class Date

# File lib/date_diff.rb, line 8
def self.diff(start_date, end_date)
  common_year_days_in_month = [ 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
  start_date, end_date = end_date, start_date if start_date > end_date

  start_date_year, start_date_month, start_date_day = start_date.year, start_date.month, start_date.day
  end_date_year, end_date_month, end_date_day = end_date.year, end_date.month, end_date.day

  day_difference = end_date_day - start_date_day

  if (day_difference < 0)
    day_difference = common_year_days_in_month[start_date_month-1] - start_date_day + end_date_day
    end_date_month -= 1
  end

  if (end_date_month < 0)
    end_date_month += 12
    end_date_year -= 1
  end

  month_difference = end_date_month - start_date_month

  if (month_difference < 0)
    month_difference += 12
    end_date_year -= 1
  end

  year_difference = end_date_year - start_date_year

  difference_hash =  { :year => year_difference, :month => month_difference, :day => day_difference }

      difference_array = []
      ["year", "month", "day"].each do |key|
    value = difference_hash[key.to_sym]
    difference_array << value.to_s + " " + ((value > 1)? I18n.t(key.to_s.pluralize, :default => key.to_s.pluralize.to_s) : I18n.t(key.to_s, :default =>  key.to_s)).to_s if value > 0
  end
  difference_hash[:difference] = difference_array.join(" ").to_s
  difference_hash
end