# -*- coding: utf-8 -*-

=begin rdoc

= SixArm.com » Ruby » Date #age_in_years and #age_in_days methods

Author:: Joel Parker Henderson, joelparkerhenderson@gmail.com
Copyright:: Copyright (c) 2006-2011 Joel Parker Henderson
License:: See LICENSE.txt file

Date extensions to calculate an age in days and years.

@example

  date=Date.new(1980,10,31)
  date.age_in_days => 11124
  date.age_in_years => 31

@example of custom dates

  date=Date.new(1980,10,31)
  new_years_eve=(2011,12,31)
  date.age_in_days_on(new_years_eve) => 11383
  date.age_in_years_on(new_years_eve) => 31


=end


class Date


  # @return [Integer] the age in days for a given date.
  #
  # @example
  #
  #   date=Date.new(1980,10,31)
  #   date.age_in_days => 11124
  #
  # @example of custom dates
  #
  #   date=Date.new(1980,10,31)
  #
  #   valentines = Date.new(2011,02,14)
  #   date.age_in_days(valentines) => 11063
  #
  #   halloween = Date.new(2011,10,31)
  #   date.age_in_days(halloween) => 11322
  #
  #   new_years_eve = Date.new(2011,12,31)
  #   date.age_in_days(new_years_eve) => 11383

  def age_in_days(compare_date=Date.today)
    (compare_date.is_a? Date) or raise ArgumentError, "compare_date must be a date"
    (compare_date-self).to_i
  end

  alias :age_in_days_on :age_in_days 


  # @return [Integer] the age in years for a given date.
  #
  # @example
  #
  #   date=Date.new(1980,10,31)
  #   date.age_in_years => 30
  #
  # @example of custom dates
  #
  #   date=Date.new(1980,10,31)
  #
  #   valentines = Date.new(2011,02,14)
  #   date.age_in_years_on(valentines) => 30  # before the birthday
  #
  #   halloween = Date.new(2011,10,31)
  #   date.age_in_years_on(halloween) => 31  # on the birthday is one year older
  #
  #   new_years_eve = Date.new(2011,12,31)
  #   date.age_years(new_years_eve) => 31  # after the birthday is one year older

  def age_in_years(compare_date=Date.today)
    (compare_date.is_a? Date) or raise ArgumentError, "compare_date must be a date"
    age=compare_date.year-year
    compare_month = compare_date.month
    age-=1 if compare_month < month or (compare_month==month and compare_date.day < day)
    age
  end

  alias :age_in_years_on :age_in_years 

end