/*
 * Copyright 2017 - 2018 Anton Tananaev (anton@traccar.org)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.traccar.protocol;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.Channel;
import io.netty.channel.ChannelHandlerContext;

import java.nio.charset.StandardCharsets;

import org.traccar.BaseFrameDecoder;

public class WatchFrameDecoder extends BaseFrameDecoder {

    @Override
    protected Object decode(
            ChannelHandlerContext ctx, Channel channel, ByteBuf buf) throws Exception {

        int idIndex = buf.indexOf(buf.readerIndex(), buf.writerIndex(), (byte) '*') + 1;
        if (idIndex <= 0) {
            return null;
        }

        int lengthIndex = buf.indexOf(idIndex, buf.writerIndex(), (byte) '*') + 1;
        if (lengthIndex <= 0) {
            return null;
        }

        int payloadIndex = buf.indexOf(lengthIndex, buf.writerIndex(), (byte) '*');
        if (payloadIndex < 0) {
            return null;
        }

        if (payloadIndex + 5 < buf.writerIndex() && buf.getByte(payloadIndex + 5) == '*'
                && buf.toString(payloadIndex + 1, 4, StandardCharsets.US_ASCII).matches("\\p{XDigit}+")) {
            lengthIndex = payloadIndex + 1;
            payloadIndex = buf.indexOf(lengthIndex, buf.writerIndex(), (byte) '*');
            if (payloadIndex < 0) {
                return null;
            }
        }

        int length = Integer.parseInt(
                buf.toString(lengthIndex, payloadIndex - lengthIndex, StandardCharsets.US_ASCII), 16);
        if (buf.readableBytes() >= payloadIndex + 1 + length + 1) {
            ByteBuf frame = Unpooled.buffer();
            int endIndex = buf.readerIndex() + payloadIndex + 1 + length + 1;
            while (buf.readerIndex() < endIndex) {
                byte b = buf.readByte();
                if (b == 0x7D) {
                    switch (buf.readByte()) {
                        case 0x01:
                            frame.writeByte(0x7D);
                            break;
                        case 0x02:
                            frame.writeByte(0x5B);
                            break;
                        case 0x03:
                            frame.writeByte(0x5D);
                            break;
                        case 0x04:
                            frame.writeByte(0x2C);
                            break;
                        case 0x05:
                            frame.writeByte(0x2A);
                            break;
                        default:
                            throw new IllegalArgumentException();
                    }
                } else {
                    frame.writeByte(b);
                }
            }
            return frame;
        }

        return null;
    }

}

@@ -798,52 +798,8 @@
 xt;%0A
-%0Aimport java.nio.charset.StandardCharsets;%0A%0A
 impo
@@ -1035,17 +1035,18 @@
     int 
-i
+en
 dIndex =
@@ -1108,1131 +1108,90 @@
 e) '
-*') + 1;%0A        if (idIndex %3C= 0) %7B%0A            return null;%0A        %7D%0A%0A        int lengthIndex = buf.indexOf(idIndex, buf.writerIndex(), (byte) '*') + 1;%0A        if (lengthIndex %3C= 0) %7B%0A            return null;%0A        %7D%0A%0A        int payloadIndex = buf.indexOf(lengthIndex, buf.writerIndex(), (byte) '*');%0A        if (payloadIndex %3C 0) %7B%0A            return null;%0A        %7D%0A%0A        if (payloadIndex + 5 %3C buf.writerIndex() && buf.getByte(payloadIndex + 5) == '*'%0A                && buf.toString(payloadIndex + 1, 4, StandardCharsets.US_ASCII).matches(%22%5C%5Cp%7BXDigit%7D+%22)) %7B%0A            lengthIndex = payloadIndex + 1;%0A            payloadIndex = buf.indexOf(lengthIndex, buf.writerIndex(), (byte) '*');%0A            if (payloadIndex %3C 0) %7B%0A                return null;%0A            %7D%0A        %7D%0A%0A        int length = Integer.parseInt(%0A                buf.toString(lengthIndex, payloadIndex - lengthIndex, StandardCharsets.US_ASCII), 16);%0A        if (buf.readableBytes() %3E= payloadIndex + 1 + length + 1) %7B%0A            ByteBuf frame = Unpooled.buffer();%0A            int endIndex = buf.readerIndex() + payloadIndex + 1 + length + 1
+%5D') + 1;%0A        if (endIndex %3E 0) %7B%0A            ByteBuf frame = Unpooled.buffer()
 ;%0A  
@@ -1305,20 +1305,19 @@
 f (b == 
-0x7D
+'%7D'
 ) %7B%0A    
@@ -1441,12 +1441,11 @@
 yte(
-0x7D
+'%7D'
 );%0A 
@@ -1561,12 +1561,11 @@
 yte(
-0x5B
+'%5B'
 );%0A 
@@ -1681,12 +1681,11 @@
 yte(
-0x5D
+'%5D'
 );%0A 
@@ -1801,12 +1801,11 @@
 yte(
-0x2C
+','
 );%0A 
@@ -1921,12 +1921,11 @@
 yte(
-0x2A
+'*'
 );%0A 

Simplify Watch frame decoder