class Country < ActiveRecord::Base
  set_primary_key :iso_3166_code
  
  has_many :rail_companies, :foreign_key => 'country_iso_3166_code'
  
  falls_back_on :name => 'fallback',
                :automobile_urbanity => lambda { united_states.automobile_urbanity }, # for now assume US represents world
                :automobile_fuel_efficiency => ((22.5 + 16.2) / 2.0).miles_per_gallon.to(:kilometres_per_litre), # average of passenger car fuel unknown and light goods vehicle fuel unknown - WRI Mobile Combustion calculation tool v2.0
                :automobile_fuel_efficiency_units => 'kilometres_per_litre',
                :automobile_city_speed => lambda { united_states.automobile_city_speed }, # for now assume US represents world
                :automobile_city_speed_units => lambda { united_states.automobile_city_speed_units }, # for now assume US represents world
                :automobile_highway_speed => lambda { united_states.automobile_highway_speed }, # for now assume US represents world
                :automobile_highway_speed_units => lambda { united_states.automobile_highway_speed_units }, # for now assume US represents world
                :automobile_trip_distance => lambda { united_states.automobile_trip_distance }, # for now assume US represents world
                :automobile_trip_distance_units => lambda { united_states.automobile_trip_distance_units }, # for now assume US represents world
                :flight_route_inefficiency_factor => lambda { maximum(:flight_route_inefficiency_factor) }, # default to the largest inefficiency factor
                :rail_trip_distance => lambda { weighted_average(:rail_trip_distance, :weighted_by => :rail_passengers) },
                :rail_trip_distance_units => 'kilometres', # FIXME TODO derive this
                :rail_speed => lambda { weighted_average(:rail_speed, :weighted_by => :rail_passengers) },
                :rail_speed_units => 'kilometres_per_hour', # FIXME TODO derive this
                :rail_trip_electricity_intensity => lambda { weighted_average(:rail_trip_electricity_intensity, :weighted_by => :rail_passengers) },
                :rail_trip_electricity_intensity_units => 'kilowatt_hour_per_passenger_kilometre', # FIXME TODO derive this
                :rail_trip_diesel_intensity => lambda { weighted_average(:rail_trip_diesel_intensity, :weighted_by => :rail_passengers) },
                :rail_trip_diesel_intensity_units => 'litres_per_passenger_kilometre', # FIXME TODO derive this
                :rail_trip_co2_emission_factor => lambda { weighted_average(:rail_trip_co2_emission_factor, :weighted_by => :rail_passengers) },
                :rail_trip_co2_emission_factor_units => 'kilograms' # FIXME TODO derive this
  
  class << self
    def united_states
      find_by_iso_3166_code('US')
    end
  end
  
  col :iso_3166_code
  col :name
  col :automobile_urbanity, :type => :float
  col :automobile_fuel_efficiency, :type => :float
  col :automobile_fuel_efficiency_units
  col :automobile_city_speed, :type => :float
  col :automobile_city_speed_units
  col :automobile_highway_speed, :type => :float
  col :automobile_highway_speed_units
  col :automobile_trip_distance, :type => :float
  col :automobile_trip_distance_units
  col :flight_route_inefficiency_factor, :type => :float
  col :rail_passengers, :type => :float
  col :rail_trip_distance, :type => :float
  col :rail_trip_distance_units
  col :rail_speed, :type => :float
  col :rail_speed_units
  col :rail_trip_electricity_intensity, :type => :float
  col :rail_trip_electricity_intensity_units
  col :rail_trip_diesel_intensity, :type => :float
  col :rail_trip_diesel_intensity_units
  col :rail_trip_co2_emission_factor, :type => :float
  col :rail_trip_co2_emission_factor_units
end