#--
# Copyright (c) 2006  Doug Fales 
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
#++
module GPX

   # This class will parse the lat/lon and time data from a Magellan track log,
   # which is a NMEA formatted CSV list of points.

   class MagellanTrackLog
      #PMGNTRK
      # This message is to be used to transmit Track information (basically a list of previous position fixes) 
      # which is often displayed on the plotter or map screen of the unit.  The first field in this message 
      # is the Latitude, followed by N or S.  The next field is the Longitude followed by E or W.  The next 
      # field is the altitude followed by “F” for feet or “M” for meters.  The next field is 
      # the UTC time of the fix.  The next field consists of a status letter of “A” to indicated that 
      # the data is valid, or “V” to indicate that the data is not valid.  The last character field is 
      # the name of the track, for those units that support named tracks.  The last field contains the UTC date 
      # of the fix.  Note that this field is (and its preceding comma) is only produced by the unit when the 
      # command PMGNCMD,TRACK,2 is given.  It is not present when a simple command of PMGNCMD,TRACK is issued.

      #NOTE: The Latitude and Longitude Fields are shown as having two decimal
      # places. As many additional decimal places may be added as long as the total
      # length of the message does not exceed 82 bytes.

      # $PMGNTRK,llll.ll,a,yyyyy.yy,a,xxxxx,a,hhmmss.ss,A,c----c,ddmmyy*hh<CR><LF>
      require 'csv' 

      LAT       = 1
      LAT_HEMI  = 2
      LON       = 3
      LON_HEMI  = 4
      ELE       = 5 
      ELE_UNITS = 6
      TIME      = 7
      INVALID_FLAG = 8
      DATE      = 10

      FEET_TO_METERS = 0.3048

      class << self

         # Takes the name of a magellan file, converts the contents to GPX, and
         # writes the result to gpx_filename.
         def  convert_to_gpx(magellan_filename, gpx_filename)

            segment = Segment.new

            CSV.open(magellan_filename, "r") do |row| 
               next if(row.size < 10 or row[INVALID_FLAG] == 'V')

               lat_deg  = row[LAT][0..1]
               lat_min  = row[LAT][2...-1]
               lat_hemi = row[LAT_HEMI]

               lat = lat_deg.to_f + (lat_min.to_f / 60.0)
               lat = (-lat) if(lat_hemi == 'S')

               lon_deg      = row[LON][0..2]
               lon_min  = row[LON][3..-1]
               lon_hemi = row[LON_HEMI]

               lon = lon_deg.to_f + (lon_min.to_f / 60.0)
               lon = (-lon) if(lon_hemi == 'W')


               ele = row[ELE]
               ele_units = row[ELE_UNITS]
               ele = ele.to_f
               if(ele_units == 'F')
                  ele *= FEET_TO_METERS
               end

               hrs  = row[TIME][0..1].to_i
               mins = row[TIME][2..3].to_i
               secs = row[TIME][4..5].to_i
               day  = row[DATE][0..1].to_i
               mon  = row[DATE][2..3].to_i
               yr   = 2000 + row[DATE][4..5].to_i

               time = Time.gm(yr, mon, day, hrs, mins, secs)

               #must create point
               pt = TrackPoint.new(:lat => lat, :lon => lon, :time => time, :elevation => ele)
               segment.append_point(pt)

            end 

            trk = Track.new
            trk.append_segment(segment)
            gpx_file = GPXFile.new(:tracks => [trk])
            gpx_file.write(gpx_filename)

         end

         # Tests to see if the given file is a magellan NMEA track log.
         def is_magellan_file?(filename)
            i = 0
            File.open(filename, "r") do |f|
               f.each do |line|
                  i +=  1
                  if line =~ /^\$PMGNTRK/
                     return true 
                  elsif line =~ /<\?xml/
                     return false
                  elsif(i > 10)
                     return false 
                  end
               end
            end
            return false
         end
      end

   end
end