Improve hands & pulling (#4389)

Content.Server/Hands/Systems/HandVirtualPullSystem.cs

@@ -0,0 +1,57 @@
+using Content.Server.Pulling;
+using Content.Shared.Hands;
+using Content.Shared.Hands.Components;
+using Content.Shared.Interaction;
+using JetBrains.Annotations;
+using Robust.Shared.GameObjects;
+
+namespace Content.Server.Hands
+{
+    [UsedImplicitly]
+    public sealed class HandVirtualPullSystem : EntitySystem
+    {
+        public override void Initialize()
+        {
+            base.Initialize();
+
+            SubscribeLocalEvent<HandVirtualPullComponent, DroppedEvent>(HandlePullerDropped);
+            SubscribeLocalEvent<HandVirtualPullComponent, UnequippedHandEvent>(HandlePullerUnequipped);
+
+            SubscribeLocalEvent<HandVirtualPullComponent, BeforeInteractEvent>(HandleBeforeInteract);
+        }
+
+        private static void HandleBeforeInteract(
+            EntityUid uid,
+            HandVirtualPullComponent component,
+            BeforeInteractEvent args)
+        {
+            // No interactions with a virtual pull, please.
+            args.Handled = true;
+        }
+
+        // If the virtual pull gets removed from the hands for any reason, cancel the pull and delete it.
+        private void HandlePullerUnequipped(EntityUid uid, HandVirtualPullComponent component, UnequippedHandEvent args)
+        {
+            MaybeDelete(component, args.User);
+        }
+
+        private void HandlePullerDropped(EntityUid uid, HandVirtualPullComponent component, DroppedEvent args)
+        {
+            MaybeDelete(component, args.User);
+        }
+
+        private void MaybeDelete(HandVirtualPullComponent comp, IEntity? user)
+        {
+            var pulled = comp.PulledEntity;
+
+            if (!ComponentManager.TryGetComponent(pulled, out PullableComponent? pullable))
+                return;
+
+            if (pullable.Puller != user)
+                return;
+
+            pullable.TryStopPull(user);
+            comp.Owner.QueueDelete();
+        }
+    }
+}