/*
 * Copyright 2013 - 2015 Anton Tananaev (anton.tananaev@gmail.com)
 *
 * 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 java.net.SocketAddress;
import java.nio.ByteOrder;
import java.nio.charset.Charset;
import java.util.Date;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.buffer.ChannelBuffers;
import org.jboss.netty.channel.Channel;
import org.traccar.BaseProtocolDecoder;
import org.traccar.helper.Log;
import org.traccar.model.Event;
import org.traccar.model.Position;

public class GalileoProtocolDecoder extends BaseProtocolDecoder {

    public GalileoProtocolDecoder(GalileoProtocol protocol) {
        super(protocol);
    }

    private static final int TAG_IMEI = 0x03;
    private static final int TAG_DATE = 0x20;
    private static final int TAG_COORDINATES = 0x30;
    private static final int TAG_SPEED_COURSE = 0x33;
    private static final int TAG_ALTITUDE = 0x34;
    private static final int TAG_STATUS = 0x40;
    private static final int TAG_POWER = 0x41;
    private static final int TAG_BATTERY = 0x42;
    private static final int TAG_ODOMETER = 0xd4;
    private static final int TAG_REFRIGERATOR = 0x5b;
    private static final int TAG_PRESSURE = 0x5c;

    private static final Map<Integer, Integer> TAG_LENGTH_MAP = new HashMap<>();

    static {
        int[] l1 = {
            0x01, 0x02, 0x35, 0x43, 0xc4, 0xc5, 0xc6, 0xc7,
            0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf,
            0xd0, 0xd1, 0xd2, 0xd5, 0x88, 0x8a, 0x8b, 0x8c,
            0xa0, 0xaf, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6,
            0xa7, 0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae
        };
        int[] l2 = {
            0x04, 0x10, 0x34, 0x40, 0x41, 0x42, 0x45, 0x46,
            0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57,
            0x58, 0x59, 0x60, 0x61, 0x62, 0x70, 0x71, 0x72,
            0x73, 0x74, 0x75, 0x76, 0x77, 0xb0, 0xb1, 0xb2,
            0xb3, 0xb4, 0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xd6,
            0xd7, 0xd8, 0xd9, 0xda
        };
        int[] l3 = {
            0x63, 0x64, 0x6f, 0x5d, 0x65, 0x66, 0x67, 0x68,
            0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e
        };
        int[] l4 = {
            0x20, 0x33, 0x44, 0x90, 0xc0, 0xc1, 0xc2, 0xc3,
            0xd3, 0xd4, 0xdb, 0xdc, 0xdd, 0xde, 0xdf, 0xf0,
            0xf9, 0x5a, 0x47, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5,
            0xf6, 0xf7, 0xf8
        };
        for (int i : l1) {
            TAG_LENGTH_MAP.put(i, 1);
        }
        for (int i : l2) {
            TAG_LENGTH_MAP.put(i, 2);
        }
        for (int i : l3) {
            TAG_LENGTH_MAP.put(i, 3);
        }
        for (int i : l4) {
            TAG_LENGTH_MAP.put(i, 4);
        }
        TAG_LENGTH_MAP.put(TAG_COORDINATES, 9);
        TAG_LENGTH_MAP.put(TAG_IMEI, 15);
        TAG_LENGTH_MAP.put(TAG_REFRIGERATOR, 7); // variable length
        TAG_LENGTH_MAP.put(TAG_PRESSURE, 68);
    }

    private static int getTagLength(int tag) {
        return TAG_LENGTH_MAP.get(tag);
    }

    private void sendReply(Channel channel, int checksum) {
        ChannelBuffer reply = ChannelBuffers.directBuffer(ByteOrder.LITTLE_ENDIAN, 3);
        reply.writeByte(0x02);
        reply.writeShort((short) checksum);
        if (channel != null) {
            channel.write(reply);
        }
    }

    @Override
    protected Object decode(
            Channel channel, SocketAddress remoteAddress, Object msg) throws Exception {

        ChannelBuffer buf = (ChannelBuffer) msg;

        buf.readUnsignedByte(); // header
        int length = (buf.readUnsignedShort() & 0x7fff) + 3;

        List<Position> positions = new LinkedList<>();
        Set<Integer> tags = new HashSet<>();
        boolean hasLocation = false;

        Position position = new Position();

        while (buf.readerIndex() < length) {

            // Check if new message started
            int tag = buf.readUnsignedByte();
            if (tags.contains(tag)) {
                if (hasLocation && position.getFixTime() != null) {
                    positions.add(position);
                }
                tags.clear();
                hasLocation = false;
                position = new Position();
            }
            tags.add(tag);

            switch (tag) {

                case TAG_IMEI:
                    String imei = buf.toString(buf.readerIndex(), 15, Charset.defaultCharset());
                    buf.skipBytes(imei.length());
                    identify(imei, channel, remoteAddress);
                    break;

                case TAG_DATE:
                    position.setTime(new Date(buf.readUnsignedInt() * 1000));
                    break;

                case TAG_COORDINATES:
                    hasLocation = true;
                    position.setValid((buf.readUnsignedByte() & 0xf0) == 0x00);
                    position.setLatitude(buf.readInt() / 1000000.0);
                    position.setLongitude(buf.readInt() / 1000000.0);
                    break;

                case TAG_SPEED_COURSE:
                    position.setSpeed(buf.readUnsignedShort() * 0.0539957);
                    position.setCourse(buf.readUnsignedShort() * 0.1);
                    break;

                case TAG_ALTITUDE:
                    position.setAltitude(buf.readShort());
                    break;

                case TAG_STATUS:
                    position.set(Event.KEY_STATUS, buf.readUnsignedShort());
                    break;

                case TAG_POWER:
                    position.set(Event.KEY_POWER, buf.readUnsignedShort());
                    break;

                case TAG_BATTERY:
                    position.set(Event.KEY_BATTERY, buf.readUnsignedShort());
                    break;

                case TAG_ODOMETER:
                    position.set(Event.KEY_ODOMETER, buf.readUnsignedInt());
                    break;

                default:
                    buf.skipBytes(getTagLength(tag));
                    break;

            }
        }
        if (hasLocation && position.getFixTime() != null) {
            positions.add(position);
        }

        if (!hasDeviceId()) {
            Log.warning("Unknown device");
            return null;
        }

        sendReply(channel, buf.readUnsignedShort());

        for (Position p : positions) {
            p.setProtocol(getProtocolName());
            p.setDeviceId(getDeviceId());
        }

        if (positions.isEmpty()) {
            return null;
        }
        return positions;
    }

}