Paper/patches/unapplied/server/0964-Fix-DamageSource-API.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Jake Potrebic <jake.m.potrebic@gmail.com>
Date: Sat, 9 Mar 2024 14:13:04 -0800
Subject: [PATCH] Fix DamageSource API

Uses the correct entity in the EntityDamageByEntity event
Returns the correct entity for API's DamageSource#getCausingEntity

diff --git a/src/main/java/net/minecraft/world/damagesource/DamageSource.java b/src/main/java/net/minecraft/world/damagesource/DamageSource.java
index 533ea6cbb813c8d1dc2bb3f65fd94d4fa5dd591e..dd9638bdb228a53e72820e0e7cf6fe6fcc08fe4b 100644
--- a/src/main/java/net/minecraft/world/damagesource/DamageSource.java
+++ b/src/main/java/net/minecraft/world/damagesource/DamageSource.java
@@ -29,7 +29,8 @@ public class DamageSource {
     private boolean sweep = false;
     private boolean melting = false;
     private boolean poison = false;
-    private Entity customEntityDamager = null; // This field is a helper for when causing entity damage is not set by vanilla
+    @Nullable
+    private Entity customEventDamager = null; // This field is a helper for when causing entity damage is not set by vanilla // Paper - fix DamageSource API
 
     public DamageSource sweep() {
         this.sweep = true;
@@ -58,18 +59,19 @@ public class DamageSource {
         return this.poison;
     }
 
-    public Entity getDamager() {
-        return (this.customEntityDamager != null) ? this.customEntityDamager : this.directEntity;
+    // Paper start - fix DamageSource API
+    @Nullable
+    public Entity getCustomEventDamager() {
+        return (this.customEventDamager != null) ? this.customEventDamager : this.directEntity;
     }
 
-    public DamageSource customEntityDamager(Entity entity) {
-        // This method is not intended for change the causing entity if is already set
-        // also is only necessary if the entity passed is not the direct entity or different from the current causingEntity
-        if (this.customEntityDamager != null || this.directEntity == entity || this.causingEntity == entity) {
-            return this;
+    public DamageSource customEventDamager(Entity entity) {
+        if (this.directEntity != null) {
+            throw new IllegalStateException("Cannot set custom event damager when direct entity is already set (report a bug to Paper)");
         }
         DamageSource damageSource = this.cloneInstance();
-        damageSource.customEntityDamager = entity;
+        damageSource.customEventDamager = entity;
+        // Paper end - fix DamageSource API
         return damageSource;
     }
 
diff --git a/src/main/java/net/minecraft/world/damagesource/DamageSources.java b/src/main/java/net/minecraft/world/damagesource/DamageSources.java
index abda6094e02ebd2589ba0e4760e574fcf44dc8e4..5ec8cbd07a1830876f58e1fd33de6df4466d7e95 100644
--- a/src/main/java/net/minecraft/world/damagesource/DamageSources.java
+++ b/src/main/java/net/minecraft/world/damagesource/DamageSources.java
@@ -258,13 +258,7 @@ public class DamageSources {
     }
 
     public DamageSource explosion(@Nullable Entity source, @Nullable Entity attacker) {
-        // CraftBukkit start
-        return this.explosion(source, attacker, attacker != null && source != null ? DamageTypes.PLAYER_EXPLOSION : DamageTypes.EXPLOSION);
-    }
-
-    public DamageSource explosion(@Nullable Entity entity, @Nullable Entity entity1, ResourceKey<DamageType> resourceKey) {
-        return this.source(resourceKey, entity, entity1);
-        // CraftBukkit end
+        return this.source(attacker != null && source != null ? DamageTypes.PLAYER_EXPLOSION : DamageTypes.EXPLOSION, source, attacker); // Paper - revert to vanilla
     }
 
     public DamageSource sonicBoom(Entity attacker) {
diff --git a/src/main/java/net/minecraft/world/entity/Entity.java b/src/main/java/net/minecraft/world/entity/Entity.java
index d6ec2fe1a4a004a2d2f7d6e5bfd8fd45b27ebb7a..62363c09111aaa31220fb260940744c097af7b3c 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -3200,7 +3200,7 @@ public abstract class Entity implements SyncedDataHolder, Nameable, EntityAccess
             return;
         }
 
-        if (!this.hurt(this.damageSources().lightningBolt().customEntityDamager(lightning), 5.0F)) {
+        if (!this.hurt(this.damageSources().lightningBolt().customEventDamager(lightning), 5.0F)) { // Paper - fix DamageSource API
             return;
         }
         // CraftBukkit end
diff --git a/src/main/java/net/minecraft/world/entity/animal/Turtle.java b/src/main/java/net/minecraft/world/entity/animal/Turtle.java
index b4d68a08ec1e4ec7bcc123bcb6c2dc90272430cf..ffffa53fcaa6ec8681b283fa20bb5a3320ad9c11 100644
--- a/src/main/java/net/minecraft/world/entity/animal/Turtle.java
+++ b/src/main/java/net/minecraft/world/entity/animal/Turtle.java
@@ -334,7 +334,7 @@ public class Turtle extends Animal {
 
     @Override
     public void thunderHit(ServerLevel world, LightningBolt lightning) {
-        this.hurt(this.damageSources().lightningBolt().customEntityDamager(lightning), Float.MAX_VALUE); // CraftBukkit
+        this.hurt(this.damageSources().lightningBolt().customEventDamager(lightning), Float.MAX_VALUE); // CraftBukkit // Paper - fix DamageSource API
     }
 
     @Override
diff --git a/src/main/java/net/minecraft/world/entity/decoration/HangingEntity.java b/src/main/java/net/minecraft/world/entity/decoration/HangingEntity.java
index 0ffff5329fa2c7833f9ec71528cb7f951cf78109..bf2d91bbb4bf401696f5f5d14a67e3920a179084 100644
--- a/src/main/java/net/minecraft/world/entity/decoration/HangingEntity.java
+++ b/src/main/java/net/minecraft/world/entity/decoration/HangingEntity.java
@@ -203,7 +203,7 @@ public abstract class HangingEntity extends Entity {
         } else {
             if (!this.isRemoved() && !this.level().isClientSide) {
                 // CraftBukkit start - fire break events
-                Entity damager = (source.isIndirect()) ? source.getEntity() : source.getDirectEntity();
+                Entity damager = (source.isIndirect() && source.getEntity() != null) ? source.getEntity() : source.getDirectEntity(); // Paper - fix DamageSource API
                 HangingBreakEvent event;
                 if (damager != null) {
                     event = new HangingBreakByEntityEvent((Hanging) this.getBukkitEntity(), damager.getBukkitEntity(), source.is(DamageTypeTags.IS_EXPLOSION) ? HangingBreakEvent.RemoveCause.EXPLOSION : HangingBreakEvent.RemoveCause.ENTITY);
diff --git a/src/main/java/net/minecraft/world/entity/monster/Creeper.java b/src/main/java/net/minecraft/world/entity/monster/Creeper.java
index 7db5de71b0353d9807978c0351870fd99b76ee67..0ae4ba060b2ce2c79e1235c939f3c1926eb6e33e 100644
--- a/src/main/java/net/minecraft/world/entity/monster/Creeper.java
+++ b/src/main/java/net/minecraft/world/entity/monster/Creeper.java
@@ -271,7 +271,7 @@ public class Creeper extends Monster implements PowerableMob {
             if (!event.isCancelled()) {
             // CraftBukkit end
             this.dead = true;
-            this.level().explode(this, this.level().damageSources().explosion(this, this.entityIgniter, net.minecraft.world.damagesource.DamageTypes.EXPLOSION), null, this.getX(), this.getY(), this.getZ(), event.getRadius(), event.getFire(), Level.ExplosionInteraction.MOB); // CraftBukkit
+            this.level().explode(this, this.getX(), this.getY(), this.getZ(), event.getRadius(), event.getFire(), Level.ExplosionInteraction.MOB); // CraftBukkit // Paper - fix DamageSource API (revert to vanilla, no, just no, don't change this)
             this.discard(EntityRemoveEvent.Cause.EXPLODE); // CraftBukkit - add Bukkit remove cause
             this.spawnLingeringCloud();
             // CraftBukkit start
diff --git a/src/main/java/net/minecraft/world/entity/projectile/EvokerFangs.java b/src/main/java/net/minecraft/world/entity/projectile/EvokerFangs.java
index edc5cfd3f3eab176df9080cf932dac3905f1b26d..f8aa723f18e28b02d4b7055404922ff8d7a73f8d 100644
--- a/src/main/java/net/minecraft/world/entity/projectile/EvokerFangs.java
+++ b/src/main/java/net/minecraft/world/entity/projectile/EvokerFangs.java
@@ -133,7 +133,7 @@ public class EvokerFangs extends Entity implements TraceableEntity {
 
         if (target.isAlive() && !target.isInvulnerable() && target != entityliving1) {
             if (entityliving1 == null) {
-                target.hurt(this.damageSources().magic().customEntityDamager(this), 6.0F); // CraftBukkit
+                target.hurt(this.damageSources().magic().customEventDamager(this), 6.0F); // CraftBukkit // Paper - fix DamageSource API
             } else {
                 if (entityliving1.isAlliedTo((Entity) target)) {
                     return;
diff --git a/src/main/java/net/minecraft/world/entity/projectile/ThrownEnderpearl.java b/src/main/java/net/minecraft/world/entity/projectile/ThrownEnderpearl.java
index ced6bf2fc4556c9b2b32ac382058506e931c1475..519755b7f8bc7e8bb9fab135fc5bf7de3a9419f9 100644
--- a/src/main/java/net/minecraft/world/entity/projectile/ThrownEnderpearl.java
+++ b/src/main/java/net/minecraft/world/entity/projectile/ThrownEnderpearl.java
@@ -85,7 +85,7 @@ public class ThrownEnderpearl extends ThrowableItemProjectile {
 
                         entityplayer.connection.teleport(teleEvent.getTo());
                         entity.resetFallDistance();
-                        entity.hurt(this.damageSources().fall().customEntityDamager(this), 5.0F); // CraftBukkit
+                        entity.hurt(this.damageSources().fall().customEventDamager(this), 5.0F); // CraftBukkit // Paper - fix DamageSource API
                     }
                     // CraftBukkit end
                     this.level().playSound((Player) null, this.getX(), this.getY(), this.getZ(), SoundEvents.PLAYER_TELEPORT, SoundSource.PLAYERS);
diff --git a/src/main/java/net/minecraft/world/entity/projectile/WitherSkull.java b/src/main/java/net/minecraft/world/entity/projectile/WitherSkull.java
index 02931861de955352e71d6f5ffc720a17304815fe..55b4b5ad5f084c9a271a716d076672478d6486ba 100644
--- a/src/main/java/net/minecraft/world/entity/projectile/WitherSkull.java
+++ b/src/main/java/net/minecraft/world/entity/projectile/WitherSkull.java
@@ -72,7 +72,7 @@ public class WitherSkull extends AbstractHurtingProjectile {
                     }
                 }
             } else {
-                flag = entity.hurt(this.damageSources().magic().customCausingEntity(this), 5.0F); // Paper - Fire EntityDamageByEntityEvent for unowned wither skulls
+                flag = entity.hurt(this.damageSources().magic().customEventDamager(this), 5.0F); // Paper - Fire EntityDamageByEntityEvent for unowned wither skulls // Paper - fix DamageSource API
             }
 
             if (flag && entity instanceof LivingEntity) {
diff --git a/src/main/java/org/bukkit/craftbukkit/damage/CraftDamageSource.java b/src/main/java/org/bukkit/craftbukkit/damage/CraftDamageSource.java
index ab67c5caaff6e8c7de293b528636f53254b805bd..6d92856b5089e946a85d519cadce080bc6c3574f 100644
--- a/src/main/java/org/bukkit/craftbukkit/damage/CraftDamageSource.java
+++ b/src/main/java/org/bukkit/craftbukkit/damage/CraftDamageSource.java
@@ -47,7 +47,7 @@ public class CraftDamageSource implements DamageSource {
 
     @Override
     public org.bukkit.entity.Entity getDirectEntity() {
-        net.minecraft.world.entity.Entity entity = this.getHandle().getDamager();
+        net.minecraft.world.entity.Entity entity = this.getHandle().getDirectEntity(); // Paper - fix DamageSource API
         return (entity != null) ? entity.getBukkitEntity() : null;
     }
 
@@ -65,7 +65,7 @@ public class CraftDamageSource implements DamageSource {
 
     @Override
     public boolean isIndirect() {
-        return this.getHandle().getEntity() != this.getHandle().getDamager();
+        return this.getHandle().isIndirect(); // Paper - fix DamageSource API
     }
 
     @Override
diff --git a/src/main/java/org/bukkit/craftbukkit/damage/CraftDamageSourceBuilder.java b/src/main/java/org/bukkit/craftbukkit/damage/CraftDamageSourceBuilder.java
index 4c6e15535fa40aad8cf1920f392589404f9ba79c..35eb95ef6fb6a0f7ea63351e90741c489fdd15f9 100644
--- a/src/main/java/org/bukkit/craftbukkit/damage/CraftDamageSourceBuilder.java
+++ b/src/main/java/org/bukkit/craftbukkit/damage/CraftDamageSourceBuilder.java
@@ -41,6 +41,11 @@ public class CraftDamageSourceBuilder implements DamageSource.Builder {
 
     @Override
     public DamageSource build() {
+        // Paper start - fix DamageCause API
+        if (this.causingEntity != null && this.directEntity == null) {
+            throw new IllegalArgumentException("Direct entity must be set if causing entity is set");
+        }
+        // Paper end - fix DamageCause API
         return CraftDamageSource.buildFromBukkit(this.damageType, this.causingEntity, this.directEntity, this.damageLocation);
     }
 }
diff --git a/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java b/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java
index e20feab675d05ae5b5b19870546585936c757970..96070da795755f71e99979288e32b7d7e2d869fb 100644
--- a/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java
+++ b/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java
@@ -1084,7 +1084,7 @@ public class CraftEventFactory {
 
     private static EntityDamageEvent handleEntityDamageEvent(Entity entity, DamageSource source, Map<DamageModifier, Double> modifiers, Map<DamageModifier, Function<? super Double, Double>> modifierFunctions, boolean cancelled) {
         CraftDamageSource bukkitDamageSource = new CraftDamageSource(source);
-        Entity damager = (source.getDamager() != null) ? source.getDamager() : source.getEntity();
+        final Entity damager = source.getCustomEventDamager(); // Paper - fix DamageSource API
         if (source.is(DamageTypeTags.IS_EXPLOSION)) {
             if (damager == null) {
                 return CraftEventFactory.callEntityDamageEvent(source.getDirectBlock(), source.getDirectBlockState(), entity, DamageCause.BLOCK_EXPLOSION, bukkitDamageSource, modifiers, modifierFunctions, cancelled);