Fix DamageSource API

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

paper-server/patches/sources/net/minecraft/world/damagesource/DamageSource.java.patch

@@ -1,6 +1,6 @@
 --- a/net/minecraft/world/damagesource/DamageSource.java
 +++ b/net/minecraft/world/damagesource/DamageSource.java
-@@ -21,7 +21,120 @@
+@@ -21,7 +21,106 @@
      private final Entity directEntity;
      @Nullable
      private final Vec3 damageSourcePosition;
@@ -12,8 +12,8 @@
 +    private boolean sweep = false;
 +    private boolean melting = false;
 +    private boolean poison = false;
-+    private Entity customEntityDamager = null; // This field is a helper for when direct entity damage is not set by vanilla
++    @Nullable
-+    private Entity customCausingEntityDamager = null; // This field is a helper for when causing entity damage is not set by vanilla
++    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;
@@ -42,33 +42,19 @@
 +        return this.poison;
 +    }
 +
-+    public Entity getDamager() {
++    // Paper start - fix DamageSource API
-+        return (this.customEntityDamager != null) ? this.customEntityDamager : this.directEntity;
++    @Nullable
++    public Entity getCustomEventDamager() {
++        return (this.customEventDamager != null) ? this.customEventDamager : this.directEntity;
 +    }
 +
-+    public Entity getCausingDamager() {
++    public DamageSource customEventDamager(Entity entity) {
-+        return (this.customCausingEntityDamager != null) ? this.customCausingEntityDamager : this.causingEntity;
++        if (this.directEntity != null) {
-+    }
++            throw new IllegalStateException("Cannot set custom event damager when direct entity is already set (report a bug to Paper)");
-+
-+    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;
 +        }
 +        DamageSource damageSource = this.cloneInstance();
-+        damageSource.customEntityDamager = entity;
++        damageSource.customEventDamager = entity;
-+        return damageSource;
++        // Paper end - fix DamageSource API
-+    }
-+
-+    public DamageSource customCausingEntityDamager(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.customCausingEntityDamager != null || this.directEntity == entity || this.causingEntity == entity) {
-+            return this;
-+        }
-+        DamageSource damageSource = this.cloneInstance();
-+        damageSource.customCausingEntityDamager = entity;
 +        return damageSource;
 +    }
 +
@@ -121,7 +107,7 @@
      public String toString() {
          return "DamageSource (" + this.type().msgId() + ")";
      }
-@@ -163,4 +276,18 @@
+@@ -163,4 +262,18 @@
      public Holder<DamageType> typeHolder() {
          return this.type;
      }

paper-server/patches/sources/net/minecraft/world/damagesource/DamageSources.java.patch

@@ -16,10 +16,11 @@
          this.inFire = this.source(DamageTypes.IN_FIRE);
          this.campfire = this.source(DamageTypes.CAMPFIRE);
          this.lightningBolt = this.source(DamageTypes.LIGHTNING_BOLT);
-@@ -84,6 +90,16 @@
+@@ -83,7 +89,17 @@
+ 
      private DamageSource source(ResourceKey<DamageType> key, @Nullable Entity source, @Nullable Entity attacker) {
          return new DamageSource(this.damageTypes.getOrThrow(key), source, attacker);
-     }
++    }
 +
 +    // CraftBukkit start
 +    public DamageSource melting() {
@@ -28,27 +29,21 @@
 +
 +    public DamageSource poison() {
 +        return this.poison;
-+    }
+     }
 +    // CraftBukkit end
  
      public DamageSource inFire() {
          return this.inFire;
-@@ -254,17 +270,29 @@
+@@ -254,7 +270,7 @@
      }
  
      public DamageSource explosion(@Nullable Entity source, @Nullable Entity attacker) {
 -        return this.source(attacker != null && source != null ? DamageTypes.PLAYER_EXPLOSION : DamageTypes.EXPLOSION, source, attacker);
-+        // CraftBukkit start
++        return this.source(attacker != null && source != null ? DamageTypes.PLAYER_EXPLOSION : DamageTypes.EXPLOSION, source, attacker); // Paper - revert to vanilla
-+        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
-+    }
-+
      public DamageSource sonicBoom(Entity attacker) {
-         return this.source(DamageTypes.SONIC_BOOM, attacker);
+@@ -262,9 +278,15 @@
      }
  
      public DamageSource badRespawnPointExplosion(Vec3 position) {

paper-server/patches/sources/net/minecraft/world/entity/Entity.java.patch

@@ -1391,7 +1391,7 @@
 +            return;
 +        }
 +
-+        if (!this.hurtServer(world, this.damageSources().lightningBolt().customEntityDamager(lightning), 5.0F)) {
++        if (!this.hurtServer(world, this.damageSources().lightningBolt().customEventDamager(lightning), 5.0F)) { // Paper - fix DamageSource API
 +            return;
 +        }
 +        // CraftBukkit end

paper-server/patches/sources/net/minecraft/world/entity/animal/Turtle.java.patch

@@ -15,7 +15,7 @@
      @Override
      public void thunderHit(ServerLevel world, LightningBolt lightning) {
 -        this.hurtServer(world, this.damageSources().lightningBolt(), Float.MAX_VALUE);
-+        this.hurtServer(world, this.damageSources().lightningBolt().customEntityDamager(lightning), Float.MAX_VALUE); // CraftBukkit
++        this.hurtServer(world, this.damageSources().lightningBolt().customEventDamager(lightning), Float.MAX_VALUE); // CraftBukkit // Paper - fix DamageSource API
      }
  
      @Override

paper-server/patches/sources/net/minecraft/world/entity/decoration/BlockAttachedEntity.java.patch

@@ -72,7 +72,7 @@
          } else {
              if (!this.isRemoved()) {
 +                // CraftBukkit start - fire break events
-+                Entity damager = (source.isDirect()) ? source.getDirectEntity() : source.getEntity();
++                Entity damager = (!source.isDirect() && 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);

paper-server/patches/sources/net/minecraft/world/entity/monster/Creeper.java.patch

@@ -73,7 +73,7 @@
 +            // CraftBukkit end
              this.dead = true;
 -            worldserver.explode(this, this.getX(), this.getY(), this.getZ(), (float) this.explosionRadius * f, Level.ExplosionInteraction.MOB);
-+            worldserver.explode(this, net.minecraft.world.level.Explosion.getDefaultDamageSource(this.level(), this).customCausingEntityDamager(this.entityIgniter), null, this.getX(), this.getY(), this.getZ(), event.getRadius(), event.getFire(), Level.ExplosionInteraction.MOB); // CraftBukkit
++            worldserver.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.spawnLingeringCloud();
              this.triggerOnDeathMobEffects(worldserver, Entity.RemovalReason.KILLED);
 -            this.discard();

paper-server/patches/sources/net/minecraft/world/entity/projectile/EvokerFangs.java.patch

@@ -24,7 +24,7 @@
          if (target.isAlive() && !target.isInvulnerable() && target != entityliving1) {
              if (entityliving1 == null) {
 -                target.hurt(this.damageSources().magic(), 6.0F);
-+                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;

paper-server/patches/sources/net/minecraft/world/entity/projectile/ThrownEnderpearl.java.patch

@@ -48,7 +48,7 @@
                                  entityplayer1.resetFallDistance();
                                  entityplayer1.resetCurrentImpulseContext();
 -                                entityplayer1.hurtServer(entityplayer.serverLevel(), this.damageSources().enderPearl(), 5.0F);
-+                                entityplayer1.hurtServer(entityplayer.serverLevel(), this.damageSources().enderPearl().customEntityDamager(this), 5.0F); // CraftBukkit
++                                entityplayer1.hurtServer(entityplayer.serverLevel(), this.damageSources().enderPearl().customEventDamager(this), 5.0F); // CraftBukkit // Paper - fix DamageSource API
                              }
  
                              this.playSound(worldserver, vec3d);

paper-server/patches/sources/net/minecraft/world/entity/projectile/WitherSkull.java.patch

@@ -21,7 +21,7 @@
                  }
              } else {
 -                flag = entity.hurtServer(worldserver, this.damageSources().magic(), 5.0F);
-+                flag = entity.hurtServer(worldserver, this.damageSources().magic().customCausingEntity(this), 5.0F); // Paper - Fire EntityDamageByEntityEvent for unowned wither skulls
++                flag = entity.hurtServer(worldserver, this.damageSources().magic().customEventDamager(this), 5.0F); // Paper - Fire EntityDamageByEntityEvent for unowned wither skulls // Paper - fix DamageSource API
              }
  
              if (flag && entity instanceof LivingEntity entityliving) {

paper-server/src/main/java/org/bukkit/craftbukkit/damage/CraftDamageSource.java

@@ -41,13 +41,13 @@ public class CraftDamageSource implements DamageSource {
 
     @Override
     public org.bukkit.entity.Entity getCausingEntity() {
-        net.minecraft.world.entity.Entity entity = this.getHandle().getCausingDamager();
+        net.minecraft.world.entity.Entity entity = this.getHandle().getEntity(); // Paper - fix DamageSource API - revert to vanilla
         return (entity != null) ? entity.getBukkitEntity() : null;
     }
 
     @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().getCausingDamager() != this.getHandle().getDamager();
+        return !this.getHandle().isDirect(); // Paper - fix DamageSource API
     }
 
     @Override

paper-server/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);
     }
 }

paper-server/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java

@@ -1092,7 +1092,7 @@ 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);