module Geocoder::Store::MongoBase

def self.included_by_model(base)
  base.class_eval do
    scope :geocoded, lambda {
      where(geocoder_options[:coordinates].ne => nil)
    }
    scope :not_geocoded, lambda {
      where(geocoder_options[:coordinates] => nil)
    }
    scope :near, lambda{ |location, *args|
      coords  = Geocoder::Calculations.extract_coordinates(location)
      # no results if no lat/lon given
      return where(:id => false) unless coords.is_a?(Array)
      radius  = args.size > 0 ? args.shift : 20
      options = args.size > 0 ? args.shift : {}
      options[:units] ||= geocoder_options[:units]
      # Use BSON::OrderedHash if Ruby's hashes are unordered.
      # Conditions must be in order required by indexes (see mongo gem).
      version = RUBY_VERSION.split('.').map { |i| i.to_i }
      empty = version[0] < 2 && version[1] < 9 ? BSON::OrderedHash.new : {}
      conds = empty.clone
      field = geocoder_options[:coordinates]
      conds[field] = empty.clone
      conds[field]["$nearSphere"]  = coords.reverse
      if radius
        conds[field]["$maxDistance"] = \
          Geocoder::Calculations.distance_to_radians(radius, options[:units])
      end
      if obj = options[:exclude]
        conds[:_id.ne] = obj.id
      end
      where(conds)
    }
  end
end