Code/net/minecraft/world/entity/animal/AbstractFish.java

package net.minecraft.world.entity.animal;

import net.minecraft.core.BlockPos;
import net.minecraft.nbt.CompoundTag;
import net.minecraft.network.syncher.EntityDataAccessor;
import net.minecraft.network.syncher.EntityDataSerializers;
import net.minecraft.network.syncher.SynchedEntityData;
import net.minecraft.sounds.SoundEvent;
import net.minecraft.sounds.SoundEvents;
import net.minecraft.tags.FluidTags;
import net.minecraft.util.Mth;
import net.minecraft.world.InteractionHand;
import net.minecraft.world.InteractionResult;
import net.minecraft.world.entity.EntitySelector;
import net.minecraft.world.entity.EntityType;
import net.minecraft.world.entity.Mob;
import net.minecraft.world.entity.MoverType;
import net.minecraft.world.entity.ai.attributes.AttributeSupplier;
import net.minecraft.world.entity.ai.attributes.Attributes;
import net.minecraft.world.entity.ai.control.MoveControl;
import net.minecraft.world.entity.ai.goal.AvoidEntityGoal;
import net.minecraft.world.entity.ai.goal.PanicGoal;
import net.minecraft.world.entity.ai.goal.RandomSwimmingGoal;
import net.minecraft.world.entity.ai.navigation.PathNavigation;
import net.minecraft.world.entity.ai.navigation.WaterBoundPathNavigation;
import net.minecraft.world.entity.player.Player;
import net.minecraft.world.item.ItemStack;
import net.minecraft.world.level.Level;
import net.minecraft.world.level.block.state.BlockState;
import net.minecraft.world.phys.Vec3;

public abstract class AbstractFish extends WaterAnimal implements Bucketable {
    private static final EntityDataAccessor<Boolean> FROM_BUCKET = SynchedEntityData.defineId(AbstractFish.class, EntityDataSerializers.BOOLEAN);
    private static final boolean DEFAULT_FROM_BUCKET = false;

    public AbstractFish(EntityType<? extends AbstractFish> p_27461_, Level p_27462_) {
        super(p_27461_, p_27462_);
        this.moveControl = new AbstractFish.FishMoveControl(this);
    }

    public static AttributeSupplier.Builder createAttributes() {
        return Mob.createMobAttributes().add(Attributes.MAX_HEALTH, 3.0);
    }

    @Override
    public boolean requiresCustomPersistence() {
        return super.requiresCustomPersistence() || this.fromBucket();
    }

    @Override
    public boolean removeWhenFarAway(double p_27492_) {
        return !this.fromBucket() && !this.hasCustomName();
    }

    @Override
    public int getMaxSpawnClusterSize() {
        return 8;
    }

    @Override
    protected void defineSynchedData(SynchedEntityData.Builder p_334315_) {
        super.defineSynchedData(p_334315_);
        p_334315_.define(FROM_BUCKET, false);
    }

    @Override
    public boolean fromBucket() {
        return this.entityData.get(FROM_BUCKET);
    }

    @Override
    public void setFromBucket(boolean p_27498_) {
        this.entityData.set(FROM_BUCKET, p_27498_);
    }

    @Override
    public void addAdditionalSaveData(CompoundTag p_27485_) {
        super.addAdditionalSaveData(p_27485_);
        p_27485_.putBoolean("FromBucket", this.fromBucket());
    }

    @Override
    public void readAdditionalSaveData(CompoundTag p_27465_) {
        super.readAdditionalSaveData(p_27465_);
        this.setFromBucket(p_27465_.getBooleanOr("FromBucket", false));
    }

    @Override
    protected void registerGoals() {
        super.registerGoals();
        this.goalSelector.addGoal(0, new PanicGoal(this, 1.25));
        this.goalSelector.addGoal(2, new AvoidEntityGoal<>(this, Player.class, 8.0F, 1.6, 1.4, EntitySelector.NO_SPECTATORS::test));
        this.goalSelector.addGoal(4, new AbstractFish.FishSwimGoal(this));
    }

    @Override
    protected PathNavigation createNavigation(Level p_27480_) {
        return new WaterBoundPathNavigation(this, p_27480_);
    }

    @Override
    public void travel(Vec3 p_27490_) {
        if (this.isInWater()) {
            this.moveRelative(0.01F, p_27490_);
            this.move(MoverType.SELF, this.getDeltaMovement());
            this.setDeltaMovement(this.getDeltaMovement().scale(0.9));
            if (this.getTarget() == null) {
                this.setDeltaMovement(this.getDeltaMovement().add(0.0, -0.005, 0.0));
            }
        } else {
            super.travel(p_27490_);
        }
    }

    @Override
    public void aiStep() {
        if (!this.isInWater() && this.onGround() && this.verticalCollision) {
            this.setDeltaMovement(this.getDeltaMovement().add((this.random.nextFloat() * 2.0F - 1.0F) * 0.05F, 0.4F, (this.random.nextFloat() * 2.0F - 1.0F) * 0.05F));
            this.setOnGround(false);
            this.hasImpulse = true;
            this.makeSound(this.getFlopSound());
        }

        super.aiStep();
    }

    @Override
    protected InteractionResult mobInteract(Player p_27477_, InteractionHand p_27478_) {
        return Bucketable.bucketMobPickup(p_27477_, p_27478_, this).orElse(super.mobInteract(p_27477_, p_27478_));
    }

    @Override
    public void saveToBucketTag(ItemStack p_27494_) {
        Bucketable.saveDefaultDataToBucketTag(this, p_27494_);
    }

    @Override
    public void loadFromBucketTag(CompoundTag p_148708_) {
        Bucketable.loadDefaultDataFromBucketTag(this, p_148708_);
    }

    @Override
    public SoundEvent getPickupSound() {
        return SoundEvents.BUCKET_FILL_FISH;
    }

    protected boolean canRandomSwim() {
        return true;
    }

    protected abstract SoundEvent getFlopSound();

    @Override
    protected SoundEvent getSwimSound() {
        return SoundEvents.FISH_SWIM;
    }

    @Override
    protected void playStepSound(BlockPos p_27482_, BlockState p_27483_) {
    }

    static class FishMoveControl extends MoveControl {
        private final AbstractFish fish;

        FishMoveControl(AbstractFish p_27501_) {
            super(p_27501_);
            this.fish = p_27501_;
        }

        @Override
        public void tick() {
            if (this.fish.isEyeInFluid(FluidTags.WATER)) {
                this.fish.setDeltaMovement(this.fish.getDeltaMovement().add(0.0, 0.005, 0.0));
            }

            if (this.operation == MoveControl.Operation.MOVE_TO && !this.fish.getNavigation().isDone()) {
                float f = (float)(this.speedModifier * this.fish.getAttributeValue(Attributes.MOVEMENT_SPEED));
                this.fish.setSpeed(Mth.lerp(0.125F, this.fish.getSpeed(), f));
                double d0 = this.wantedX - this.fish.getX();
                double d1 = this.wantedY - this.fish.getY();
                double d2 = this.wantedZ - this.fish.getZ();
                if (d1 != 0.0) {
                    double d3 = Math.sqrt(d0 * d0 + d1 * d1 + d2 * d2);
                    this.fish.setDeltaMovement(this.fish.getDeltaMovement().add(0.0, this.fish.getSpeed() * (d1 / d3) * 0.1, 0.0));
                }

                if (d0 != 0.0 || d2 != 0.0) {
                    float f1 = (float)(Mth.atan2(d2, d0) * 180.0F / (float)Math.PI) - 90.0F;
                    this.fish.setYRot(this.rotlerp(this.fish.getYRot(), f1, 90.0F));
                    this.fish.yBodyRot = this.fish.getYRot();
                }
            } else {
                this.fish.setSpeed(0.0F);
            }
        }
    }

    static class FishSwimGoal extends RandomSwimmingGoal {
        private final AbstractFish fish;

        public FishSwimGoal(AbstractFish p_27505_) {
            super(p_27505_, 1.0, 40);
            this.fish = p_27505_;
        }

        @Override
        public boolean canUse() {
            return this.fish.canRandomSwim() && super.canUse();
        }
    }
}