# 2010-01-01 K.OHWADA

require "csv"

header = <<EOS
<?xml version="1.0" encoding="UTF-8" ?>
<gpx version="1.1" xmlns="http://www.topografix.com/GPX/1/1">
<trk>
EOS

footer = <<EOS
</trkseg>
</trk>
</gpx>
EOS

trkseg_begin = '<trkseg>'

def name(fname)
  n = fname.split(".")[0]
  s ='<name>' + n + '</name>'
  return s
end

def trkpt_conv(a)
  time = time_conv( a[1] )
  lat = lat_conv( a[2] )
  lon = lon_conv( a[4] )
  ele = ele_conv( a[9] )
  s  = '<trkpt lat="' + lat + '" lon="' + lon +'">' + "\n"
  s += '<ele>' + ele + '</ele>' + "\n"
  s += '<time>' + time + '</time>' + "\n"
  s += '</trkpt>' + "\n"
  return s
end

def time_conv(str)
  /(\d\d)(\d\d)(\d\d)/ =~ str
  ret = @date + 'T' + $1 + ':' + $2 + ':' + $3 + 'Z'
  return ret
end

def lat_conv(str)
  /(\d\d)(.*)/ =~ str
  ret = $1.to_f + ( $2.to_f / 60 )
  return format("%.8f", ret)
end

def lon_conv(str)
  /(\d\d\d)(.*)/ =~ str
  ret = $1.to_f + ( $2.to_f / 60 )
  return format("%.8f", ret)
end

def ele_conv(str)
  ret = str.to_i.to_s
  return ret
end

fname = ARGV[0]
@date = ARGV[1]

if fname.nil? then
  puts 'usage:'
  puts 'ruby nmea_gpx.rb input.nmea.txt year-month-day > output.gpx.txt'
  puts 'ex) year-month-day 2009-12-25'
  exit
end

if @date.nil?
  @date = Time.now.strftime("%Y-%m-%d")
end

puts header
puts name(fname)
puts trkseg_begin

CSV.open(fname, 'r') do |row|
  if ( row[0] == '$GPGGA')
    puts trkpt_conv(row)
  end
end

puts footer