AsyncHitDetectionListener.java

package io.github.sasuke.newvalencia.core.tooling.nms.combat;

import com.comphenix.protocol.ProtocolLibrary;
import com.comphenix.protocol.events.PacketAdapter;
import com.comphenix.protocol.events.PacketContainer;
import com.comphenix.protocol.events.PacketEvent;
import com.comphenix.protocol.wrappers.EnumWrappers.EntityUseAction;
import io.github.sasuke.newvalencia.core.CorePlugin;
import io.github.sasuke.newvalencia.core.tooling.event.async.AsyncPlayerPreDamageEntityEvent;
import org.bukkit.Bukkit;
import org.bukkit.entity.Damageable;
import org.bukkit.entity.Entity;
import org.bukkit.entity.Player;

import static com.comphenix.protocol.PacketType.Play.Client.USE_ENTITY;
import static com.comphenix.protocol.PacketType.Play.Server.ENTITY_STATUS;

public class AsyncHitDetectionListener extends PacketAdapter {
	
	private static final float MAX_DISTANCE = (float) 3.85 * (float) 3.85;
	
	public AsyncHitDetectionListener() {
		super(CorePlugin.getInstance(), USE_ENTITY);
	}
	
	@Override
	public void onPacketReceiving(PacketEvent event) {
		if (event.getPacketType() != USE_ENTITY) {
			return;
		}
		
		PacketContainer packet = event.getPacket();
		Player player = event.getPlayer();
		
		Entity entity = packet.getEntityModifier(event).read(0);
		if (!(entity instanceof Damageable)) {
			return;
		}
		
		if (player.getLocation().distanceSquared(entity.getLocation()) > MAX_DISTANCE) {
			return;
		}
		
		if (!player.getWorld().getName().equalsIgnoreCase(entity.getWorld().getName())) {
			return;
		}
		
		EntityUseAction action = packet.getEntityUseActions().read(0);
		if (action != EntityUseAction.ATTACK) {
			return;
		}
		
		AsyncPlayerPreDamageEntityEvent preDamageEntityEvent = new AsyncPlayerPreDamageEntityEvent(
			player,
			entity
		);
		
		Bukkit.getPluginManager().callEvent(preDamageEntityEvent);
		
		if (!preDamageEntityEvent.isCancelled()) {
			sendDamageAnimation(player, entity.getEntityId());
		}
	}
	
	private void sendDamageAnimation(Player player, int entityId) {
		PacketContainer damagePacket = new PacketContainer(ENTITY_STATUS);
		damagePacket.getIntegers().write(0, entityId);
		damagePacket.getBytes().write(0, (byte) 2);
		
		try {
			ProtocolLibrary.getProtocolManager().sendServerPacket(player, damagePacket);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}