package org.rse.network.codec;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ByteToMessageDecoder;

import java.util.List;

import org.rse.network.packets.incoming.Incoming;

public final class RS2GameDecoder extends ByteToMessageDecoder {

    private int opcode = -1;

    private int size = -1;

    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf buffer, List<Object> out) throws Exception {
        if (opcode == -1) {
            if (buffer.readableBytes() >= 1) {
                opcode = buffer.readByte() & 0xFF;
                size = Incoming.SIZES[opcode];
            } else {
                return;
            }
        }
        switch (size) {
        case -1:
            if (buffer.readableBytes() < 1)
                return;
            size = buffer.readByte() & 0xff;
            break;
        case -2:
            if (buffer.readableBytes() < 2)
                return;
            size = buffer.readShort() & 0xffff;
            break;
        }
        if (buffer.readableBytes() >= size) {
            if (Incoming.isIgnored(opcode)) {
                buffer.skipBytes(size);
                opcode = size = -1;
                return;
            }
            byte[] incomingPayload = new byte[size];
            buffer.readBytes(incomingPayload);
            try {
                out.add(new Message(opcode, incomingPayload));
                return;
            } finally {
                opcode = -1;
                size = -1;
            }
        }
    }

}