Paper/patches/server/0202-Add-EntityKnockbackByEntityEvent-and-EntityPushedByE.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Brokkonaut <hannos17@gmx.de>
Date: Mon, 18 Jun 2018 15:46:23 +0200
Subject: [PATCH] Add EntityKnockbackByEntityEvent and
 EntityPushedByEntityAttackEvent

Co-authored-by: aerulion <aerulion@gmail.com>

This event is called when an entity receives knockback by another entity.

diff --git a/src/main/java/net/minecraft/world/entity/Entity.java b/src/main/java/net/minecraft/world/entity/Entity.java
index fe314015f8cbc44e29a8ec73ecca4eeadd1da39f..d2d1a3e3c8accbdfeecafa86f9cc9f16007c3930 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -1868,9 +1868,23 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource, S
         }
     }
 
-    public void push(double deltaX, double deltaY, double deltaZ) {
-        this.setDeltaMovement(this.getDeltaMovement().add(deltaX, deltaY, deltaZ));
+    public final void push(double deltaX, double deltaY, double deltaZ) { // Paper - override the added overload below
+        // Paper start - Add EntityKnockbackByEntityEvent and EntityPushedByEntityAttackEvent
+        this.push(deltaX, deltaY, deltaZ, null);
+    }
+
+    public void push(double deltaX, double deltaY, double deltaZ, @org.jetbrains.annotations.Nullable Entity pushingEntity) {
+        org.bukkit.util.Vector delta = new org.bukkit.util.Vector(deltaX, deltaY, deltaZ);
+        if (pushingEntity != null) {
+            io.papermc.paper.event.entity.EntityPushedByEntityAttackEvent event = new io.papermc.paper.event.entity.EntityPushedByEntityAttackEvent(getBukkitEntity(), pushingEntity.getBukkitEntity(), delta);
+            if (!event.callEvent()) {
+                return;
+            }
+            delta = event.getAcceleration();
+        }
+        this.setDeltaMovement(this.getDeltaMovement().add(delta.getX(), delta.getY(), delta.getZ()));
         this.hasImpulse = true;
+        // Paper end - Add EntityKnockbackByEntityEvent and EntityPushedByEntityAttackEvent
     }
 
     protected void markHurt() {
diff --git a/src/main/java/net/minecraft/world/entity/LivingEntity.java b/src/main/java/net/minecraft/world/entity/LivingEntity.java
index 21bef887193c777ec1e311b3bf5c0213180ea4ca..83a56061ce23d3d6f7d8ad3201ce325106f8a4d0 100644
--- a/src/main/java/net/minecraft/world/entity/LivingEntity.java
+++ b/src/main/java/net/minecraft/world/entity/LivingEntity.java
@@ -1569,7 +1569,7 @@ public abstract class LivingEntity extends Entity implements Attackable {
     }
 
     protected void blockedByShield(LivingEntity target) {
-        target.knockback(0.5D, target.getX() - this.getX(), target.getZ() - this.getZ(), null, EntityKnockbackEvent.KnockbackCause.SHIELD_BLOCK); // CraftBukkit
+        target.knockback(0.5D, target.getX() - this.getX(), target.getZ() - this.getZ(), this, EntityKnockbackEvent.KnockbackCause.SHIELD_BLOCK); // CraftBukkit // Paper - fix attacker
     }
 
     private boolean checkTotemDeathProtection(DamageSource source) {
@@ -1832,7 +1832,7 @@ public abstract class LivingEntity extends Entity implements Attackable {
         this.knockback(strength, x, z, null, EntityKnockbackEvent.KnockbackCause.UNKNOWN);
     }
 
-    public void knockback(double d0, double d1, double d2, Entity attacker, EntityKnockbackEvent.KnockbackCause cause) {
+    public void knockback(double d0, double d1, double d2, @Nullable Entity attacker, EntityKnockbackEvent.KnockbackCause cause) { // Paper - add nullable to attacker param
         d0 *= 1.0D - this.getAttributeValue(Attributes.KNOCKBACK_RESISTANCE);
         if (true || d0 > 0.0D) { // CraftBukkit - Call event even when force is 0
             //this.hasImpulse = true; // CraftBukkit - Move down
@@ -1844,8 +1844,22 @@ public abstract class LivingEntity extends Entity implements Attackable {
                 return;
             }
 
+            // Paper start - Add EntityKnockbackByEntityEvent and EntityPushedByEntityAttackEvent
+            final org.bukkit.util.Vector currentMovement = this.getBukkitEntity().getVelocity();
+            org.bukkit.util.Vector resultingMovement = event.getFinalKnockback();
+            final org.bukkit.util.Vector deltaMovement = resultingMovement.clone().subtract(currentMovement);
+            if (attacker != null) {
+                final com.destroystokyo.paper.event.entity.EntityKnockbackByEntityEvent knockbackEvent = new com.destroystokyo.paper.event.entity.EntityKnockbackByEntityEvent(this.getBukkitLivingEntity(), attacker.getBukkitEntity(), (float) event.getForce(), deltaMovement);
+                if (!knockbackEvent.callEvent()) {
+                    return;
+                }
+
+                // Back from delta to the absolute vector
+                resultingMovement = currentMovement.add(knockbackEvent.getAcceleration());
+            }
             this.hasImpulse = true;
-            this.setDeltaMovement(event.getFinalKnockback().getX(), event.getFinalKnockback().getY(), event.getFinalKnockback().getZ());
+            this.setDeltaMovement(resultingMovement.getX(), resultingMovement.getY(), resultingMovement.getZ());
+            // Paper end - Add EntityKnockbackByEntityEvent and EntityPushedByEntityAttackEvent
             // CraftBukkit end
         }
     }
diff --git a/src/main/java/net/minecraft/world/entity/ai/behavior/RamTarget.java b/src/main/java/net/minecraft/world/entity/ai/behavior/RamTarget.java
index e319a46a21a94314c5d496820b1ac4879dcf56b9..fcc0a7789c79b956f097bc6d34e0c37e0b90a2db 100644
--- a/src/main/java/net/minecraft/world/entity/ai/behavior/RamTarget.java
+++ b/src/main/java/net/minecraft/world/entity/ai/behavior/RamTarget.java
@@ -77,7 +77,7 @@ public class RamTarget extends Behavior<Goat> {
             float f = 0.25F * (float)(i - j);
             float g = Mth.clamp(entity.getSpeed() * 1.65F, 0.2F, 3.0F) + f;
             float h = livingEntity.isDamageSourceBlocked(world.damageSources().mobAttack(entity)) ? 0.5F : 1.0F;
-            livingEntity.knockback((double)(h * g) * this.getKnockbackForce.applyAsDouble(entity), this.ramDirection.x(), this.ramDirection.z());
+            livingEntity.knockback((double)(h * g) * this.getKnockbackForce.applyAsDouble(entity), this.ramDirection.x(), this.ramDirection.z(), entity, org.bukkit.event.entity.EntityKnockbackEvent.KnockbackCause.ENTITY_ATTACK); // Paper - Add EntityKnockbackByEntityEvent and EntityPushedByEntityAttackEvent
             this.finishRam(world, entity);
             world.playSound((Player)null, entity, this.getImpactSound.apply(entity), SoundSource.NEUTRAL, 1.0F, 1.0F);
         } else if (this.hasRammedHornBreakingBlock(world, entity)) {
diff --git a/src/main/java/net/minecraft/world/entity/ai/behavior/warden/SonicBoom.java b/src/main/java/net/minecraft/world/entity/ai/behavior/warden/SonicBoom.java
index 29cfd065f246bbd3d3c2a5bbd32c3f4813a02951..771d798fa3b367043129f41101c65f13f0b466fa 100644
--- a/src/main/java/net/minecraft/world/entity/ai/behavior/warden/SonicBoom.java
+++ b/src/main/java/net/minecraft/world/entity/ai/behavior/warden/SonicBoom.java
@@ -68,7 +68,7 @@ public class SonicBoom extends Behavior<Warden> {
                 target.hurt(world.damageSources().sonicBoom(entity), 10.0F);
                 double d = 0.5D * (1.0D - target.getAttributeValue(Attributes.KNOCKBACK_RESISTANCE));
                 double e = 2.5D * (1.0D - target.getAttributeValue(Attributes.KNOCKBACK_RESISTANCE));
-                target.push(vec33.x() * e, vec33.y() * d, vec33.z() * e);
+                target.push(vec33.x() * e, vec33.y() * d, vec33.z() * e, entity); // Paper - Add EntityKnockbackByEntityEvent and EntityPushedByEntityAttackEvent
             });
         }
     }
diff --git a/src/main/java/net/minecraft/world/entity/boss/enderdragon/EnderDragon.java b/src/main/java/net/minecraft/world/entity/boss/enderdragon/EnderDragon.java
index 9ab60fb1b7f9c8a342d9116e99f7f0a1e463a626..0d84f1fb53384a827d7418c322a32e3286f4081a 100644
--- a/src/main/java/net/minecraft/world/entity/boss/enderdragon/EnderDragon.java
+++ b/src/main/java/net/minecraft/world/entity/boss/enderdragon/EnderDragon.java
@@ -459,7 +459,7 @@ public class EnderDragon extends Mob implements Enemy {
                 double d3 = entity.getZ() - d1;
                 double d4 = Math.max(d2 * d2 + d3 * d3, 0.1D);
 
-                entity.push(d2 / d4 * 4.0D, 0.20000000298023224D, d3 / d4 * 4.0D);
+                entity.push(d2 / d4 * 4.0D, 0.20000000298023224D, d3 / d4 * 4.0D, this); // Paper - Add EntityKnockbackByEntityEvent and EntityPushedByEntityAttackEvent
                 if (!this.phaseManager.getCurrentPhase().isSitting() && ((LivingEntity) entity).getLastHurtByMobTimestamp() < entity.tickCount - 2) {
                     entity.hurt(this.damageSources().mobAttack(this), 5.0F);
                     this.doEnchantDamageEffects(this, entity);
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 b3d05578f38af41f242f6634864ce1d2ecac14f8..aaa579ba04445aa350a439610d460a2415320cfc 100644
--- a/src/main/java/net/minecraft/world/entity/decoration/HangingEntity.java
+++ b/src/main/java/net/minecraft/world/entity/decoration/HangingEntity.java
@@ -250,7 +250,7 @@ public abstract class HangingEntity extends Entity {
     }
 
     @Override
-    public void push(double deltaX, double deltaY, double deltaZ) {
+    public void push(double deltaX, double deltaY, double deltaZ, @org.jetbrains.annotations.Nullable Entity pushingEntity) { // Paper - add push source entity param
         if (false && !this.level().isClientSide && !this.isRemoved() && deltaX * deltaX + deltaY * deltaY + deltaZ * deltaZ > 0.0D) { // CraftBukkit - not needed
             this.kill();
             this.dropItem((Entity) null);
diff --git a/src/main/java/net/minecraft/world/entity/decoration/ItemFrame.java b/src/main/java/net/minecraft/world/entity/decoration/ItemFrame.java
index 78a3c87b74218a0d5792801c07e3a263c15fcd5b..f90878e0449f39f66ae3a7036a65c374b36b7dbc 100644
--- a/src/main/java/net/minecraft/world/entity/decoration/ItemFrame.java
+++ b/src/main/java/net/minecraft/world/entity/decoration/ItemFrame.java
@@ -159,9 +159,9 @@ public class ItemFrame extends HangingEntity {
     }
 
     @Override
-    public void push(double deltaX, double deltaY, double deltaZ) {
+    public void push(double deltaX, double deltaY, double deltaZ, @org.jetbrains.annotations.Nullable Entity pushingEntity) { // Paper - add push source entity param
         if (!this.fixed) {
-            super.push(deltaX, deltaY, deltaZ);
+            super.push(deltaX, deltaY, deltaZ, pushingEntity); // Paper - add push source entity param
         }
 
     }
diff --git a/src/main/java/net/minecraft/world/entity/monster/Ravager.java b/src/main/java/net/minecraft/world/entity/monster/Ravager.java
index 041f1650b853138e4286fe83a08d79d276054ce7..aba20a4352d8983b01ab5d329187588f68d3e405 100644
--- a/src/main/java/net/minecraft/world/entity/monster/Ravager.java
+++ b/src/main/java/net/minecraft/world/entity/monster/Ravager.java
@@ -265,7 +265,7 @@ public class Ravager extends Raider {
         double d1 = entity.getZ() - this.getZ();
         double d2 = Math.max(d0 * d0 + d1 * d1, 0.001D);
 
-        entity.push(d0 / d2 * 4.0D, 0.2D, d1 / d2 * 4.0D);
+        entity.push(d0 / d2 * 4.0D, 0.2D, d1 / d2 * 4.0D, this); // Paper - Add EntityKnockbackByEntityEvent and EntityPushedByEntityAttackEvent
     }
 
     @Override
diff --git a/src/main/java/net/minecraft/world/entity/monster/hoglin/HoglinBase.java b/src/main/java/net/minecraft/world/entity/monster/hoglin/HoglinBase.java
index 81003ce3f05c6be6f52a92b86a4721235f4ce12a..cae7e3e85c3b911f50f8a06badf695c3df2847e5 100644
--- a/src/main/java/net/minecraft/world/entity/monster/hoglin/HoglinBase.java
+++ b/src/main/java/net/minecraft/world/entity/monster/hoglin/HoglinBase.java
@@ -40,7 +40,7 @@ public interface HoglinBase {
             double j = f * (double)(attacker.level().random.nextFloat() * 0.5F + 0.2F);
             Vec3 vec3 = (new Vec3(g, 0.0D, h)).normalize().scale(j).yRot(i);
             double k = f * (double)attacker.level().random.nextFloat() * 0.5D;
-            target.push(vec3.x, k, vec3.z);
+            target.push(vec3.x, k, vec3.z, attacker); // Paper - Add EntityKnockbackByEntityEvent and EntityPushedByEntityAttackEvent
             target.hurtMarked = true;
         }
     }
diff --git a/src/main/java/net/minecraft/world/entity/player/Player.java b/src/main/java/net/minecraft/world/entity/player/Player.java
index 0bff92eeade590852b9b37105a18df35f587559b..c934c7614281f77376858909c86d9a1a73c8e174 100644
--- a/src/main/java/net/minecraft/world/entity/player/Player.java
+++ b/src/main/java/net/minecraft/world/entity/player/Player.java
@@ -1279,7 +1279,7 @@ public abstract class Player extends LivingEntity {
                             if (target instanceof LivingEntity) {
                                 ((LivingEntity) target).knockback((double) ((float) i * 0.5F), (double) Mth.sin(this.getYRot() * 0.017453292F), (double) (-Mth.cos(this.getYRot() * 0.017453292F)), this, EntityKnockbackEvent.KnockbackCause.ENTITY_ATTACK); // CraftBukkit
                             } else {
-                                target.push((double) (-Mth.sin(this.getYRot() * 0.017453292F) * (float) i * 0.5F), 0.1D, (double) (Mth.cos(this.getYRot() * 0.017453292F) * (float) i * 0.5F));
+                                target.push((double) (-Mth.sin(this.getYRot() * 0.017453292F) * (float) i * 0.5F), 0.1D, (double) (Mth.cos(this.getYRot() * 0.017453292F) * (float) i * 0.5F), this); // Paper - Add EntityKnockbackByEntityEvent and EntityPushedByEntityAttackEvent
                             }
 
                             this.setDeltaMovement(this.getDeltaMovement().multiply(0.6D, 1.0D, 0.6D));
diff --git a/src/main/java/net/minecraft/world/entity/projectile/AbstractArrow.java b/src/main/java/net/minecraft/world/entity/projectile/AbstractArrow.java
index c210ae3795b1bbaefbe84a6f62b9d3dd75d642a4..f1d7f202b99b8ae4c16d10956d68d74efae8445b 100644
--- a/src/main/java/net/minecraft/world/entity/projectile/AbstractArrow.java
+++ b/src/main/java/net/minecraft/world/entity/projectile/AbstractArrow.java
@@ -410,7 +410,7 @@ public abstract class AbstractArrow extends Projectile {
                     Vec3 vec3d = this.getDeltaMovement().multiply(1.0D, 0.0D, 1.0D).normalize().scale((double) this.knockback * 0.6D * d0);
 
                     if (vec3d.lengthSqr() > 0.0D) {
-                        entityliving.push(vec3d.x, 0.1D, vec3d.z);
+                        entityliving.push(vec3d.x, 0.1D, vec3d.z, this); // Paper
                     }
                 }
 
diff --git a/src/main/java/net/minecraft/world/level/Explosion.java b/src/main/java/net/minecraft/world/level/Explosion.java
index 00cfa26783ce0772c75166266ead258a415097bc..ade10a9fd93f4c0f04cd56ce5e1da06af4a05060 100644
--- a/src/main/java/net/minecraft/world/level/Explosion.java
+++ b/src/main/java/net/minecraft/world/level/Explosion.java
@@ -298,7 +298,17 @@ public class Explosion {
                             Vec3 result = entity.getDeltaMovement().add(vec3d1);
                             org.bukkit.event.entity.EntityKnockbackEvent event = CraftEventFactory.callEntityKnockbackEvent((org.bukkit.craftbukkit.entity.CraftLivingEntity) entity.getBukkitEntity(), this.source, org.bukkit.event.entity.EntityKnockbackEvent.KnockbackCause.EXPLOSION, d13, vec3d1, result.x, result.y, result.z);
 
-                            vec3d1 = (event.isCancelled()) ? Vec3.ZERO : new Vec3(event.getFinalKnockback().getX(), event.getFinalKnockback().getY(), event.getFinalKnockback().getZ());
+                            // Paper start - call EntityKnockbackByEntityEvent for explosions
+                            vec3d1 = (event.isCancelled()) ? Vec3.ZERO : new Vec3(event.getFinalKnockback().getX(), event.getFinalKnockback().getY(), event.getFinalKnockback().getZ()).subtract(entity.getDeltaMovement()); // changes on this line fix a bug where vec3d1 wasn't reassigned with the "change", but instead the final deltaMovement
+                            if (this.damageSource.getEntity() != null || this.source != null) {
+                                final org.bukkit.entity.Entity hitBy = this.damageSource.getEntity() != null ? this.damageSource.getEntity().getBukkitEntity() : this.source.getBukkitEntity();
+                                com.destroystokyo.paper.event.entity.EntityKnockbackByEntityEvent paperEvent = new com.destroystokyo.paper.event.entity.EntityKnockbackByEntityEvent(((LivingEntity) entity).getBukkitLivingEntity(), hitBy, (float) event.getForce(), org.bukkit.craftbukkit.util.CraftVector.toBukkit(vec3d1));
+                                if (!paperEvent.callEvent()) {
+                                    continue;
+                                }
+                                vec3d1 = org.bukkit.craftbukkit.util.CraftVector.toNMS(paperEvent.getAcceleration());
+                            }
+                            // Paper end - call EntityKnockbackByEntityEvent for explosions
                         }
                         // CraftBukkit end
                         entity.setDeltaMovement(entity.getDeltaMovement().add(vec3d1));