ooptictactoe.rb

require 'pry'

class Board
  WINNING_LINES = [[1,2,3], [4,5,6], [7,8,9]] +
                  [[1,4,7], [2,5,8], [3,6,9]] +
                  [[1,5,9], [3,5,7]]

  def initialize
    @squares = {}
    reset
  end

  def get_square_at(key)
    @squares[key]
  end

  def set_square_at(key, marker)
    @squares[key].marker = marker
  end

  def unmarked_keys
    @squares.keys.select {|key| @squares[key].unmarked? }
  end

  def full?
    unmarked_keys.empty?
  end

  def someone_won?
    !!detect_winner
  end

  def count_human_marker(squares)
    squares.collect(&:marker).count(TTTGame::HUMAN_MARKER)
  end

  def count_computer_marker(squares)
    squares.collect(&:marker).count(TTTGame::COMPUTER_MARKER)
  end

  def detect_winner
    WINNING_LINES.each do |line|
      if count_human_marker(@squares.values_at(*line)) == 3
        return TTTGame::HUMAN_MARKER
      elsif count_computer_marker(@squares.values_at(*line)) == 3
        return TTTGame::COMPUTER_MARKER
      end
    end
    nil
  end

  def reset
    (1..9).each {|key| @squares[key] = Square.new}
  end
end

class Square
  INITIAL_MARKER = " "

  attr_accessor :marker

  def initialize(marker=INITIAL_MARKER)
    @marker = marker
  end

  def to_s
    @marker
  end

  def unmarked?
    marker == INITIAL_MARKER
  end
end

class Player
  attr_reader :marker
  def initialize(marker)
      @marker = marker
  end
end

class TTTGame
  HUMAN_MARKER = "X"
  COMPUTER_MARKER = "O"

  attr_reader :board, :human, :computer

  def initialize
    @board = Board.new
    @human = Player.new(HUMAN_MARKER)
    @computer = Player.new(COMPUTER_MARKER)
  end

  def display_welcome_message
    puts "Welcome to Tic Tac Toe!"
    puts ""
  end

  def display_goodbye_message
    puts "Thanks for playing Tic Tac Toe! Goodbye!"
  end

  def display_board(clear = true)
    system 'clear' if clear
    puts "You're a #{human.marker}. Computer is a #{computer.marker}."
    puts ""
    puts "     |     |"
    puts "  #{board.get_square_at(1)}  |  #{board.get_square_at(2)}  |  #{board.get_square_at(3)}"
    puts "     |     |"
    puts "-----+-----+-----"
    puts "     |     |     "
    puts "  #{board.get_square_at(4)}  |  #{board.get_square_at(5)}  |  #{board.get_square_at(6)}   "
    puts "     |     |     "
    puts "-----+-----+-----"
    puts "     |     |"
    puts "  #{board.get_square_at(7)}  |  #{board.get_square_at(8)}  |  #{board.get_square_at(9)}"
    puts "     |     |"
    puts ""
  end

  def human_moves
    puts "Choose a square: #{board.unmarked_keys.join(', ')}:"
    square = nil

    loop do
      square = gets.chomp.to_i
      break if board.unmarked_keys.include?(square)
      puts "Sorry, that's not a valid choice."
    end

    board.set_square_at(square, human.marker)
  end

  def computer_moves
    board.set_square_at(board.unmarked_keys.sample, computer.marker)
  end
   
  def display_result
    display_board

    case board.detect_winner
    when human.marker
      puts "You won!"
    when computer.marker
      puts "Computer won!"
    else
      puts "It's a tie!"
    end
  end

  def play_again?
    answer = nil
    loop do
      puts "Would you like to play again? (Y/N)"
      answer = gets.chomp.downcase
      break if %w(y n).include? answer
      puts "Sorry, must be y or n."
    end

     answer == 'y'
  end
  
  def play
    system 'clear'
    display_welcome_message

    loop do
      display_board(false)

      loop do
        human_moves
        break if board.someone_won? || board.full?

        computer_moves
        break if board.someone_won? || board.full?

        display_board
      end
      display_result
      break unless play_again?
      board.reset
      system 'clear'
      puts "Let's play again!"
    end

    display_goodbye_message
  end
end

game = TTTGame.new
game.play