Fix some tabletop prediction jank (#12758)

Content.Shared/Tabletop/SharedTabletopSystem.cs

@@ -2,7 +2,11 @@ using Content.Shared.ActionBlocker;
 using Content.Shared.Hands.Components;
 using Content.Shared.Interaction;
 using Content.Shared.Tabletop.Components;
+using Content.Shared.Tabletop.Events;
+using Robust.Shared.GameStates;
+using Robust.Shared.Map;
 using Robust.Shared.Network;
+using Robust.Shared.Players;
 using Robust.Shared.Serialization;
 using System.Diagnostics.CodeAnalysis;
 
@@ -10,8 +14,66 @@ namespace Content.Shared.Tabletop
 {
     public abstract class SharedTabletopSystem : EntitySystem
     {
-        [Dependency] protected readonly ActionBlockerSystem _actionBlockerSystem = default!;
+        [Dependency] protected readonly ActionBlockerSystem ActionBlockerSystem = default!;
         [Dependency] private readonly SharedInteractionSystem _interactionSystem = default!;
+        [Dependency] private readonly SharedAppearanceSystem _appearance = default!;
+        [Dependency] private readonly SharedTransformSystem _transforms = default!;
+        [Dependency] private readonly IMapManager _mapMan = default!;
+
+        public override void Initialize()
+        {
+            SubscribeLocalEvent<TabletopDraggableComponent, ComponentGetState>(GetDraggableState);
+            SubscribeAllEvent<TabletopDraggingPlayerChangedEvent>(OnDraggingPlayerChanged);
+            SubscribeAllEvent<TabletopMoveEvent>(OnTabletopMove);
+        }
+
+        /// <summary>
+        ///     Move an entity which is dragged by the user, but check if they are allowed to do so and to these coordinates
+        /// </summary>
+        protected virtual void OnTabletopMove(TabletopMoveEvent msg, EntitySessionEventArgs args)
+        {
+            if (args.SenderSession is not { AttachedEntity: { } playerEntity } playerSession)
+                return;
+
+            if (!CanSeeTable(playerEntity, msg.TableUid) || !CanDrag(playerEntity, msg.MovedEntityUid, out _))
+                return;
+
+            // Move the entity and dirty it (we use the map ID from the entity so noone can try to be funny and move the item to another map)
+            var transform = EntityManager.GetComponent<TransformComponent>(msg.MovedEntityUid);
+            _transforms.SetParent(transform, _mapMan.GetMapEntityId(transform.MapID));
+            _transforms.SetLocalPositionNoLerp(transform, msg.Coordinates.Position);
+        }
+
+        private void GetDraggableState(EntityUid uid, TabletopDraggableComponent component, ref ComponentGetState args)
+        {
+            args.State = new TabletopDraggableComponentState(component.DraggingPlayer);
+        }
+
+        private void OnDraggingPlayerChanged(TabletopDraggingPlayerChangedEvent msg, EntitySessionEventArgs args)
+        {
+            var dragged = msg.DraggedEntityUid;
+
+            if (!TryComp(dragged, out TabletopDraggableComponent? draggableComponent))
+                return;
+
+            draggableComponent.DraggingPlayer = msg.IsDragging ? args.SenderSession.UserId : null;
+            Dirty(draggableComponent);
+
+            if (!TryComp(dragged, out AppearanceComponent? appearance))
+                return;
+
+            if (draggableComponent.DraggingPlayer != null)
+            {
+                _appearance.SetData(dragged, TabletopItemVisuals.Scale, new Vector2(1.25f, 1.25f), appearance);
+                _appearance.SetData(dragged, TabletopItemVisuals.DrawDepth, (int) DrawDepth.DrawDepth.Items + 1, appearance);
+            }
+            else
+            {
+                _appearance.SetData(dragged, TabletopItemVisuals.Scale, Vector2.One, appearance);
+                _appearance.SetData(dragged, TabletopItemVisuals.DrawDepth, (int) DrawDepth.DrawDepth.Items, appearance);
+            }
+        }
+
 
         [Serializable, NetSerializable]
         public sealed class TabletopDraggableComponentState : ComponentState
@@ -41,7 +103,7 @@ namespace Content.Shared.Tabletop
                 return false;
             }
 
-            return _interactionSystem.InRangeUnobstructed(playerEntity, table.Value) && _actionBlockerSystem.CanInteract(playerEntity, table);
+            return _interactionSystem.InRangeUnobstructed(playerEntity, table.Value) && ActionBlockerSystem.CanInteract(playerEntity, table);
         }
 
         protected bool CanDrag(EntityUid playerEntity, EntityUid target, [NotNullWhen(true)] out TabletopDraggableComponent? draggable)
@@ -51,7 +113,7 @@ namespace Content.Shared.Tabletop
 
             // CanSeeTable checks interaction action blockers. So no need to check them here.
             // If this ever changes, so that ghosts can spectate games, then the check needs to be moved here.
-            
+
             return TryComp(playerEntity, out SharedHandsComponent? hands) && hands.Hands.Count > 0;
         }
         #endregion