Inventory2/scripts/MultiplayerManager.cs

public partial class MultiplayerManager : Node
{
	[Export] public PackedScene PlayerScene { get; set; }
	[Export] public PackedScene WorkshopScene { 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 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()
	{
		SetAuthorityAndName(Game.LocalPlayer, Multiplayer.GetUniqueId());
		SetAuthorityAndName(Game.LocalWorkshop, Multiplayer.GetUniqueId());

		// 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()
	{
		Multiplayer.MultiplayerPeer.Close();
		Multiplayer.MultiplayerPeer = new OfflineMultiplayerPeer();

		foreach (var player in Game.Players)
			if (player != Game.LocalPlayer)
				OnPeerDisconnected(player.PeerId);

		SetAuthorityAndName(Game.LocalPlayer, Multiplayer.GetUniqueId());
		SetAuthorityAndName(Game.LocalWorkshop, Multiplayer.GetUniqueId());
	}

	void OnPeerConnected(long _peerId)
	{
		var player = PlayerScene.Instantiate<Player>();
		SetAuthorityAndName(player, (int)_peerId);
		Game.Players.AddChild(player);

		PlayerJoined?.Invoke(player);
	}

	void OnPeerDisconnected(long _peerId)
	{
		var player = Game.Players.ByPeerId((int)_peerId);
		Game.Players.RemoveChild(player);
		player.QueueFree();

		var workshop = Game.Workshops.ByPeerId((int)_peerId);
		Game.Workshops.RemoveChild(workshop);
		workshop.QueueFree();

		PlayerLeft?.Invoke(player);
	}


	static void SetAuthorityAndName(Node node, int peerId)
	{
		node.SetMultiplayerAuthority(peerId);
		node.Name = peerId.ToString();
	}
}