Code/net/minecraft/world/item/MaceItem.java

package net.minecraft.world.item;

import java.util.List;
import java.util.function.Predicate;
import javax.annotation.Nullable;
import net.minecraft.core.Direction;
import net.minecraft.network.protocol.game.ClientboundSetEntityMotionPacket;
import net.minecraft.server.level.ServerLevel;
import net.minecraft.server.level.ServerPlayer;
import net.minecraft.sounds.SoundEvent;
import net.minecraft.sounds.SoundEvents;
import net.minecraft.world.damagesource.DamageSource;
import net.minecraft.world.entity.Entity;
import net.minecraft.world.entity.EquipmentSlotGroup;
import net.minecraft.world.entity.LivingEntity;
import net.minecraft.world.entity.TamableAnimal;
import net.minecraft.world.entity.ai.attributes.AttributeModifier;
import net.minecraft.world.entity.ai.attributes.Attributes;
import net.minecraft.world.entity.decoration.ArmorStand;
import net.minecraft.world.item.component.ItemAttributeModifiers;
import net.minecraft.world.item.component.Tool;
import net.minecraft.world.item.enchantment.EnchantmentHelper;
import net.minecraft.world.level.Level;
import net.minecraft.world.phys.Vec3;

public class MaceItem extends Item {
    private static final int DEFAULT_ATTACK_DAMAGE = 5;
    private static final float DEFAULT_ATTACK_SPEED = -3.4F;
    public static final float SMASH_ATTACK_FALL_THRESHOLD = 1.5F;
    private static final float SMASH_ATTACK_HEAVY_THRESHOLD = 5.0F;
    public static final float SMASH_ATTACK_KNOCKBACK_RADIUS = 3.5F;
    private static final float SMASH_ATTACK_KNOCKBACK_POWER = 0.7F;

    public MaceItem(Item.Properties p_329217_) {
        super(p_329217_);
    }

    public static ItemAttributeModifiers createAttributes() {
        return ItemAttributeModifiers.builder()
            .add(Attributes.ATTACK_DAMAGE, new AttributeModifier(BASE_ATTACK_DAMAGE_ID, 5.0, AttributeModifier.Operation.ADD_VALUE), EquipmentSlotGroup.MAINHAND)
            .add(Attributes.ATTACK_SPEED, new AttributeModifier(BASE_ATTACK_SPEED_ID, -3.4F, AttributeModifier.Operation.ADD_VALUE), EquipmentSlotGroup.MAINHAND)
            .build();
    }

    public static Tool createToolProperties() {
        return new Tool(List.of(), 1.0F, 2, false);
    }

    @Override
    public void hurtEnemy(ItemStack p_329476_, LivingEntity p_332492_, LivingEntity p_333391_) {
        if (canSmashAttack(p_333391_)) {
            ServerLevel serverlevel = (ServerLevel)p_333391_.level();
            p_333391_.setDeltaMovement(p_333391_.getDeltaMovement().with(Direction.Axis.Y, 0.01F));
            if (p_333391_ instanceof ServerPlayer serverplayer) {
                serverplayer.currentImpulseImpactPos = this.calculateImpactPosition(serverplayer);
                serverplayer.setIgnoreFallDamageFromCurrentImpulse(true);
                serverplayer.connection.send(new ClientboundSetEntityMotionPacket(serverplayer));
            }

            if (p_332492_.onGround()) {
                if (p_333391_ instanceof ServerPlayer serverplayer1) {
                    serverplayer1.setSpawnExtraParticlesOnFall(true);
                }

                SoundEvent soundevent = p_333391_.fallDistance > 5.0 ? SoundEvents.MACE_SMASH_GROUND_HEAVY : SoundEvents.MACE_SMASH_GROUND;
                serverlevel.playSound(null, p_333391_.getX(), p_333391_.getY(), p_333391_.getZ(), soundevent, p_333391_.getSoundSource(), 1.0F, 1.0F);
            } else {
                serverlevel.playSound(
                    null, p_333391_.getX(), p_333391_.getY(), p_333391_.getZ(), SoundEvents.MACE_SMASH_AIR, p_333391_.getSoundSource(), 1.0F, 1.0F
                );
            }

            knockback(serverlevel, p_333391_, p_332492_);
        }
    }

    private Vec3 calculateImpactPosition(ServerPlayer p_365711_) {
        return p_365711_.isIgnoringFallDamageFromCurrentImpulse() && p_365711_.currentImpulseImpactPos != null && p_365711_.currentImpulseImpactPos.y <= p_365711_.position().y
            ? p_365711_.currentImpulseImpactPos
            : p_365711_.position();
    }

    @Override
    public void postHurtEnemy(ItemStack p_344750_, LivingEntity p_344000_, LivingEntity p_342605_) {
        if (canSmashAttack(p_342605_)) {
            p_342605_.resetFallDistance();
        }
    }

    @Override
    public float getAttackDamageBonus(Entity p_344513_, float p_333106_, DamageSource p_345351_) {
        if (p_345351_.getDirectEntity() instanceof LivingEntity livingentity) {
            if (!canSmashAttack(livingentity)) {
                return 0.0F;
            } else {
                double d3 = 3.0;
                double d0 = 8.0;
                double d1 = livingentity.fallDistance;
                double d2;
                if (d1 <= 3.0) {
                    d2 = 4.0 * d1;
                } else if (d1 <= 8.0) {
                    d2 = 12.0 + 2.0 * (d1 - 3.0);
                } else {
                    d2 = 22.0 + d1 - 8.0;
                }

                return livingentity.level() instanceof ServerLevel serverlevel
                    ? (float)(d2 + EnchantmentHelper.modifyFallBasedDamage(serverlevel, livingentity.getWeaponItem(), p_344513_, p_345351_, 0.0F) * d1)
                    : (float)d2;
            }
        } else {
            return 0.0F;
        }
    }

    private static void knockback(Level p_332228_, Entity p_335011_, Entity p_364373_) {
        p_332228_.levelEvent(2013, p_364373_.getOnPos(), 750);
        p_332228_.getEntitiesOfClass(LivingEntity.class, p_364373_.getBoundingBox().inflate(3.5), knockbackPredicate(p_335011_, p_364373_)).forEach(p_341573_ -> {
            Vec3 vec3 = p_341573_.position().subtract(p_364373_.position());
            double d0 = getKnockbackPower(p_335011_, p_341573_, vec3);
            Vec3 vec31 = vec3.normalize().scale(d0);
            if (d0 > 0.0) {
                p_341573_.push(vec31.x, 0.7F, vec31.z);
                if (p_341573_ instanceof ServerPlayer serverplayer) {
                    serverplayer.connection.send(new ClientboundSetEntityMotionPacket(serverplayer));
                }
            }
        });
    }

    private static Predicate<LivingEntity> knockbackPredicate(Entity p_334480_, Entity p_363363_) {
        return p_390813_ -> {
            boolean flag = !p_390813_.isSpectator();
            boolean flag1 = p_390813_ != p_334480_ && p_390813_ != p_363363_;
            boolean flag2 = !p_334480_.isAlliedTo(p_390813_);
            boolean flag3 = !(
                p_390813_ instanceof TamableAnimal tamableanimal
                    && p_363363_ instanceof LivingEntity livingentity
                    && tamableanimal.isTame()
                    && tamableanimal.isOwnedBy(livingentity)
            );
            boolean flag4 = !(p_390813_ instanceof ArmorStand armorstand && armorstand.isMarker());
            boolean flag5 = p_363363_.distanceToSqr(p_390813_) <= Math.pow(3.5, 2.0);
            return flag && flag1 && flag2 && flag3 && flag4 && flag5;
        };
    }

    private static double getKnockbackPower(Entity p_361841_, LivingEntity p_334129_, Vec3 p_335583_) {
        return (3.5 - p_335583_.length()) * 0.7F * (p_361841_.fallDistance > 5.0 ? 2 : 1) * (1.0 - p_334129_.getAttributeValue(Attributes.KNOCKBACK_RESISTANCE));
    }

    public static boolean canSmashAttack(LivingEntity p_345213_) {
        return p_345213_.fallDistance > 1.5 && !p_345213_.isFallFlying();
    }

    @Nullable
    @Override
    public DamageSource getDamageSource(LivingEntity p_362356_) {
        return canSmashAttack(p_362356_) ? p_362356_.damageSources().mace(p_362356_) : super.getDamageSource(p_362356_);
    }
}