minecraft-src/net/minecraft/world/level/block/entity/ChiseledBookShelfBlockEntity.java

package net.minecraft.world.level.block.entity;

import com.mojang.logging.LogUtils;
import java.util.Objects;
import java.util.function.Predicate;
import net.minecraft.core.BlockPos;
import net.minecraft.core.NonNullList;
import net.minecraft.core.HolderLookup.Provider;
import net.minecraft.core.component.DataComponents;
import net.minecraft.core.component.DataComponentMap.Builder;
import net.minecraft.nbt.CompoundTag;
import net.minecraft.tags.ItemTags;
import net.minecraft.world.Container;
import net.minecraft.world.ContainerHelper;
import net.minecraft.world.entity.player.Player;
import net.minecraft.world.item.ItemStack;
import net.minecraft.world.item.component.ItemContainerContents;
import net.minecraft.world.level.Level;
import net.minecraft.world.level.block.ChiseledBookShelfBlock;
import net.minecraft.world.level.block.state.BlockState;
import net.minecraft.world.level.block.state.properties.BooleanProperty;
import net.minecraft.world.level.gameevent.GameEvent;
import net.minecraft.world.level.gameevent.GameEvent.Context;
import org.slf4j.Logger;

public class ChiseledBookShelfBlockEntity extends BlockEntity implements Container {
	public static final int MAX_BOOKS_IN_STORAGE = 6;
	private static final Logger LOGGER = LogUtils.getLogger();
	private final NonNullList<ItemStack> items = NonNullList.withSize(6, ItemStack.EMPTY);
	private int lastInteractedSlot = -1;

	public ChiseledBookShelfBlockEntity(BlockPos pos, BlockState state) {
		super(BlockEntityType.CHISELED_BOOKSHELF, pos, state);
	}

	private void updateState(int slot) {
		if (slot >= 0 && slot < 6) {
			this.lastInteractedSlot = slot;
			BlockState blockState = this.getBlockState();

			for (int i = 0; i < ChiseledBookShelfBlock.SLOT_OCCUPIED_PROPERTIES.size(); i++) {
				boolean bl = !this.getItem(i).isEmpty();
				BooleanProperty booleanProperty = (BooleanProperty)ChiseledBookShelfBlock.SLOT_OCCUPIED_PROPERTIES.get(i);
				blockState = blockState.setValue(booleanProperty, bl);
			}

			((Level)Objects.requireNonNull(this.level)).setBlock(this.worldPosition, blockState, 3);
			this.level.gameEvent(GameEvent.BLOCK_CHANGE, this.worldPosition, Context.of(blockState));
		} else {
			LOGGER.error("Expected slot 0-5, got {}", slot);
		}
	}

	@Override
	protected void loadAdditional(CompoundTag tag, Provider registries) {
		super.loadAdditional(tag, registries);
		this.items.clear();
		ContainerHelper.loadAllItems(tag, this.items, registries);
		this.lastInteractedSlot = tag.getInt("last_interacted_slot");
	}

	@Override
	protected void saveAdditional(CompoundTag tag, Provider registries) {
		super.saveAdditional(tag, registries);
		ContainerHelper.saveAllItems(tag, this.items, true, registries);
		tag.putInt("last_interacted_slot", this.lastInteractedSlot);
	}

	public int count() {
		return (int)this.items.stream().filter(Predicate.not(ItemStack::isEmpty)).count();
	}

	@Override
	public void clearContent() {
		this.items.clear();
	}

	@Override
	public int getContainerSize() {
		return 6;
	}

	@Override
	public boolean isEmpty() {
		return this.items.stream().allMatch(ItemStack::isEmpty);
	}

	@Override
	public ItemStack getItem(int slot) {
		return this.items.get(slot);
	}

	@Override
	public ItemStack removeItem(int slot, int amount) {
		ItemStack itemStack = (ItemStack)Objects.requireNonNullElse(this.items.get(slot), ItemStack.EMPTY);
		this.items.set(slot, ItemStack.EMPTY);
		if (!itemStack.isEmpty()) {
			this.updateState(slot);
		}

		return itemStack;
	}

	@Override
	public ItemStack removeItemNoUpdate(int slot) {
		return this.removeItem(slot, 1);
	}

	@Override
	public void setItem(int slot, ItemStack stack) {
		if (stack.is(ItemTags.BOOKSHELF_BOOKS)) {
			this.items.set(slot, stack);
			this.updateState(slot);
		} else if (stack.isEmpty()) {
			this.removeItem(slot, 1);
		}
	}

	@Override
	public boolean canTakeItem(Container target, int slot, ItemStack stack) {
		return target.hasAnyMatching(
			itemStack2 -> itemStack2.isEmpty()
				? true
				: ItemStack.isSameItemSameComponents(stack, itemStack2) && itemStack2.getCount() + stack.getCount() <= target.getMaxStackSize(itemStack2)
		);
	}

	@Override
	public int getMaxStackSize() {
		return 1;
	}

	@Override
	public boolean stillValid(Player player) {
		return Container.stillValidBlockEntity(this, player);
	}

	@Override
	public boolean canPlaceItem(int slot, ItemStack stack) {
		return stack.is(ItemTags.BOOKSHELF_BOOKS) && this.getItem(slot).isEmpty() && stack.getCount() == this.getMaxStackSize();
	}

	public int getLastInteractedSlot() {
		return this.lastInteractedSlot;
	}

	@Override
	protected void applyImplicitComponents(BlockEntity.DataComponentInput componentInput) {
		super.applyImplicitComponents(componentInput);
		componentInput.getOrDefault(DataComponents.CONTAINER, ItemContainerContents.EMPTY).copyInto(this.items);
	}

	@Override
	protected void collectImplicitComponents(Builder components) {
		super.collectImplicitComponents(components);
		components.set(DataComponents.CONTAINER, ItemContainerContents.fromItems(this.items));
	}

	@Override
	public void removeComponentsFromTag(CompoundTag tag) {
		tag.remove("Items");
	}
}