package net.minecraft.network;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelHandler.Sharable;
import io.netty.handler.codec.EncoderException;
import io.netty.handler.codec.MessageToByteEncoder;

@Sharable
public class Varint21LengthFieldPrepender extends MessageToByteEncoder<ByteBuf> {
	public static final int MAX_VARINT21_BYTES = 3;

	protected void encode(final ChannelHandlerContext ctx, final ByteBuf msg, final ByteBuf out) {
		int bodyLength = msg.readableBytes();
		int headerLength = VarInt.getByteSize(bodyLength);
		if (headerLength > 3) {
			throw new EncoderException("Packet too large: size " + bodyLength + " is over 8");
		} else {
			out.ensureWritable(headerLength + bodyLength);
			VarInt.write(out, bodyLength);
			out.writeBytes(msg, msg.readerIndex(), bodyLength);
		}
	}
}