From fc858f551b1e9cf832bc392a9c8cd29b901b9a0b Mon Sep 17 00:00:00 2001
From: Ethan Moffat <ethan@moffat.io>
Date: Wed, 3 May 2023 22:40:38 -0700
Subject: [PATCH] Feature parity with vanilla client: making space for
 inventory items that aren't displayed causes them to appear

---
 EndlessClient/HUD/Panels/InventoryPanel.cs | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/EndlessClient/HUD/Panels/InventoryPanel.cs b/EndlessClient/HUD/Panels/InventoryPanel.cs
index d95cfea3..a83e58e9 100644
--- a/EndlessClient/HUD/Panels/InventoryPanel.cs
+++ b/EndlessClient/HUD/Panels/InventoryPanel.cs
@@ -256,6 +256,11 @@ protected override void OnUpdateControl(GameTime gameTime)
                 }
 
                 _cachedInventory = _characterInventoryProvider.ItemInventory.ToHashSet();
+
+                if (removed.Any())
+                {
+                    RemoveHiddenItemsFromCachedInventory();
+                }
             }
 
             base.OnUpdateControl(gameTime);
@@ -498,6 +503,10 @@ private void HandleItemDoneDragging(object sender, DragCompletedEventArgs<EIFRec
                         e.RestoreOriginalSlot = true;
                     }
                 }
+                else
+                {
+                    RemoveHiddenItemsFromCachedInventory();
+                }
             }
         }
 
@@ -510,6 +519,16 @@ private void ResetSlotMap(IEnumerable<InventoryPanelItem> childItems)
                 _inventoryService.SetSlots(_inventorySlotRepository.FilledSlots, childItem.Slot, childItem.Data.Size);
         }
 
+        private void RemoveHiddenItemsFromCachedInventory()
+        {
+            // the item fits in the new slot, and there is no chained drag, snapback, or continued drag
+            // under these conditions, check if there are any items that don't have a matching childItem and remove them from the cached list
+            // the next update loop will detect these items as 'added' and attempt to show them in the empty space
+
+            var notDisplayedItems = _cachedInventory.Where(x => _childItems.All(ci => x != ci.InventoryItem));
+            _cachedInventory.RemoveWhere(notDisplayedItems.Contains);
+        }
+
         private static IEnumerable<int> GetOverlappingTakenSlots(int newSlot, ItemSize size, IEnumerable<(int Slot, ItemSize Size)> items)
         {
             var slotX = newSlot % InventoryRowSlots;