PaperMC/patches/server/0935-Fix-several-issues-with-EntityBreedEvent.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Jake Potrebic <jake.m.potrebic@gmail.com>
Date: Thu, 15 Dec 2022 00:14:44 -0800
Subject: [PATCH] Fix several issues with EntityBreedEvent

Upstream did not account for different hands when storing
the breed item for later use in the event. Also they only
stored a reference to the stack, not a copy so if the stack
changed after love mode was started, the breed item in the event
also changed. Also in several places, the breed item was stored after
it was decreased by one to consume the item.

diff --git a/src/main/java/net/minecraft/world/entity/animal/Animal.java b/src/main/java/net/minecraft/world/entity/animal/Animal.java
index 3bd13c9b8c7573726ae7defdc3c0f32876d1cf1f..5193cf1d3c922d750a11e492b7636215e23ad0d6 100644
--- a/src/main/java/net/minecraft/world/entity/animal/Animal.java
+++ b/src/main/java/net/minecraft/world/entity/animal/Animal.java
@@ -147,8 +147,9 @@ public abstract class Animal extends AgeableMob {
             int i = this.getAge();
 
             if (!this.level().isClientSide && i == 0 && this.canFallInLove()) {
+                final ItemStack breedCopy = itemstack.copy(); // Paper - Fix EntityBreedEvent copying
                 this.usePlayerItem(player, hand, itemstack);
-                this.setInLove(player);
+                this.setInLove(player, breedCopy); // Paper - Fix EntityBreedEvent copying
                 return InteractionResult.SUCCESS;
             }
 
@@ -174,10 +175,18 @@ public abstract class Animal extends AgeableMob {
         return this.inLove <= 0;
     }
 
+    @Deprecated @io.papermc.paper.annotation.DoNotUse // Paper - Fix EntityBreedEvent copying
     public void setInLove(@Nullable Player player) {
+        // Paper start - Fix EntityBreedEvent copying
+        this.setInLove(player, null);
+    }
+    public void setInLove(@Nullable Player player, @Nullable ItemStack breedItemCopy) {
+        if (breedItemCopy != null) this.breedItem = breedItemCopy;
+        // Paper end - Fix EntityBreedEvent copying
         // CraftBukkit start
         EntityEnterLoveModeEvent entityEnterLoveModeEvent = CraftEventFactory.callEntityEnterLoveModeEvent(player, this, 600);
         if (entityEnterLoveModeEvent.isCancelled()) {
+            this.breedItem = null; // Paper - Fix EntityBreedEvent copying; clear if cancelled
             return;
         }
         this.inLove = entityEnterLoveModeEvent.getTicksInLove();
@@ -185,7 +194,7 @@ public abstract class Animal extends AgeableMob {
         if (player != null) {
             this.loveCause = player.getUUID();
         }
-        this.breedItem = player.getInventory().getSelected(); // CraftBukkit
+        // Paper - Fix EntityBreedEvent copying; set breed item in better place
 
         this.level().broadcastEntityEvent(this, (byte) 18);
     }
diff --git a/src/main/java/net/minecraft/world/entity/animal/Panda.java b/src/main/java/net/minecraft/world/entity/animal/Panda.java
index 0440fd2d1bb3f87641ad88de6d5ae64617536a6d..db60b91c2b26ca8cdb66e05deab7742ffe212767 100644
--- a/src/main/java/net/minecraft/world/entity/animal/Panda.java
+++ b/src/main/java/net/minecraft/world/entity/animal/Panda.java
@@ -668,8 +668,9 @@ public class Panda extends Animal {
                 this.usePlayerItem(player, hand, itemstack);
                 this.ageUp((int) ((float) (-this.getAge() / 20) * 0.1F), true);
             } else if (!this.level().isClientSide && this.getAge() == 0 && this.canFallInLove()) {
+                final ItemStack breedCopy = itemstack.copy(); // Paper - Fix EntityBreedEvent copying
                 this.usePlayerItem(player, hand, itemstack);
-                this.setInLove(player);
+                this.setInLove(player, breedCopy); // Paper - Fix EntityBreedEvent copying
             } else {
                 if (this.level().isClientSide || this.isSitting() || this.isInWater()) {
                     return InteractionResult.PASS;
diff --git a/src/main/java/net/minecraft/world/entity/animal/camel/Camel.java b/src/main/java/net/minecraft/world/entity/animal/camel/Camel.java
index 33531cbdd9b2a5607092d2364ce5655a63c2361c..9229948c90e278cbdacd0f82689144c8dc50956f 100644
--- a/src/main/java/net/minecraft/world/entity/animal/camel/Camel.java
+++ b/src/main/java/net/minecraft/world/entity/animal/camel/Camel.java
@@ -389,7 +389,7 @@ public class Camel extends AbstractHorse implements PlayerRideableJumping, Saddl
             boolean flag1 = this.isTamed() && this.getAge() == 0 && this.canFallInLove();
 
             if (flag1) {
-                this.setInLove(player);
+                this.setInLove(player, item.copy()); // Paper - Fix EntityBreedEvent copying
             }
 
             boolean flag2 = this.isBaby();
diff --git a/src/main/java/net/minecraft/world/entity/animal/horse/AbstractHorse.java b/src/main/java/net/minecraft/world/entity/animal/horse/AbstractHorse.java
index 8cae4e154ca07493aba9acadd4ff7150d7ae4f67..9357cf0179d19fbdfe76413e909a99b924c85780 100644
--- a/src/main/java/net/minecraft/world/entity/animal/horse/AbstractHorse.java
+++ b/src/main/java/net/minecraft/world/entity/animal/horse/AbstractHorse.java
@@ -571,7 +571,7 @@ public abstract class AbstractHorse extends Animal implements ContainerListener,
             b0 = 5;
             if (!this.level().isClientSide && this.isTamed() && this.getAge() == 0 && !this.isInLove()) {
                 flag = true;
-                this.setInLove(player);
+                this.setInLove(player, item.copy()); // Paper - Fix EntityBreedEvent copying
             }
         } else if (item.is(Items.GOLDEN_APPLE) || item.is(Items.ENCHANTED_GOLDEN_APPLE)) {
             f = 10.0F;
@@ -579,7 +579,7 @@ public abstract class AbstractHorse extends Animal implements ContainerListener,
             b0 = 10;
             if (!this.level().isClientSide && this.isTamed() && this.getAge() == 0 && !this.isInLove()) {
                 flag = true;
-                this.setInLove(player);
+                this.setInLove(player, item.copy()); // Paper - Fix EntityBreedEvent copying
             }
         }
 
diff --git a/src/main/java/net/minecraft/world/entity/animal/horse/Llama.java b/src/main/java/net/minecraft/world/entity/animal/horse/Llama.java
index d4eceb535561e11f5f7ab891e81aac285f3cd828..1dd4290287725898ace29e46b439b55df8fdd1af 100644
--- a/src/main/java/net/minecraft/world/entity/animal/horse/Llama.java
+++ b/src/main/java/net/minecraft/world/entity/animal/horse/Llama.java
@@ -183,7 +183,7 @@ public class Llama extends AbstractChestedHorse implements VariantHolder<Llama.V
             f = 10.0F;
             if (this.isTamed() && this.getAge() == 0 && this.canFallInLove()) {
                 flag = true;
-                this.setInLove(player);
+                this.setInLove(player, item.copy()); // Paper - Fix EntityBreedEvent copying
             }
         }