package com.example.agvcontroller.protocol;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ByteToMessageDecoder;
import io.netty.util.ReferenceCountUtil;
import com.example.agvcontroller.socket.RadixTools;

import java.net.InetSocketAddress;
import java.util.List;

/**
 * Created by vincent on 2019-04-10
 */
public class ProtocolDecoder extends ByteToMessageDecoder {

    private final int maxFrameLength;

    public ProtocolDecoder(int maxFrameLength){
        this.maxFrameLength = maxFrameLength;
    }

    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
        String ip = ((InetSocketAddress) ctx.channel().remoteAddress()).getAddress().getHostAddress();
//        log.info("ip:{} ===>> {}", ip, ByteBufUtil.hexDump(in).toUpperCase());

        int startMark = indexOfStartMark(in);
        if (startMark == -1){
            in.skipBytes(in.readableBytes());
            return;
        }
        if (in.readableBytes() > maxFrameLength) {
            in.skipBytes(in.readableBytes());
            return;
        }
        // 去除无用前缀报文
        if (startMark != 0){
            in.readerIndex(startMark);
            in.discardReadBytes();
        }
        // 粘包处理
        in.markReaderIndex();
        in.readerIndex(PackagePart.CONTENT_LENGTH.getStartIndex());
        int pacTotalLen = PackagePart.START_SYMBOL.getLen()
                + PackagePart.CONTENT_LENGTH.getLen()
                + in.readShortLE()
                + PackagePart.VALIDE_CODE.getLen()
                ;
        in.resetReaderIndex();
        ByteBuf byteBuf = in.readSlice(pacTotalLen);

        // 生成和初始化消息包装类
        AgvPackage pac = AgvPackage.valueOfEmpty();
        pac.setSourceBuff(byteBuf);
        // 解析
        out.add(analyzeProtocol(pac));

        //        byteBuf.resetReaderIndex(); // tip: 如果 ridx == widx，则 refCnt = 0
        in.resetReaderIndex();
        in.skipBytes(pacTotalLen); // tip: This method will be called till either the input has nothing to read，无语！

        ReferenceCountUtil.retain(in);  // 解码器自动释放 refCnt - 1

    }

    public AgvPackage analyzeProtocol(AgvPackage pac){
        ByteBuf byteBuf = pac.getSourceBuff();
        PacHeader pacHeader = pac.getHeader();
        // 唯一标识码
        byteBuf.readerIndex(PackagePart.UNIQUENO.getStartIndex());
        byte[] bytes = new byte[PackagePart.UNIQUENO.getLen()];
        byteBuf.readBytes(bytes);
        Utils.reverse(bytes);
        String uniqueno = String.valueOf(RadixTools.bytesToInt(bytes));
        if (!Cools.isEmpty(uniqueno)) {
            pacHeader.setUniqueNo(uniqueno);
            byteBuf.resetReaderIndex();
        } else {
            return pac.setErrorPac(Boolean.TRUE).setPacErrorType(PacErrorType.PAC_ANALYZE_ERROR);
        }
        // 获取标识符
        byte startSymbol = byteBuf.readByte();
        DirectionType  direction = null;
        if ((0xEE&0xFF) == (startSymbol&0xFF)) {
            pacHeader.setStartSymbol(startSymbol);
            direction = DirectionType.DOWN;
        } else if ((0xAA&0xFF) == (startSymbol&0xFF)) {
            pacHeader.setStartSymbol(startSymbol);
            direction = DirectionType.UP;
        } else {
            return pac.setErrorPac(Boolean.TRUE).setPacErrorType(PacErrorType.PAC_ANALYZE_ERROR);
        }
        // 获取协议体长度
        int contentLength = byteBuf.readShortLE();
        if (contentLength >= 0) {
            pacHeader.setContentLength(contentLength);
        } else {
            return pac.setErrorPac(Boolean.TRUE).setPacErrorType(PacErrorType.PAC_ANALYZE_ERROR);
        }
        // skip uniqueNo
        byteBuf.readerIndex(byteBuf.readerIndex() + PackagePart.UNIQUENO.getLen());
        // 获取时间戳
        byteBuf.readerIndex(PackagePart.TIMESTAMP.getStartIndex());
        int timestamp = byteBuf.readIntLE();
        if (timestamp > 0) {
            pacHeader.setTimestamp(timestamp);
        } else {
            return pac.setErrorPac(Boolean.TRUE).setPacErrorType(PacErrorType.PAC_ANALYZE_ERROR);
        }
        // 获取命令标识
        int commandByte = byteBuf.readByte() & 0xFF;
        ProtocolType protocolType = ProtocolType.getByCode(commandByte, direction);
        if (null != protocolType) {
            pacHeader.setProtocolType(protocolType);
        } else {
            return pac.setErrorPac(Boolean.TRUE).setPacErrorType(PacErrorType.PAC_ANALYZE_ERROR);
        }
        // 获取协议体
        if (contentLength > 0) {
            ByteBuf body = byteBuf.readSlice(pac.getHeader().getContentLength() - (
                        + PackagePart.UNIQUENO.getLen()
                        + PackagePart.TIMESTAMP.getLen()
                        + PackagePart.COMMAND_MARK.getLen()
                    ));
            if (null != body && body.readableBytes() >= 0) {
                pac.getBody().setContent(body);
            } else {
                return pac.setErrorPac(Boolean.TRUE).setPacErrorType(PacErrorType.PAC_ANALYZE_ERROR);
            }
        }
        // 校验码
        if(byteBuf.readableBytes() == 2) {
            pac.setValidCode(byteBuf.readUnsignedShortLE());
        } else {
            return pac.setErrorPac(Boolean.TRUE).setPacErrorType(PacErrorType.PAC_ANALYZE_ERROR);
        }
        return pac;
    }

    // 获取标识位下标
    private int indexOfStartMark(ByteBuf inputBuffer){
        int length = inputBuffer.writerIndex();
        // 报文长度至少大于2
        if (length < 2) {
            return -1;
        }
        int readerIndex = inputBuffer.readerIndex();
        for(int i = readerIndex; i < length - 1; i ++) {
            byte b1 = inputBuffer.getByte(i);
            if ((0xEE&0xFF) == (b1&0xFF) || (0xAA&0xFF) == (b1&0xFF)) {
                return i;
            }
        }
        return -1;
    }

}