require 'geo_calc/geo'
require 'geo_calc/calc'

 #  Sample usage:                                                                                 
 #    p1 = GeoPoint.new(51.5136, -0.0983)                                                      
 #    p2 = GeoPoint.new(51.4778, -0.0015)                                                      
 #    dist = p1.distance_to(p2)          # in km                                             
 #    brng = p1.bearing_to(p2)           # in degrees clockwise from north                   
 #    ... etc                                                                                     
 # - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  
 #                                                                                                
 # - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  
 #  Note that minimal error checking is performed in this example code!                           
 # - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  

class GeoPoint
  include GeoCalc::Calc::All
  # Creates a point on the earth's surface at the supplied latitude / longitude
  # 
  # Constructor
  # - Numeric lat: latitude in numeric degrees
  # - Numeric lon: longitude in numeric degrees
  # - Numeric [rad=6371]: radius of earth if different value is required from standard 6,371km

  attr_reader   :lat, :lon
  attr_accessor :radius
  
  def initialize *args
    rad = args.delete(args.size) if is_numeric?(args.last) && args.last.is_between?(6350, 6380)
    rad ||= 6371 # default
    case args.size
    when 1
      create_from_one *args, rad
    when 2
      create_from_two *args, rad
    else
      raise "GeoPoint must be initialized with either one or to arguments defining the (latitude, longitude) coordinate on the map"
    end
  end

  def unit
    :degrees
  end

  def lat= value 
    @lat = value.to_lat
  end

  def lon= value
    @lon = value.to_lng
  end

  (Symbol.lng_symbols - [:lon]).each do |sym|
    class_eval %{
      alias_method :#{sym}, :lon
      alias_method :#{sym}=, :lon=
    }
  end    
  alias_method :to_lng, :lng

  (Symbol.lat_symbols - [:lat]).each do |sym|
    class_eval %{
      alias_method :#{sym}, :lat
      alias_method :#{sym}=, :lat=
    }
  end
  alias_method :to_lat, :lat

  def [] key
    case key
    when Fixnum   
      raise ArgumentError, "Index must be 0 or 1" if !(0..1).cover?(key)
      to_arr[key] 
    when String, Symbol
      send(key) if respond_to? key
    else
      raise ArgumentError, "Key must be a Fixnum (index) or a method name"  
    end    
  end

  alias_method :to_dms, :to_s

  def reverse_point!
    self.lat = lat * -1
    self.lng = lng * -1
    self    
  end

  def reverse_point
    self.dup.reverse_point!
  end

  def to_lat_lng
    [lat, lng]
  end

  def to_lng_lat
    [lng, lat]
  end

  def to_arr
    a = to_lat_lng
    reverse_arr? ? a.reverse : a
  end

  def reverse_arr?
    @reverse_arr
  end

  def reverse_arr!
    @reverse_arr = true
  end

  def normal_arr!
    @reverse_arr = false
  end
  
  protected

  include NumericCheckExt
  
  def create_from_one points, rad = 6371
    create_from_two *points.to_lat_lng, rad
  end
  
  def create_from_two lat, lon, rad = 6371  
    rad ||= 6371  # earth's mean radius in km
    @lat    = lat.to_lat
    @lon    = lon.to_lng
    @radius = rad    
  end  
end