tic tac toe

tictactoe.rb

# Usage: ruby -e "$(curl -s https://gist.githubusercontent.com/ricardotealdi/797f25e4020c5f8e8aff/raw/<HASH>/tictactoe.rb)"

board_add = -> (board, x, y, piece) { board[y][x] ? nil : board[y][x] = piece }

board_print = lambda do |board|
  puts ""
  puts '    1   2   3'
  board.each_with_index do |row, index|
    format_row = row.map { |it| it.nil? ? ' ' : it.to_s.upcase }.join ' | '
    puts(
      " #{index + 1}  #{format_row}  "
    )
    puts "   #{"-" * 11} " if index < 2
  end
  puts ""
end

board_full = -> (board) { board.all? { |row| row.none?(&:nil?) } }

board_winner_horizontally = lambda do |board|
  winner_row = board.detect { |row| row.uniq.size == 1 }
  winner_row && winner_row.first
end

board_winner_vertically = lambda do |board|
  winner_column = (0..2).to_a.detect do |row|
    (0..2).to_a.map { |column| board[column][row] }.uniq.size == 1
  end
  winner_column && board[0][winner_column]
end

board_winner_transversely = lambda do |board|
  winner_column = [0, 2].detect do |column|
    (0..2).map { |index| board[index][(-(column) + index).abs] }.uniq.size == 1
  end
  winner_column && board[0][winner_column]
end

board_winner = lambda do |board|
  board_winner_horizontally.call(board) || 
    board_winner_vertically.call(board) ||
    board_winner_transversely.call(board)
end

board_finished = lambda do |board|
  winner = board_winner.call(board)
  return winner if winner

  board_full.call(board) ? :tie : nil
end

game = lambda do
  players = %i(X O).shuffle
  turn = 0

  board = Array.new(3) { |it| it = Array.new(3) }
  
  while !(result = board_finished.call(board))
    system('clear')

    board_print.call(board)
    
    current_player = players[turn % 2]

    puts "Turn: #{turn}"
    puts "Player: #{current_player}"

    begin
      puts "Choose your position (X):"
      x = gets.strip.to_s.to_i - 1
    end until x >= 0 && x <= 2

    begin
      puts "Choose your position (Y):"
      y = gets.strip.to_s.to_i - 1
    end until y >= 0 && y <= 2

    next unless board_add.call(board, x, y, current_player)

    turn += 1
  end

  system('clear')

  board_print.call(board)

  puts "The winner is: #{result}"
end

game.call