class GeoZone

# File lib/geozone.rb, line 11
def initialize(locations: nil, journey: nil)

  @dx = Dynarex.new locations if locations
  @journey = journey

end

# File lib/geozone.rb, line 18
def zone(location)

  a = @dx.all.map do |x|
    [x.label, distance(location, x.coords.split(/, */).map(&:to_f)).round]
  end

  label, distance = a.min_by(&:last)
  {zone: label.to_sym, distance: distance}

end

# File lib/geozone.rb, line 31
def distance(loc1, loc2)

  rad = Math::PI/180
  rkm = 6371          # Earth radius in kilometers
  rm = rkm * 1000     # Radius in meters

  dlat_rad = (loc2[0]-loc1[0]) * rad     # Delta, converted to rad
  dlon_rad = (loc2[1]-loc1[1]) * rad

  lat1_rad, lon1_rad = loc1.map {|i| i * rad }
  lat2_rad, lon2_rad = loc2.map {|i| i * rad }

  a = Math.sin(dlat_rad/2)**2 + Math.cos(lat1_rad) * Math.cos(lat2_rad) \
      * Math.sin(dlon_rad/2)**2
  c = 2 * Math::atan2(Math::sqrt(a), Math::sqrt(1-a))

  rm * c     # Distance in meters
end