Paper/patches/server/0918-Restore-vanilla-entity-drops-behavior.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Jake Potrebic <jake.m.potrebic@gmail.com>
Date: Tue, 22 Mar 2022 09:34:41 -0700
Subject: [PATCH] Restore vanilla entity drops behavior

Instead of just tracking the itemstacks, this tracks with it, the
action to take with that itemstack to apply the correct logic
on dropping the item instead of generalizing it for all dropped
items like CB does.

diff --git a/src/main/java/net/minecraft/server/level/ServerPlayer.java b/src/main/java/net/minecraft/server/level/ServerPlayer.java
index 184f3c7a1304f4f9d2aaeae27172be9d853c30de..3cbb59df34156479d24a8251f2b3acbb5e60dc2c 100644
--- a/src/main/java/net/minecraft/server/level/ServerPlayer.java
+++ b/src/main/java/net/minecraft/server/level/ServerPlayer.java
@@ -978,22 +978,20 @@ public class ServerPlayer extends net.minecraft.world.entity.player.Player {
         if (this.isRemoved()) {
             return;
         }
-        java.util.List<org.bukkit.inventory.ItemStack> loot = new java.util.ArrayList<org.bukkit.inventory.ItemStack>(this.getInventory().getContainerSize());
+        List<DefaultDrop> loot = new java.util.ArrayList<>(this.getInventory().getContainerSize()); // Paper - Restore vanilla drops behavior
         boolean keepInventory = this.level().getGameRules().getBoolean(GameRules.RULE_KEEPINVENTORY) || this.isSpectator();
 
         if (!keepInventory) {
             for (ItemStack item : this.getInventory().getContents()) {
                 if (!item.isEmpty() && !EnchantmentHelper.has(item, EnchantmentEffectComponents.PREVENT_EQUIPMENT_DROP)) {
-                    loot.add(CraftItemStack.asCraftMirror(item));
+                    loot.add(new DefaultDrop(item, stack -> this.drop(stack, true, false, false))); // Paper - Restore vanilla drops behavior; drop function taken from Inventory#dropAll (don't fire drop event)
                 }
             }
         }
         if (this.shouldDropLoot() && this.level().getGameRules().getBoolean(GameRules.RULE_DOMOBLOOT)) { // Paper - fix player loottables running when mob loot gamerule is false
         // SPIGOT-5071: manually add player loot tables (SPIGOT-5195 - ignores keepInventory rule)
         this.dropFromLootTable(damageSource, this.lastHurtByPlayerTime > 0);
-        for (org.bukkit.inventory.ItemStack item : this.drops) {
-            loot.add(item);
-        }
+        loot.addAll(this.drops); // Paper
         this.drops.clear(); // SPIGOT-5188: make sure to clear
         } // Paper - fix player loottables running when mob loot gamerule is false
 
@@ -2530,8 +2528,8 @@ public class ServerPlayer extends net.minecraft.world.entity.player.Player {
     }
 
     @Override
-    public ItemEntity drop(ItemStack stack, boolean throwRandomly, boolean retainOwnership) {
-        ItemEntity entityitem = super.drop(stack, throwRandomly, retainOwnership);
+    public ItemEntity drop(ItemStack stack, boolean throwRandomly, boolean retainOwnership, boolean callDropEvent) { // Paper - Restore vanilla drops behavior; override method with most params
+        ItemEntity entityitem = super.drop(stack, throwRandomly, retainOwnership, callDropEvent); // Paper - Restore vanilla drops behavior; override method with most params
 
         if (entityitem == null) {
             return null;
diff --git a/src/main/java/net/minecraft/world/entity/Entity.java b/src/main/java/net/minecraft/world/entity/Entity.java
index d25bf5d1f0335e75edd78aa7b9706228e4d7fdec..1052133e22d90c90e5345ba423f6872cb5d2ad2d 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -2564,6 +2564,25 @@ public abstract class Entity implements SyncedDataHolder, Nameable, EntityAccess
 
     @Nullable
     public ItemEntity spawnAtLocation(ItemStack stack, float yOffset) {
+        // Paper start - Restore vanilla drops behavior
+        return this.spawnAtLocation(stack, yOffset, null);
+    }
+    public record DefaultDrop(Item item, org.bukkit.inventory.ItemStack stack, @Nullable java.util.function.Consumer<ItemStack> dropConsumer) {
+        public DefaultDrop(final ItemStack stack, final java.util.function.Consumer<ItemStack> dropConsumer) {
+            this(stack.getItem(), org.bukkit.craftbukkit.inventory.CraftItemStack.asCraftMirror(stack), dropConsumer);
+        }
+
+        public void runConsumer(final org.bukkit.World fallbackWorld, final Location fallbackLoc) {
+            if (this.dropConsumer == null || org.bukkit.craftbukkit.inventory.CraftItemType.bukkitToMinecraft(this.stack.getType()) != this.item) {
+                fallbackWorld.dropItem(fallbackLoc, this.stack);
+            } else {
+                this.dropConsumer.accept(org.bukkit.craftbukkit.inventory.CraftItemStack.asNMSCopy(this.stack));
+            }
+        }
+    }
+    @Nullable
+    public ItemEntity spawnAtLocation(ItemStack stack, float yOffset, @Nullable java.util.function.Consumer<? super ItemEntity> delayedAddConsumer) {
+        // Paper end - Restore vanilla drops behavior
         if (stack.isEmpty()) {
             return null;
         } else if (this.level().isClientSide) {
@@ -2571,14 +2590,21 @@ public abstract class Entity implements SyncedDataHolder, Nameable, EntityAccess
         } else {
             // CraftBukkit start - Capture drops for death event
             if (this instanceof net.minecraft.world.entity.LivingEntity && !((net.minecraft.world.entity.LivingEntity) this).forceDrops) {
-                ((net.minecraft.world.entity.LivingEntity) this).drops.add(org.bukkit.craftbukkit.inventory.CraftItemStack.asCraftMirror(stack)); // Paper - mirror so we can destroy it later
+                // Paper start - Restore vanilla drops behavior
+                ((net.minecraft.world.entity.LivingEntity) this).drops.add(new net.minecraft.world.entity.Entity.DefaultDrop(stack, itemStack -> {
+                    ItemEntity itemEntity = new ItemEntity(this.level, this.getX(), this.getY() + (double) yOffset, this.getZ(), itemStack); // stack is copied before consumer
+                    itemEntity.setDefaultPickUpDelay();
+                    this.level.addFreshEntity(itemEntity);
+                    if (delayedAddConsumer != null) delayedAddConsumer.accept(itemEntity);
+                }));
+                // Paper end - Restore vanilla drops behavior
                 return null;
             }
             // CraftBukkit end
             ItemEntity entityitem = new ItemEntity(this.level(), this.getX(), this.getY() + (double) yOffset, this.getZ(), stack.copy()); // Paper - copy so we can destroy original
             stack.setCount(0); // Paper - destroy this item - if this ever leaks due to game bugs, ensure it doesn't dupe
 
-            entityitem.setDefaultPickUpDelay();
+            entityitem.setDefaultPickUpDelay(); // Paper - diff on change (in dropConsumer)
             // Paper start - Call EntityDropItemEvent
             return this.spawnAtLocation(entityitem);
         }
diff --git a/src/main/java/net/minecraft/world/entity/LivingEntity.java b/src/main/java/net/minecraft/world/entity/LivingEntity.java
index 3f788e88604b77761c5add39450cf1640604c0f0..3e58fa4160fd4e4e5b5d00ba8f963b1b74be2663 100644
--- a/src/main/java/net/minecraft/world/entity/LivingEntity.java
+++ b/src/main/java/net/minecraft/world/entity/LivingEntity.java
@@ -278,7 +278,7 @@ public abstract class LivingEntity extends Entity implements Attackable {
     protected float appliedScale;
     // CraftBukkit start
     public int expToDrop;
-    public ArrayList<org.bukkit.inventory.ItemStack> drops = new ArrayList<org.bukkit.inventory.ItemStack>();
+    public ArrayList<DefaultDrop> drops = new ArrayList<>(); // Paper - Restore vanilla drops behavior
     public final org.bukkit.craftbukkit.attribute.CraftAttributeMap craftAttributes;
     public boolean collides = true;
     public Set<UUID> collidableExemptions = new HashSet<>();
diff --git a/src/main/java/net/minecraft/world/entity/boss/wither/WitherBoss.java b/src/main/java/net/minecraft/world/entity/boss/wither/WitherBoss.java
index 1b49090a466bc74d9e5f2815314955b6dfbb83dc..62271e74399a827a488159da234465ef18e15e6e 100644
--- a/src/main/java/net/minecraft/world/entity/boss/wither/WitherBoss.java
+++ b/src/main/java/net/minecraft/world/entity/boss/wither/WitherBoss.java
@@ -538,10 +538,9 @@ public class WitherBoss extends Monster implements PowerableMob, RangedAttackMob
     @Override
     protected void dropCustomDeathLoot(ServerLevel world, DamageSource source, boolean causedByPlayer) {
         super.dropCustomDeathLoot(world, source, causedByPlayer);
-        ItemEntity entityitem = this.spawnAtLocation((ItemLike) Items.NETHER_STAR);
-
+        ItemEntity entityitem = this.spawnAtLocation(new net.minecraft.world.item.ItemStack(Items.NETHER_STAR), 0, ItemEntity::setExtendedLifetime); // Paper - Restore vanilla drops behavior; spawnAtLocation returns null so modify the item entity with a consumer
         if (entityitem != null) {
-            entityitem.setExtendedLifetime();
+            entityitem.setExtendedLifetime(); // Paper - diff on change
         }
 
     }
diff --git a/src/main/java/net/minecraft/world/entity/decoration/ArmorStand.java b/src/main/java/net/minecraft/world/entity/decoration/ArmorStand.java
index 5bcb9a53ebebeef4bd6ec2458df4b63002ebd804..2f398750bfee5758ad8b1367b6fc14364e4de776 100644
--- a/src/main/java/net/minecraft/world/entity/decoration/ArmorStand.java
+++ b/src/main/java/net/minecraft/world/entity/decoration/ArmorStand.java
@@ -621,7 +621,7 @@ public class ArmorStand extends LivingEntity {
         ItemStack itemstack = new ItemStack(Items.ARMOR_STAND);
 
         itemstack.set(DataComponents.CUSTOM_NAME, this.getCustomName());
-        this.drops.add(org.bukkit.craftbukkit.inventory.CraftItemStack.asBukkitCopy(itemstack)); // CraftBukkit - add to drops
+        this.drops.add(new DefaultDrop(itemstack, stack -> Block.popResource(this.level(), this.blockPosition(), stack))); // CraftBukkit - add to drops // Paper - Restore vanilla drops behavior
         return this.brokenByAnything(world, damageSource); // Paper
     }
 
@@ -635,7 +635,7 @@ public class ArmorStand extends LivingEntity {
         for (i = 0; i < this.handItems.size(); ++i) {
             itemstack = (ItemStack) this.handItems.get(i);
             if (!itemstack.isEmpty()) {
-                this.drops.add(org.bukkit.craftbukkit.inventory.CraftItemStack.asCraftMirror(itemstack)); // CraftBukkit - add to drops // Paper - mirror so we can destroy it later - though this call site was safe
+                this.drops.add(new DefaultDrop(itemstack, stack -> Block.popResource(this.level(), this.blockPosition().above(), stack))); // CraftBukkit - add to drops // Paper - Restore vanilla drops behavior; mirror so we can destroy it later - though this call site was safe & spawn drops correctly
                 this.handItems.set(i, ItemStack.EMPTY);
             }
         }
@@ -643,7 +643,7 @@ public class ArmorStand extends LivingEntity {
         for (i = 0; i < this.armorItems.size(); ++i) {
             itemstack = (ItemStack) this.armorItems.get(i);
             if (!itemstack.isEmpty()) {
-                this.drops.add(org.bukkit.craftbukkit.inventory.CraftItemStack.asCraftMirror(itemstack)); // CraftBukkit - add to drops // Paper - mirror so we can destroy it later - though this call site was safe
+                this.drops.add(new DefaultDrop(itemstack, stack -> Block.popResource(this.level(), this.blockPosition().above(), stack))); // CraftBukkit - add to drops // Paper - Restore vanilla drops behavior; mirror so we can destroy it later - though this call site was safe & spawn drops correctly
                 this.armorItems.set(i, ItemStack.EMPTY);
             }
         }
diff --git a/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java b/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java
index c9a38f6b91ac538aea4c4a6f23d18415585a931b..bec1f62559b42acee6c955baf7851aecb9179e16 100644
--- a/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java
+++ b/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java
@@ -965,18 +965,24 @@ public class CraftEventFactory {
     }
 
     public static EntityDeathEvent callEntityDeathEvent(net.minecraft.world.entity.LivingEntity victim, DamageSource damageSource) {
-        return CraftEventFactory.callEntityDeathEvent(victim, damageSource, new ArrayList<org.bukkit.inventory.ItemStack>(0));
+        return CraftEventFactory.callEntityDeathEvent(victim, damageSource, new ArrayList<>(0)); // Paper - Restore vanilla drops behavior
     }
 
-    public static EntityDeathEvent callEntityDeathEvent(net.minecraft.world.entity.LivingEntity victim, DamageSource damageSource, List<org.bukkit.inventory.ItemStack> drops) {
+    public static EntityDeathEvent callEntityDeathEvent(net.minecraft.world.entity.LivingEntity victim, DamageSource damageSource, List<Entity.DefaultDrop> drops) { // Paper - Restore vanilla drops behavior
         // Paper start
         return CraftEventFactory.callEntityDeathEvent(victim, damageSource, drops, com.google.common.util.concurrent.Runnables.doNothing());
     }
-    public static EntityDeathEvent callEntityDeathEvent(net.minecraft.world.entity.LivingEntity victim, DamageSource damageSource, List<org.bukkit.inventory.ItemStack> drops, Runnable lootCheck) {
+
+    private static final java.util.function.Function<org.bukkit.inventory.ItemStack, Entity.DefaultDrop> FROM_FUNCTION = stack -> {
+        if (stack == null) return null;
+        return new Entity.DefaultDrop(CraftItemType.bukkitToMinecraft(stack.getType()), stack, null);
+    };
+
+    public static EntityDeathEvent callEntityDeathEvent(net.minecraft.world.entity.LivingEntity victim, DamageSource damageSource, List<Entity.DefaultDrop> drops, Runnable lootCheck) { // Paper
         // Paper end
         CraftLivingEntity entity = (CraftLivingEntity) victim.getBukkitEntity();
         CraftDamageSource bukkitDamageSource = new CraftDamageSource(damageSource);
-        EntityDeathEvent event = new EntityDeathEvent(entity, bukkitDamageSource, drops, victim.getExpReward(damageSource.getEntity()));
+        EntityDeathEvent event = new EntityDeathEvent(entity, bukkitDamageSource, new io.papermc.paper.util.TransformingRandomAccessList<>(drops, Entity.DefaultDrop::stack, FROM_FUNCTION), victim.getExpReward(damageSource.getEntity())); // Paper - Restore vanilla drops behavior
         populateFields(victim, event); // Paper - make cancellable
         CraftWorld world = (CraftWorld) entity.getWorld();
         Bukkit.getServer().getPluginManager().callEvent(event);
@@ -990,20 +996,24 @@ public class CraftEventFactory {
         victim.expToDrop = event.getDroppedExp();
         lootCheck.run(); // Paper - advancement triggers before destroying items
 
-        for (org.bukkit.inventory.ItemStack stack : event.getDrops()) {
+        // Paper start - Restore vanilla drops behavior
+        for (Entity.DefaultDrop drop : drops) {
+            if (drop == null) continue;
+            final org.bukkit.inventory.ItemStack stack = drop.stack();
+            // Paper end - Restore vanilla drops behavior
             if (stack == null || stack.getType() == Material.AIR || stack.getAmount() == 0) continue;
 
-            world.dropItem(entity.getLocation(), stack); // Paper - note: dropItem already clones due to this being bukkit -> NMS
+            drop.runConsumer(world, entity.getLocation()); // Paper - Restore vanilla drops behavior
             if (stack instanceof CraftItemStack) stack.setAmount(0); // Paper - destroy this item - if this ever leaks due to game bugs, ensure it doesn't dupe, but don't nuke bukkit stacks of manually added items
         }
 
         return event;
     }
 
-    public static PlayerDeathEvent callPlayerDeathEvent(ServerPlayer victim, DamageSource damageSource, List<org.bukkit.inventory.ItemStack> drops, net.kyori.adventure.text.Component deathMessage, boolean keepInventory) { // Paper - Adventure
+    public static PlayerDeathEvent callPlayerDeathEvent(ServerPlayer victim, DamageSource damageSource, List<Entity.DefaultDrop> drops, net.kyori.adventure.text.Component deathMessage, boolean keepInventory) { // Paper - Adventure & Restore vanilla drops behavior
         CraftPlayer entity = victim.getBukkitEntity();
         CraftDamageSource bukkitDamageSource = new CraftDamageSource(damageSource);
-        PlayerDeathEvent event = new PlayerDeathEvent(entity, bukkitDamageSource, drops, victim.getExpReward(damageSource.getEntity()), 0, deathMessage);
+        PlayerDeathEvent event = new PlayerDeathEvent(entity, bukkitDamageSource, new io.papermc.paper.util.TransformingRandomAccessList<>(drops, Entity.DefaultDrop::stack, FROM_FUNCTION), victim.getExpReward(damageSource.getEntity()), 0, deathMessage); // Paper - Restore vanilla drops behavior
         event.setKeepInventory(keepInventory);
         event.setKeepLevel(victim.keepLevel); // SPIGOT-2222: pre-set keepLevel
         populateFields(victim, event); // Paper - make cancellable
@@ -1022,10 +1032,14 @@ public class CraftEventFactory {
         victim.expToDrop = event.getDroppedExp();
         victim.newExp = event.getNewExp();
 
-        for (org.bukkit.inventory.ItemStack stack : event.getDrops()) {
+        // Paper start - Restore vanilla drops behavior
+        for (Entity.DefaultDrop drop : drops) {
+            if (drop == null) continue;
+            final org.bukkit.inventory.ItemStack stack = drop.stack();
+            // Paper end - Restore vanilla drops behavior
             if (stack == null || stack.getType() == Material.AIR) continue;
 
-            world.dropItem(entity.getLocation(), stack);
+            drop.runConsumer(world, entity.getLocation()); // Paper - Restore vanilla drops behavior
         }
 
         return event;