New Status Effects system: Relay events (#38579)

Content.Shared/StatusEffectNew/StatusEffectSystem.Relay.cs

@@ -0,0 +1,51 @@
+using Content.Shared.StatusEffectNew.Components;
+using Robust.Shared.Player;
+
+namespace Content.Shared.StatusEffectNew;
+
+public abstract partial class SharedStatusEffectsSystem
+{
+    protected void InitializeRelay()
+    {
+        SubscribeLocalEvent<StatusEffectContainerComponent, LocalPlayerAttachedEvent>(RelayStatusEffectEvent);
+        SubscribeLocalEvent<StatusEffectContainerComponent, LocalPlayerDetachedEvent>(RelayStatusEffectEvent);
+    }
+
+    protected void RefRelayStatusEffectEvent<T>(EntityUid uid, StatusEffectContainerComponent component, ref T args) where T : struct
+    {
+        RelayEvent((uid, component), ref args);
+    }
+
+    protected void RelayStatusEffectEvent<T>(EntityUid uid, StatusEffectContainerComponent component, T args) where T : class
+    {
+        RelayEvent((uid, component), args);
+    }
+
+    public void RelayEvent<T>(Entity<StatusEffectContainerComponent> statusEffect, ref T args) where T : struct
+    {
+        // this copies the by-ref event if it is a struct
+        var ev = new StatusEffectRelayedEvent<T>(args);
+        foreach (var activeEffect in statusEffect.Comp.ActiveStatusEffects)
+        {
+            RaiseLocalEvent(activeEffect, ref ev);
+        }
+        // and now we copy it back
+        args = ev.Args;
+    }
+
+    public void RelayEvent<T>(Entity<StatusEffectContainerComponent> statusEffect, T args) where T : class
+    {
+        // this copies the by-ref event if it is a struct
+        var ev = new StatusEffectRelayedEvent<T>(args);
+        foreach (var activeEffect in statusEffect.Comp.ActiveStatusEffects)
+        {
+            RaiseLocalEvent(activeEffect, ref ev);
+        }
+    }
+}
+
+/// <summary>
+/// Event wrapper for relayed events.
+/// </summary>
+[ByRefEvent]
+public record struct StatusEffectRelayedEvent<TEvent>(TEvent Args);