Code/net/minecraft/world/entity/ai/goal/FollowParentGoal.java

package net.minecraft.world.entity.ai.goal;

import java.util.List;
import javax.annotation.Nullable;
import net.minecraft.world.entity.animal.Animal;

public class FollowParentGoal extends Goal {
    public static final int HORIZONTAL_SCAN_RANGE = 8;
    public static final int VERTICAL_SCAN_RANGE = 4;
    public static final int DONT_FOLLOW_IF_CLOSER_THAN = 3;
    private final Animal animal;
    @Nullable
    private Animal parent;
    private final double speedModifier;
    private int timeToRecalcPath;

    public FollowParentGoal(Animal p_25319_, double p_25320_) {
        this.animal = p_25319_;
        this.speedModifier = p_25320_;
    }

    @Override
    public boolean canUse() {
        if (this.animal.getAge() >= 0) {
            return false;
        } else {
            List<? extends Animal> list = this.animal
                .level()
                .getEntitiesOfClass((Class<? extends Animal>)this.animal.getClass(), this.animal.getBoundingBox().inflate(8.0, 4.0, 8.0));
            Animal animal = null;
            double d0 = Double.MAX_VALUE;

            for (Animal animal1 : list) {
                if (animal1.getAge() >= 0) {
                    double d1 = this.animal.distanceToSqr(animal1);
                    if (!(d1 > d0)) {
                        d0 = d1;
                        animal = animal1;
                    }
                }
            }

            if (animal == null) {
                return false;
            } else if (d0 < 9.0) {
                return false;
            } else {
                this.parent = animal;
                return true;
            }
        }
    }

    @Override
    public boolean canContinueToUse() {
        if (this.animal.getAge() >= 0) {
            return false;
        } else if (!this.parent.isAlive()) {
            return false;
        } else {
            double d0 = this.animal.distanceToSqr(this.parent);
            return !(d0 < 9.0) && !(d0 > 256.0);
        }
    }

    @Override
    public void start() {
        this.timeToRecalcPath = 0;
    }

    @Override
    public void stop() {
        this.parent = null;
    }

    @Override
    public void tick() {
        if (--this.timeToRecalcPath <= 0) {
            this.timeToRecalcPath = this.adjustedTickDelay(10);
            this.animal.getNavigation().moveTo(this.parent, this.speedModifier);
        }
    }
}