customer.rb

class Customer
  attr_reader :name

  def initialize(name)
    @name = name
    @rentals = []
  end

  def add_rental(arg)
    @rentals << arg
  end

  def statement
    total_amount, frequent_renter_points = 0, 0
    result = "Rental Record for #{@name}\n"
    @rentals.each do |element|
      this_amount = 0

      # determine amounts for each line
      case element.movie.price_code
      when Movie::REGULAR
        this_amount += 2
        this_amount += (element.days_rented - 2) * 1.5 if element.days_rented > 2
      when Movie::NEW_RELEASE
        this_amount += element.days_rented * 3
      when Movie::CHILDRENS
        this_amount += 1.5
        this_amount += (element.days_rented - 3) * 1.5 if element.days_rented > 3
      end

      # add frequent renter points
      frequent_renter_points += 1
      # add bonus for a two day new release rental
      frequent_renter_points += 1 if element.movie.price_code == Movie.NEW_RELEASE && element.days_rented > 1

      # show figures for this rental
      result += "\t" + element.movie.title + "\t" + this_amount.to_s + "\n"
      total_amount += this_amount
    end
    # add footer lines
    result += "Amount owed is #{total_amount.to_s}\n"
    result += "You earned #{frequent_renter_points.to_s} frequent renter points"
    result
  end
end

movie.rb

class Movie
  CHILDRENS = 2
  REGULAR = 0
  NEW_RELEASE = 1

  attr_reader :title
  attr_accessor :price_code

  def initialize(title, price_code)
    @title, @price_code = title, price_code
  end
end

rental.rb

class Rental
  attr_reader :movie, :days_rented

  def initialize(movie, days_rented)
    @movie, @days_rented = movie, days_rented
  end
end