#----------global variables------------
#https://www.youtube.com/watch?v=BHh654_7Cmw
#Create a board
import random

board = ['-','-','-',
		     '-','-','-',
		     '-','-','-']

#if game is still going
GAME_GOING = True
#who won?
WINNER = None
#define valid symbols
SYMBOLS = {'X','O'}
#define players
PLAYER1 = ""
PLAYER2 = ""
#define how many players
SINGLE_PLAYER = True

CURRENT_PLAYER = random.choice(list(SYMBOLS))

def main():
  global CURRENT_PLAYER
  global SINGLE_PLAYER
  global PLAYER1
  global PLAYER2
  
  
  mode = input("Single player mode y/n: ")
  if mode not in "yn":
    print("You did not select a valid option no game for you")
    exit(1)


  if mode == "y":
    SINGLE_PLAYER = True
  else:
    SINGLE_PLAYER = False

  player_1 = input("Choose X or O for Player 1: ")

  if player_1 not in SYMBOLS:
    print("You did not select a valid option no game for you")
    exit(1)
  PLAYER1 =  player_1
  PLAYER2 =  (SYMBOLS - {player_1}).pop()

  display_board ()
  
  #while the game is still going
  while GAME_GOING:
    #handle a turn 
	  handle_turn()
  	#check if he game has ended
	  check_if_game_over()
	  # cahnge to the other player
	  CURRENT_PLAYER = (SYMBOLS - {CURRENT_PLAYER}).pop()
	
  #the game has ended
  if WINNER == 'X' or WINNER == 'O':
    print (WINNER + "won.")
  elif WINNER == None:
    print ("Tie.")
  
def display_board ():
  print(board [0]+ '|'+ board[1]+'|'+ board [2])
  print(board [3]+ '|'+ board[4]+'|'+ board [5])
  print(board [6]+ '|'+ board[7]+'|'+ board [8])
  
#play game of tic tac toe	
	
def handle_turn():
 # import pdb; pdb.set_trace()
  print("Current Player {}".format(CURRENT_PLAYER))
  while True:
    if SINGLE_PLAYER:
      if CURRENT_PLAYER == PLAYER1:
      #take player input
        choice = input('Choose a position from 1 to 9: ')
      else:
        choice = random.choice(find_open_spaces())
    else:
      #take player input
      choice = input('Choose a position from 1 to 9: ')
    if validate_choice(choice):
      break
    else:
      print("Invalid choice")

  board[choice] == current_player
  

 
def validate_choice(choice):
  is_valid = False
  try:
    choice = int(choice)
  except ValueError:
    return is_valid
  import pdb; pdb.set_trace()
  if choice in list(range(0,9)) and choice in find_open_spaces():
      valid = True
  else:
    brake

  return is_valid

  
  
def check_if_game_over():
  check_if_win()
  
  check_if_tie()

  
def check_if_win():
  #call global variable
  global winner
  #check rows
  row_winner = check_rows()
  #check columns
  column_winner = check_columns()
  #check diagonals
  diagonal_winner = check_diagonal()
  
  
  if row_winner:
  #there is a winner
    winner = row_winner
  elif column_winner:
  #there is a winner
    winner = column_winner
  elif diagonal_winner:
  #there is a winner
    winner = diagonal_winner
  else:
    winner = None
  return

def check_rows():
  row_1 = board[0] == board[1] == board[2] != '-'
  row_2 = board[3] == board[4] == board[5] != '-'
  row_3 = board[6] == board[7] == board[8] != '-'
  if row_1 or row_2 or row_3:
    game_going = False
	#display the winner
  if row_1: 
    return board[0]
  if row_2:
    return board[3]
  if row_3:
    return board[6]
  return

def check_columns():
  column_1 = board[0] == board[3] == board[6] != '-'
  column_2 = board[1] == board[4] == board[7] != '-'
  column_3 = board[2] == board[5] == board[8] != '-'
  	#display the winner
  if column_1: 
    return board[0]
  if column_2:
    return board[1]
  if column_3:
    return board[2]
  return
  
def check_diagonal():
  diagonal_1 = board[0] == board[4] == board[8] != '-'
  diagonal_2 = board[2] == board[4] == board[6] != '-'
  	#display the winner
  if diagonal_1: 
    return board[0]
  if diagonal_2:
    return board[2]
  return
  
#check_if_tie

def check_if_tie():
  global game_going
  if "-" not in board:
    game_going = False
  return

#change between players
def change_player():
#call global variable
  global current_player
  #if the current player was X we change to O
  if current_player == 'X':
    current_player = 'O'
  #if current player is O, change to X	
  elif current_player == 'O':
    current_player = 'X'
  return

def find_open_spaces():
  #find a random space to select
  open_spaces = [] 
  for i in board:
    if i == "-":
      open_spaces.append(i)

    return open_spaces

if __name__ == "__main__":
  main()