actor_brule.rb

class ComputePrice < Actor
  play ComputePricePerDay,
       if: -> input { input.selected_at < Time.utc(2020, 9, 1) }
  play ComputePricePerMinute,
       if: -> input { Time.utc(2020, 9, 1) <= input.selected_at }
  play ApplyDiscount,
       if: -> input { Time.utc(2020, 6, 1) <= input.selected_at }
end

class ComputePricePerDay < Actor
  input :period
  input :car_price_per_day
  output :price

  def call
    self.price = period.duration_in_days * car_price_per_day
  end
end

class ComputePricePerMinute < Actor
  input :period
  input :car_price_per_day
  output :price

  def call
    price_per_minute = car_price_per_day / (24 * 60).to_f
    self.price = period.duration_in_minutes * price_per_minute
  end
end

class ApplyDiscount < Actor
  input :period
  input :price
  output :price

  def call
    discount = (2 * period.duration_in_days - 4).clamp(0, 40)
    self.price *= 1 - discount / 100.0
  end
end