tic_tac_toe.rb

class Player
  private_class_method :new
  
  class << self 
    def one ; 1 ; end
    def two ; 2 ; end
  end
end

class TTTEngine
  attr_accessor :board
  
  BOTTOM_LEFT    = 2 ** 0
  BOTTOM_CENTER  = 2 ** 1
  BOTTOM_RIGHT   = 2 ** 2
  CENTER_LEFT    = 2 ** 3
  CENTER_CENTER  = 2 ** 4
  CENTER_RIGHT   = 2 ** 5
  TOP_LEFT       = 2 ** 6
  TOP_CENTER     = 2 ** 7
  TOP_RIGHT      = 2 ** 8

  WIN_CONDITIONS = [
    [BOTTOM_LEFT,   BOTTOM_RIGHT,  BOTTOM_RIGHT],
    [CENTER_LEFT,   CENTER_RIGHT,  CENTER_RIGHT],
    [TOP_LEFT,      TOP_RIGHT,     TOP_RIGHT],
    [BOTTOM_LEFT,   CENTER_LEFT,   TOP_LEFT],
    [BOTTOM_CENTER, CENTER_CENTER, TOP_CENTER],
    [BOTTOM_RIGHT,  CENTER_RIGHT,  TOP_RIGHT],
    [BOTTOM_LEFT,   CENTER_CENTER, TOP_Rclass Player
  private_class_method :new
  
  class << self 
    def one ; 1 ; end
    def two ; 2 ; end
  end
end

class TTTEngine
  attr_accessor :board
  
  BOTTOM_LEFT    = 2 ** 0
  BOTTOM_CENTER  = 2 ** 1
  BOTTOM_RIGHT   = 2 ** 2
  CENTER_LEFT    = 2 ** 3
  CENTER_CENTER  = 2 ** 4
  CENTER_RIGHT   = 2 ** 5
  TOP_LEFT       = 2 ** 6
  TOP_CENTER     = 2 ** 7
  TOP_RIGHT      = 2 ** 8

  WIN_CONDITIONS = [
    [BOTTOM_LEFT,   BOTTOM_RIGHT,  BOTTOM_RIGHT],
    [CENTER_LEFT,   CENTER_RIGHT,  CENTER_RIGHT],
    [TOP_LEFT,      TOP_RIGHT,     TOP_RIGHT],
    [BOTTOM_LEFT,   CENTER_LEFT,   TOP_LEFT],
    [BOTTOM_CENTER, CENTER_CENTER, TOP_CENTER],
    [BOTTOM_RIGHT,  CENTER_RIGHT,  TOP_RIGHT],
    [BOTTOM_LEFT,   CENTER_CENTER, TOP_RIGHT],
    [TOP_LEFT,      CENTER_CENTER, BOTTOM_RIGHT]
  ]

  def initialize
    @board = 0
  end

  def move(player, x, y)
    b = transpose_for_read(player, @board)
    coord = translate_coords(x, y)
    msg = "Great move!"
    status = "Success"

    if game_won?
      msg = "Game has already been won!"
      status = "Failure"
    elsif !coord
      msg = "Invalid position!"
      status = "Failure"
    elsif !valid_move?(player, @board, coord)
      msg = "Invalid move!"
      status = "Failure"
    else
      b += coord
      @board |= transpose_for_write(player, b)
      if game_won?
        msg = "Player #{player} has won!"
        status = "Completion"
      end
    end
    { board_state: @board, message: msg, status: status}
  end

  private

  def count_moves(board)
    count = 0
    while board > 0
      count += 1 if board & 1 == 1
      board >>= 1
    end
    count
  end

  def valid_move?(player, board, coord)
    ## Check if it's their turn
    if count_moves(board).even? && player == Player.two
      return false
    end
    ## Check if anyone's taken this space
    (transpose_for_read(Player.one, board) & coord == 0) &&
      (transpose_for_read(Player.two, board) & coord == 0)
  end

  def game_won?
    WIN_CONDITIONS.each do |cond|
      mask = cond[0] | cond[1] | cond[2]
      if (transpose_for_read(Player.one, @board) & mask) == mask
        puts "Player One has won!"
        return Player.one
      elsif (transpose_for_read(Player.two, @board) & mask) == mask
        puts "Player Two has won!"
        return Player.two
      end
    end
    false
  end

  def translate_coords(x, y)
    bx = translate_x(x)
    by = translate_y(y)

    if bx && by
      Object.const_get("TTTEngine::#{by}_#{bx}")
    else 
      nil
    end
  end
  
  def translate_x(coord)
    case coord
    when 0
      :LEFT
    when 1
      :CENTER
    when 2
      :RIGHT
    end
  end
  
  def translate_y(coord)
    case coord
    when 0
      :BOTTOM
    when 1
      :CENTER
    when 2
      :TOP
    end
  end
  
  def transpose_for_read(player, board)
    if player == Player.one
      board & (2 ** 9 - 1)
    else
      (board >> 9) & (2 ** 9 - 1)
    end
  end
  
  def transpose_for_write(player, board)
    if player == Player.two
      board << 9
    else 
      board
    end
  end
end

t = TTTEngine.new

puts t.move(Player.one, 0, 0)

puts t.move(Player.two, 0, 3)
puts t.move(Player.two, 0, 2)
puts t.move(Player.two, 0, 1)

puts t.move(Player.one, 1, 0)

puts t.move(Player.two, 0, 1)

puts t.move(Player.one, 2, 0)IGHT],
    [TOP_LEFT,      CENTER_CENTER, BOTTOM_RIGHT]
  ]

  def initialize
    @board = 0
  end

  def move(player, x, y)
    b = transpose_in(player, @board)
    coord = translate_coords(x, y)
    msg = "Great move!"
    status = "Success"

    if game_won?
      msg = "Game has already been won!"
      status = "Failure"
    elsif !coord
      msg = "Invalid position!"
      status = "Failure"
    elsif !valid_move?(player, @board, coord)
      msg = "Invalid move!"
      status = "Failure"
    else
      b += coord
      @board |= transpose_out(player, b)
      if game_won?
        msg = "Player #{player} has won!"
        status = "Completion"
      end
    end
    { board_state: @board, message: msg, status: status}
  end

  private

  def count_moves(board)
    count = 0
    while board > 0
      count += 1 if board & 1 == 1
      board >>= 1
    end
    count
  end

  def valid_move?(player, board, coord)
    ## Check if it's their turn
    if count_moves(board).even? && player == Player.two
      return false
    end
    ## Check if anyone's taken this space
    (transpose_in(Player.one, board) & coord == 0) &&
      (transpose_in(Player.two, board) & coord == 0)
  end

  def game_won?
    WIN_CONDITIONS.each do |cond|
      mask = cond[0] | cond[1] | cond[2]
      if (transpose_in(Player.one, @board) & mask) == mask
        puts "Player One has won!"
        return Player.one
      elsif (transpose_in(Player.two, @board) & mask) == mask
        puts "Player Two has won!"
        return Player.two
      end
    end
    false
  end

  def translate_coords(x, y)
    bx = translate_x(x)
    by = translate_y(y)

    if bx && by
      Object.const_get("TTTEngine::#{by}_#{bx}")
    else 
      nil
    end
  end
  
  def translate_x(coord)
    case coord
    when 0
      :LEFT
    when 1
      :CENTER
    when 2
      :RIGHT
    end
  end
  
  def translate_y(coord)
    case coord
    when 0
      :BOTTOM
    when 1
      :CENTER
    when 2
      :TOP
    end
  end
  
  def transpose_in(player, board)
    if player == Player.one
      board & (2 ** 9 - 1)
    else
      (board >> 9) & (2 ** 9 - 1)
    end
  end
  
  def transpose_out(player, board)
    if player == Player.two
      board << 9
    else 
      board
    end
  end
end

t = TTTEngine.new

puts t.move(Player.one, 0, 0)

puts t.move(Player.two, 0, 3)
puts t.move(Player.two, 0, 2)
puts t.move(Player.two, 0, 1)

puts t.move(Player.one, 1, 0)

puts t.move(Player.two, 0, 1)

puts t.move(Player.one, 2, 0)