make printed items from lathes automatically stack (#13603)

Closes https://github.com/space-wizards/space-station-14/issues/10402

Content.Server/Lathe/LatheSystem.cs

@@ -6,6 +6,7 @@ using Content.Server.Lathe.Components;
 using Content.Server.Materials;
 using Content.Server.Power.Components;
 using Content.Server.Power.EntitySystems;
+using Content.Server.Stack;
 using Content.Server.UserInterface;
 using Content.Shared.Database;
 using Content.Shared.Lathe;
@@ -29,6 +30,7 @@ namespace Content.Server.Lathe
         [Dependency] private readonly SharedAudioSystem _audio = default!;
         [Dependency] private readonly UserInterfaceSystem _uiSys = default!;
         [Dependency] private readonly MaterialStorageSystem _materialStorage = default!;
+        [Dependency] private readonly StackSystem _stack = default!;
 
         public override void Initialize()
         {
@@ -85,22 +87,22 @@ namespace Content.Server.Lathe
         }
 
         [PublicAPI]
-        public bool TryGetAvailableRecipes(EntityUid uid, [NotNullWhen(true)] out List<string>? recipes, LatheComponent? component = null)
+        public bool TryGetAvailableRecipes(EntityUid uid, [NotNullWhen(true)] out List<string>? recipes, [NotNullWhen(true)] LatheComponent? component = null)
         {
             recipes = null;
             if (!Resolve(uid, ref component))
                 return false;
-            recipes = GetAvailableRecipes(component);
+            recipes = GetAvailableRecipes(uid, component);
             return true;
         }
 
-        public List<string> GetAvailableRecipes(LatheComponent component)
+        public List<string> GetAvailableRecipes(EntityUid uid, LatheComponent component)
         {
-            var ev = new LatheGetRecipesEvent(component.Owner)
+            var ev = new LatheGetRecipesEvent(uid)
             {
                 Recipes = component.StaticRecipes
             };
-            RaiseLocalEvent(component.Owner, ev);
+            RaiseLocalEvent(uid, ev);
             return ev.Recipes;
         }
 
@@ -147,7 +149,7 @@ namespace Content.Server.Lathe
             lathe.ProductionLength = recipe.CompleteTime * component.TimeMultiplier;
             component.CurrentRecipe = recipe;
 
-            _audio.PlayPvs(component.ProducingSound, component.Owner);
+            _audio.PlayPvs(component.ProducingSound, uid);
             UpdateRunningAppearance(uid, true);
             UpdateUserInterfaceState(uid, component);
             return true;
@@ -159,13 +161,17 @@ namespace Content.Server.Lathe
                 return;
 
             if (comp.CurrentRecipe != null)
-                Spawn(comp.CurrentRecipe.Result, Transform(uid).Coordinates);
+            {
+                var result = Spawn(comp.CurrentRecipe.Result, Transform(uid).Coordinates);
+                _stack.TryMergeToContacts(result);
+            }
+
             comp.CurrentRecipe = null;
             prodComp.StartTime = _timing.CurTime;
 
             if (!TryStartProducing(uid, comp))
             {
-                RemCompDeferred(prodComp.Owner, prodComp);
+                RemCompDeferred(uid, prodComp);
                 UpdateUserInterfaceState(uid, comp);
                 UpdateRunningAppearance(uid, false);
             }
@@ -179,7 +185,7 @@ namespace Content.Server.Lathe
             var ui = _uiSys.GetUi(uid, LatheUiKey.Key);
             var producing = component.CurrentRecipe ?? component.Queue.FirstOrDefault();
 
-            var state = new LatheUpdateState(GetAvailableRecipes(component), component.Queue, producing);
+            var state = new LatheUpdateState(GetAvailableRecipes(uid, component), component.Queue, producing);
             _uiSys.SetUiState(ui, state);
         }
 
@@ -254,7 +260,7 @@ namespace Content.Server.Lathe
 
         protected override bool HasRecipe(EntityUid uid, LatheRecipePrototype recipe, LatheComponent component)
         {
-            return GetAvailableRecipes(component).Contains(recipe.ID);
+            return GetAvailableRecipes(uid, component).Contains(recipe.ID);
         }
 
         #region UI Messages

Content.Shared/Stacks/SharedStackSystem.cs

@@ -5,6 +5,7 @@ using Content.Shared.Interaction;
 using Content.Shared.Popups;
 using JetBrains.Annotations;
 using Robust.Shared.GameStates;
+using Robust.Shared.Physics.Systems;
 using Robust.Shared.Player;
 using Robust.Shared.Prototypes;
 using Robust.Shared.Timing;
@@ -14,13 +15,15 @@ namespace Content.Shared.Stacks
     [UsedImplicitly]
     public abstract class SharedStackSystem : EntitySystem
     {
+        [Dependency] private readonly IGameTiming _gameTiming = default!;
         [Dependency] private readonly IPrototypeManager _prototype = default!;
+        [Dependency] private readonly IViewVariablesManager _vvm = default!;
         [Dependency] protected readonly SharedAppearanceSystem Appearance = default!;
-        [Dependency] protected readonly SharedPopupSystem PopupSystem = default!;
         [Dependency] protected readonly SharedHandsSystem HandsSystem = default!;
         [Dependency] protected readonly SharedTransformSystem Xform = default!;
-        [Dependency] private readonly IGameTiming _gameTiming = default!;
+        [Dependency] private readonly EntityLookupSystem _entityLookup = default!;
-        [Dependency] private readonly IViewVariablesManager _vvm = default!;
+        [Dependency] private readonly SharedPhysicsSystem _physics = default!;
+        [Dependency] protected readonly SharedPopupSystem PopupSystem = default!;
 
         public override void Initialize()
         {
@@ -96,6 +99,9 @@ namespace Content.Shared.Stacks
             StackComponent? recipientStack = null)
         {
             transfered = 0;
+            if (donor == recipient)
+                return false;
+
             if (!Resolve(recipient, ref recipientStack, false) || !Resolve(donor, ref donorStack, false))
                 return false;
 
@@ -190,6 +196,35 @@ namespace Content.Shared.Stacks
             return true;
         }
 
+        /// <summary>
+        /// Tries to merge a stack into any of the stacks it is touching.
+        /// </summary>
+        /// <returns>Whether or not it was successfully merged into another stack</returns>
+        public bool TryMergeToContacts(EntityUid uid, StackComponent? stack = null, TransformComponent? xform = null)
+        {
+            if (!Resolve(uid, ref stack, ref xform, false))
+                return false;
+
+            var map = xform.MapID;
+            var bounds = _physics.GetWorldAABB(uid);
+            var intersecting = _entityLookup.GetComponentsIntersecting<StackComponent>(map, bounds,
+                LookupFlags.Dynamic | LookupFlags.Sundries);
+
+            var merged = false;
+            foreach (var otherStack in intersecting)
+            {
+                var otherEnt = otherStack.Owner;
+
+                if (!TryMergeStacks(uid, otherEnt, out _, stack, otherStack))
+                    continue;
+                merged = true;
+
+                if (stack.Count <= 0)
+                    break;
+            }
+            return merged;
+        }
+
         /// <summary>
         /// Gets the max count for a given entity prototype
         /// </summary>