Fix potions splash events

Fix PotionSplashEvent for water splash potions
Fixes SPIGOT-6221: https://hub.spigotmc.org/jira/projects/SPIGOT/issues/SPIGOT-6221
Fix splash events cancellation that still show particles/sound

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

@@ -55,47 +55,98 @@
          super(EntityType.POTION, owner, world, stack);
      }
  
-@@ -101,28 +111,28 @@
+@@ -99,64 +109,86 @@
+             ItemStack itemstack = this.getItem();
+             PotionContents potioncontents = (PotionContents) itemstack.getOrDefault(DataComponents.POTION_CONTENTS, PotionContents.EMPTY);
  
++            boolean showParticles = true; // Paper - Fix potions splash events
              if (potioncontents.is(Potions.WATER)) {
-                 this.applyWater(worldserver);
+-                this.applyWater(worldserver);
 -            } else if (potioncontents.hasEffects()) {
++                showParticles = this.applyWater(worldserver, hitResult); // Paper - Fix potions splash events
 +            } else if (true || potioncontents.hasEffects()) { // CraftBukkit - Call event even if no effects to apply
                  if (this.isLingering()) {
 -                    this.makeAreaOfEffectCloud(potioncontents);
-+                    this.makeAreaOfEffectCloud(potioncontents, hitResult); // CraftBukkit - Pass MovingObjectPosition
++                    showParticles = this.makeAreaOfEffectCloud(potioncontents, hitResult); // CraftBukkit - Pass MovingObjectPosition // Paper
                  } else {
 -                    this.applySplash(worldserver, potioncontents.getAllEffects(), hitResult.getType() == HitResult.Type.ENTITY ? ((EntityHitResult) hitResult).getEntity() : null);
-+                    this.applySplash(worldserver, potioncontents.getAllEffects(), hitResult.getType() == HitResult.Type.ENTITY ? ((EntityHitResult) hitResult).getEntity() : null, hitResult); // CraftBukkit - Pass MovingObjectPosition
++                    showParticles = this.applySplash(worldserver, potioncontents.getAllEffects(), hitResult.getType() == HitResult.Type.ENTITY ? ((EntityHitResult) hitResult).getEntity() : null, hitResult); // CraftBukkit - Pass MovingObjectPosition // Paper
                  }
              }
  
++            if (showParticles) { // Paper - Fix potions splash events
              int i = potioncontents.potion().isPresent() && ((Potion) ((Holder) potioncontents.potion().get()).value()).hasInstantEffects() ? 2007 : 2002;
  
              worldserver.levelEvent(i, this.blockPosition(), potioncontents.getColor());
 -            this.discard();
++            } // Paper - Fix potions splash events
 +            this.discard(EntityRemoveEvent.Cause.HIT); // CraftBukkit - add Bukkit remove cause
          }
      }
  
-     private void applyWater(ServerLevel world) {
+-    private void applyWater(ServerLevel world) {
++    private static final Predicate<net.minecraft.world.entity.LivingEntity> APPLY_WATER_GET_ENTITIES_PREDICATE = ThrownPotion.WATER_SENSITIVE_OR_ON_FIRE.or(Axolotl.class::isInstance); // Paper - Fix potions splash events
++    private boolean applyWater(ServerLevel world, @Nullable HitResult hitResult) { // Paper - Fix potions splash events
          AABB axisalignedbb = this.getBoundingBox().inflate(4.0D, 2.0D, 4.0D);
 -        List<LivingEntity> list = this.level().getEntitiesOfClass(LivingEntity.class, axisalignedbb, ThrownPotion.WATER_SENSITIVE_OR_ON_FIRE);
-+        List<net.minecraft.world.entity.LivingEntity> list = this.level().getEntitiesOfClass(net.minecraft.world.entity.LivingEntity.class, axisalignedbb, ThrownPotion.WATER_SENSITIVE_OR_ON_FIRE);
++        // Paper start - Fix potions splash events
++        List<net.minecraft.world.entity.LivingEntity> list = this.level().getEntitiesOfClass(net.minecraft.world.entity.LivingEntity.class, axisalignedbb, ThrownPotion.APPLY_WATER_GET_ENTITIES_PREDICATE);
++        Map<LivingEntity, Double> affected = new HashMap<>();
++        java.util.Set<LivingEntity> rehydrate = new java.util.HashSet<>();
++        java.util.Set<LivingEntity> extinguish = new java.util.HashSet<>();
          Iterator iterator = list.iterator();
  
          while (iterator.hasNext()) {
 -            LivingEntity entityliving = (LivingEntity) iterator.next();
 +            net.minecraft.world.entity.LivingEntity entityliving = (net.minecraft.world.entity.LivingEntity) iterator.next();
++            if (entityliving instanceof Axolotl axolotl) {
++                rehydrate.add(((org.bukkit.entity.Axolotl) axolotl.getBukkitEntity()));
++            }
              double d0 = this.distanceToSqr((Entity) entityliving);
  
              if (d0 < 16.0D) {
-@@ -147,16 +157,17 @@
+                 if (entityliving.isSensitiveToWater()) {
+-                    entityliving.hurtServer(world, this.damageSources().indirectMagic(this, this.getOwner()), 1.0F);
++                    affected.put(entityliving.getBukkitLivingEntity(), 1.0);
+                 }
+ 
+                 if (entityliving.isOnFire() && entityliving.isAlive()) {
+-                    entityliving.extinguishFire();
++                    extinguish.add(entityliving.getBukkitLivingEntity());
+                 }
+             }
+         }
+ 
+-        List<Axolotl> list1 = this.level().getEntitiesOfClass(Axolotl.class, axisalignedbb);
+-        Iterator iterator1 = list1.iterator();
+-
+-        while (iterator1.hasNext()) {
+-            Axolotl axolotl = (Axolotl) iterator1.next();
+-
+-            axolotl.rehydrate();
++        io.papermc.paper.event.entity.WaterBottleSplashEvent event = org.bukkit.craftbukkit.event.CraftEventFactory.callWaterBottleSplashEvent(
++            this, hitResult, affected, rehydrate, extinguish
++        );
++        if (!event.isCancelled()) {
++            for (LivingEntity affectedEntity : event.getToDamage()) {
++                ((CraftLivingEntity) affectedEntity).getHandle().hurtServer(world, this.damageSources().indirectMagic(this, this.getOwner()), 1.0F);
++            }
++            for (LivingEntity toExtinguish : event.getToExtinguish()) {
++                ((CraftLivingEntity) toExtinguish).getHandle().extinguishFire();
++            }
++            for (LivingEntity toRehydrate : event.getToRehydrate()) {
++                if (((CraftLivingEntity) toRehydrate).getHandle() instanceof Axolotl axolotl) {
++                    axolotl.rehydrate();
++                }
++            }
++            // Paper end - Fix potions splash events
+         }
++        return !event.isCancelled(); // Paper - Fix potions splash events
  
      }
  
 -    private void applySplash(ServerLevel world, Iterable<MobEffectInstance> effects, @Nullable Entity entity) {
-+    private void applySplash(ServerLevel worldserver, Iterable<MobEffectInstance> iterable, @Nullable Entity entity, HitResult position) { // CraftBukkit - Pass MovingObjectPosition
++    private boolean applySplash(ServerLevel worldserver, Iterable<MobEffectInstance> iterable, @Nullable Entity entity, HitResult position) { // CraftBukkit - Pass MovingObjectPosition // Paper - Fix potions splash events
          AABB axisalignedbb = this.getBoundingBox().inflate(4.0D, 2.0D, 4.0D);
 -        List<LivingEntity> list = world.getEntitiesOfClass(LivingEntity.class, axisalignedbb);
 +        List<net.minecraft.world.entity.LivingEntity> list = worldserver.getEntitiesOfClass(net.minecraft.world.entity.LivingEntity.class, axisalignedbb);
@@ -111,7 +162,14 @@
  
                  if (entityliving.isAffectedByPotions()) {
                      double d0 = this.distanceToSqr((Entity) entityliving);
-@@ -170,37 +181,63 @@
+@@ -164,43 +196,71 @@
+                     if (d0 < 16.0D) {
+                         double d1;
+ 
++                        // Paper - diff on change, used when calling the splash event for water splash potions
+                         if (entityliving == entity) {
+                             d1 = 1.0D;
+                         } else {
                              d1 = 1.0D - Math.sqrt(d0) / 4.0D;
                          }
  
@@ -179,11 +237,12 @@
                  }
              }
          }
++        return !event.isCancelled(); // Paper - Fix potions splash events
  
      }
  
 -    private void makeAreaOfEffectCloud(PotionContents potion) {
-+    private void makeAreaOfEffectCloud(PotionContents potioncontents, HitResult position) { // CraftBukkit - Pass MovingObjectPosition
++    private boolean makeAreaOfEffectCloud(PotionContents potioncontents, HitResult position) { // CraftBukkit - Pass MovingObjectPosition
          AreaEffectCloud entityareaeffectcloud = new AreaEffectCloud(this.level(), this.getX(), this.getY(), this.getZ());
          Entity entity = this.getOwner();
  
@@ -192,25 +251,27 @@
              entityareaeffectcloud.setOwner(entityliving);
          }
  
-@@ -208,8 +245,15 @@
+@@ -208,8 +268,17 @@
          entityareaeffectcloud.setRadiusOnUse(-0.5F);
          entityareaeffectcloud.setWaitTime(10);
          entityareaeffectcloud.setRadiusPerTick(-entityareaeffectcloud.getRadius() / (float) entityareaeffectcloud.getDuration());
 -        entityareaeffectcloud.setPotionContents(potion);
 -        this.level().addFreshEntity(entityareaeffectcloud);
 +        entityareaeffectcloud.setPotionContents(potioncontents);
++        boolean noEffects = potioncontents.hasEffects(); // Paper - Fix potions splash events
 +        // CraftBukkit start
 +        org.bukkit.event.entity.LingeringPotionSplashEvent event = org.bukkit.craftbukkit.event.CraftEventFactory.callLingeringPotionSplashEvent(this, position, entityareaeffectcloud);
-+        if (!(event.isCancelled() || entityareaeffectcloud.isRemoved())) {
++        if (!(event.isCancelled() || entityareaeffectcloud.isRemoved() || (noEffects && !entityareaeffectcloud.potionContents.hasEffects()))) { // Paper - don't spawn area effect cloud if the effects were empty and not changed during the event handling
 +            this.level().addFreshEntity(entityareaeffectcloud);
 +        } else {
 +            entityareaeffectcloud.discard(null); // CraftBukkit - add Bukkit remove cause
 +        }
 +        // CraftBukkit end
++        return !event.isCancelled(); // Paper - Fix potions splash events
      }
  
      public boolean isLingering() {
-@@ -220,19 +264,31 @@
+@@ -220,19 +289,31 @@
          BlockState iblockdata = this.level().getBlockState(pos);
  
          if (iblockdata.is(BlockTags.FIRE)) {

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

@@ -884,6 +884,32 @@ public class CraftEventFactory {
         return event;
     }
 
+    // Paper start - Fix potions splash events
+    public static io.papermc.paper.event.entity.WaterBottleSplashEvent callWaterBottleSplashEvent(net.minecraft.world.entity.projectile.ThrownPotion potion, @Nullable HitResult hitResult, Map<LivingEntity, Double> affectedEntities, java.util.Set<LivingEntity> rehydrate, java.util.Set<LivingEntity> extinguish) {
+        ThrownPotion thrownPotion = (ThrownPotion) potion.getBukkitEntity();
+
+        Block hitBlock = null;
+        BlockFace hitFace = null;
+        org.bukkit.entity.Entity hitEntity = null;
+
+        if (hitResult != null) {
+            if (hitResult.getType() == HitResult.Type.BLOCK) {
+                BlockHitResult blockHitResult = (BlockHitResult) hitResult;
+                hitBlock = CraftBlock.at(potion.level(), blockHitResult.getBlockPos());
+                hitFace = CraftBlock.notchToBlockFace(blockHitResult.getDirection());
+            } else if (hitResult.getType() == HitResult.Type.ENTITY) {
+                hitEntity = ((EntityHitResult) hitResult).getEntity().getBukkitEntity();
+            }
+        }
+
+        io.papermc.paper.event.entity.WaterBottleSplashEvent event = new io.papermc.paper.event.entity.WaterBottleSplashEvent(
+            thrownPotion, hitEntity, hitBlock, hitFace, affectedEntities, rehydrate, extinguish
+        );
+        event.callEvent();
+        return event;
+    }
+    // Paper end - Fix potions splash events
+
     /**
      * BlockFadeEvent
      */