Deduplicate inventory drag slots

Author: NichtStudioCode

invui/src/main/java/xyz/xenondevs/invui/inventory/ReferencingInventory.java

@@ -22,6 +22,7 @@
 import java.util.function.BiFunction;
 import java.util.function.Function;
 
+// TODO: equals+hashCode for normal referencing inventories
 /**
  * A {@link xyz.xenondevs.invui.inventory.Inventory} which is backed by a bukkit {@link Inventory}.
  * <p>
@@ -271,6 +272,17 @@ protected void setDirectBackingItem(int slot, @Nullable ItemStack itemStack) {
         public PlayerInventory getReferencedInventory() {
             return (PlayerInventory) super.getReferencedInventory();
         }
+        
+        @Override
+        public int hashCode() {
+            return getReferencedInventory().hashCode();
+        }
+        
+        @Override
+        public boolean equals(Object obj) {
+            return obj instanceof ReferencingInventory.PlayerStorageContents other &&
+                getReferencedInventory().equals(other.getReferencedInventory());
+        }
     }
 
 }

invui/src/main/java/xyz/xenondevs/invui/window/AbstractWindow.java

@@ -295,7 +295,7 @@ public void handleDrag(IntSet slots, ClickType mode) {
         if (mode == ClickType.MIDDLE && viewer.getGameMode() != GameMode.CREATIVE)
             return;
 
-        List<InventorySlot> invSlots = getActiveInventorySlots(slots);
+        SequencedSet<InventorySlot> invSlots = getActiveInventorySlots(slots);
         if (invSlots.isEmpty())
             return;
 
@@ -349,8 +349,8 @@ public void handleDrag(IntSet slots, ClickType mode) {
      * @param slots The window slots
      * @return A list of all active inventory slots referenced by the window slots
      */
-    private List<InventorySlot> getActiveInventorySlots(IntSet slots) {
-        List<InventorySlot> invSlots = new ArrayList<>();
+    private SequencedSet<InventorySlot> getActiveInventorySlots(IntSet slots) {
+        SequencedSet<InventorySlot> invSlots = new LinkedHashSet<>();
 
         slotLoop:
         for (int slot : slots) {
@@ -375,7 +375,7 @@ private List<InventorySlot> getActiveInventorySlots(IntSet slots) {
         return invSlots;
     }
 
-    private boolean distributeItems(UpdateReason updateReason, List<InventorySlot> slots) {
+    private boolean distributeItems(UpdateReason updateReason, Set<InventorySlot> slots) {
         ItemStack cursor = viewer.getItemOnCursor();
         int amount = cursor.getAmount();
         int itemsPerSlot = amount / slots.size();