highlow.rb

require "tty-reader"

class HighLow
  @@DESK = [?A, *'2'..'10', ?J, ?Q, ?K].product(%w[♠ ♥ ♦ ♣])

  def initialize
    @deck = @@DESK.shuffle
    @score = 0
  end

  attr_reader :deck
  attr_reader :score

  def play
    prompt = TTY::Reader.new

    last = nil
    @deck.each do
      current = [?A, *'2'..'10', ?J, ?Q, ?K].index(_1)

      unless last.nil?
        correct = nil
        while correct.nil? do
          case prompt.read_keypress
          when "\e[B" then correct = current <= last
          when "\e[A" then correct = current >= last
          end
        end

        @score += 1 if correct
      end

      puts " #{@score.to_s.ljust(2)} | #{_1} #{_2}"
      last = current
    end

    @score
  end
end