegates.Add(onClientConnecting);
        }
        if (onClientConnected != null)
        {
            Assert.IsTrue(!OnServerConnectedDelegates.Contains(onClientConnected));
            OnServerConnectedDelegates.Add(onClientConnected);
        }
    }
    public static void UnregisterServerCallbacks(OnMessageDecl onMessage, OnClientConnectingDecl onClientConnecting, OnClientConnectedDecl onClientConnected)
    {
        Assert.IsTrue(OnServerMessageDelegates.Contains(onMessage));
        OnServerMessageDelegates.Remove(onMessage);

        if (onClientConnecting != null)
        {
            Assert.IsTrue(OnServerConnectingDelegates.Contains(onClientConnecting));
            OnServerConnectingDelegates.Remove(onClientConnecting);
        }
        if (onClientConnected != null)
        {
            Assert.IsTrue(OnServerConnectedDelegates.Contains(onClientConnected));
            OnServerConnectedDelegates.Remove(onClientConnected);
        }
    }

    public static string DebugLastHandledMessage = "";

    //public static bool IsServer = false;
    //public static bool IsClient = false;
    // static bool IsLocalClient = false; // Context dependant, true when message is handled by local client

    public static void Init()
    {
        if (initialized)
            return;

        /*if (Engine.CommandLine.Contains("-server"))
        {
            StartServer();
            ServerAddress = "localhost";
            ConnectServer();
        }
        else if (Engine.CommandLine.Contains("-client"))
        {
            ServerAddress = "localhost";
            ConnectServer();
        }
//#if FLAX_EDITOR
        else
        {
            StartServer();
            ServerAddress = "localhost";
            ConnectServer();
        }*/
//#endif

        initialized = true;
#if FLAX_EDITOR
        Editor.Instance.PlayModeEnd += Cleanup;
#endif

        //WorldStateManager.Init(); // FIXME
    }

    public static void Cleanup()
    {
        Scripting.Exit -= Cleanup;
        Scripting.Update -= OnDemoUpdate;
        Scripting.Update -= OnServerNetworkUpdate;
        Level.ActorSpawned -= OnServerActorSpawned;
        Scripting.Update -= OnClientNetworkUpdate;
        Level.ActorSpawned -= OnClientActorSpawned;

        if (server != null)
        {
            NetworkPeer.ShutdownPeer(server);
            server = null;
        }

        if (client != null)
        {
            NetworkPeer.ShutdownPeer(client);
            client = null;
        }

        //LocalPlayerClientId = 0;

#if FLAX_EDITOR
        Editor.Instance.PlayModeEnd -= Cleanup;
        //GameModeManager.Cleanup(); // FIXME
#endif
        World.CleanupClient();
        World.CleanupServer();

        StopRecording();

        initialized = false;
    }

    private static void OnNetworkMessage(ref NetworkEvent networkEvent, Span<OnMessageDecl> funcs)
    {
        byte messageTypeByte = networkEvent.Message.ReadByte();
        if (!Enum.IsDefined(typeof(NetworkMessageType), messageTypeByte))
        {
            Console.PrintError($"Unsupported message type received from client: {messageTypeByte}");
            return;
        }

        NetworkMessageType messageType = (NetworkMessageType)messageTypeByte;

        switch (messageType)
        {
            case NetworkMessageType.Handshake:
            {
                string message = networkEvent.Message.ReadString();
                Console.Print($"Received handshake from {networkEvent.Sender.ConnectionId}, msg: " + message);
                break;
            }
            case NetworkMessageType.Message:
            {
                var messageStartPosition = networkEvent.Message.Position;
                foreach (var func in funcs)
                {
                    networkEvent.Message.Position = messageStartPosition;
                    bool handled = func(ref networkEvent);
                    if (handled)
                        break;
                }

                //if (OnMessage != null)
                /*{
                    // GetInvocationList() allocates, use allocation-free but unsafe way to iterate
                    //
                    //foreach (OnMessageDecl func in OnMessage.GetInvocationList()
                    //             .Cast<OnMessageDecl>().ToArray())
                    foreach (OnMessageDecl func in OnMessageDelegates)
                    {
                        bool ret = func.Invoke(ref networkEvent);
                        if (ret)
                            break;
                    }
                }*/
                break;
            }
            default:
                Console.PrintError($"Unsupported message type received from client: {messageTypeByte}");
                break;
        }
    }
}