From 4992aa1b5d516c1aa38380347ef2486d1a8f894f Mon Sep 17 00:00:00 2001
From: CraftBukkit/Spigot <noreply+git-craftbukkit@papermc.io>
Date: Sun, 24 Nov 2024 11:06:35 +1100
Subject: [PATCH] Fix Inventory#addItem not respecting max stack size

By: md_5 <git@md-5.net>
---
 .../craftbukkit/inventory/CraftInventory.java | 28 ++++++-------------
 1 file changed, 8 insertions(+), 20 deletions(-)

diff --git a/paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftInventory.java b/paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftInventory.java
index 8a17d178f9..820d06ede0 100644
--- a/paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftInventory.java
+++ b/paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftInventory.java
@@ -255,19 +255,6 @@ public class CraftInventory implements Inventory {
         return inventory.isEmpty();
     }
 
-    public int firstPartial(Material material) {
-        Preconditions.checkArgument(material != null, "Material cannot be null");
-        material = CraftLegacy.fromLegacy(material);
-        ItemStack[] inventory = getStorageContents();
-        for (int i = 0; i < inventory.length; i++) {
-            ItemStack item = inventory[i];
-            if (item != null && item.getType() == material && item.getAmount() < item.getMaxStackSize()) {
-                return i;
-            }
-        }
-        return -1;
-    }
-
     private int firstPartial(ItemStack item) {
         ItemStack[] inventory = getStorageContents();
         ItemStack filteredItem = CraftItemStack.asCraftCopy(item);
@@ -276,7 +263,7 @@ public class CraftInventory implements Inventory {
         }
         for (int i = 0; i < inventory.length; i++) {
             ItemStack cItem = inventory[i];
-            if (cItem != null && cItem.getAmount() < cItem.getMaxStackSize() && cItem.isSimilar(filteredItem)) {
+            if (cItem != null && cItem.getAmount() < getMaxItemStack(cItem) && cItem.isSimilar(filteredItem)) {
                 return i;
             }
         }
@@ -312,11 +299,12 @@ public class CraftInventory implements Inventory {
                         break;
                     } else {
                         // More than a single stack!
-                        if (item.getAmount() > getMaxItemStack()) {
+                        int maxAmount = getMaxItemStack(item);
+                        if (item.getAmount() > maxAmount) {
                             CraftItemStack stack = CraftItemStack.asCraftCopy(item);
-                            stack.setAmount(getMaxItemStack());
+                            stack.setAmount(maxAmount);
                             setItem(firstFree, stack);
-                            item.setAmount(item.getAmount() - getMaxItemStack());
+                            item.setAmount(item.getAmount() - maxAmount);
                         } else {
                             // Just store it
                             setItem(firstFree, item);
@@ -329,7 +317,7 @@ public class CraftInventory implements Inventory {
 
                     int amount = item.getAmount();
                     int partialAmount = partialItem.getAmount();
-                    int maxAmount = partialItem.getMaxStackSize();
+                    int maxAmount = getMaxItemStack(partialItem);
 
                     // Check if it fully fits
                     if (amount + partialAmount <= maxAmount) {
@@ -395,8 +383,8 @@ public class CraftInventory implements Inventory {
         return leftover;
     }
 
-    private int getMaxItemStack() {
-        return getInventory().getMaxStackSize();
+    private int getMaxItemStack(ItemStack itemstack) {
+        return Math.min(itemstack.getMaxStackSize(), getInventory().getMaxStackSize());
     }
 
     @Override