Engine-Pong/Game/Network/NetworkBase.cs

using System;
using System.Collections.Generic;
using System.Diagnostics;

using LiteNetLib;
using LiteNetLib.Utils;

using Syntriax.Engine.Core;
using Syntriax.Engine.Network.Abstract;

namespace Syntriax.Engine.Network;

public abstract class NetworkBase : BehaviourOverride, INetworkCommunicator
{
    private readonly NetPacketProcessor netPacketProcessor = new();

    private readonly Dictionary<uint, INetworkEntity> networkEntities = [];
    private readonly Dictionary<Type, List<INetworkCommunicator.EntityPacketReceivedDelegate>> callbacks = [];

    private BehaviourCollector<INetworkEntity> networkEntityCollector = null!;

    public EventBasedNetListener Listener { get; private set; } = null!;
    public NetManager Manager { get; private set; } = null!;

    public NetworkBase()
    {
        Priority = 10;

        Listener = new EventBasedNetListener();
        Manager = new NetManager(Listener);

        Listener.NetworkReceiveEvent += NetworkReceiveEvent;
    }

    protected override void OnInitialize()
    {
        base.OnInitialize();

        networkEntityCollector = new(GameObject.GameManager);
        networkEntityCollector.OnCollected += OnNetworkEntityCollected;
        networkEntityCollector.OnRemoved += OnNetworkEntityRemoved;
    }
    protected override void OnFinalize()
    {
        networkEntityCollector.OnCollected -= OnNetworkEntityCollected;
        networkEntityCollector.OnRemoved -= OnNetworkEntityRemoved;
        Stop();
    }

    private void OnNetworkEntityCollected(BehaviourCollector<INetworkEntity> sender, INetworkEntity behaviourCollected)
        => networkEntities.Add(behaviourCollected.NetworkId, behaviourCollected);

    private void OnNetworkEntityRemoved(BehaviourCollector<INetworkEntity> sender, INetworkEntity behaviourRemoved)
        => networkEntities.Remove(behaviourRemoved.NetworkId);

    private void NetworkReceiveEvent(NetPeer peer, NetPacketReader reader, byte channel, DeliveryMethod deliveryMethod)
    {
        netPacketProcessor.ReadAllPackets(reader, peer);
    }

    public void PollEvents() => Manager.PollEvents();
    public void Stop() => Manager.Stop();

    protected override void OnUpdate() => PollEvents();

    public void RegisterEntityPacketListener<T>(INetworkEntity networkEntity, INetworkCommunicator.EntityPacketReceivedDelegate onPacketReceived) where T : INetSerializable
    {
        if (!callbacks.TryGetValue(typeof(T), out var list))
        {
            list = [];
            callbacks.Add(typeof(T), list);
            netPacketProcessor.SubscribeReusable<NetworkPacket<T>, NetPeer>(OnPacketReceived);
        }

        if (list.Contains(onPacketReceived))
            return;

        list.Add(onPacketReceived);
    }

    public void UnregisterEntityPacketListener<T>(INetworkEntity networkEntity, INetworkCommunicator.EntityPacketReceivedDelegate onPacketReceived) where T : INetSerializable
    {
        if (!callbacks.TryGetValue(typeof(T), out var list))
            return;

        list.Remove(onPacketReceived);
    }

    public void SendEntityPacket<T>(INetworkEntity networkEntity, T packet, params NetPeer[] netPeers) where T : INetSerializable
    {
        NetworkPacket<T> networkPacket = new() { NetworkId = networkEntity.NetworkId, Data = packet };
        NetDataWriter netDataWriter = new();
        netPacketProcessor.Write(netDataWriter, networkPacket);
        foreach (var netPeer in netPeers)
            netPeer.Send(netDataWriter, DeliveryMethod.ReliableOrdered);
    }

    private void OnPacketReceived<T>(NetworkPacket<T> packet, NetPeer peer) where T : INetSerializable
    {
        Debug.WriteLine($"Packet Received: {packet.NetworkId} - {typeof(T)}");

        if (!callbacks.TryGetValue(typeof(T), out var list))
            return;

        INetworkEntity networkEntity = networkEntities[packet.NetworkId];
        foreach (INetworkCommunicator.EntityPacketReceivedDelegate callback in list)
            callback.Invoke(networkEntity, packet, peer);
    }
}