#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# usage: gegps [-i] [-d kmldir]
#
# Feed location data from a running GPSD to a Google Earth instance.
# The -d argument is the location of the Google Earth installation
# directory.  If not specified, it defaults to the current directory.
#
# If you have the free (non-subscription) version, start by running with
# the -i option to drop a clue in the Google Earth installation directory,
# as 'Open_in_Google_Earth_RT_GPS.kml', then open that file in Places
# (File > Open...),
#
# The basic recipe is here:
# http://tjworld.net/wiki/Linux/Ubuntu/GoogleEarthPlusRealTimeGPS
#
# This code originally by Jaroslaw Zachwieja and a guy referring
# to himself/herself as TJ(http://tjworld.net)
# Modified by Chen Wei <weichen302@aol.com> for use with gpsd
# Cleaned up and adapted for the GPSD project by Eric S. Raymond.

# This code runs under both Python 2 and Python 3. Preserve this property!
from __future__ import print_function, division

import sys, os, getopt
import gps

KML_OPEN_IN_GE = '''\
<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://earth.google.com/kml/2.2">
<NetworkLink>
	<name>Realtime GPS</name>
	<open>1</open>
	<Link>
		<href>Realtime_GPS.kml</href>
		<refreshMode>onInterval</refreshMode>
	</Link>
</NetworkLink>
</kml>
'''


def kmlize(tpv):
    '''http://code.google.com/apis/kml/documentation/kmlreference.html
       for official kml document'''
    latitude =  tpv['lat']
    longitude = tpv['lon']
    speed_in =  tpv['speed'] # meter/second
    speed = speed_in * gps.MPS_TO_KPH # Km/h
    heading =   int(round(tpv['track'], 0))
    altitude =  tpv['alt']

    if speed < 1:
        heading = 0

    return """<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://earth.google.com/kml/2.0">
<Placemark>
    <name>%s km/h,heading %s</name>
    <description>Realtime GPS feeding</description>
    <LookAt>
        <longitude>%s</longitude>
        <latitude>%s</latitude>
    </LookAt>
    <Point>
        <coordinates>%s,%s,%s</coordinates>
    </Point>
</Placemark>
</kml>""" % (speed, heading, longitude, latitude, longitude, latitude, altitude)


if __name__ == "__main__":
    session = gps.gps()
    session.stream(gps.WATCH_ENABLE)

    kmldir = "."
    initialize = False
    (options, arguments) = getopt.getopt(sys.argv[1:], "d:i")
    for (opt, arg) in options:
        if opt == '-d':
            kmldir = arg
        elif opt == '-i':
            initialize = True

    if initialize:
        f = open(os.path.join(kmldir, 'Open_in_Google_Earth_RT_GPS.kml'), 'w')
        f.write(KML_OPEN_IN_GE)
        f.close()
    else:
        try:
            while True:
                report = session.next()
                if report['class'] == 'TPV':
                    f = open(os.path.join(kmldir, 'Realtime_GPS.kml'), 'w')
                    f.write(kmlize(report))
                    f.close()
        except StopIteration:
            pass
        except KeyboardInterrupt:
            print('gegpsd stopped ')

# end