class NMEAParser

# File lib/nmea_parser.rb, line 14
def initialize(s=nil)
  parse(s) if s
end

# File lib/nmea_parser.rb, line 22
def parse(raw_line)

  msgcode = raw_line[/^\$GP(\w+)/]
  return unless msgcode

  a = raw_line.split(',')

  case msgcode

    when /GGA/

      _, raw_time, raw_lat, ns, raw_lon, ew = a
      @time, @latitude, @longitude = Time.parse(raw_time), 
                             decimalize(raw_lat, ns), decimalize(raw_lon, ew)

      # additional data captured
      #
      # Fix quality, Number of satellites being tracked, Horizontal dilution
      # of position, Altitude (Meters, above mean sea level), Height of
      # geoid, time in seconds since last DGPS update, DGPS station ID number

      @quality, @num_sat, @hdop, @altitude, @alt_unit, @height_geoid,
      @height_geoid_unit, @last_dgps, @dgps = a[6..-2] << a[-1][/^[^\*]+/]

    when /RMC/

      _, raw_time, _, raw_lat, ns, raw_lon, ew = a
      @time, @latitude, @longitude = Time.parse(raw_time), 
                             decimalize(raw_lat, ns), decimalize(raw_lon, ew)

      # additional data captured
      #
      # Speed over the ground in knots, Track angle in degrees True,
      # Date, Magnetic Variation,

      @speed, @course = a[7..8]
      @date, @variation = Date.parse(a[9]), a[10]
      @var_direction =  a[-1][/^[^\*]+/]

    when /VTG/

      # data captured
    
      # True track made good (degrees), Magnetic track made good,
      # Ground speed (knots), Ground speed (Kilometers per hour)

      @track, @mag_track, @speed, @speed_kph = a.values_at(1,3,5,7)

  end
  
  self

end

# File lib/nmea_parser.rb, line 76
def to_h()  
  {
    time: @time, latitude: @latitude, longitude: @longitude, 
    quality: @quality, num_sat: @num_sat, hdop: @hdop, altitude: @altitude,
    alt_unit: @alt_unit, height_geoid: @height_geoid, 
    height_geoid_unit: @height_geoid_unit, last_dgps: @last_dgps, 
    dgps: @dgps, speed: @speed, course: @course, date: @date, 
    variation: @variation, var_direction: @var_direction, track: @track, 
    mag_track: @mag_track, speed: @speed, speed_kph: @speed_kph
  }
end

# File lib/nmea_parser.rb, line 88
def to_struct()
  h = self.to_h
  Struct.new(*h.keys.map(&:to_sym)).new(*h.values).freeze    
end

# File lib/nmea_parser.rb, line 95
def decimalize(raw_x, raw_nesw)

  nesw = {n: :+, e: :+, s: :-, w: :-}
  x = 0.method(nesw[raw_nesw.downcase.to_sym]).call(raw_x.to_f)

  degrees = (x / 100).to_i
  minutes = x - (degrees * 100.0)
  (degrees + (minutes / 60)).round(8)
end