# ----------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()

    # while the game is still going
    while GAME_GOING:
        display_board()
        # handle a turn
        handle_turn()
        # import pdb; pdb.set_trace()
        # 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
    display_board()
    if WINNER == 'X' or WINNER == 'O':
        print(WINNER + " won.")
    elif WINNER == None:
        print("Tie.")
    exit(0)

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()
    global board
    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()) + 1
        else:
            # take player input
            choice = input('Choose a position from 1 to 9: ')
        choice = int(choice) - 1
        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

    if choice in list(range(0, 9)) and choice in find_open_spaces():
        is_valid = True

    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():
    global GAME_GOING
    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():
    global GAME_GOING
    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 any((column_1, column_2, column_3)):
        GAME_GOING = False
    if column_1:
        return board[0]
    if column_2:
        return board[1]
    if column_3:
        return board[2]
    return


def check_diagonal():
    global GAME_GOING
    diagonal_1 = board[0] == board[4] == board[8] != '-'
    diagonal_2 = board[2] == board[4] == board[6] != '-'
    # display the winner
    if diagonal_1 or diagonal_2:
        GAME_GOING = False
    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


def find_open_spaces():
    # find a random space to select
    open_spaces = []
    for i in range(0, len(board)):
        if board[i] == "-":
            open_spaces.append(i)

    return open_spaces


if __name__ == "__main__":
    main()