石取りゲーム

stone_tori.rb

class StoneTori
  class Stones
    def initialize(count)
      @count = count
    end

    def empty?
      @count.zero?
    end

    def count
      @count
    end

    def get(n)
      @count -= n
    end
  end

  class Players
    def initialize(*player_types)
      @players = player_types.map { |type| create_player(type) }
      @current_player_index = 0
    end

    def shuffle
      @players.shuffle!
    end

    def current_player
      @players[@current_player_index]
    end

    def next!
      @current_player_index = (@current_player_index + 1) % @players.size
    end

    private

    def create_player(type)
      case type
      when :computer
        Player::Computer.new
      when :human
        Player::Human.new
      end
    end
  end

  class Player
    MAX_COUNT = 5

    @@index = 0

    def initialize
      @player_index = @@index

      @@index += 1
    end

    def name
      "<Player##{@player_index}>"
    end

    alias to_s name

    class Computer < Player
      def deside(current_stone_count)
        return 1 if current_stone_count == 1

        # 10 回に 1 回はランダムな選択, 9 回は賢い選択をする
        if rand(10) == 0
          randome_deside(current_stone_count)
        else
          intelligent_deside(current_stone_count)
        end
      end

      def randome_deside(current_stone_count)
        (1..current_stone_count - 1).to_a.sample
      end

      def intelligent_deside(current_stone_count)
        count = current_stone_count % (MAX_COUNT + 1) - 1
        return count if count >= 1

        randome_deside(current_stone_count)
      end
    end

    class Human < Player
      def deside(current_stone_count)
        return 1 if current_stone_count == 1

        loop do
          max_count = current_stone_count > MAX_COUNT ? MAX_COUNT : current_stone_count
          print "Hit get count [1..#{max_count}] > "

          count = $stdin.gets.to_i

          next puts("Over max count: #{max_count}") if count > max_count
          next puts("Zero is invalid.") if count == 0

          return count
        end
      end
    end
  end

  def initialize(n = 50)
    @stones = Stones.new(n)
    @players = Players.new(:computer, :human)
  end

  def shuffle
    @players.shuffle
  end

  def start
    loop do
      player = @players.current_player

      get_count = player.deside(@stones.count)
      next if @stones.count < get_count

      @stones.get(get_count)

      puts "#{player.name} get #{get_count}."

      if @stones.empty?
        puts "#{player.name} loose .."

        return
      else
        @players.next!

        puts "next! Rest #{@stones.count}."
      end
    end
  end
end

if __FILE__ == $0
  game = StoneTori.new(20)
  game.shuffle
  game.start
end