Sending a mob out of a disposals unit shouldn't push them into a wall anymore (#5411)

* Sending a mob out of a disposals unit shouldn't push them into a wall anymore.

* Something something resolves vs. OnRemove fighting it out

* Disposals yeet reduction: Address reviews and other oddities

Content.Server/Disposal/Unit/EntitySystems/DisposableSystem.cs

@@ -1,18 +1,181 @@
-using Content.Server.Disposal.Unit.Components;
+using System.Linq;
+using Content.Server.Atmos;
+using Content.Server.Atmos.EntitySystems;
+using Content.Server.Disposal.Tube.Components;
+using Content.Server.Disposal.Tube;
+using Content.Server.Disposal.Unit.Components;
 using JetBrains.Annotations;
+using Robust.Shared.Containers;
 using Robust.Shared.GameObjects;
+using Robust.Shared.IoC;
+using Robust.Shared.Map;
+using Robust.Shared.Maths;
+using Robust.Shared.Physics;
 
 namespace Content.Server.Disposal.Unit.EntitySystems
 {
     [UsedImplicitly]
     internal sealed class DisposableSystem : EntitySystem
     {
+        [Dependency] private readonly IMapManager _mapManager = default!;
+        [Dependency] private readonly DisposalUnitSystem _disposalUnitSystem = default!;
+        [Dependency] private readonly DisposalTubeSystem _disposalTubeSystem = default!;
+
+        public void ExitDisposals(EntityUid uid, DisposalHolderComponent? holder = null, TransformComponent? holderTransform = null)
+        {
+            if (!Resolve(uid, ref holder, ref holderTransform))
+                return;
+
+            // Check for a disposal unit to throw them into and then eject them from it.
+            // *This ejection also makes the target not collide with the unit.*
+            // *This is on purpose.*
+            var grid = _mapManager.GetGrid(holderTransform.GridID);
+            var gridTileContents = grid.GetLocal(holderTransform.Coordinates);
+            DisposalUnitComponent? duc = null;
+            foreach (var contentUid in gridTileContents)
+            {
+                if (EntityManager.TryGetComponent(contentUid, out duc))
+                    break;
+            }
+
+            foreach (var entity in holder.Container.ContainedEntities.ToArray())
+            {
+                if (entity.TryGetComponent(out IPhysBody? physics))
+                {
+                    physics.CanCollide = true;
+                }
+
+                holder.Container.ForceRemove(entity);
+
+                if (entity.Transform.Parent == holderTransform)
+                {
+                    if (duc != null)
+                    {
+                        // Insert into disposal unit
+                        entity.Transform.Coordinates = new EntityCoordinates(duc.OwnerUid, Vector2.Zero);
+                        duc.Container.Insert(entity);
+                    }
+                    else
+                    {
+                        entity.Transform.AttachParentToContainerOrGrid();
+                    }
+                }
+            }
+
+            if (duc != null)
+            {
+                _disposalUnitSystem.TryEjectContents(duc);
+            }
+
+            var atmosphereSystem = EntitySystem.Get<AtmosphereSystem>();
+
+            if (atmosphereSystem.GetTileMixture(holderTransform.Coordinates, true) is {} environment)
+            {
+                atmosphereSystem.Merge(environment, holder.Air);
+                holder.Air.Clear();
+            }
+
+            EntityManager.DeleteEntity(uid);
+        }
+
+        // Note: This function will cause an ExitDisposals on any failure that does not make an ExitDisposals impossible.
+        public bool EnterTube(EntityUid holderUid, EntityUid toUid, DisposalHolderComponent? holder = null, TransformComponent? holderTransform = null, IDisposalTubeComponent? to = null, TransformComponent? toTransform = null)
+        {
+            if (!Resolve(holderUid, ref holder, ref holderTransform))
+                return false;
+            if (!Resolve(toUid, ref to, ref toTransform))
+            {
+                ExitDisposals(holderUid, holder, holderTransform);
+                return false;
+            }
+
+            // Insert into next tube
+            holderTransform.Coordinates = new EntityCoordinates(toUid, Vector2.Zero);
+            if (!to.Contents.Insert(holder.Owner))
+            {
+                ExitDisposals(holderUid, holder, holderTransform);
+                return false;
+            }
+
+            if (holder.CurrentTube != null)
+            {
+                holder.PreviousTube = holder.CurrentTube;
+                holder.PreviousDirection = holder.CurrentDirection;
+            }
+            var dir = to.NextDirection(holder);
+            // Invalid direction = exit now!
+            if (dir == Direction.Invalid)
+            {
+                ExitDisposals(holderUid, holder, holderTransform);
+                return false;
+            }
+
+            holderTransform.Coordinates = toTransform.Coordinates;
+            holder.CurrentTube = to;
+            holder.CurrentDirection = dir;
+            holder.StartingTime = 0.1f;
+            holder.TimeLeft = 0.1f;
+            return true;
+        }
 
         public override void Update(float frameTime)
         {
             foreach (var comp in EntityManager.EntityQuery<DisposalHolderComponent>())
             {
-                comp.Update(frameTime);
+                UpdateComp(comp, frameTime);
+            }
+        }
+
+        private void UpdateComp(DisposalHolderComponent holder, float frameTime)
+        {
+            while (frameTime > 0)
+            {
+                var time = frameTime;
+                if (time > holder.TimeLeft)
+                {
+                    time = holder.TimeLeft;
+                }
+
+                holder.TimeLeft -= time;
+                frameTime -= time;
+
+                var currentTube = holder.CurrentTube;
+                if (currentTube == null || currentTube.Deleted)
+                {
+                    ExitDisposals(holder.OwnerUid);
+                    break;
+                }
+
+                if (holder.TimeLeft > 0)
+                {
+                    var progress = 1 - holder.TimeLeft / holder.StartingTime;
+                    var origin = currentTube.Owner.Transform.Coordinates;
+                    var destination = holder.CurrentDirection.ToVec();
+                    var newPosition = destination * progress;
+
+                    holder.Owner.Transform.Coordinates = origin.Offset(newPosition);
+
+                    continue;
+                }
+
+                // Past this point, we are performing inter-tube transfer!
+                // Remove current tube content
+                currentTube.Contents.ForceRemove(holder.Owner);
+
+                // Find next tube
+                var nextTube = _disposalTubeSystem.NextTubeFor(currentTube.OwnerUid, holder.CurrentDirection);
+                if (nextTube == null || nextTube.Deleted)
+                {
+                    ExitDisposals(holder.OwnerUid);
+                    break;
+                }
+
+                // Perform remainder of entry process
+                if (!EnterTube(holder.OwnerUid, nextTube.OwnerUid, holder, null, nextTube, null))
+                {
+                    ExitDisposals(holder.OwnerUid);
+                    break;
+                }
             }
         }
     }