PaperMC/patches/server/0737-Make-hoppers-respect-inventory-max-stack-size.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Jake Potrebic <jake.m.potrebic@gmail.com>
Date: Wed, 7 Jul 2021 16:30:17 -0700
Subject: [PATCH] Make hoppers respect inventory max stack size


diff --git a/src/main/java/net/minecraft/world/level/block/entity/HopperBlockEntity.java b/src/main/java/net/minecraft/world/level/block/entity/HopperBlockEntity.java
index 3b1442bf4c83650369e925d76f07dc67c6cbbc83..a3f0e2ab3eeebeb7c43fda3ddb1f16f8696255d3 100644
--- a/src/main/java/net/minecraft/world/level/block/entity/HopperBlockEntity.java
+++ b/src/main/java/net/minecraft/world/level/block/entity/HopperBlockEntity.java
@@ -588,13 +588,22 @@ public class HopperBlockEntity extends RandomizableContainerBlockEntity implemen
             boolean flag1 = to.isEmpty();
 
             if (itemstack1.isEmpty()) {
+                int originalCount = stack.getCount(); // Paper
+                stack.setCount(Math.min(to.getMaxStackSize(), stack.getCount())); // Paper
                 IGNORE_TILE_UPDATES = true; // Paper
                 to.setItem(slot, stack);
                 IGNORE_TILE_UPDATES = false; // Paper
+                if (originalCount - stack.getCount() == 0) { // Paper
                 stack = ItemStack.EMPTY;
+                // Paper start
+                } else {
+                    stack = stack.copy(); // Paper - copy stack to return leftover stack
+                    stack.setCount(originalCount - stack.getCount());
+                }
+                // Paper end
                 flag = true;
             } else if (HopperBlockEntity.canMergeItems(itemstack1, stack)) {
-                int j = stack.getMaxStackSize() - itemstack1.getCount();
+                int j = Math.min(stack.getMaxStackSize(), to.getMaxStackSize()) - itemstack1.getCount(); // Paper
                 int k = Math.min(stack.getCount(), j);
 
                 stack.shrink(k);