date_calculator_final.rb

class DateCalculator
  attr_accessor :days, :year
  def initialize(origin_year)
    @origin_year = origin_year
  end

  def current_year_from_days(days_since_origin)
    @current_year = @origin_year
    @days_since_origin = days_since_origin
    while (@days_since_origin > 365) do
      if leap_year?(year)
        advance_by_leap_year
      else
        advance_by_regular_year
      end
    end
    @current_year
  end

  def advance_by_leap_year
    if @days_since_origin >= 366
      @days_since_origin -= 366
      @current_year += 1
    end
  end

  def advance_by_regular_year
    @days_since_origin -= 365
    @current_year += 1
  end

  def leap_year?(year)
    every_400_years?(year)  ||  every_4_years_except_centuries?(year)
  end

  def every_400_years?(year)
    year % 400 == 0
  end

  def every_4_years_except_centuries?(year)
    (year % 4 == 0  &&  year % 100 != 0)
  end

end