Engine.Systems/Network/Abstract/IConnection.cs

@@ -0,0 +1,12 @@
+namespace Syntriax.Engine.Systems.Network;
+
+public interface IConnection
+{
+    string Id { get; }
+
+    float Ping { get; }
+    float RoundTrip { get; }
+
+    int PingMs { get; }
+    int RoundTripMs { get; }
+}

Engine.Systems/Network/Abstract/IEntityNetworkPacket.cs

@@ -0,0 +1,6 @@
+namespace Syntriax.Engine.Systems.Network;
+
+public interface IEntityNetworkPacket : INetworkPacket
+{
+    string EntityId { get; }
+}

Engine.Systems/Network/Abstract/INetworkCommunicator.cs

@@ -0,0 +1,37 @@
+using System.Collections.Generic;
+
+using Syntriax.Engine.Core;
+
+namespace Syntriax.Engine.Systems.Network;
+
+public interface INetworkCommunicator
+{
+    Event<INetworkCommunicator, IConnection> OnConnectionEstablished { get; }
+    Event<INetworkCommunicator, IConnection> OnConnectionAbolished { get; }
+
+    IReadOnlyDictionary<string, IConnection> Connections { get; }
+
+    INetworkCommunicator Stop();
+
+    INetworkCommunicator SubscribeToPackets<T>(Event<IConnection, T>.EventHandler callback);
+    INetworkCommunicator UnsubscribeFromPackets<T>(Event<IConnection, T>.EventHandler callback);
+}
+
+public interface INetworkCommunicatorClient : INetworkCommunicator
+{
+    INetworkCommunicatorClient Connect(string address, int port, string? password = null);
+
+    INetworkCommunicatorClient SendToServer<T>(T packet, PacketDelivery packetDelivery = PacketDelivery.ReliableInOrder) where T : class, new();
+}
+
+public interface INetworkCommunicatorServer : INetworkCommunicator
+{
+    string Password { get; }
+    int MaxConnectionCount { get; }
+    int Port { get; }
+
+    INetworkCommunicatorServer Start(int port, int maxConnectionCount, string? password = null);
+
+    INetworkCommunicatorServer SendToClient<T>(IConnection connection, T packet, PacketDelivery packetDelivery = PacketDelivery.ReliableInOrder) where T : class, new();
+    INetworkCommunicatorServer SendToAll<T>(T packet, PacketDelivery packetDelivery = PacketDelivery.ReliableInOrder) where T : class, new();
+}

Engine.Systems/Network/Abstract/INetworkEntity.cs

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+using Syntriax.Engine.Core;
+
+namespace Syntriax.Engine.Systems.Network;
+
+public interface INetworkEntity : IEntity;

Engine.Systems/Network/Abstract/INetworkManager.cs

@@ -0,0 +1,11 @@
+using System.Collections.Generic;
+
+using Syntriax.Engine.Core;
+
+namespace Syntriax.Engine.Systems.Network;
+
+public interface INetworkManager
+{
+    IReadOnlyDictionary<string, INetworkEntity> NetworkEntities { get; }
+    IBehaviourCollector<INetworkEntity> NetworkEntityCollector { get; }
+}

Engine.Systems/Network/Abstract/INetworkPacket.cs

@@ -0,0 +1,3 @@
+namespace Syntriax.Engine.Systems.Network;
+
+public interface INetworkPacket;

Engine.Systems/Network/Abstract/IPacketListenerClient.cs

@@ -0,0 +1,6 @@
+namespace Syntriax.Engine.Systems.Network;
+
+public interface IPacketListenerClient<T> : INetworkEntity
+{
+    void OnClientPacketArrived(IConnection sender, T packet);
+}

Engine.Systems/Network/Abstract/IPacketListenerServer.cs

@@ -0,0 +1,6 @@
+namespace Syntriax.Engine.Systems.Network;
+
+public interface IPacketListenerServer<T> : INetworkEntity
+{
+    void OnServerPacketArrived(IConnection sender, T packet);
+}

Engine.Systems/Network/Abstract/PacketDelivery.cs

@@ -0,0 +1,9 @@
+namespace Syntriax.Engine.Systems.Network;
+
+public enum PacketDelivery
+{
+    ReliableInOrder,
+    ReliableOutOfOrder,
+    UnreliableInOrder,
+    UnreliableOutOfOrder,
+};

Engine.Systems/Network/NetworkManager.cs

@@ -0,0 +1,332 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+
+using Syntriax.Engine.Core;
+
+namespace Syntriax.Engine.Systems.Network;
+
+/// <summary>
+/// Intermediary manager that looks up in it's hierarchy for a <see cref="INetworkCommunicator"/> to route/broadcast it's received packets to their destinations.
+/// </summary>
+public class NetworkManager : Behaviour, INetworkManager
+{
+    private readonly Dictionary<Type, Dictionary<Type, List<MethodInfo>>> clientPacketArrivalMethods = [];
+    private readonly Dictionary<Type, Dictionary<Type, List<MethodInfo>>> serverPacketArrivalMethods = [];
+
+    private readonly Dictionary<Type, Dictionary<string, object>> clientPacketRouters = [];
+    private readonly Dictionary<Type, Dictionary<string, object>> serverPacketRouters = [];
+
+    private readonly List<(Type packetType, Delegate @delegate)> packetRetrievalDelegates = [];
+
+    private readonly Dictionary<Type, MethodInfo> clearRoutesMethods = [];
+    private readonly Dictionary<Type, MethodInfo> registerPacketListenersMethods = [];
+
+    private readonly Dictionary<string, INetworkEntity> _networkEntities = [];
+    public IReadOnlyDictionary<string, INetworkEntity> NetworkEntities => _networkEntities;
+
+    private readonly BehaviourCollector<INetworkEntity> _networkEntityCollector = new();
+    public IBehaviourCollector<INetworkEntity> NetworkEntityCollector => _networkEntityCollector;
+
+    private INetworkCommunicator _networkCommunicator = null!;
+    public INetworkCommunicator NetworkCommunicator
+    {
+        get => _networkCommunicator;
+        set
+        {
+            if (_networkCommunicator == value)
+                return;
+
+            INetworkCommunicator? previousCommunicator = _networkCommunicator;
+            _networkCommunicator = value;
+
+            if (previousCommunicator is not null) UnsubscribeCommunicatorMethods(previousCommunicator);
+            if (_networkCommunicator is not null) SubscribeCommunicatorMethods(_networkCommunicator);
+        }
+    }
+
+    #region Communicator Subscriptions
+    private void SubscribeCommunicatorMethods(INetworkCommunicator networkCommunicator)
+    {
+        MethodInfo subscribeToPacketsMethod = typeof(INetworkCommunicator)
+            .GetMethod(nameof(INetworkCommunicator.SubscribeToPackets), BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Instance)!;
+
+        foreach ((Type packetType, Delegate @delegate) in packetRetrievalDelegates)
+        {
+            MethodInfo genericSubscribeMethod = subscribeToPacketsMethod.MakeGenericMethod(packetType);
+            genericSubscribeMethod.Invoke(networkCommunicator, [@delegate]);
+        }
+    }
+
+    private void UnsubscribeCommunicatorMethods(INetworkCommunicator networkCommunicator)
+    {
+        MethodInfo unsubscribeFromPacketsMethod = typeof(INetworkCommunicator)
+            .GetMethod(nameof(INetworkCommunicator.UnsubscribeFromPackets), BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Instance)!;
+
+        foreach ((Type packetType, Delegate @delegate) in packetRetrievalDelegates)
+        {
+            MethodInfo genericUnsubscribeMethod = unsubscribeFromPacketsMethod.MakeGenericMethod(packetType);
+            genericUnsubscribeMethod.Invoke(networkCommunicator, [@delegate]);
+        }
+    }
+    #endregion
+
+    #region Packet Routing
+    private void OnPacketReceived<T>(IConnection sender, T entityDataPacket)
+    {
+        if (entityDataPacket is IEntityNetworkPacket entityPacket)
+            RoutePacket(sender, entityDataPacket, entityPacket);
+        else
+            BroadcastPacket(sender, entityDataPacket);
+    }
+
+    private void RoutePacket<T>(IConnection sender, T entityDataPacket, IEntityNetworkPacket entityPacket)
+    {
+        if (NetworkCommunicator is INetworkCommunicatorClient)
+            RoutePacket(clientPacketRouters, entityPacket.EntityId, sender, entityDataPacket);
+        if (NetworkCommunicator is INetworkCommunicatorServer)
+            RoutePacket(serverPacketRouters, entityPacket.EntityId, sender, entityDataPacket);
+    }
+
+    private void BroadcastPacket<T>(IConnection sender, T entityDataPacket)
+    {
+        if (NetworkCommunicator is INetworkCommunicatorClient)
+            BroadcastPacket(clientPacketRouters, sender, entityDataPacket);
+        if (NetworkCommunicator is INetworkCommunicatorServer)
+            BroadcastPacket(serverPacketRouters, sender, entityDataPacket);
+    }
+
+    private static void BroadcastPacket<T>(
+        Dictionary<Type, Dictionary<string, object>> packetRouters,
+        IConnection sender,
+        T entityDataPacket)
+    {
+        if (!packetRouters.TryGetValue(entityDataPacket!.GetType(), out Dictionary<string, object>? routers))
+            return;
+
+        foreach ((string behaviourId, object routerEventReference) in routers)
+        {
+            Event<IConnection, T> routerEvent = (Event<IConnection, T>)routerEventReference;
+            routerEvent.Invoke(sender, entityDataPacket!);
+        }
+    }
+
+    private static void RoutePacket<T>(
+        Dictionary<Type, Dictionary<string, object>> packetRouters,
+        string entityId,
+        IConnection sender,
+        T entityDataPacket)
+    {
+        if (!packetRouters.TryGetValue(entityDataPacket!.GetType(), out Dictionary<string, object>? routers))
+            return;
+
+        if (!routers.TryGetValue(entityId, out object? routerEventReference))
+            return;
+
+        Event<IConnection, T> routerEvent = (Event<IConnection, T>)routerEventReference;
+        routerEvent.Invoke(sender, entityDataPacket!);
+    }
+    #endregion
+
+    #region Packet Routers
+    private void RegisterPacketRoutersFor(
+        INetworkEntity behaviour,
+        Dictionary<Type, Dictionary<string, object>> packetRouters,
+        Dictionary<Type, Dictionary<Type, List<MethodInfo>>> packetArrivalMethods,
+        NetworkType networkType)
+    {
+        if (!packetArrivalMethods.TryGetValue(behaviour.GetType(), out Dictionary<Type, List<MethodInfo>>? arrivalMethods))
+            return;
+
+        foreach ((Type packetType, List<MethodInfo> methods) in arrivalMethods)
+            foreach (MethodInfo receiveMethod in methods)
+            {
+                if (!packetRouters.TryGetValue(packetType, out Dictionary<string, object>? routers))
+                {
+                    routers = [];
+                    packetRouters.Add(packetType, routers);
+                }
+
+                object packetListenerEvent = CreateEventAndRegister(packetType, behaviour, networkType);
+                routers.Add(behaviour.Id, packetListenerEvent);
+            }
+    }
+
+    private object CreateEventAndRegister(Type packetType, INetworkEntity behaviour, NetworkType networkType)
+    {
+        Type genericEventType = typeof(Event<,>).MakeGenericType(typeof(IConnection), packetType);
+        object packetListenerEvent = Activator.CreateInstance(genericEventType)!;
+
+        if (!registerPacketListenersMethods.TryGetValue(packetType, out MethodInfo? registerPacketListenerMethod))
+            throw new($"{nameof(RegisterPacketListenerEvent)} for {packetType.Name} has not been cached.");
+
+        registerPacketListenerMethod.Invoke(this, [behaviour, packetListenerEvent, networkType]);
+        return packetListenerEvent;
+    }
+
+    private static void RegisterPacketListenerEvent<T>(
+        INetworkEntity behaviour,
+        Event<IConnection, T> packetListenerEvent,
+        NetworkType networkType)
+    {
+        switch (networkType)
+        {
+            case NetworkType.Client: packetListenerEvent.AddListener((sender, packet) => ((IPacketListenerClient<T>)behaviour).OnClientPacketArrived(sender, packet)); break;
+            case NetworkType.Server: packetListenerEvent.AddListener((sender, packet) => ((IPacketListenerServer<T>)behaviour).OnServerPacketArrived(sender, packet)); break;
+        }
+    }
+
+    private void UnregisterPacketRoutersFor(
+        INetworkEntity behaviour,
+        Dictionary<Type, Dictionary<string, object>> packetRouters,
+        Dictionary<Type, Dictionary<Type, List<MethodInfo>>> packetArrivalMethods)
+    {
+        if (!packetArrivalMethods.TryGetValue(behaviour.GetType(), out Dictionary<Type, List<MethodInfo>>? arrivalMethods))
+            return;
+
+        foreach ((Type packetType, List<MethodInfo> methods) in arrivalMethods)
+        {
+            if (!packetRouters.TryGetValue(packetType, out Dictionary<string, object>? routers))
+                continue;
+
+            if (!routers.TryGetValue(behaviour.Id, out object? routerEventReference))
+                continue;
+
+            if (!clearRoutesMethods.TryGetValue(packetType, out MethodInfo? clearRouterMethod))
+                continue;
+
+            clearRouterMethod.Invoke(this, [routerEventReference]);
+        }
+    }
+
+    private static void ClearRouter<T>(object routerEventReference)
+    {
+        Event<IConnection, T> routerEvent = (Event<IConnection, T>)routerEventReference;
+        routerEvent.Clear();
+    }
+
+    #endregion
+
+    #region Engine Callbacks
+    private void OnCollected(IBehaviourCollector<INetworkEntity> sender, IBehaviourCollector<INetworkEntity>.BehaviourCollectedArguments args)
+    {
+        INetworkEntity collectedBehaviour = args.BehaviourCollected;
+
+        if (!_networkEntities.TryAdd(collectedBehaviour.Id, collectedBehaviour))
+            throw new($"Unable to add {collectedBehaviour.Id} to {nameof(NetworkManager)}");
+
+        RegisterPacketRoutersFor(collectedBehaviour, clientPacketRouters, clientPacketArrivalMethods, NetworkType.Client);
+        RegisterPacketRoutersFor(collectedBehaviour, serverPacketRouters, serverPacketArrivalMethods, NetworkType.Server);
+    }
+
+    private void OnRemoved(IBehaviourCollector<INetworkEntity> sender, IBehaviourCollector<INetworkEntity>.BehaviourRemovedArguments args)
+    {
+        INetworkEntity removedBehaviour = args.BehaviourRemoved;
+        if (!_networkEntities.Remove(args.BehaviourRemoved.Id))
+            return;
+
+        UnregisterPacketRoutersFor(removedBehaviour, clientPacketRouters, clientPacketArrivalMethods);
+        UnregisterPacketRoutersFor(removedBehaviour, serverPacketRouters, serverPacketArrivalMethods);
+    }
+
+    protected override void OnExitedUniverse(IUniverse universe) => _networkEntityCollector.Unassign();
+    protected override void OnEnteredUniverse(IUniverse universe)
+    {
+        _networkEntityCollector.Assign(universe);
+        NetworkCommunicator = BehaviourController.GetRequiredBehaviourInParent<INetworkCommunicator>();
+    }
+    #endregion
+
+    #region Initialization
+    public NetworkManager()
+    {
+        CachePacketRetrievalDelegates();
+        CacheRegistrationMethods();
+        CachePacketArrivalMethods();
+
+        _networkEntityCollector.OnCollected.AddListener(OnCollected);
+        _networkEntityCollector.OnRemoved.AddListener(OnRemoved);
+    }
+
+    private void CachePacketRetrievalDelegates()
+    {
+        IEnumerable<Type> packetTypes = AppDomain.CurrentDomain.GetAssemblies().SelectMany(a => a.GetTypes())
+            .Where(t => typeof(INetworkPacket).IsAssignableFrom(t) && !t.IsInterface && !t.IsAbstract && !t.IsGenericType);
+
+        MethodInfo onPacketArrivedMethod = GetType()
+            .GetMethod(nameof(OnPacketReceived), BindingFlags.NonPublic | BindingFlags.Instance)!;
+
+        foreach (Type packetType in packetTypes)
+        {
+            MethodInfo genericOnPacketArrivedMethod = onPacketArrivedMethod.MakeGenericMethod(packetType);
+
+            Type genericDelegateType = typeof(Event<,>.EventHandler).MakeGenericType(typeof(IConnection), packetType);
+            Delegate genericPacketReceivedDelegate = Delegate.CreateDelegate(genericDelegateType, this, genericOnPacketArrivedMethod);
+
+            packetRetrievalDelegates.Add((packetType, genericPacketReceivedDelegate));
+        }
+    }
+
+    private void CacheRegistrationMethods()
+    {
+        CacheRegistrationMethods(registerPacketListenersMethods, nameof(RegisterPacketListenerEvent));
+        CacheRegistrationMethods(clearRoutesMethods, nameof(ClearRouter));
+    }
+
+    private void CacheRegistrationMethods(Dictionary<Type, MethodInfo> registrationMethods, string methodName)
+    {
+        MethodInfo registerPacketMethod = typeof(NetworkManager).GetMethod(methodName, BindingFlags.NonPublic | BindingFlags.Static)!;
+        foreach ((Type packetType, Delegate @delegate) in packetRetrievalDelegates)
+        {
+            MethodInfo genericMethod = registerPacketMethod.MakeGenericMethod(packetType);
+            registrationMethods.Add(packetType, genericMethod);
+        }
+    }
+
+    private void CachePacketArrivalMethods()
+    {
+        CachePacketArrivalMethods(clientPacketArrivalMethods, typeof(IPacketListenerClient<>), nameof(IPacketListenerClient<INetworkEntity>.OnClientPacketArrived));
+        CachePacketArrivalMethods(serverPacketArrivalMethods, typeof(IPacketListenerServer<>), nameof(IPacketListenerServer<INetworkEntity>.OnServerPacketArrived));
+    }
+
+    private static void CachePacketArrivalMethods(Dictionary<Type, Dictionary<Type, List<MethodInfo>>> packetArrivalMethods, Type listenerType, string packetArrivalMethodName)
+    {
+        foreach (Type listenerClass in GetGenericsWith(listenerType))
+        {
+            Dictionary<Type, List<MethodInfo>> packetRouters = [];
+            packetArrivalMethods.Add(listenerClass, packetRouters);
+
+            foreach (Type packetListener in GetGenericInterfacesWith(listenerType, listenerClass))
+            {
+                Type packetType = packetListener.GetGenericArguments().First();
+
+                List<MethodInfo> arrivalMethods = packetListener
+                    .GetMethods()
+                    .Where(m => m.Name == packetArrivalMethodName)
+                    .ToList();
+
+                packetRouters.Add(packetType, arrivalMethods);
+            }
+        }
+    }
+
+    private static IEnumerable<Type> GetGenericsWith(Type type)
+        => AppDomain.CurrentDomain
+            .GetAssemblies()
+            .SelectMany(a =>
+                a.GetTypes().Where(
+                    t => t.GetInterfaces().Any(
+                        i => i.IsGenericType && i.GetGenericTypeDefinition() == type
+                    )
+                )
+            );
+
+    private static IEnumerable<Type> GetGenericInterfacesWith(Type interfaceType, Type type)
+        => type.GetInterfaces().Where(
+            i => i.IsGenericType && i.GetGenericTypeDefinition() == interfaceType
+        );
+    #endregion
+
+    private enum NetworkType { Client, Server }
+}