Add faction context API methods

Source/API/Dummy.cs

@@ -179,4 +179,22 @@ public void SetCurrentSessionWithTransferables(ISessionWithTransferables session
     {
         throw new UninitializedAPI();
     }
+
+    public bool IsMultifaction => false;
+
+    public Faction SpectatorFaction => null;
+
+    public void PushFaction(Map map, Faction faction)
+    {
+        throw new UninitializedAPI();
+    }
+
+    public void PopFaction(Map map = null)
+    {
+        throw new UninitializedAPI();
+    }
+
+    public void RepeatForWorldFactions(Action action) { }
+
+    public void RepeatForMapFactions(Map map, Action action) { }
 }

Source/API/IAPI.cs

@@ -61,4 +61,11 @@ public interface IAPI
     ISessionManager GetGlobalSessionManager();
     ISessionManager GetLocalSessionManager(Map map);
     void SetCurrentSessionWithTransferables(ISessionWithTransferables session);
+
+    bool IsMultifaction { get; }
+    Faction SpectatorFaction { get; }
+    void PushFaction(Map map, Faction faction);
+    void PopFaction(Map map = null);
+    void RepeatForWorldFactions(Action action);
+    void RepeatForMapFactions(Map map, Action action);
 }

Source/API/MP.cs

@@ -406,6 +406,38 @@ public static ISyncDelegate RegisterSyncDelegateLocalFunc(Type parentType, strin
     /// </summary>
     /// <returns>The global (world) session manager.</returns>
     /// <remarks>As long as a multiplayer session is active, there should always be a global session manager. This method should never return <see langword="null"/> in such cases, unless something is very broken.</remarks>
+    /// <summary>
+    /// Returns <see langword="true"/> if multifaction is enabled in the current multiplayer session.
+    /// </summary>
+    public static bool IsMultifaction => Sync.IsMultifaction;
+
+    /// <summary>
+    /// The spectator faction used internally by Multiplayer. Useful for skipping it when iterating player factions.
+    /// </summary>
+    public static Faction SpectatorFaction => Sync.SpectatorFaction;
+
+    /// <summary>
+    /// Pushes a faction context for the given map. Use <see cref="PopFaction"/> to restore the previous context.
+    /// Pass <see langword="null"/> for map when operating at world level.
+    /// </summary>
+    public static void PushFaction(Map map, Faction faction) => Sync.PushFaction(map, faction);
+
+    /// <summary>
+    /// Pops the current faction context, restoring the previous one.
+    /// Pass <see langword="null"/> for map when operating at world level.
+    /// </summary>
+    public static void PopFaction(Map map = null) => Sync.PopFaction(map);
+
+    /// <summary>
+    /// Calls <paramref name="action"/> once for each non-spectator player faction with the world faction context set appropriately.
+    /// </summary>
+    public static void RepeatForWorldFactions(Action action) => Sync.RepeatForWorldFactions(action);
+
+    /// <summary>
+    /// Calls <paramref name="action"/> once for each non-spectator player faction with the map and world faction context set appropriately.
+    /// </summary>
+    public static void RepeatForMapFactions(Map map, Action action) => Sync.RepeatForMapFactions(map, action);
+
     public static ISessionManager GetGlobalSessionManager() => Sync.GetGlobalSessionManager();
     /// <summary>
     /// Retrieves the local (map) session manager.