Disposal trunks now eject incoming entities (#1942)

* Implement disposal trunk eject on incomming entities

* Move variable declaration into if block

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

Content.Server/GameObjects/Components/Disposal/DisposalEntryComponent.cs

@@ -1,7 +1,11 @@
 using System.Collections.Generic;
+using System.Linq;
 using Robust.Shared.GameObjects;
 using Robust.Shared.Interfaces.GameObjects;
+using Robust.Shared.Interfaces.Random;
+using Robust.Shared.IoC;
 using Robust.Shared.Maths;
+using Robust.Shared.Random;
 
 namespace Content.Server.GameObjects.Components.Disposal
 {
@@ -9,6 +13,8 @@ namespace Content.Server.GameObjects.Components.Disposal
     [ComponentReference(typeof(IDisposalTubeComponent))]
     public class DisposalEntryComponent : DisposalTubeComponent
     {
+        [Dependency] private readonly IRobustRandom _random = default!;
+
         private const string HolderPrototypeId = "DisposalHolder";
 
         public override string Name => "DisposalEntry";
@@ -43,8 +49,19 @@ namespace Content.Server.GameObjects.Components.Disposal
             return new[] {Owner.Transform.LocalRotation.GetDir()};
         }
 
+        /// <summary>
+        ///     Ejects contents when they come from the same direction the entry is facing.
+        /// </summary>
         public override Direction NextDirection(DisposalHolderComponent holder)
         {
+            if (holder.PreviousTube != null && DirectionTo(holder.PreviousTube) == ConnectableDirections()[0])
+            {
+                var invalidDirections = new Direction[] { ConnectableDirections()[0], Direction.Invalid };
+                var directions = System.Enum.GetValues(typeof(Direction))
+                    .Cast<Direction>().Except(invalidDirections).ToList();
+                return _random.Pick<Direction>(directions);
+            }
+
             return ConnectableDirections()[0];
         }
     }