feat: implement multiplayer session state management and add invalid port exception

src/Features/Multiplayer/Contracts/Exceptions/MultiplayerAlreadyConnectedException.cs

@@ -1,6 +1,7 @@
 namespace Game.Features.Multiplayer.Contracts.Exceptions;
 
 /// <summary>
-/// Thrown when trying to host or join while already connected to a session.
+/// Thrown when trying to host or join while connecting or already connected to a session.
 /// </summary>
-public sealed class MultiplayerAlreadyConnectedException() : MultiplayerException("Already connected to a session.");
+public sealed class MultiplayerAlreadyConnectedException()
+    : MultiplayerException("Already connected to or connecting with a session.");

src/Features/Multiplayer/Contracts/Exceptions/MultiplayerInvalidPortException.cs

@@ -0,0 +1,4 @@
+namespace Game.Features.Multiplayer.Contracts.Exceptions;
+
+public sealed class MultiplayerInvalidPortException(int port)
+    : MultiplayerException($"Invalid port {port}. Port must be between 1 and 65535.");

src/Features/Multiplayer/Contracts/Exceptions/MultiplayerInvalidPortException.cs.uid

@@ -0,0 +1 @@
+uid://d3n8p5w2y7c4h

src/Features/Multiplayer/Domain/MultiplayerSession.cs

@@ -8,8 +8,7 @@ public sealed class MultiplayerSession
     public const int MaxPlayers = 4;
     public IReadOnlyCollection<PeerId> PeerIds => _peerIds;
     public bool IsFull => _peerIds.Count >= MaxPlayers;
-    public bool IsHosting { get; set; }
-    public bool IsConnected { get; set; }
+    public MultiplayerSessionState State { get; private set; } = MultiplayerSessionState.Disconnected;
 
     private readonly HashSet<PeerId> _peerIds = [];
 
@@ -17,10 +16,25 @@ public sealed class MultiplayerSession
 
     public void RemovePeer(PeerId peerId) => _peerIds.Remove(peerId);
 
+    public void StartHosting(PeerId hostPeerId)
+    {
+        _peerIds.Add(hostPeerId);
+        State = MultiplayerSessionState.Hosting;
+    }
+
+    public void StartConnecting()
+    {
+        State = MultiplayerSessionState.Connecting;
+    }
+
+    public void MarkConnected()
+    {
+        State = MultiplayerSessionState.Connected;
+    }
+
     public void Reset()
     {
         _peerIds.Clear();
-        IsHosting = false;
-        IsConnected = false;
+        State = MultiplayerSessionState.Disconnected;
     }
 }

src/Features/Multiplayer/Domain/MultiplayerSessionState.cs

@@ -0,0 +1,9 @@
+namespace Game.Features.Multiplayer.Domain;
+
+public enum MultiplayerSessionState
+{
+    Disconnected,
+    Hosting,
+    Connecting,
+    Connected
+}

src/Features/Multiplayer/Domain/MultiplayerSessionState.cs.uid

@@ -0,0 +1 @@
+uid://b7m2q9r4v6x1k

src/Features/Multiplayer/Godot/MultiplayerController.cs

@@ -8,6 +8,9 @@ namespace Game.Features.Multiplayer.Godot;
 
 public partial class MultiplayerController : Node, IMultiplayerPeer
 {
+    private const int MinPort = 1;
+    private const int MaxPort = 65535;
+
     private readonly MultiplayerSession _session = new();
     private IMultiplayerPeerFactory _multiplayerPeerFactory;
 
@@ -33,29 +36,45 @@ public partial class MultiplayerController : Node, IMultiplayerPeer
 
     private void OnConnectedToServer()
     {
+        _session.MarkConnected();
         Connected?.Invoke();
     }
 
     private void OnConnectionFailed()
     {
-        _session.Reset();
+        ResetConnection();
         ConnectionFailed?.Invoke();
     }
 
     private void OnServerDisconnected()
     {
-        _session.Reset();
+        ResetConnection();
         Disconnected?.Invoke();
     }
+
+    private static void ValidatePort(int port)
+    {
+        if (port is < MinPort or > MaxPort)
+        {
+            throw new MultiplayerInvalidPortException(port);
+        }
+    }
+
+    private void ResetConnection()
+    {
+        Multiplayer.MultiplayerPeer?.Close();
+        Multiplayer.MultiplayerPeer = null;
+        _session.Reset();
+    }
     
     private void AssertNoActiveSession()
     {
-        if (_session.IsHosting)
+        if (_session.State == MultiplayerSessionState.Hosting)
         {
             throw new MultiplayerAlreadyHostingException();
         }
 
-        if (_session.IsConnected)
+        if (_session.State is MultiplayerSessionState.Connecting or MultiplayerSessionState.Connected)
         {
             throw new MultiplayerAlreadyConnectedException();
         }
@@ -68,26 +87,25 @@ public partial class MultiplayerController : Node, IMultiplayerPeer
 
     public void Host(int port)
     {
+        ValidatePort(port);
         AssertNoActiveSession();
 
         Multiplayer.MultiplayerPeer = _multiplayerPeerFactory.CreateHost(port, MultiplayerSession.MaxPlayers - 1);
-        _session.AddPeer(new PeerId(Multiplayer.GetUniqueId()));
-        _session.IsHosting = true;
+        _session.StartHosting(new PeerId(Multiplayer.GetUniqueId()));
     }
 
     public void Join(string address, int port)
     {
+        ValidatePort(port);
         AssertNoActiveSession();
 
         Multiplayer.MultiplayerPeer = _multiplayerPeerFactory.CreateClient(address, port);
-        _session.IsConnected = true;
+        _session.StartConnecting();
     }
 
     public void Disconnect()
     {
-        Multiplayer.MultiplayerPeer?.Close();
-        Multiplayer.MultiplayerPeer = null;
-        _session.Reset();
+        ResetConnection();
     }
 
     public override void _Ready()