PaperMC/patches/server/0969-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 907ed82fea71254d6624eda878e2668cd26422a7..081d1e38b7b1f286e138b0981aaa760e58761215 100644
--- a/src/main/java/net/minecraft/world/entity/animal/Animal.java
+++ b/src/main/java/net/minecraft/world/entity/animal/Animal.java
@@ -152,8 +152,9 @@ 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;
             }
 
@@ -182,10 +183,18 @@ 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();
@@ -193,7 +202,7 @@ 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 f783fe169141d33e8569ec7f5d71985b74bdbcb6..be554dbaa9900207753e4f67f0ba402333e21338 100644
--- a/src/main/java/net/minecraft/world/entity/animal/Panda.java
+++ b/src/main/java/net/minecraft/world/entity/animal/Panda.java
@@ -649,8 +649,9 @@ 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 e89f454fe178483a7db381591a4a345ac24db2b8..f693d4d6a6a3c3d31c2d85ceb5b5b01366c970a1 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 bl2 = this.isTamed() && this.getAge() == 0 && this.canFallInLove();
             if (bl2) {
-                this.setInLove(player);
+                this.setInLove(player, item.copy()); // Paper - Fix EntityBreedEvent copying
             }
 
             boolean bl3 = 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 94dd97662ba07689fbfa16ef5c7d99fe12ce83de..815eb15086976b8f9e03bf8182d9ed50aec14720 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
@@ -513,7 +513,7 @@ 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;
@@ -521,7 +521,7 @@ 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 9b5b894d43f25566ab9c3698705e978ab823a0d2..6623674136b0f865d5b3d7a10d3bf05793b82f87 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
@@ -191,7 +191,7 @@ 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
             }
         }