Move BrainSystem and necessary components to Shared (#40499)

* yowza

* Update Content.Shared/Body/Systems/BrainSystem.cs

Co-authored-by: slarticodefast <161409025+slarticodefast@users.noreply.github.com>

* Update Content.Shared/Ghost/GhostOnMoveComponent.cs

Co-authored-by: slarticodefast <161409025+slarticodefast@users.noreply.github.com>

* Update BrainSystem.cs

* Update Content.Shared/Body/Systems/BrainSystem.cs

* Update Content.Shared/Body/Systems/BrainSystem.cs

* Update Content.Shared/Body/Systems/BrainSystem.cs

---------

Co-authored-by: slarticodefast <161409025+slarticodefast@users.noreply.github.com>

Content.Shared/Body/Components/BrainComponent.cs

@@ -0,0 +1,6 @@
+using Content.Shared.Body.Systems;
+
+namespace Content.Shared.Body.Components;
+
+[RegisterComponent, Access(typeof(BrainSystem))]
+public sealed partial class BrainComponent : Component;

Content.Shared/Body/Systems/BrainSystem.cs

@@ -0,0 +1,45 @@
+using Content.Shared.Body.Components;
+using Content.Shared.Body.Events;
+using Content.Shared.Ghost;
+using Content.Shared.Mind;
+using Content.Shared.Mind.Components;
+using Content.Shared.Mobs.Components;
+using Content.Shared.Pointing;
+
+namespace Content.Shared.Body.Systems;
+
+public sealed class BrainSystem : EntitySystem
+{
+    [Dependency] private readonly SharedMindSystem _mindSystem = default!;
+
+    public override void Initialize()
+    {
+        base.Initialize();
+
+        SubscribeLocalEvent<BrainComponent, OrganAddedToBodyEvent>((uid, _, args) => HandleMind(args.Body, uid));
+        SubscribeLocalEvent<BrainComponent, OrganRemovedFromBodyEvent>((uid, _, args) => HandleMind(uid, args.OldBody));
+        SubscribeLocalEvent<BrainComponent, PointAttemptEvent>(OnPointAttempt);
+    }
+
+    private void HandleMind(EntityUid newEntity, EntityUid oldEntity)
+    {
+        if (TerminatingOrDeleted(newEntity) || TerminatingOrDeleted(oldEntity))
+            return;
+
+        EnsureComp<MindContainerComponent>(newEntity);
+        EnsureComp<MindContainerComponent>(oldEntity);
+
+        var ghostOnMove = EnsureComp<GhostOnMoveComponent>(newEntity);
+        ghostOnMove.MustBeDead = HasComp<MobStateComponent>(newEntity); // Don't ghost living players out of their bodies.
+
+        if (!_mindSystem.TryGetMind(oldEntity, out var mindId, out var mind))
+            return;
+
+        _mindSystem.TransferTo(mindId, newEntity, mind: mind);
+    }
+
+    private void OnPointAttempt(Entity<BrainComponent> ent, ref PointAttemptEvent args)
+    {
+        args.Cancel();
+    }
+}

Content.Shared/Ghost/GhostOnMoveComponent.cs

@@ -0,0 +1,13 @@
+using Robust.Shared.GameStates;
+
+namespace Content.Shared.Ghost;
+
+[RegisterComponent, NetworkedComponent]
+public sealed partial class GhostOnMoveComponent : Component
+{
+    [DataField]
+    public bool CanReturn = true;
+
+    [DataField]
+    public bool MustBeDead;
+}