src/com/grahamedgecombe/smpd/net/codec/CompressedChunkMessageCodec.java

package com.grahamedgecombe.smpd.net.codec;

import java.io.IOException;
import java.util.zip.DataFormatException;
import java.util.zip.Deflater;
import java.util.zip.Inflater;

import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.buffer.ChannelBuffers;

import com.grahamedgecombe.smpd.msg.CompressedChunkMessage;

public final class CompressedChunkMessageCodec extends MessageCodec<CompressedChunkMessage> {

	private static final int COMPRESSION_LEVEL = Deflater.BEST_SPEED;

	public CompressedChunkMessageCodec() {
		super(CompressedChunkMessage.class, 0x33);
	}

	@Override
	public CompressedChunkMessage decode(ChannelBuffer buffer) throws IOException {
		int x = buffer.readInt();
		int y = buffer.readShort();
		int z = buffer.readInt();

		int width = buffer.readByte() + 1;
		int depth = buffer.readByte() + 1;
		int height = buffer.readByte() + 1;

		int compressedSize = buffer.readInt();
		byte[] compressedData = new byte[compressedSize];
		buffer.readBytes(compressedData);

		byte[] data = new byte[(width * depth * height * 5) / 2];

		Inflater inflater = new Inflater();
		inflater.setInput(compressedData);

		try {
			int uncompressed = inflater.inflate(data);
			if (uncompressed == 0) {
				throw new IOException("Not all bytes uncompressed.");
			}
		} catch (DataFormatException e) {
			throw new IOException("Bad compressed data.", e);
		} finally {
			inflater.end();
		}

		return new CompressedChunkMessage(x, z, y, width, height, depth, data);
	}

	@Override
	public ChannelBuffer encode(CompressedChunkMessage message) throws IOException {
		ChannelBuffer buffer = ChannelBuffers.dynamicBuffer();

		buffer.writeInt(message.getX());
		buffer.writeShort(message.getY());
		buffer.writeInt(message.getZ());

		buffer.writeByte(message.getWidth() - 1);
		buffer.writeByte(message.getDepth() - 1);
		buffer.writeByte(message.getHeight() - 1);

		byte[] data = message.getData();
		byte[] compressedData = new byte[(message.getWidth() * message.getDepth() * message.getHeight() * 5) / 2];

		Deflater deflater = new Deflater(COMPRESSION_LEVEL);
		deflater.setInput(data);
		deflater.finish();

		int compressed = deflater.deflate(compressedData);
		try {
			if (compressed == 0) {
				throw new IOException("Not all bytes compressed.");
			}
		} finally {
			deflater.end();
		}

		buffer.writeInt(compressed);
		buffer.writeBytes(compressedData, 0, compressed);

		return buffer;
	}

}