Make grinder use item slots (& misc eject-button changes) (#7197)

Content.Shared/Containers/ItemSlot/ItemSlotEvents.cs

@@ -0,0 +1,32 @@
+using Robust.Shared.Serialization;
+
+namespace Content.Shared.Containers.ItemSlots;
+
+/// <summary>
+///     Used for various "eject this item" buttons.
+/// </summary>
+[Serializable, NetSerializable]
+public sealed class ItemSlotButtonPressedEvent : BoundUserInterfaceMessage
+{
+    /// <summary>
+    ///     The name of the slot/container from which to insert or eject an item.
+    /// </summary>
+    public string SlotId;
+
+    /// <summary>
+    ///     Whether to attempt to insert an item into the slot, if there is not already one inside.
+    /// </summary>
+    public bool TryInsert;
+
+    /// <summary>
+    ///     Whether to attempt to eject the item from the slot, if it has one.
+    /// </summary>
+    public bool TryEject;
+
+    public ItemSlotButtonPressedEvent(string slotId, bool tryEject = true, bool tryInsert = true)
+    {
+        SlotId = slotId;
+        TryEject = tryEject;
+        TryInsert = tryInsert;
+    }
+}

Content.Shared/Containers/ItemSlot/ItemSlotsSystem.cs

@@ -45,6 +45,8 @@ namespace Content.Shared.Containers.ItemSlots
 
             SubscribeLocalEvent<ItemSlotsComponent, ComponentGetState>(GetItemSlotsState);
             SubscribeLocalEvent<ItemSlotsComponent, ComponentHandleState>(HandleItemSlotsState);
+
+            SubscribeLocalEvent<ItemSlotsComponent, ItemSlotButtonPressedEvent>(HandleButtonPressed);
         }
 
         #region ComponentManagement
@@ -291,7 +293,7 @@ namespace Content.Shared.Containers.ItemSlots
                 return false;
 
             // hands.Drop(item) checks CanDrop action blocker
-            if (_handsSystem.TryDrop(user, hands.ActiveHand))
+            if (!_handsSystem.TryDrop(user, hands.ActiveHand))
                 return false;
 
             Insert(uid, slot, held, user);
@@ -490,6 +492,19 @@ namespace Content.Shared.Containers.ItemSlots
         }
         #endregion
 
+        #region BUIs
+        private void HandleButtonPressed(EntityUid uid, ItemSlotsComponent component, ItemSlotButtonPressedEvent args)
+        {
+            if (!component.Slots.TryGetValue(args.SlotId, out var slot))
+                return;
+
+            if (args.TryEject && slot.HasItem)
+                TryEjectToHands(uid, slot, args.Session.AttachedEntity);
+            else if (args.TryInsert && !slot.HasItem && args.Session.AttachedEntity is EntityUid user)
+                TryInsertFromHand(uid, slot, user);
+        }
+        #endregion
+
         /// <summary>
         ///     Eject items from (some) slots when the entity is destroyed.
         /// </summary>