Add client pulling prediction (#2041)

* WIP changes

* Merge conflict fixes

* Bring pull controlelr to current year

* Sync and predict PullController on the client

* Clean imports

* Slow down pullers and make pulling tighter

* Stop pulls on pullable or puller component removals

* Make pulling not occur when moving towards the pulled entity

Content.Shared/GameObjects/EntitySystems/SharedPullingSystem.cs

@@ -0,0 +1,117 @@
+#nullable enable
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using Content.Shared.GameObjects.Components.Pulling;
+using Content.Shared.Input;
+using Content.Shared.Physics.Pull;
+using JetBrains.Annotations;
+using Robust.Shared.GameObjects;
+using Robust.Shared.GameObjects.Systems;
+using Robust.Shared.Input.Binding;
+using Robust.Shared.Interfaces.GameObjects;
+using Robust.Shared.Map;
+using Robust.Shared.Players;
+
+namespace Content.Shared.GameObjects.EntitySystems
+{
+    [UsedImplicitly]
+    public class SharedPullingSystem : EntitySystem
+    {
+        private readonly Dictionary<IEntity, IEntity> _pullers =
+            new Dictionary<IEntity, IEntity>();
+
+        public override void Initialize()
+        {
+            base.Initialize();
+
+            SubscribeLocalEvent<PullStartedMessage>(OnPullStarted);
+            SubscribeLocalEvent<PullStoppedMessage>(OnPullStopped);
+
+            CommandBinds.Builder
+                .Bind(ContentKeyFunctions.MovePulledObject, new PointerInputCmdHandler(HandleMovePulledObject))
+                .Bind(ContentKeyFunctions.ReleasePulledObject, InputCmdHandler.FromDelegate(HandleReleasePulledObject))
+                .Register<SharedPullingSystem>();
+        }
+
+        private void OnPullStarted(PullStartedMessage message)
+        {
+            SetPuller(message.Puller.Owner, message.Pulled.Owner);
+        }
+
+        private void OnPullStopped(PullStoppedMessage message)
+        {
+            RemovePuller(message.Puller.Owner);
+        }
+
+        private bool HandleMovePulledObject(ICommonSession? session, EntityCoordinates coords, EntityUid uid)
+        {
+            var player = session?.AttachedEntity;
+
+            if (player == null)
+            {
+                return false;
+            }
+
+            if (!TryGetPulled(player, out var pulled))
+            {
+                return false;
+            }
+
+            if (!pulled.TryGetComponent(out SharedPullableComponent? pullable))
+            {
+                return false;
+            }
+
+            pullable.TryMoveTo(coords);
+
+            return false;
+        }
+
+        private void HandleReleasePulledObject(ICommonSession? session)
+        {
+            var player = session?.AttachedEntity;
+
+            if (player == null)
+            {
+                return;
+            }
+
+            if (!TryGetPulled(player, out var pulled))
+            {
+                return;
+            }
+
+            if (!pulled.TryGetComponent(out SharedPullableComponent? pullable))
+            {
+                return;
+            }
+
+            pullable.TryStopPull();
+        }
+
+        private void SetPuller(IEntity puller, IEntity pulled)
+        {
+            _pullers[puller] = pulled;
+        }
+
+        private bool RemovePuller(IEntity puller)
+        {
+            return _pullers.Remove(puller);
+        }
+
+        public IEntity? GetPulled(IEntity by)
+        {
+            return _pullers.GetValueOrDefault(by);
+        }
+
+        public bool TryGetPulled(IEntity by, [NotNullWhen(true)] out IEntity? pulled)
+        {
+            return (pulled = GetPulled(by)) != null;
+        }
+
+        public bool IsPulling(IEntity puller)
+        {
+            return _pullers.ContainsKey(puller);
+        }
+    }
+}