# coding: utf-8

DEF = "   "
PLAYS = [DEF, DEF, DEF, DEF, DEF, DEF, DEF, DEF, DEF]
SCENARIOS = [[0,1,2],[3,4,5],[6,7,8],[0,3,6],[1,4,7],[2,5,8],[0,4,8],[2,4,6]]
COM = "COM"
COM_VAL = " O "
PLAYER = "PLAYER"
GAME_DONE = false
PLAYER_VAL = " X "


class Array
  def same_values?
    self.uniq.length == 1
  end
end

def check_win board, player
  cur_play = player == PLAYER ? PLAYER_VAL : COM_VAL
  
  SCENARIOS.each do |s|
    tmp = s.map {|i| board[i]}
   # p board
    if (not tmp.include? "   ") and  tmp.same_values? and tmp[0] == cur_play then
      # p tmp
      # p SCENARIOS
      return true
    else
      return false
    end
  end
end




def check_full board
  if not board.include? "   " then
    return true
  else
    return false
  end
end


def draw_board board
  return "
  |#{board[0]}|#{board[1]}|#{board[2]}|
  -------------
  |#{board[3]}|#{board[4]}|#{board[5]}|
  -------------
  |#{board[6]}|#{board[7]}|#{board[8]}|
  -------------"
end

def set player, idx
  if player == PLAYER
    PLAYS[idx] = PLAYER_VAL
  elsif
    PLAYS[idx] = COM_VAL
  end
  
end




def ai_turn board, player, depth=0
  if (check_win board, player == PLAYER ? COM : PLAYER) then
    return -10 + depth
  end

  if check_full board then
    return 0
  end

  max_seen = -(Float::INFINITY)
  index = 0
  value = player == PLAYER ? PLAYER_VAL : COM_VAL

  (0...9).each do |x|
    if board[x] == DEF then
      new_board = board.dup
      new_board[x] = value
      lol = player == PLAYER ? COM : PLAYER
      move_eval = -(ai_turn new_board, lol, depth+1)

      if move_eval > max_seen then
#        p [move_eval, x]
        max_seen = move_eval
        index = x
      end
    end
  end
  if depth == 0 then
    set COM, index
  end
  return max_seen
end


def play_game
  while true do
    #  system "clear"

    # if (check_win PLAYS, PLAYER) == true then
    #   print "We have a winner!\n"
    #   break
    # end
    # if check_full board then
    #   print "Game over!\n"
    #   break
    # end
    
    print draw_board PLAYS
    puts "\nPick one between 0-8"
    choice = gets
    
    if PLAYS[choice.to_i] != "   " then
      print "Space is already taken"
    else
      set PLAYER, choice.to_i
      ai_turn PLAYS, COM
    end
    
  end
end

play_game