From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Jake Potrebic <jake.m.potrebic@gmail.com>
Date: Mon, 12 Dec 2022 12:14:03 -0800
Subject: [PATCH] Properly track the changed item from dispense events


diff --git a/src/main/java/net/minecraft/core/dispenser/DispenseItemBehavior.java b/src/main/java/net/minecraft/core/dispenser/DispenseItemBehavior.java
index 32084df594649d8da04052bbfa111896d8ea1f91..5dab1e10303177e5a4d97a91ee46ede66f30ae35 100644
--- a/src/main/java/net/minecraft/core/dispenser/DispenseItemBehavior.java
+++ b/src/main/java/net/minecraft/core/dispenser/DispenseItemBehavior.java
@@ -133,10 +133,14 @@ public interface DispenseItemBehavior {
                         idispensebehavior.dispense(pointer, eventStack);
                         return stack;
                     }
+                    // Paper start - track changed items in the dispense event
+                    itemstack1 = CraftItemStack.unwrap(event.getItem()); // unwrap is safe because the stack won't be modified
+                    entitytypes = ((SpawnEggItem) itemstack1.getItem()).getType(itemstack1);
+                    // Paper end - track changed item from dispense event
                 }
 
                 try {
-                    entitytypes.spawn(pointer.level(), stack, (Player) null, pointer.pos().relative(enumdirection), MobSpawnType.DISPENSER, enumdirection != Direction.UP, false);
+                    entitytypes.spawn(pointer.level(), itemstack1, (Player) null, pointer.pos().relative(enumdirection), MobSpawnType.DISPENSER, enumdirection != Direction.UP, false); // Paper - track changed item in dispense event
                 } catch (Exception exception) {
                     DispenseItemBehavior.LOGGER.error("Error while dispensing spawn egg from dispenser at {}", pointer.pos(), exception); // CraftBukkit - decompile error
                     return ItemStack.EMPTY;
@@ -191,9 +195,10 @@ public interface DispenseItemBehavior {
                 }
                 // CraftBukkit end
 
+                final ItemStack newStack = CraftItemStack.unwrap(event.getItem()); // Paper - use event itemstack (unwrap is fine here because the stack won't be modified)
                 Consumer<ArmorStand> consumer = EntityType.appendDefaultStackConfig((entityarmorstand) -> {
                     entityarmorstand.setYRot(enumdirection.toYRot());
-                }, worldserver, stack, (Player) null);
+                }, worldserver, newStack, (Player) null); // Paper - track changed items in the dispense event
                 ArmorStand entityarmorstand = (ArmorStand) EntityType.ARMOR_STAND.spawn(worldserver, consumer, blockposition, MobSpawnType.DISPENSER, false, false);
 
                 if (entityarmorstand != null) {
@@ -413,6 +418,7 @@ public interface DispenseItemBehavior {
                 int y = blockposition.getY();
                 int z = blockposition.getZ();
                 BlockState iblockdata = worldserver.getBlockState(blockposition);
+                ItemStack dispensedItem = stack; // Paper - track changed item from the dispense event
                 // Paper start - correctly check if the bucket place will succeed
                 /* Taken from SolidBucketItem#emptyContents */
                 boolean willEmptyContentsSolidBucketItem = dispensiblecontaineritem instanceof net.minecraft.world.item.SolidBucketItem && worldserver.isInWorldBounds(blockposition) && iblockdata.isAir();
@@ -442,12 +448,15 @@ public interface DispenseItemBehavior {
                         }
                     }
 
-                    dispensiblecontaineritem = (DispensibleContainerItem) CraftItemStack.asNMSCopy(event.getItem()).getItem();
+                    // Paper start - track changed item from dispense event
+                    dispensedItem = CraftItemStack.unwrap(event.getItem()); // unwrap is safe here as the stack isn't mutated
+                    dispensiblecontaineritem = (DispensibleContainerItem) dispensedItem.getItem();
+                    // Paper end - track changed item from dispense event
                 }
                 // CraftBukkit end
 
                 if (dispensiblecontaineritem.emptyContents((Player) null, worldserver, blockposition, (BlockHitResult) null)) {
-                    dispensiblecontaineritem.checkExtraContent((Player) null, worldserver, stack, blockposition);
+                    dispensiblecontaineritem.checkExtraContent((Player) null, worldserver, dispensedItem, blockposition); // Paper - track changed item from dispense event
                     // CraftBukkit start - Handle stacked buckets
                     Item item = Items.BUCKET;
                     stack.shrink(1);
diff --git a/src/main/java/net/minecraft/core/dispenser/ProjectileDispenseBehavior.java b/src/main/java/net/minecraft/core/dispenser/ProjectileDispenseBehavior.java
index 985954030654d521291cccbfc3ca49b67ee4357d..e37d2d29f3ba67cfe28abe4847a3dca07121f0be 100644
--- a/src/main/java/net/minecraft/core/dispenser/ProjectileDispenseBehavior.java
+++ b/src/main/java/net/minecraft/core/dispenser/ProjectileDispenseBehavior.java
@@ -36,7 +36,7 @@ public class ProjectileDispenseBehavior extends DefaultDispenseItemBehavior {
         ServerLevel worldserver = pointer.level();
         Direction enumdirection = (Direction) pointer.state().getValue(DispenserBlock.FACING);
         Position iposition = this.dispenseConfig.positionFunction().getDispensePosition(pointer, enumdirection);
-        Projectile iprojectile = this.projectileItem.asProjectile(worldserver, iposition, stack, enumdirection);
+        // Paper - move down
 
         // CraftBukkit start
         // this.projectileItem.shoot(iprojectile, (double) enumdirection.getStepX(), (double) enumdirection.getStepY(), (double) enumdirection.getStepZ(), this.dispenseConfig.power(), this.dispenseConfig.uncertainty());
@@ -66,6 +66,7 @@ public class ProjectileDispenseBehavior extends DefaultDispenseItemBehavior {
             }
         }
 
+        Projectile iprojectile = this.projectileItem.asProjectile(worldserver, iposition, CraftItemStack.unwrap(event.getItem()), enumdirection); // Paper - move from above and track changed items in the dispense event; unwrap is safe here because all uses of the stack make their own copies
         this.projectileItem.shoot(iprojectile, event.getVelocity().getX(), event.getVelocity().getY(), event.getVelocity().getZ(), this.dispenseConfig.power(), this.dispenseConfig.uncertainty());
         ((Entity) iprojectile).projectileSource = new org.bukkit.craftbukkit.projectiles.CraftBlockProjectileSource(pointer.blockEntity());
         // CraftBukkit end
diff --git a/src/main/java/net/minecraft/core/dispenser/ShulkerBoxDispenseBehavior.java b/src/main/java/net/minecraft/core/dispenser/ShulkerBoxDispenseBehavior.java
index 6f2adf2334e35e8a617a4ced0c1af2abf32bbd8d..cb308808906a8cdb127df8284e106e00553473ca 100644
--- a/src/main/java/net/minecraft/core/dispenser/ShulkerBoxDispenseBehavior.java
+++ b/src/main/java/net/minecraft/core/dispenser/ShulkerBoxDispenseBehavior.java
@@ -57,7 +57,12 @@ public class ShulkerBoxDispenseBehavior extends OptionalDispenseItemBehavior {
             // CraftBukkit end
 
             try {
-                this.setSuccess(((BlockItem) item).place(new DirectionalPlaceContext(pointer.level(), blockposition, enumdirection, stack, enumdirection1)).consumesAction());
+                // Paper start - track changed items in the dispense event
+                this.setSuccess(((BlockItem) item).place(new DirectionalPlaceContext(pointer.level(), blockposition, enumdirection, CraftItemStack.asNMSCopy(event.getItem()), enumdirection1)).consumesAction());
+                if (this.isSuccess()) {
+                    stack.shrink(1); // vanilla shrink is in the place function above, manually handle it here
+                }
+                // Paper end - track changed items in the dispense event
             } catch (Exception exception) {
                 ShulkerBoxDispenseBehavior.LOGGER.error("Error trying to place shulker box at {}", blockposition, exception);
             }
