class HamRadio

# File lib/hamradio.rb, line 3
def initialize()

end

# File lib/hamradio.rb, line 41
def grid_decode(gridsquare)
  gridsquare += 'MM' if gridsquare.size == 4

  a = gridsquare[0].ord - 'A'.ord
  b = gridsquare[1].ord - 'A'.ord
  c = gridsquare[2].ord - '0'.ord
  d = gridsquare[3].ord - '0'.ord
  e = gridsquare[4].upcase.ord - 'A'.ord
  f = gridsquare[5].upcase.ord - 'A'.ord
  lon = (a*20) + (c*2) + ((e+0.5)/12) - 180
  lat = (b*10) + d + ((f+0.5)/24) - 90
  [lat,lon]
end

# File lib/hamradio.rb, line 7
def grid_encode(dms)

  # return nil if this isn't a valid gridsquare
  return nil if self.valid_gridsquare(dms) == nil
  grid = ''

  lat = dms[0].to_f+90
  lon = dms[1].to_f+180

  v = (lon/20).to_i
  lon -= (v*20)
  grid += ((?A.ord + v).chr).to_s # first letter

  v = (lat/10).to_i
  lat -= (v*10)
  grid += ((?A.ord + v).chr).to_s # second letter

  p3 = (lon/2).to_i
  grid += p3.to_s # third number
  p4 = (lat).to_i
  grid += p4.to_s # fourth number

  lon -= p3*2
  lat -= p4
  p3 = (?0.ord + p3.to_i).chr
  p4 = (?0.ord + p4).chr
  p5 = (12.ord * lon).to_i
  p6 = (24.ord * lat).to_i

  grid += ((?a.ord + p5).chr).to_s # fifth letter
  grid += ((?a.ord + p6).chr).to_s # sixth letter

end

# File lib/hamradio.rb, line 59
def lookup_callsign(call)
  require 'nestful'

  c = Nestful.get 'http://callbytxt.org/db/'+call+'.json', :format => :json #=> {:json_hash => 1}
  c['calls']
end

# File lib/hamradio.rb, line 66
def valid_callsign(call)
  (call =~ /^([BFGIKMNTW]|[A-Z0-9]{2})[0-9][A-Z0-9]{0,3}[A-Z]$/i) != nil
end

# File lib/hamradio.rb, line 55
def valid_gridsquare(grid)
  (grid =~ /[a-z][a-z]\d\d[a-z]*/i) != nil
end