After Damage Event (FabricMC#4051)

* after damage event

* add after damage event to testmod

* remove amount > 0 check to capture shield blocking

* add javadoc

* dont fire event if killed

* clarify javadoc a bit more

* fix checkstyle issue

* fix other checkstyle issues lol

* rename damageDealt to baseDamageTaken

(cherry picked from commit 2122d82)

fabric-entity-events-v1/src/main/java/net/fabricmc/fabric/api/entity/event/v1/ServerLivingEntityEvents.java

@@ -42,6 +42,22 @@ public final class ServerLivingEntityEvents {
 		return true;
 	});
 
+	/**
+	 * An event that is called after an entity is damaged. This is fired from {@link LivingEntity#damage} after damage
+	 * is applied, or after that damage was blocked by a shield.
+	 *
+	 * <p>The base damage taken is the damage initially applied to the entity. Damage taken is the amount of damage the
+	 * entity actually took, after effects such as shields and extra freezing damage are applied. Damage taken does NOT
+	 * include damage reduction from armor and enchantments.
+	 *
+	 * <p>This event is not fired if the entity was killed by the damage.
+	 */
+	public static final Event<AfterDamage> AFTER_DAMAGE = EventFactory.createArrayBacked(AfterDamage.class, callbacks -> (entity, source, baseDamageTaken, damageTaken, blocked) -> {
+		for (AfterDamage callback : callbacks) {
+			callback.afterDamage(entity, source, baseDamageTaken, damageTaken, blocked);
+		}
+	});
+
 	/**
 	 * An event that is called when an entity takes fatal damage.
 	 *
@@ -104,6 +120,21 @@ public interface AllowDamage {
 		boolean allowDamage(LivingEntity entity, DamageSource source, float amount);
 	}
 
+	@FunctionalInterface
+	public interface AfterDamage {
+		/**
+		 * Called after a living entity took damage, unless they were killed. The base damage taken is given as damage
+		 * taken before armor or enchantments are applied, but after other effects like shields are applied.
+		 *
+		 * @param entity the entity that was damaged
+		 * @param source the source of the damage
+		 * @param baseDamageTaken the amount of damage initially dealt
+		 * @param damageTaken the amount of damage actually taken by the entity, before armor and enchantment effects
+		 * @param blocked whether the damage was blocked by a shield
+		 */
+		void afterDamage(LivingEntity entity, DamageSource source, float baseDamageTaken, float damageTaken, boolean blocked);
+	}
+
 	@FunctionalInterface
 	public interface AllowDeath {
 		/**

fabric-entity-events-v1/src/main/java/net/fabricmc/fabric/mixin/entity/event/LivingEntityMixin.java

@@ -30,6 +30,7 @@
 import org.spongepowered.asm.mixin.injection.Redirect;
 import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
 import org.spongepowered.asm.mixin.injection.callback.CallbackInfoReturnable;
+import org.spongepowered.asm.mixin.injection.callback.LocalCapture;
 
 import net.minecraft.block.BedBlock;
 import net.minecraft.block.BlockState;
@@ -83,6 +84,13 @@ private void beforeDamage(DamageSource source, float amount, CallbackInfoReturna
 		}
 	}
 
+	@Inject(method = "damage", at = @At("TAIL"), locals = LocalCapture.CAPTURE_FAILHARD)
+	private void afterDamage(DamageSource source, float amount, CallbackInfoReturnable<Boolean> cir, float dealt, boolean blocked) {
+		if (!isDead()) {
+			ServerLivingEntityEvents.AFTER_DAMAGE.invoker().afterDamage((LivingEntity) (Object) this, source, dealt, amount, blocked);
+		}
+	}
+
 	@Inject(method = "sleep", at = @At("RETURN"))
 	private void onSleep(BlockPos pos, CallbackInfo info) {
 		EntitySleepEvents.START_SLEEPING.invoker().onStartSleeping((LivingEntity) (Object) this, pos);

fabric-entity-events-v1/src/testmod/java/net/fabricmc/fabric/test/entity/event/EntityEventTests.java

@@ -90,6 +90,10 @@ public void onInitialize() {
 			return true;
 		});
 
+		ServerLivingEntityEvents.AFTER_DAMAGE.register((entity, source, baseDamageTaken, damageTaken, blocked) -> {
+			LOGGER.info("Entity {} received {} damage from {} (initially dealt {}, blocked {})", entity.getName().getString(), damageTaken, source.getName(), baseDamageTaken, blocked);
+		});
+
 		ServerLivingEntityEvents.ALLOW_DEATH.register((entity, source, amount) -> {
 			LOGGER.info("{} is going to die to {} damage from {} damage source", entity.getName().getString(), amount, source.getName());