/*******************************************************************************
 * Copyright (C) 2013 JMaNGOS <http://jmangos.org/>
 * 
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.
 * 
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 * 
 * You should have received a copy of the GNU General Public License along
 * with this program. If not, see <http://www.gnu.org/licenses/>.
 ******************************************************************************/
package org.jmangos.realm.network.decoder;

import java.nio.ByteOrder;

import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.buffer.ChannelBuffers;
import org.jboss.netty.channel.Channel;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.handler.codec.frame.FrameDecoder;
import org.jmangos.commons.OpcodeTable;
import org.jmangos.realm.network.crypt.Crypt;
import org.jmangos.realm.network.handler.RealmToClientChannelHandler;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

// TODO: Auto-generated Javadoc
/**
 * The Class PacketFrameDecoder.
 */
public class PacketFrameDecoder extends FrameDecoder {

    /** The Constant log. */
    private static final Logger log = LoggerFactory.getLogger(PacketFrameDecoder.class);

    /*
     * (non-Javadoc)
     * 
     * @see
     * org.jboss.netty.handler.codec.frame.FrameDecoder#decode(org.jboss.netty
     * .channel.
     * ChannelHandlerContext, org.jboss.netty.channel.Channel,
     * org.jboss.netty.buffer.ChannelBuffer)
     */
    @Override
    protected Object decode(final ChannelHandlerContext ctx, final Channel channel,
            final ChannelBuffer msg) throws Exception {

        final ChannelBuffer message = msg;
        if (message.readableBytes() < 6) {
            return null;
        }
        final RealmToClientChannelHandler channelHandler =
                (RealmToClientChannelHandler) ctx.getPipeline().getLast();
        final long opcode;
        int size;
        if (channelHandler.getLastOpcode() == null) {
            final Crypt crypt = channelHandler.getCrypt();
            byte[] header = new byte[6];
            message.readBytes(header);
            header = crypt.encrypt(header);
            final ChannelBuffer clientHeader =
                    ChannelBuffers.wrappedBuffer(ByteOrder.LITTLE_ENDIAN, header);
            size = clientHeader.readByte() << 8;
            size |= clientHeader.readByte() & 0xFF;
            size -= 4;
            opcode = clientHeader.readUnsignedInt();
            if ((size < 0) || (size > 10240) || (opcode > 10240)) {
                log.error("PacketFrameDecoder::decode: client sent malformed packet size = " +
                    size +
                    " , opcode = " +
                    opcode);
                channel.close();
                return null;
            }
        } else {
            opcode = channelHandler.getLastOpcode();
            size = channelHandler.getLastOpcodeSize();
        }
        log.info(String.format(
                "[RECIVE PACKET] :  0x%02X - %s size :  0x%02X, readeble size: 0x%02X", opcode,
                OpcodeTable.getOpcode((int) opcode), size, message.readableBytes()));
        if (message.readableBytes() < size) {
            channelHandler.setLastOpcode(opcode);
            channelHandler.setLastOpcodeSize(size);
            return null;
        } else {
            channelHandler.setLastOpcode(null);
        }
        final ChannelBuffer frame = ChannelBuffers.buffer(ByteOrder.LITTLE_ENDIAN, (size + 4));
        frame.writeInt((int) opcode);
        frame.writeBytes(message.readBytes(size));
        return frame;
    }
}