module Billing
  module Stripe
    module SubscriptionPeriod
      module_function

      def times(stripe_sub)
        item = stripe_sub.items&.data&.first
        start_at = read_value(stripe_sub, :current_period_start) || read_value(item, :current_period_start)
        end_at = read_value(stripe_sub, :current_period_end) || read_value(item, :current_period_end)
        [unix_time(start_at), unix_time(end_at)]
      end

      def read_value(object, field)
        return nil if object.blank?
        return nil unless object.respond_to?(field)

        object.public_send(field)
      end

      def unix_time(value)
        return nil if value.blank?

        Time.zone.at(value.to_i)
      end
    end
  end
end