Trigger Refactor (#39034)

Content.Server/Trigger/Systems/PolymorphOnTriggerSystem.cs

@@ -0,0 +1,51 @@
+using Content.Server.Polymorph.Systems;
+using Content.Shared.Polymorph;
+using Content.Shared.Trigger;
+using Content.Shared.Trigger.Components.Effects;
+using Robust.Shared.Prototypes;
+
+namespace Content.Server.Trigger.Systems;
+
+public sealed partial class PolymorphOnTriggerSystem : EntitySystem
+{
+    [Dependency] private readonly PolymorphSystem _polymorph = default!;
+
+    /// <summary>
+    /// Need to do this so we don't get a collection enumeration error in physics by polymorphing
+    /// an entity we're colliding with in case of TriggerOnCollide.
+    /// Also makes sure other trigger effects don't activate in nullspace after we have polymorphed.
+    /// </summary>
+    private Queue<(EntityUid Uid, ProtoId<PolymorphPrototype> Polymorph)> _queuedPolymorphUpdates = new();
+
+    public override void Initialize()
+    {
+        base.Initialize();
+
+        SubscribeLocalEvent<PolymorphOnTriggerComponent, TriggerEvent>(OnTrigger);
+    }
+
+    private void OnTrigger(Entity<PolymorphOnTriggerComponent> ent, ref TriggerEvent args)
+    {
+        if (args.Key != null && !ent.Comp.KeysIn.Contains(args.Key))
+            return;
+
+        var target = ent.Comp.TargetUser ? args.User : ent.Owner;
+
+        if (target == null)
+            return;
+
+        _queuedPolymorphUpdates.Enqueue((target.Value, ent.Comp.Polymorph));
+        args.Handled = true;
+    }
+
+    public override void Update(float frametime)
+    {
+        while (_queuedPolymorphUpdates.TryDequeue(out var data))
+        {
+            if (TerminatingOrDeleted(data.Uid))
+                continue;
+
+            _polymorph.PolymorphEntity(data.Uid, data.Polymorph);
+        }
+    }
+}