The disposals pushing and pulling update (#1875)

* Add collision to disposal unit and pipes
Make disposal unit and pipes pullable
Implement proper handling of collisions in disposals

* Implement IsExiting
Move DisposalSystem to shared

* Change SharedDisosalUnitComponent to call manager.ContainsEntity directly

* Update saltern.yml

Co-authored-by: Julian Giebel <j.giebel@netrocks.info>

Content.Shared/GameObjects/Components/Disposal/SharedDisposalUnitComponent.cs

@@ -1,14 +1,25 @@
 using System;
+using System.Collections.Generic;
+using System.Linq;
 using Robust.Shared.GameObjects;
+using Robust.Shared.GameObjects.Components;
 using Robust.Shared.GameObjects.Components.UserInterface;
+using Robust.Shared.Interfaces.GameObjects;
+using Robust.Shared.Interfaces.GameObjects.Components;
+using Robust.Shared.IoC;
+using Robust.Shared.Physics;
 using Robust.Shared.Serialization;
 
 namespace Content.Shared.GameObjects.Components.Disposal
 {
-    public abstract class SharedDisposalUnitComponent : Component
+    public abstract class SharedDisposalUnitComponent : Component, ICollideSpecial
     {
+        [Dependency] private readonly IEntityManager _entityManager = default!;
+
         public override string Name => "DisposalUnit";
 
+        private readonly List<IEntity> _intersecting = new List<IEntity>();
+
         [Serializable, NetSerializable]
         public enum Visuals
         {
@@ -57,6 +68,46 @@ namespace Content.Shared.GameObjects.Components.Disposal
             Pressurizing
         }
 
+        bool ICollideSpecial.PreventCollide(IPhysBody collided)
+        {
+            if (IsExiting(collided.Entity)) return true;
+            if (!Owner.TryGetComponent(out IContainerManager manager)) return false;
+
+            if (manager.ContainsEntity(collided.Entity))
+            {
+                if (!_intersecting.Contains(collided.Entity))
+                {
+                    _intersecting.Add(collided.Entity);
+                }
+                return true;
+            }
+            return false;
+        }
+
+        public virtual void Update(float frameTime)
+        {
+            UpdateIntersecting();
+        }
+
+        private bool IsExiting(IEntity entity)
+        {
+            return _intersecting.Contains(entity);
+        }
+
+        private void UpdateIntersecting()
+        {
+            if(_intersecting.Count == 0) return;
+
+            var intersectingEntities = _entityManager.GetEntitiesIntersecting(Owner);
+            for (var i = _intersecting.Count - 1; i >= 0; i--)
+            {
+                if (!intersectingEntities.Contains(_intersecting[i]))
+                {
+                    _intersecting.RemoveAt(i);
+                }
+            }
+        }
+
         [Serializable, NetSerializable]
         public class DisposalUnitBoundUserInterfaceState : BoundUserInterfaceState, IEquatable<DisposalUnitBoundUserInterfaceState>
         {