Code/net/minecraft/network/protocol/game/ClientboundLevelChunkPacketData.java

package net.minecraft.network.protocol.game;

import com.google.common.collect.Lists;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import java.util.EnumMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.function.Consumer;
import java.util.stream.Collectors;
import javax.annotation.Nullable;
import net.minecraft.core.BlockPos;
import net.minecraft.core.SectionPos;
import net.minecraft.core.registries.Registries;
import net.minecraft.nbt.CompoundTag;
import net.minecraft.network.FriendlyByteBuf;
import net.minecraft.network.RegistryFriendlyByteBuf;
import net.minecraft.network.codec.ByteBufCodecs;
import net.minecraft.network.codec.StreamCodec;
import net.minecraft.world.level.block.entity.BlockEntity;
import net.minecraft.world.level.block.entity.BlockEntityType;
import net.minecraft.world.level.chunk.LevelChunk;
import net.minecraft.world.level.chunk.LevelChunkSection;
import net.minecraft.world.level.levelgen.Heightmap;

public class ClientboundLevelChunkPacketData {
    private static final StreamCodec<ByteBuf, Map<Heightmap.Types, long[]>> HEIGHTMAPS_STREAM_CODEC = ByteBufCodecs.map(
        p_389934_ -> new EnumMap<>(Heightmap.Types.class), Heightmap.Types.STREAM_CODEC, ByteBufCodecs.LONG_ARRAY
    );
    private static final int TWO_MEGABYTES = 2097152;
    private final Map<Heightmap.Types, long[]> heightmaps;
    private final byte[] buffer;
    private final List<ClientboundLevelChunkPacketData.BlockEntityInfo> blockEntitiesData;

    public ClientboundLevelChunkPacketData(LevelChunk p_195651_) {
        this.heightmaps = p_195651_.getHeightmaps()
            .stream()
            .filter(p_389936_ -> p_389936_.getKey().sendToClient())
            .collect(Collectors.toMap(Entry::getKey, p_389935_ -> (long[])p_389935_.getValue().getRawData().clone()));
        this.buffer = new byte[calculateChunkSize(p_195651_)];
        extractChunkData(new FriendlyByteBuf(this.getWriteBuffer()), p_195651_);
        this.blockEntitiesData = Lists.newArrayList();

        for (Entry<BlockPos, BlockEntity> entry : p_195651_.getBlockEntities().entrySet()) {
            this.blockEntitiesData.add(ClientboundLevelChunkPacketData.BlockEntityInfo.create(entry.getValue()));
        }
    }

    public ClientboundLevelChunkPacketData(RegistryFriendlyByteBuf p_335775_, int p_195654_, int p_195655_) {
        this.heightmaps = HEIGHTMAPS_STREAM_CODEC.decode(p_335775_);
        int i = p_335775_.readVarInt();
        if (i > 2097152) {
            throw new RuntimeException("Chunk Packet trying to allocate too much memory on read.");
        } else {
            this.buffer = new byte[i];
            p_335775_.readBytes(this.buffer);
            this.blockEntitiesData = ClientboundLevelChunkPacketData.BlockEntityInfo.LIST_STREAM_CODEC.decode(p_335775_);
        }
    }

    public void write(RegistryFriendlyByteBuf p_331012_) {
        HEIGHTMAPS_STREAM_CODEC.encode(p_331012_, this.heightmaps);
        p_331012_.writeVarInt(this.buffer.length);
        p_331012_.writeBytes(this.buffer);
        ClientboundLevelChunkPacketData.BlockEntityInfo.LIST_STREAM_CODEC.encode(p_331012_, this.blockEntitiesData);
    }

    private static int calculateChunkSize(LevelChunk p_195665_) {
        int i = 0;

        for (LevelChunkSection levelchunksection : p_195665_.getSections()) {
            i += levelchunksection.getSerializedSize();
        }

        return i;
    }

    private ByteBuf getWriteBuffer() {
        ByteBuf bytebuf = Unpooled.wrappedBuffer(this.buffer);
        bytebuf.writerIndex(0);
        return bytebuf;
    }

    public static void extractChunkData(FriendlyByteBuf p_195669_, LevelChunk p_195670_) {
        for (LevelChunkSection levelchunksection : p_195670_.getSections()) {
            levelchunksection.write(p_195669_);
        }
    }

    public Consumer<ClientboundLevelChunkPacketData.BlockEntityTagOutput> getBlockEntitiesTagsConsumer(int p_195658_, int p_195659_) {
        return p_195663_ -> this.getBlockEntitiesTags(p_195663_, p_195658_, p_195659_);
    }

    private void getBlockEntitiesTags(ClientboundLevelChunkPacketData.BlockEntityTagOutput p_195675_, int p_195676_, int p_195677_) {
        int i = 16 * p_195676_;
        int j = 16 * p_195677_;
        BlockPos.MutableBlockPos blockpos$mutableblockpos = new BlockPos.MutableBlockPos();

        for (ClientboundLevelChunkPacketData.BlockEntityInfo clientboundlevelchunkpacketdata$blockentityinfo : this.blockEntitiesData) {
            int k = i + SectionPos.sectionRelative(clientboundlevelchunkpacketdata$blockentityinfo.packedXZ >> 4);
            int l = j + SectionPos.sectionRelative(clientboundlevelchunkpacketdata$blockentityinfo.packedXZ);
            blockpos$mutableblockpos.set(k, clientboundlevelchunkpacketdata$blockentityinfo.y, l);
            p_195675_.accept(
                blockpos$mutableblockpos, clientboundlevelchunkpacketdata$blockentityinfo.type, clientboundlevelchunkpacketdata$blockentityinfo.tag
            );
        }
    }

    public FriendlyByteBuf getReadBuffer() {
        return new FriendlyByteBuf(Unpooled.wrappedBuffer(this.buffer));
    }

    public Map<Heightmap.Types, long[]> getHeightmaps() {
        return this.heightmaps;
    }

    static class BlockEntityInfo {
        public static final StreamCodec<RegistryFriendlyByteBuf, ClientboundLevelChunkPacketData.BlockEntityInfo> STREAM_CODEC = StreamCodec.ofMember(
            ClientboundLevelChunkPacketData.BlockEntityInfo::write, ClientboundLevelChunkPacketData.BlockEntityInfo::new
        );
        public static final StreamCodec<RegistryFriendlyByteBuf, List<ClientboundLevelChunkPacketData.BlockEntityInfo>> LIST_STREAM_CODEC = STREAM_CODEC.apply(
            ByteBufCodecs.list()
        );
        final int packedXZ;
        final int y;
        final BlockEntityType<?> type;
        @Nullable
        final CompoundTag tag;

        private BlockEntityInfo(int p_195685_, int p_195686_, BlockEntityType<?> p_195687_, @Nullable CompoundTag p_195688_) {
            this.packedXZ = p_195685_;
            this.y = p_195686_;
            this.type = p_195687_;
            this.tag = p_195688_;
        }

        private BlockEntityInfo(RegistryFriendlyByteBuf p_335103_) {
            this.packedXZ = p_335103_.readByte();
            this.y = p_335103_.readShort();
            this.type = ByteBufCodecs.registry(Registries.BLOCK_ENTITY_TYPE).decode(p_335103_);
            this.tag = p_335103_.readNbt();
        }

        private void write(RegistryFriendlyByteBuf p_332659_) {
            p_332659_.writeByte(this.packedXZ);
            p_332659_.writeShort(this.y);
            ByteBufCodecs.registry(Registries.BLOCK_ENTITY_TYPE).encode(p_332659_, this.type);
            p_332659_.writeNbt(this.tag);
        }

        static ClientboundLevelChunkPacketData.BlockEntityInfo create(BlockEntity p_195692_) {
            CompoundTag compoundtag = p_195692_.getUpdateTag(p_195692_.getLevel().registryAccess());
            BlockPos blockpos = p_195692_.getBlockPos();
            int i = SectionPos.sectionRelative(blockpos.getX()) << 4 | SectionPos.sectionRelative(blockpos.getZ());
            return new ClientboundLevelChunkPacketData.BlockEntityInfo(
                i, blockpos.getY(), p_195692_.getType(), compoundtag.isEmpty() ? null : compoundtag
            );
        }
    }

    @FunctionalInterface
    public interface BlockEntityTagOutput {
        void accept(BlockPos p_195696_, BlockEntityType<?> p_195697_, @Nullable CompoundTag p_195698_);
    }
}