module TimeSet
  module TwentyFourHour

    def self.included(klass)
      klass.class_eval do
        extend  ClassMethods
        include InstanceMethods
      end
    end

    module ClassMethods
      attr :times_for

      def twenty_four_hour_time_for(*args)
        @times_for = args
        args.each do |attribute|
          attr_writer "#{attribute}_hour", "#{attribute}_minute", "#{attribute}_meridian"

          define_method "#{attribute}_hour" do
            time = eval("#{attribute}") ? eval("#{attribute}") : Time.now
            (time.hour > 12 ? time.hour - 12 : time.hour).to_s
          end

          define_method "#{attribute}_minute" do
            eval("#{attribute}") ? eval("#{attribute}").min.to_s : "00"
          end

          define_method "#{attribute}_meridian" do
            if eval("#{attribute}")
              eval("#{attribute}").hour < 12 ? "AM" : "PM"
            else
              Time.now.hour < 12 ? "AM" : "PM"
            end
          end
        end
      end
    end

    module InstanceMethods
      def there_are_times_for
        self.class.times_for
      end
    end
  end
end


class SomeClass
  include TimeSet::TwentyFourHour
  twenty_four_hour_time_for :start, :end
end

class OtherClass
  include TimeSet::TwentyFourHour
  twenty_four_hour_time_for :commencement, :finality
end

x = SomeClass.new
y = OtherClass.new

puts x.there_are_times_for
puts y.there_are_times_for
# =>
# start
# end
# commencement
# finality