source: josm/trunk/src/org/openstreetmap/josm/io/NmeaReader.java@ 1073

//License: GPL. Copyright 2008 by Christoph Brill

package org.openstreetmap.josm.io;

import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;

import org.openstreetmap.josm.data.coor.LatLon;
import org.openstreetmap.josm.data.gpx.GpxData;
import org.openstreetmap.josm.data.gpx.GpxTrack;
import org.openstreetmap.josm.data.gpx.WayPoint;

/**
 * Read a nmea file. Based on information from
 * http://www.kowoma.de/gps/zusatzerklaerungen/NMEA.htm
 * 
 * @author cbrill
 */
public class NmeaReader {

        /** Handler for the different types that NMEA speaks. */
        public static enum NMEA_TYPE {

                /** RMC = recommended minimum sentence C. */
                GPRMC("$GPRMC"),
                /** GPS positions. */
                GPGGA("$GPGGA"),
                /** SA = satellites active. */
                GPGSA("$GPGSA");

                private final String type;

                NMEA_TYPE(String type) {
                        this.type = type;
                }

                public String getType() {
                        return this.type;
                }

                public boolean equals(String type) {
                        return this.type.equals(type);
                }
        }

        private static final int TYPE = 0;

        // The following only applies to GPRMC
        public static enum GPRMC {
                TIME(1),
                /** Warning from the receiver (A = data ok, V = warning) */
                RECEIVER_WARNING(2), 
                WIDTH_NORTH(3), WIDTH_NORTH_NAME(4), 
                LENGTH_EAST(5), LENGTH_EAST_NAME(6),
                /** Speed in knots */
                SPEED(7), COURSE(8), DATE(9),
                /** magnetic declination */
                MAGNETIC_DECLINATION(10), UNKNOWN(11),
                /**
                 * Mode (A = autonom; D = differential; E = estimated; N = not valid; S
                 * = simulated)
                 * 
                 * @since NMEA 2.3
                 */
                MODE(12);

                public final int position;

                GPRMC(int position) {
                        this.position = position;
                }
        }

        // The following only applies to GPGGA
        public static enum GPGGA {
                TIME(1), LATITUDE(2), LATITUDE_NAME(3), LONGITUDE(4), LONGITUDE_NAME(5),
                /**
                 * Quality (0 = invalid, 1 = GPS, 2 = DGPS, 6 = estimanted (@since NMEA
                 * 2.3))
                 */
                QUALITY(6), SATELLITE_COUNT(7),
                /** HDOP (horizontal dilution of precision) */
                HDOP(8),
                /** height above NN (above geoid) */
                HEIGHT(9), HEIGHT_UNTIS(10),
                /** height geoid - height ellipsoid (WGS84) */
                HEIGHT_2(11), HEIGHT_2_UNTIS(12);

                public final int position;

                GPGGA(int position) {
                        this.position = position;
                }
        }

        // The following only applies to GPGGA
        public static enum GPGSA {
                AUTOMATIC(1),
                /** 1 = not fixed, 2 = 2D fixed, 3 = 3D fixed) */
                FIX_TYPE(2),
                // PRN numbers for max 12 satellites
                PRN_1(3), PRN_2(4), PRN_3(5), PRN_4(6), PRN_5(7), PRN_6(8), PRN_7(9), PRN_8(
                        10), PRN_9(11), PRN_10(12), PRN_11(13), PRN_12(14),
                /** PDOP (precision) */
                PDOP(15),
                /** HDOP (horizontal precision) */
                HDOP(16),
                /** VDOP (vertical precision) */
                VDOP(17), ;

                public final int position;

                GPGSA(int position) {
                        this.position = position;
                }
        }

        public GpxData data;

        public NmeaReader(InputStream source, File relativeMarkerPath) {
                data = new GpxData();
                GpxTrack currentTrack = new GpxTrack();
                Collection<WayPoint> currentTrackSeg = new ArrayList<WayPoint>();
                currentTrack.trackSegs.add(currentTrackSeg);
                data.tracks.add(currentTrack);

                BufferedReader rd;
                String nmeaWithChecksum;

                try {
                        rd = new BufferedReader(new InputStreamReader(source));
                        while ((nmeaWithChecksum = rd.readLine()) != null) {
                                String[] nmeaAndChecksum = nmeaWithChecksum.split("\\*");
                                String nmea = nmeaAndChecksum[0];
                                // XXX: No need for it: String checksum = nmeaAndChecksum[1];
                                String[] e = nmea.split(",");
                                if (e.length == 0) {
                                    continue;
                                }
                                if (NMEA_TYPE.GPRMC.equals(e[TYPE])) {
                                        LatLon latLon = parseLatLon(e);
                                        if (latLon == null) {
                                                continue;
                                        }
                                        WayPoint currentWayPoint = new WayPoint(latLon);
                                        currentTrackSeg.add(currentWayPoint);
                                }
                        }
                        rd.close();
                } catch (final IOException e) {
                        System.out.println("Error reading file");
                }

        }

        private LatLon parseLatLon(String[] e) throws NumberFormatException {
            // If the array looks bogus don't try to get valuable information from it
            // But remember that the array is stripped of checksum and GPRMC is only 12 elements and split strips empty trailing elements  
            if (e.length < 10) {
                return null;
            }
        String widthNorth = e[GPRMC.WIDTH_NORTH.position].trim();
                String lengthEast = e[GPRMC.LENGTH_EAST.position].trim();
                if ("".equals(widthNorth) || "".equals(lengthEast)) {
                        return null;
                }

                // The format is xxDDLL.LLLL
                // xx optional whitespace
                // DD (int) degres
                // LL.LLLL (double) latidude
                int latdegsep = widthNorth.indexOf('.') - 2;
                if (latdegsep < 0) {
                        return null;
                }
                int latdeg = Integer.parseInt(widthNorth.substring(0, latdegsep));
                double latmin = Double.parseDouble(widthNorth.substring(latdegsep));
                double lat = latdeg + latmin / 60;
                if ("S".equals(e[GPRMC.WIDTH_NORTH_NAME.position])) {
                        lat = -lat;
                }       

                int londegsep = lengthEast.indexOf('.') - 2;
                if (londegsep < 0) {
                        return null;
                }
                int londeg = Integer.parseInt(lengthEast.substring(0, londegsep));
                double lonmin = Double.parseDouble(lengthEast.substring(londegsep));
                double lon = londeg + lonmin / 60;
                if ("W".equals(e[GPRMC.LENGTH_EAST_NAME.position])) {
                        lon = -lon;
                }
                
                return new LatLon(lat, lon);
        }
}