SentinelNMSHelper.java

package org.mcmonkey.sentinel.utilities;

import net.citizensnpcs.util.NMS;
import org.bukkit.Bukkit;
import org.bukkit.entity.Enderman;
import org.bukkit.entity.Entity;
import org.bukkit.entity.IronGolem;
import org.bukkit.entity.Player;

import java.lang.invoke.MethodHandle;
import java.lang.reflect.Field;

/**
 * Helper for NMS-based actions.
 */
public class SentinelNMSHelper {

    public static MethodHandle CRAFTENTITY_GETHANDLE, NMSENTITY_WORLDGETTER, NMSWORLD_BROADCASTENTITYEFFECT, NMSENTITY_GETDATAWATCHER, DATWATCHER_SET,
            SERVERPLAYER_ATTACK, LIVINGENTITY_ATTACKSTRENGTHTICKS;

    public static Object ENTITYENDERMAN_DATAWATCHER_ANGRY;

    private static boolean nmsWorks = true, endermanValid = false;

    public static void init() {
        try {
            if (!SentinelVersionCompat.v1_12) {
                nmsWorks = false;
                return;
            }
            // Will be like "org.bukkit.craftbukkit.v1_16_R3"
            String bukkitPackageName = Bukkit.getServer().getClass().getPackage().getName();
            // Should be like "v1_16_R3"
            String packageVersion = bukkitPackageName.substring(bukkitPackageName.lastIndexOf('.') + 1);
            Class craftEntity = Class.forName(bukkitPackageName + ".entity.CraftEntity");
            CRAFTENTITY_GETHANDLE = NMS.getMethodHandle(craftEntity, "getHandle", true);
            Class nmsEntity, nmsWorld, nmsDataWatcher, nmsDataWatcherObject, nmsEntityEnderman, nmsHuman, nmsLivingEntity;
            String endermanAngryField = null;
            String broadcastEffectMethod = "broadcastEntityEffect", dataWatcherSet = "set";
            if (SentinelVersionCompat.v1_17) { // 1.17+ - Mojang mappings update
                nmsEntity = Class.forName("net.minecraft.world.entity.Entity");
                nmsWorld = Class.forName("net.minecraft.world.level.World"); // Level
                nmsDataWatcher = Class.forName("net.minecraft.network.syncher.DataWatcher"); // SynchedEntityData
                nmsDataWatcherObject = Class.forName("net.minecraft.network.syncher.DataWatcherObject"); // EntityDataAccessor
                nmsEntityEnderman = Class.forName("net.minecraft.world.entity.monster.EntityEnderman");
                nmsHuman = Class.forName("net.minecraft.world.entity.player.EntityHuman");
                nmsLivingEntity = Class.forName("net.minecraft.world.entity.EntityLiving");
                String playerAttackMethod = null, attackStrengthField = null;
                boolean isCompat = false;
                if (SentinelVersionCompat.v1_18 && !SentinelVersionCompat.vFuture) { // 1.18 names
                    // https://minidigger.github.io/MiniMappingViewer/#/mojang/server/1.18.2
                    endermanAngryField = "bX"; // net.minecraft.world.entity.monster.EnderMan#DATA_CREEPY
                    playerAttackMethod = "d"; // net.minecraft.world.entity.player.Player#attack(Entity)
                    attackStrengthField = "aQ"; // net.minecraft.world.entity.LivingEntity#attackStrengthTicker
                    broadcastEffectMethod = "a"; // net.minecraft.world.level.Level#broadcastEntityEvent(Entity,byte)
                    dataWatcherSet = "b"; // net.minecraft.network.syncher.SynchedEntityData#set
                    isCompat = true;
                }
                else if (!SentinelVersionCompat.v1_18) { // 1.17 names
                    endermanAngryField = "bV"; // EnderMan#DATA_CREEPY
                    playerAttackMethod = "attack"; // Player#attack(Entity)
                    attackStrengthField = "aQ"; // LivingEntity#attackStrengthTicker
                    isCompat = true;
                }
                if (isCompat) {
                    SERVERPLAYER_ATTACK = NMS.getMethodHandle(nmsHuman, playerAttackMethod, true, nmsEntity);
                    LIVINGENTITY_ATTACKSTRENGTHTICKS = NMS.getSetter(nmsLivingEntity, attackStrengthField);
                }
            }
            else { // 1.12 through 1.16 - Original Spigot NMS versioned mappings
                String nmsPackageName = "net.minecraft.server." + packageVersion;
                nmsEntity = Class.forName(nmsPackageName + ".Entity");
                nmsWorld = Class.forName(nmsPackageName + ".World");
                nmsDataWatcher = Class.forName(nmsPackageName + ".DataWatcher");
                nmsDataWatcherObject = Class.forName(nmsPackageName + ".DataWatcherObject");
                nmsEntityEnderman = Class.forName(nmsPackageName + ".EntityEnderman");
                if (SentinelVersionCompat.v1_16) {
                    endermanAngryField = "bo";
                }
            }
            NMSENTITY_WORLDGETTER = NMS.getFirstGetter(nmsEntity, nmsWorld);
            NMSENTITY_GETDATAWATCHER = NMS.getFirstGetter(nmsEntity, nmsDataWatcher);
            NMSWORLD_BROADCASTENTITYEFFECT = NMS.getMethodHandle(nmsWorld, broadcastEffectMethod, true, nmsEntity, byte.class);
            DATWATCHER_SET = NMS.getMethodHandle(nmsDataWatcher, dataWatcherSet, true, nmsDataWatcherObject, Object.class);
            if (endermanAngryField != null && nmsEntityEnderman != null) {
                Field dataWatcherAngryField = NMS.getField(nmsEntityEnderman, endermanAngryField);
                dataWatcherAngryField.setAccessible(true);
                ENTITYENDERMAN_DATAWATCHER_ANGRY = dataWatcherAngryField.get(null);
                endermanValid = true;
            }
        }
        catch (Throwable ex) {
            ex.printStackTrace();
            nmsWorks = false;
            endermanValid = false;
        }
    }

    public static boolean doPlayerAttack(Player attacker, Entity victim) {
        if (!nmsWorks || SERVERPLAYER_ATTACK == null) {
            return false;
        }
        try {
            Object nmsHandleAttacker = CRAFTENTITY_GETHANDLE.invoke(attacker);
            Object nmsHandleVictim = CRAFTENTITY_GETHANDLE.invoke(victim);
            // 100 is just a random high value - attack strength doesn't tick itself for NPCs, so just set it a value too high to matter.
            LIVINGENTITY_ATTACKSTRENGTHTICKS.invoke(nmsHandleAttacker, 100);
            SERVERPLAYER_ATTACK.invoke(nmsHandleAttacker, nmsHandleVictim);
            return true;
        }
        catch (Throwable ex) {
            nmsWorks = false;
            ex.printStackTrace();
            return false;
        }
    }

    public static void animateIronGolemSwing(IronGolem entity) {
        if (!nmsWorks) {
            return;
        }
        try {
            Object nmsHandle = CRAFTENTITY_GETHANDLE.invoke(entity);
            Object world = NMSENTITY_WORLDGETTER.invoke(nmsHandle);
            NMSWORLD_BROADCASTENTITYEFFECT.invoke(world, nmsHandle, (byte) 4);
        }
        catch (Throwable ex) {
            nmsWorks = false;
            ex.printStackTrace();
        }
    }

    public static void setEndermanAngry(Enderman entity, boolean angry) {
        if (!nmsWorks || !endermanValid) {
            return;
        }
        try {
            Object nmsHandle = CRAFTENTITY_GETHANDLE.invoke(entity);
            Object dataWatcher = NMSENTITY_GETDATAWATCHER.invoke(nmsHandle);
            DATWATCHER_SET.invoke(dataWatcher, ENTITYENDERMAN_DATAWATCHER_ANGRY, angry);
        }
        catch (Throwable ex) {
            endermanValid = false;
        }
    }
}