/*
 * Copyright 2013 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.nio.charset.Charset;
import java.util.Date;
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.traccar.BaseProtocolDecoder;
import org.traccar.ServerManager;
import org.traccar.helper.Crc;
import org.traccar.helper.Log;
import org.traccar.model.ExtendedInfoFormatter;
import org.traccar.model.Position;

public class AtrackProtocolDecoder extends BaseProtocolDecoder {

    public AtrackProtocolDecoder(ServerManager serverManager) {
        super(serverManager);
    }

    private String readImei(ChannelBuffer buf) {
        int b = buf.readUnsignedByte();
        StringBuilder imei = new StringBuilder();
        imei.append(b & 0x0F);
        for (int i = 0; i < 7; i++) {
            b = buf.readUnsignedByte();
            imei.append((b & 0xF0) >> 4);
            imei.append(b & 0x0F);
        }
        return imei.toString();
    }

    private static final int MSG_HEARTBEAT = 0x1A;
    private static final int MSG_DATA = 0x10;

    private static void sendResponse(Channel channel, long rawId, int index) {
        if (channel != null) {
            ChannelBuffer response = ChannelBuffers.directBuffer(12);
            response.writeShort(0xfe02);
            response.writeLong(rawId);
            response.writeShort(index);
            channel.write(response);
        }
    }
    
    @Override
    protected Object decode(
            ChannelHandlerContext ctx, Channel channel, Object msg)
            throws Exception {

        ChannelBuffer buf = (ChannelBuffer) msg;

        buf.skipBytes(2); // prefix
        buf.readUnsignedShort(); // checksum
        buf.readUnsignedShort(); // length
        int index = buf.readUnsignedShort();

        // Create new position
        Position position = new Position();
        ExtendedInfoFormatter extendedInfo = new ExtendedInfoFormatter("atrack");

        // Get device id
        long rawId = buf.readLong();
        String id = String.valueOf(rawId);
        try {
            position.setDeviceId(getDataManager().getDeviceByImei(id).getId());
        } catch(Exception error) {
            Log.warning("Unknown device - " + id);
            return null;
        }
        
        // Send acknowledgement
        sendResponse(channel, rawId, index);

        // Date and time
        position.setTime(new Date(buf.readUnsignedInt() * 1000)); // gps time
        buf.readUnsignedInt(); // rtc time
        buf.readUnsignedInt(); // send time

        // Coordinates
        position.setValid(true);
        position.setLongitude(buf.readInt() * 0.000001);
        position.setLatitude(buf.readInt() * 0.000001);
        position.setAltitude(0.0);

        // Course
        position.setCourse((double) buf.readUnsignedShort());
        
        // Report type
        extendedInfo.set("type", buf.readUnsignedByte());
        
        // Milage
        extendedInfo.set("milage", buf.readUnsignedInt() * 0.1);
        
        // Accuracy
        extendedInfo.set("hdop", buf.readUnsignedShort() * 0.1);
        
        // Input
        extendedInfo.set("input", buf.readUnsignedByte());

        // Speed
        position.setSpeed(buf.readUnsignedShort() * 0.539957);

        // Output
        extendedInfo.set("output", buf.readUnsignedByte());

        // ADC
        extendedInfo.set("adc", buf.readUnsignedShort() * 0.001);

        // Driver
        int length = 0;
        while (buf.getByte(buf.readerIndex() + length) != 0) {
            length += 1;
        }
        if (length != 0) {
            extendedInfo.set("driver",
                    buf.toString(buf.readerIndex(), length, Charset.defaultCharset()));
            buf.skipBytes(length);
        }
        buf.readByte();
        
        // Temperature
        extendedInfo.set("temperature1", buf.readShort() * 0.1);
        extendedInfo.set("temperature2", buf.readShort() * 0.1);
        
        // TODO: text message

        position.setExtendedInfo(extendedInfo.toString());
        return position;
    }

}