Inventory2/scripts/MultiplayerManager.cs

public partial class MultiplayerManager : Node
{
	[Export] public Player LocalPlayer { get; set; }
	[Export] public Node3D Players { get; set; }
	[Export] public PackedScene PlayerScene { get; set; }

	public event Action<Player> PlayerJoined;
	public event Action<Player> PlayerLeft;

	public override void _Ready()
	{
		Multiplayer.ConnectedToServer  += OnMultiplayerReady;
		Multiplayer.ServerDisconnected += OnMultiplayerDisconnected;
		Multiplayer.PeerConnected      += OnPeerConnected;
		Multiplayer.PeerDisconnected   += OnPeerDisconnected;
	}


	public Player GetPlayerByPeerId(int peerId)
		=> Players.GetNode<Player>(peerId.ToString());


	public void Connect(string address, ushort port)
	{
		var peer = new ENetMultiplayerPeer();
		peer.CreateClient(address, port);
		Multiplayer.MultiplayerPeer = peer;
	}

	public bool CreateServer(ushort port)
	{
		var peer = new ENetMultiplayerPeer();
		if (peer.CreateServer(port) == Error.Ok) {
			Multiplayer.MultiplayerPeer = peer;
			OnMultiplayerReady();
			return true;
		} else
			return false;
	}

	public void Disconnect()
		=> OnMultiplayerDisconnected();


	void OnMultiplayerReady()
	{
		var localId = Multiplayer.GetUniqueId();
		LocalPlayer.PeerId = localId;
		LocalPlayer.SetMultiplayerAuthority(localId);

		if (!Multiplayer.IsServer())
			// Spawn players for all the other peers. This excludes the server,
			// since `OnPeerConnected` will already be called for it on connecting.
			foreach (var peerId in Multiplayer.GetPeers())
				if (peerId != 1) OnPeerConnected(peerId);
	}

	void OnMultiplayerDisconnected()
	{
		foreach (var player in Players.GetChildren().Cast<Player>()) {
			if (player.IsLocal) player.PeerId = 0;
			else OnPeerDisconnected(player.PeerId);
		}
		Multiplayer.MultiplayerPeer.Close();
		Multiplayer.MultiplayerPeer = null;
	}


	void OnPeerConnected(long peerId)
	{
		var player = PlayerScene.Instantiate<Player>();
		player.SetMultiplayerAuthority((int)peerId);
		player.PeerId = (int)peerId;
		Players.AddChild(player);
		PlayerJoined?.Invoke(player);
	}

	void OnPeerDisconnected(long peerId)
	{
		var player = GetPlayerByPeerId((int)peerId);
		PlayerLeft?.Invoke(player);
		player.QueueFree();
	}
}