tictactoe

# Tic Tac toe
require 'pry'
INITITAL_MARKER = ' '
PLAYER_MARKER = 'X'
COMPUTER_MARKER = 'O'

def prompt(msg)
  puts "=>#{msg}"
end

def display_board(brd)
  system 'clear'
  puts "You're a #{PLAYER_MARKER}. Computer is #{COMPUTER_MARKER}."
  puts ""
  puts "     |     |"
  puts "  #{brd[1]}  |  #{brd[2]}  |  #{brd[3]}"
  puts "     |     |"
  puts "-----+-----+-----"
  puts "     |     |"
  puts "  #{brd[4]}  |  #{brd[5]}  |  #{brd[6]}"
  puts "     |     |"
  puts "-----+-----+-----"
  puts "     |     |"
  puts "  #{brd[7]}  |  #{brd[8]}  |  #{brd[9]}"
  puts "     |     |"
  puts ""
end

def initialize_board
  new_board = {}
  (1..9).each {|num| new_board[num] = INITITAL_MARKER}
  new_board
end

def empty_squares(brd)
  brd.keys.select {|num| brd[num] == INITITAL_MARKER}
end

def player_places_piece!(brd)
  square = ""
  loop do
    prompt "Choose a square, #{empty_squares(brd).join(',')}:"
    square = gets.chomp.to_i
    break if empty_squares(brd).include?(square)
      prompt 'not a valid choice'
  end
  brd[square] = PLAYER_MARKER
end

def computer_places_piece!(brd)
  square = empty_squares(brd).sample
  brd[square] = COMPUTER_MARKER
end

def board_full?(brd)
  empty_squares(brd).empty?
end

def someone_won?(brd)
  !!detect_winner(brd)
end

def detect_winner(brd)
  winning_lines = [[1,2,3], [4,5,6], [7,8,9]] + # rows
                  [[1,4,7], [2,5,8], [3,6,9]] + # columns
                  [[1,5,9], [3,5,7]]            # diagonols

  winning_lines.each do |line|
    if brd[line[0]] == PLAYER_MARKER &&
       brd[line[1]] == PLAYER_MARKER &&
       brd[line[2]] == PLAYER_MARKER
       return 'Player'
    elsif brd[line[0]] == COMPUTER_MARKER &&
          brd[line[1]] == COMPUTER_MARKER &&
          brd[line[2]] == COMPUTER_MARKER
          return 'computer'
    end
  end
  nil
end

loop do
  board = initialize_board

  loop do
    display_board(board)

    player_places_piece!(board)
    break if someone_won?(board) || board_full?(board)

    computer_places_piece!(board)
    break if someone_won?(board) || board_full?(board)
  end

  display_board(board)

  if someone_won?(board)
    prompt "#{detect_winner(board)} won!"
  else
    prompt "It's a tie!"
  end

  prompt "Play Again? (y or n)"
  answer = gets.chomp
  break unless answer.downcase.start_with?('y')
end

prompt "thanks for playing tic tac toe!"