Fix ObscuredInventory not mapping iteration order slots

Author: NichtStudioCode

invui/src/main/java/xyz/xenondevs/invui/internal/util/ArrayUtils.java

@@ -130,4 +130,17 @@ public static <T> SequencedSet<T> toSequencedSet(T[] array) {
         return set;
     }
 
+    /**
+     * Creates a new int array of the given size, filled with the given value.
+     *
+     * @param size  the size of the array
+     * @param value the value to fill the array with
+     * @return a new int array of the given size, filled with the given value
+     */
+    public static int[] newIntArray(int size, int value) {
+        int[] array = new int[size];
+        Arrays.fill(array, value);
+        return array;
+    }
+    
 }

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

@@ -3,27 +3,26 @@
 import org.bukkit.inventory.ItemStack;
 import org.jspecify.annotations.Nullable;
 import xyz.xenondevs.invui.Click;
+import xyz.xenondevs.invui.internal.util.ArrayUtils;
 import xyz.xenondevs.invui.inventory.event.InventoryClickEvent;
 import xyz.xenondevs.invui.inventory.event.ItemPostUpdateEvent;
 import xyz.xenondevs.invui.inventory.event.ItemPreUpdateEvent;
 import xyz.xenondevs.invui.inventory.event.UpdateReason;
 import xyz.xenondevs.invui.window.AbstractWindow;
 
-import java.util.ArrayList;
-import java.util.BitSet;
 import java.util.List;
-import java.util.function.BiConsumer;
 import java.util.function.Consumer;
 import java.util.function.IntPredicate;
+import java.util.stream.IntStream;
 
 /**
  * An {@link Inventory} that delegates to another {@link Inventory} while hiding certain slots.
  */
 public final class ObscuredInventory extends Inventory {
 
     private final Inventory inventory;
-    private final BitSet mask;
-    private final int[] slots;
+    private final int[] slots; // this slot -> delegate slot
+    private final int[] inverseSlots; // delegate slot -> this slot
 
     /**
      * Constructs a new {@link ObscuredInventory}.
@@ -34,18 +33,13 @@ public final class ObscuredInventory extends Inventory {
     public ObscuredInventory(Inventory inventory, IntPredicate isObscured) {
         super(calculateSize(inventory, isObscured));
         this.inventory = inventory;
-        this.mask = new BitSet(inventory.getSize());
-        
-        ArrayList<Integer> slots = new ArrayList<>();
-        for (int slot = 0; slot < inventory.getSize(); slot++) {
-            if (isObscured.test(slot))
-                continue;
-            
-            mask.set(slot);
-            slots.add(slot);
+        this.slots = IntStream.range(0, inventory.getSize())
+            .filter(slot -> !isObscured.test(slot))
+            .toArray();
+        this.inverseSlots = ArrayUtils.newIntArray(inventory.getSize(), -1);
+        for (int i = 0; i < this.slots.length; i++) {
+            inverseSlots[this.slots[i]] = i;
         }
-        
-        this.slots = slots.stream().mapToInt(Integer::intValue).toArray();
     }
 
     private static int calculateSize(Inventory inventory, IntPredicate isObscured) {
@@ -62,8 +56,8 @@ public int[] getIterationOrder() {
         int[] iterationOrder = new int[slots.length];
         int i = 0;
         for (int slot : inventory.getIterationOrder()) {
-            if (mask.get(slot)) {
-                iterationOrder[i++] = slot;
+            if (slot < inverseSlots.length && inverseSlots[slot] != -1) {
+                iterationOrder[i++] = inverseSlots[slot];
             }
         }
         return iterationOrder;

invui/src/test/java/xyz/xenondevs/invui/inventory/ObscuredInventoryTest.java

@@ -25,7 +25,7 @@ public void testIterationOrder() {
         inv.setIterationOrder(new int[] {4, 3, 0, 1, 2});
 
         var obscured = new ObscuredInventory(inv, i -> i % 2 == 0);
-        assertArrayEquals(new int[] {3, 1}, obscured.getIterationOrder());
+        assertArrayEquals(new int[] {1, 0}, obscured.getIterationOrder());
     }
 
 }