ChunkManager.java

package us.myles.ViaVersion.chunks;

import io.netty.buffer.ByteBuf;
import org.bukkit.Bukkit;
import us.myles.ViaVersion.api.ViaVersion;
import us.myles.ViaVersion.util.PacketUtil;

import java.util.BitSet;
import java.util.logging.Level;
import java.util.logging.Logger;

public class ChunkManager {
    /**
     * Amount of sections in a chunk.
     */
    private static final int SECTION_COUNT = 16;
    /**
     * size of each chunk section (16x16x16).
     */
    private static final int SECTION_SIZE = 16;
    /**
     * Length of biome data.
     */
    private static final int BIOME_DATA_LENGTH = 256;

    /**
     * Read chunk from 1.8 chunk data.
     *
     * @param input data
     * @return Chunk
     */
    public Chunk readChunk(ByteBuf input) {
        // Primary data
        int chunkX = PacketUtil.readVarInt(input);
        int chunkZ = PacketUtil.readVarInt(input);
        boolean groundUp = input.readBoolean();
        int bitmap = input.readShort();

        // Data to be read
        BitSet usedSections = new BitSet(16);
        ChunkSection[] sections = new ChunkSection[16];
        byte[] biomeData = null;

        // Calculate section count from bitmap
        for(int i = 0; i < 16; i++) {
            if(((bitmap >> i) & 0x1) == 1) {
                usedSections.set(i);
            }
        }
        int sectionCount = usedSections.cardinality(); // the amount of sections set

        // Predict the size of the remaining data
        boolean hasSkyLight;
        boolean hasBiomeData;
        int bytesLeft = input.readableBytes();
        bytesLeft -= sectionCount * ChunkSection.BLOCK_LENGTH; // Subtract block data
        bytesLeft -= sectionCount * ChunkSection.LIGHT_LENGTH; // Block light
        bytesLeft -= (hasSkyLight = bytesLeft >= sectionCount * ChunkSection.LIGHT_LENGTH) ? sectionCount * ChunkSection.LIGHT_LENGTH : 0;
        bytesLeft -= (hasBiomeData = bytesLeft >= BIOME_DATA_LENGTH) ? BIOME_DATA_LENGTH : 0;
        if(bytesLeft > 0) {
            Bukkit.getLogger().log(Level.WARNING, bytesLeft + " Bytes left after reading chunk!");
        }

        // Read block ids
        for(int i = 0; i < SECTION_COUNT; i++) {
            if(!usedSections.get(i)) continue; // Section not set
            sections[i] = new ChunkSection();
            for(int y = 0; y < SECTION_SIZE; y++) {
                for(int z = 0; z < SECTION_SIZE; z++) {
                    for(int x = 0; x < SECTION_SIZE; x++) {
                        byte data = input.readByte();
                        byte id = input.readByte();
                        // TODO: Save to chunk section
                    }
                }
            }
        }

        // Read block light
        for(int i = 0; i < SECTION_COUNT; i++) {
            if(!usedSections.get(i)) continue; // Section not set, has no light
            byte[] blockLightArray = new byte[ChunkSection.LIGHT_LENGTH];
            input.readBytes(blockLightArray);
        }
    }
}