From 6a8ac9dce345e77096bcb316b79bd9c6c4f5bfb0 Mon Sep 17 00:00:00 2001
From: NichtStudioCode <51272202+NichtStudioCode@users.noreply.github.com>
Date: Sat, 15 Apr 2023 17:56:32 +0200
Subject: [PATCH] Fix ItemPostUpdateEvent receiving air item stack when
 shift-clicking out of gui-embedded inventory

---
 .../java/xyz/xenondevs/invui/gui/AbstractGui.java    | 12 ++++++++----
 .../java/xyz/xenondevs/invui/util/ItemUtils.java     | 12 ++++++++++++
 2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/invui/src/main/java/xyz/xenondevs/invui/gui/AbstractGui.java b/invui/src/main/java/xyz/xenondevs/invui/gui/AbstractGui.java
index f4701d4..1ea758f 100644
--- a/invui/src/main/java/xyz/xenondevs/invui/gui/AbstractGui.java
+++ b/invui/src/main/java/xyz/xenondevs/invui/gui/AbstractGui.java
@@ -11,17 +11,18 @@ import org.jetbrains.annotations.Nullable;
 import xyz.xenondevs.invui.animation.Animation;
 import xyz.xenondevs.invui.gui.structure.Marker;
 import xyz.xenondevs.invui.gui.structure.Structure;
+import xyz.xenondevs.invui.inventory.Inventory;
+import xyz.xenondevs.invui.inventory.event.ItemPreUpdateEvent;
+import xyz.xenondevs.invui.inventory.event.PlayerUpdateReason;
+import xyz.xenondevs.invui.inventory.event.UpdateReason;
 import xyz.xenondevs.invui.item.Item;
 import xyz.xenondevs.invui.item.ItemProvider;
 import xyz.xenondevs.invui.item.ItemWrapper;
 import xyz.xenondevs.invui.item.impl.controlitem.ControlItem;
 import xyz.xenondevs.invui.util.ArrayUtils;
 import xyz.xenondevs.invui.util.InventoryUtils;
+import xyz.xenondevs.invui.util.ItemUtils;
 import xyz.xenondevs.invui.util.SlotUtils;
-import xyz.xenondevs.invui.inventory.Inventory;
-import xyz.xenondevs.invui.inventory.event.ItemPreUpdateEvent;
-import xyz.xenondevs.invui.inventory.event.PlayerUpdateReason;
-import xyz.xenondevs.invui.inventory.event.UpdateReason;
 import xyz.xenondevs.invui.window.*;
 
 import java.util.*;
@@ -222,6 +223,9 @@ public abstract class AbstractGui implements Gui, GuiParent {
             }
             
             clicked.setAmount(leftOverAmount);
+            if (ItemUtils.isEmpty(clicked))
+                clicked = null;
+            
             inventory.setItemSilently(slot, clicked);
             
             inventory.callPostUpdateEvent(updateReason, slot, previousStack, clicked);
diff --git a/invui/src/main/java/xyz/xenondevs/invui/util/ItemUtils.java b/invui/src/main/java/xyz/xenondevs/invui/util/ItemUtils.java
index 00bbf27..3ea9053 100644
--- a/invui/src/main/java/xyz/xenondevs/invui/util/ItemUtils.java
+++ b/invui/src/main/java/xyz/xenondevs/invui/util/ItemUtils.java
@@ -18,6 +18,18 @@ public class ItemUtils {
         return itemStack == null || itemStack.getType().isAir() || itemStack.getAmount() <= 0;
     }
     
+    /**
+     * Checks whether the given {@link ItemStack} is empty and returns null if it is.
+     * @param itemStack The {@link ItemStack} to check.
+     * @return The {@link ItemStack} if it is not empty or null otherwise.
+     */
+    public static @Nullable ItemStack takeUnlessEmpty(@Nullable ItemStack itemStack) {
+        if (isEmpty(itemStack))
+            return null;
+        
+        return itemStack;
+    }
+    
     /**
      * Creates a new array with clones of the given {@link ItemStack ItemStacks}.
      *