year, or range of years with en dash if needed - for example for copyright messages

footer_helper.rb

# /app/helpers/footer_helper.rb
module FooterHelper
  # year, or range of years with en dash if needed
  # @param start_year [Integer]
  # @return [String] this year, or range of years if started before this year
  # rubocop:disable Style/AsciiComments
  # for example in 2019, copyright_year_range(2019) is '2019' and
  # copyright_year_range(2016) is '2016–2019'
  # rubocop:enable Style/AsciiComments
  #
  # inspired by https://rietta.com/blog/how-to-automate-copyright-notice/
  def copyright_year_range(start_year)
    start_year = start_year.to_i
    current_year = Time.zone.today.year
    current_year > start_year ? "#{start_year}–#{current_year}" : current_year.to_s
  end
end

# in a mailer you'll need to include this file with the class method call `helper :footer`