Code/net/minecraft/world/entity/animal/horse/TraderLlama.java

package net.minecraft.world.entity.animal.horse;

import java.util.EnumSet;
import javax.annotation.Nullable;
import net.minecraft.nbt.CompoundTag;
import net.minecraft.server.level.ServerLevel;
import net.minecraft.world.DifficultyInstance;
import net.minecraft.world.entity.AgeableMob;
import net.minecraft.world.entity.Entity;
import net.minecraft.world.entity.EntitySpawnReason;
import net.minecraft.world.entity.EntityType;
import net.minecraft.world.entity.LivingEntity;
import net.minecraft.world.entity.SpawnGroupData;
import net.minecraft.world.entity.ai.goal.Goal;
import net.minecraft.world.entity.ai.goal.PanicGoal;
import net.minecraft.world.entity.ai.goal.target.NearestAttackableTargetGoal;
import net.minecraft.world.entity.ai.goal.target.TargetGoal;
import net.minecraft.world.entity.ai.targeting.TargetingConditions;
import net.minecraft.world.entity.monster.AbstractIllager;
import net.minecraft.world.entity.monster.Zombie;
import net.minecraft.world.entity.npc.WanderingTrader;
import net.minecraft.world.entity.player.Player;
import net.minecraft.world.level.Level;
import net.minecraft.world.level.ServerLevelAccessor;

public class TraderLlama extends Llama {
    private static final int DEFAULT_DESPAWN_DELAY = 47999;
    private int despawnDelay = 47999;

    public TraderLlama(EntityType<? extends TraderLlama> p_30939_, Level p_30940_) {
        super(p_30939_, p_30940_);
    }

    @Override
    public boolean isTraderLlama() {
        return true;
    }

    @Nullable
    @Override
    protected Llama makeNewLlama() {
        return EntityType.TRADER_LLAMA.create(this.level(), EntitySpawnReason.BREEDING);
    }

    @Override
    public void addAdditionalSaveData(CompoundTag p_30950_) {
        super.addAdditionalSaveData(p_30950_);
        p_30950_.putInt("DespawnDelay", this.despawnDelay);
    }

    @Override
    public void readAdditionalSaveData(CompoundTag p_30948_) {
        super.readAdditionalSaveData(p_30948_);
        this.despawnDelay = p_30948_.getIntOr("DespawnDelay", 47999);
    }

    @Override
    protected void registerGoals() {
        super.registerGoals();
        this.goalSelector.addGoal(1, new PanicGoal(this, 2.0));
        this.targetSelector.addGoal(1, new TraderLlama.TraderLlamaDefendWanderingTraderGoal(this));
        this.targetSelector
            .addGoal(2, new NearestAttackableTargetGoal<>(this, Zombie.class, true, (p_390669_, p_390670_) -> p_390669_.getType() != EntityType.ZOMBIFIED_PIGLIN));
        this.targetSelector.addGoal(2, new NearestAttackableTargetGoal<>(this, AbstractIllager.class, true));
    }

    public void setDespawnDelay(int p_149556_) {
        this.despawnDelay = p_149556_;
    }

    @Override
    protected void doPlayerRide(Player p_30958_) {
        Entity entity = this.getLeashHolder();
        if (!(entity instanceof WanderingTrader)) {
            super.doPlayerRide(p_30958_);
        }
    }

    @Override
    public void aiStep() {
        super.aiStep();
        if (!this.level().isClientSide) {
            this.maybeDespawn();
        }
    }

    private void maybeDespawn() {
        if (this.canDespawn()) {
            this.despawnDelay = this.isLeashedToWanderingTrader() ? ((WanderingTrader)this.getLeashHolder()).getDespawnDelay() - 1 : this.despawnDelay - 1;
            if (this.despawnDelay <= 0) {
                this.removeLeash();
                this.discard();
            }
        }
    }

    private boolean canDespawn() {
        return !this.isTamed() && !this.isLeashedToSomethingOtherThanTheWanderingTrader() && !this.hasExactlyOnePlayerPassenger();
    }

    private boolean isLeashedToWanderingTrader() {
        return this.getLeashHolder() instanceof WanderingTrader;
    }

    private boolean isLeashedToSomethingOtherThanTheWanderingTrader() {
        return this.isLeashed() && !this.isLeashedToWanderingTrader();
    }

    @Nullable
    @Override
    public SpawnGroupData finalizeSpawn(ServerLevelAccessor p_30942_, DifficultyInstance p_30943_, EntitySpawnReason p_367657_, @Nullable SpawnGroupData p_30945_) {
        if (p_367657_ == EntitySpawnReason.EVENT) {
            this.setAge(0);
        }

        if (p_30945_ == null) {
            p_30945_ = new AgeableMob.AgeableMobGroupData(false);
        }

        return super.finalizeSpawn(p_30942_, p_30943_, p_367657_, p_30945_);
    }

    protected static class TraderLlamaDefendWanderingTraderGoal extends TargetGoal {
        private final Llama llama;
        private LivingEntity ownerLastHurtBy;
        private int timestamp;

        public TraderLlamaDefendWanderingTraderGoal(Llama p_149558_) {
            super(p_149558_, false);
            this.llama = p_149558_;
            this.setFlags(EnumSet.of(Goal.Flag.TARGET));
        }

        @Override
        public boolean canUse() {
            if (!this.llama.isLeashed()) {
                return false;
            } else if (!(this.llama.getLeashHolder() instanceof WanderingTrader wanderingtrader)) {
                return false;
            } else {
                this.ownerLastHurtBy = wanderingtrader.getLastHurtByMob();
                int i = wanderingtrader.getLastHurtByMobTimestamp();
                return i != this.timestamp && this.canAttack(this.ownerLastHurtBy, TargetingConditions.DEFAULT);
            }
        }

        @Override
        public void start() {
            this.mob.setTarget(this.ownerLastHurtBy);
            Entity entity = this.llama.getLeashHolder();
            if (entity instanceof WanderingTrader) {
                this.timestamp = ((WanderingTrader)entity).getLastHurtByMobTimestamp();
            }

            super.start();
        }
    }
}