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

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

import java.util.EnumSet;
import java.util.List;
import net.minecraft.world.entity.Entity;
import net.minecraft.world.entity.EntityType;
import net.minecraft.world.entity.animal.horse.Llama;
import net.minecraft.world.entity.decoration.LeashFenceKnotEntity;
import net.minecraft.world.phys.Vec3;

public class LlamaFollowCaravanGoal extends Goal {
    public final Llama llama;
    private double speedModifier;
    private static final int CARAVAN_LIMIT = 8;
    private int distCheckCounter;

    public LlamaFollowCaravanGoal(Llama p_25501_, double p_25502_) {
        this.llama = p_25501_;
        this.speedModifier = p_25502_;
        this.setFlags(EnumSet.of(Goal.Flag.MOVE));
    }

    @Override
    public boolean canUse() {
        if (!this.llama.isLeashed() && !this.llama.inCaravan()) {
            List<Entity> list = this.llama.level().getEntities(this.llama, this.llama.getBoundingBox().inflate(9.0, 4.0, 9.0), p_25505_ -> {
                EntityType<?> entitytype = p_25505_.getType();
                return entitytype == EntityType.LLAMA || entitytype == EntityType.TRADER_LLAMA;
            });
            Llama llama = null;
            double d0 = Double.MAX_VALUE;

            for (Entity entity : list) {
                Llama llama1 = (Llama)entity;
                if (llama1.inCaravan() && !llama1.hasCaravanTail()) {
                    double d1 = this.llama.distanceToSqr(llama1);
                    if (!(d1 > d0)) {
                        d0 = d1;
                        llama = llama1;
                    }
                }
            }

            if (llama == null) {
                for (Entity entity1 : list) {
                    Llama llama2 = (Llama)entity1;
                    if (llama2.isLeashed() && !llama2.hasCaravanTail()) {
                        double d2 = this.llama.distanceToSqr(llama2);
                        if (!(d2 > d0)) {
                            d0 = d2;
                            llama = llama2;
                        }
                    }
                }
            }

            if (llama == null) {
                return false;
            } else if (d0 < 4.0) {
                return false;
            } else if (!llama.isLeashed() && !this.firstIsLeashed(llama, 1)) {
                return false;
            } else {
                this.llama.joinCaravan(llama);
                return true;
            }
        } else {
            return false;
        }
    }

    @Override
    public boolean canContinueToUse() {
        if (this.llama.inCaravan() && this.llama.getCaravanHead().isAlive() && this.firstIsLeashed(this.llama, 0)) {
            double d0 = this.llama.distanceToSqr(this.llama.getCaravanHead());
            if (d0 > 676.0) {
                if (this.speedModifier <= 3.0) {
                    this.speedModifier *= 1.2;
                    this.distCheckCounter = reducedTickDelay(40);
                    return true;
                }

                if (this.distCheckCounter == 0) {
                    return false;
                }
            }

            if (this.distCheckCounter > 0) {
                this.distCheckCounter--;
            }

            return true;
        } else {
            return false;
        }
    }

    @Override
    public void stop() {
        this.llama.leaveCaravan();
        this.speedModifier = 2.1;
    }

    @Override
    public void tick() {
        if (this.llama.inCaravan()) {
            if (!(this.llama.getLeashHolder() instanceof LeashFenceKnotEntity)) {
                Llama llama = this.llama.getCaravanHead();
                double d0 = this.llama.distanceTo(llama);
                float f = 2.0F;
                Vec3 vec3 = new Vec3(
                        llama.getX() - this.llama.getX(), llama.getY() - this.llama.getY(), llama.getZ() - this.llama.getZ()
                    )
                    .normalize()
                    .scale(Math.max(d0 - 2.0, 0.0));
                this.llama
                    .getNavigation()
                    .moveTo(
                        this.llama.getX() + vec3.x,
                        this.llama.getY() + vec3.y,
                        this.llama.getZ() + vec3.z,
                        this.speedModifier
                    );
            }
        }
    }

    private boolean firstIsLeashed(Llama p_25507_, int p_25508_) {
        if (p_25508_ > 8) {
            return false;
        } else if (p_25507_.inCaravan()) {
            return p_25507_.getCaravanHead().isLeashed() ? true : this.firstIsLeashed(p_25507_.getCaravanHead(), ++p_25508_);
        } else {
            return false;
        }
    }
}