Add pulling (#1409)

* Initial framework for pulling.

* Make it possible to pull items via (temporary) keybind Ctrl+Click, make items follow the player correctly.

* Make other objects pullable, implement functionality for moving an object being pulled, make only one object able to be pulled at a time.

* Make sure that MoveTo won't allow collisions with the player

* Update everything to work with the new physics engine

* Update Content.Server/GameObjects/EntitySystems/Click/InteractionSystem.cs

Co-authored-by: ComicIronic <comicironic@gmail.com>

* Physics update and convert to direct type casts

* Add notnull checks

* Add pull keybinds to the tutorial window

* Move PullController to shared

* Fix pulled items getting left behind

* Fix moving pulled objects into walls

* Remove flooring of coordinates when moving pulled objects

* Add missing null check in PutInHand

* Change pulling keybind to control and throwing to alt

* Change PhysicsComponent references to IPhysicsComponent

* Add trying to pull a pulled entity disabling the pull

* Add pulled status effect

* Fix merge conflicts

* Merge fixes

* Make players pullable

* Fix being able to pull yourself

* Change pull moving to use a velocity

* Update pulled and pulling icons to not be buckle

A tragedy

* Make pulled and pulling icons more consistent

* Remove empty not pulled and not pulling images

* Pulled icon update

* Pulled icon update

* Add clicking pulling status effect to stop the pull

* Fix spacewalking when pulling

* Merge conflict fixes

* Add a pull verb

* Fix nullable error

* Add pulling through the entity drop down menu

Co-authored-by: Jackson Lewis <inquisitivepenguin@protonmail.com>
Co-authored-by: ComicIronic <comicironic@gmail.com>

Content.Server/GameObjects/EntitySystems/Click/InteractionSystem.cs

@@ -1,6 +1,8 @@
 using System;
 using System.Linq;
+using Content.Server.GameObjects.Components.GUI;
 using Content.Server.GameObjects.Components.Mobs;
+using Content.Server.GameObjects.Components.Movement;
 using Content.Server.GameObjects.Components.Timing;
 using Content.Server.Interfaces.GameObjects.Components.Items;
 using Content.Server.Utility;
@@ -9,11 +11,13 @@ using Content.Shared.GameObjects.EntitySystemMessages;
 using Content.Shared.GameObjects.EntitySystems;
 using Content.Shared.Input;
 using Content.Shared.Interfaces.GameObjects.Components;
+using Content.Shared.Physics;
 using JetBrains.Annotations;
 using Robust.Server.GameObjects;
 using Robust.Server.Interfaces.Player;
 using Robust.Shared.Containers;
 using Robust.Shared.GameObjects;
+using Robust.Shared.GameObjects.Components;
 using Robust.Shared.Input;
 using Robust.Shared.Input.Binding;
 using Robust.Shared.Interfaces.GameObjects;
@@ -48,6 +52,7 @@ namespace Content.Server.GameObjects.EntitySystems.Click
                     new PointerInputCmdHandler(HandleWideAttack))
                 .Bind(ContentKeyFunctions.ActivateItemInWorld,
                     new PointerInputCmdHandler(HandleActivateItemInWorld))
+                .Bind(ContentKeyFunctions.TryPullObject, new PointerInputCmdHandler(HandleTryPullObject))
                 .Register<InteractionSystem>();
         }
 
@@ -221,6 +226,72 @@ namespace Content.Server.GameObjects.EntitySystems.Click
             return true;
         }
 
+        private bool HandleTryPullObject(ICommonSession session, GridCoordinates coords, EntityUid uid)
+        {
+            // client sanitization
+            if (!_mapManager.GridExists(coords.GridID))
+            {
+                Logger.InfoS("system.interaction", $"Invalid Coordinates for pulling: client={session}, coords={coords}");
+                return false;
+            }
+
+            if (uid.IsClientSide())
+            {
+                Logger.WarningS("system.interaction",
+                    $"Client sent pull interaction with client-side entity. Session={session}, Uid={uid}");
+                return false;
+            }
+
+            var player = session.AttachedEntity;
+
+            if (player == null)
+            {
+                Logger.WarningS("system.interaction",
+                    $"Client sent pulling interaction with no attached entity. Session={session}, Uid={uid}");
+                return false;
+            }
+
+            if (!EntityManager.TryGetEntity(uid, out var pulledObject))
+            {
+                return false;
+            }
+
+            if (player == pulledObject)
+            {
+                return false;
+            }
+
+            if (!pulledObject.TryGetComponent<PullableComponent>(out var pull))
+            {
+                return false;
+            }
+
+            if (!player.TryGetComponent<HandsComponent>(out var hands))
+            {
+                return false;
+            }
+
+            var dist = player.Transform.GridPosition.Position - pulledObject.Transform.GridPosition.Position;
+            if (dist.LengthSquared > InteractionRangeSquared)
+            {
+                return false;
+            }
+
+            var physics = pull.Owner.GetComponent<IPhysicsComponent>();
+            var controller = physics.EnsureController<PullController>();
+
+            if (controller.GettingPulled)
+            {
+                hands.StopPull();
+            }
+            else
+            {
+                hands.StartPull(pull);
+            }
+
+            return false;
+        }
+
         private void UserInteraction(IEntity player, GridCoordinates coordinates, EntityUid clickedUid)
         {
             // Get entity clicked upon from UID if valid UID, if not assume no entity clicked upon and null