Paper/patches/unapplied/server/0976-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 2bb82dcffd8fdc25d658ec36a34f959b25217396..bd6c60ebfc76d19313bf01048268f8ce7e6603c5 100644
--- a/src/main/java/net/minecraft/server/level/ServerPlayer.java
+++ b/src/main/java/net/minecraft/server/level/ServerPlayer.java
@@ -891,22 +891,20 @@ public class ServerPlayer extends 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.hasVanishingCurse(item)) {
-                    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
 
@@ -2389,8 +2387,8 @@ public class ServerPlayer extends 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 2848be4604e08d0d651d16e960cda9a4d0234d41..5275e7a34f86830d43edcab3a0e94f8d8e9cfae5 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -2496,6 +2496,25 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource, S
 
     @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) {
@@ -2503,14 +2522,21 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource, S
         } 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 a648cc01f2cdfac46fd2e760705cf85e534e926f..d396201655fde7ff35cf2a342fa458e5ea3f80a8 100644
--- a/src/main/java/net/minecraft/world/entity/LivingEntity.java
+++ b/src/main/java/net/minecraft/world/entity/LivingEntity.java
@@ -255,7 +255,7 @@ public abstract class LivingEntity extends Entity implements Attackable {
     // CraftBukkit start
     public int expToDrop;
     public boolean forceDrops;
-    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 6c215470ad05d59f903cbeff15088a03b42c3f66..12440ee2dccc0a697fb403765f2e1b987ccc0283 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
@@ -535,10 +535,10 @@ public class WitherBoss extends Monster implements PowerableMob, RangedAttackMob
     @Override
     protected void dropCustomDeathLoot(DamageSource source, int lootingMultiplier, boolean allowDrops) {
         super.dropCustomDeathLoot(source, lootingMultiplier, allowDrops);
-        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 f62b5976e307a69ca40d51ae76126005c801df0c..bbe299afd361a107e3936c8ea1a62067fcac9b7e 100644
--- a/src/main/java/net/minecraft/world/entity/decoration/ArmorStand.java
+++ b/src/main/java/net/minecraft/world/entity/decoration/ArmorStand.java
@@ -611,7 +611,7 @@ public class ArmorStand extends LivingEntity {
             itemstack.setHoverName(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(damageSource); // Paper
     }
 
@@ -625,7 +625,7 @@ 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);
             }
         }
@@ -633,7 +633,7 @@ 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 53c3b2123d6fa78367aef53d6949e58170cb9fce..99292a908b36e3c75d51c6877c7a0c01d9671aa6 100644
--- a/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java
+++ b/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java
@@ -965,17 +965,23 @@ public class CraftEventFactory {
     }
 
     public static EntityDeathEvent callEntityDeathEvent(net.minecraft.world.entity.LivingEntity victim) {
-        return CraftEventFactory.callEntityDeathEvent(victim, new ArrayList<org.bukkit.inventory.ItemStack>(0));
+        return CraftEventFactory.callEntityDeathEvent(victim, new ArrayList<>(0)); // Paper - Restore vanilla drops behavior
     }
 
-    public static EntityDeathEvent callEntityDeathEvent(net.minecraft.world.entity.LivingEntity victim, List<org.bukkit.inventory.ItemStack> drops) {
+    public static EntityDeathEvent callEntityDeathEvent(net.minecraft.world.entity.LivingEntity victim, List<Entity.DefaultDrop> drops) { // Paper - Restore vanilla drops behavior
         // Paper start
         return CraftEventFactory.callEntityDeathEvent(victim, drops, com.google.common.util.concurrent.Runnables.doNothing());
     }
-    public static EntityDeathEvent callEntityDeathEvent(net.minecraft.world.entity.LivingEntity victim, 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, List<Entity.DefaultDrop> drops, Runnable lootCheck) { // Paper
         // Paper end
         CraftLivingEntity entity = (CraftLivingEntity) victim.getBukkitEntity();
-        EntityDeathEvent event = new EntityDeathEvent(entity, drops, victim.getExpReward());
+        EntityDeathEvent event = new EntityDeathEvent(entity, new io.papermc.paper.util.TransformingRandomAccessList<>(drops, Entity.DefaultDrop::stack, FROM_FUNCTION), victim.getExpReward()); // Paper - Restore vanilla drops behavior
         populateFields(victim, event); // Paper - make cancellable
         CraftWorld world = (CraftWorld) entity.getWorld();
         Bukkit.getServer().getPluginManager().callEvent(event);
@@ -989,19 +995,23 @@ 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, List<org.bukkit.inventory.ItemStack> drops, net.kyori.adventure.text.Component deathMessage, boolean keepInventory) { // Paper - Adventure
+    public static PlayerDeathEvent callPlayerDeathEvent(ServerPlayer victim, List<Entity.DefaultDrop> drops, net.kyori.adventure.text.Component deathMessage, boolean keepInventory) { // Paper - Adventure & Restore vanilla drops behavior
         CraftPlayer entity = victim.getBukkitEntity();
-        PlayerDeathEvent event = new PlayerDeathEvent(entity, drops, victim.getExpReward(), 0, deathMessage);
+        PlayerDeathEvent event = new PlayerDeathEvent(entity, new io.papermc.paper.util.TransformingRandomAccessList<>(drops, Entity.DefaultDrop::stack, FROM_FUNCTION), victim.getExpReward(), 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
@@ -1020,10 +1030,14 @@ 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;