import random
board = ['0','1','2','3','4','5','6','7','8']
a = None
player_select = None
comp_select = None

def post_move_stuff():
    check_for_win()
    player_moves()

def AI_move_part_1():
    global board
    global a
    if board[0]==board[3] and board[6] == '6':
        board[6]=comp_select
        a = 1
        post_move_stuff()
    if board[0]==board[6] and board[3] == '3':
        board[3]=comp_select
        a = 1
        post_move_stuff()
    if board[3]==board[6] and board[0] == '0':
        board[0]=comp_select
        a = 1
        post_move_stuff()
    if board[1]==board[4] and board[7] == '7':
        board[7]=comp_select
        a = 1
        post_move_stuff()
    if board[1]==board[7] and board[4] == '4':
        board[4]=comp_select
        a = 1
        post_move_stuff()
    if board[4]==board[7] and board[1] == '1':
        board[1]=comp_select
        a = 1
        post_move_stuff()
    if board[2]==board[5] and board[8] == '8':
        board[8]=comp_select
        a = 1
        post_move_stuff()
    if board[2]==board[8] and board[5] == '5':
        board[5]=comp_select
        a = 1
        post_move_stuff()
    if board[5]==board[8] and board[2] == '2':
        board[2]=comp_select
        a = 1
        post_move_stuff()
    if board[0]==board[1] and board[2] == '2':
        board[2]=comp_select
        a = 1
        post_move_stuff()
    if board[0]==board[2] and board[1] == '1':
        board[1]=comp_select
        a = 1
        post_move_stuff()
    if board[1]==board[2] and board[0] =='0':
        board[0]=comp_select
        a = 1
        post_move_stuff()
    if board[3]==board[4] and board[5] =='5':
        board[5]=comp_select
        a = 1
        post_move_stuff()
    if board[3]==board[5] and board[4] == '4':
        board[4]=comp_select
        a = 1
        post_move_stuff()
    if board[4]==board[5] and board[3] == '3':
        board[3]=comp_select
        a = 1
        post_move_stuff()
    if board[6]==board[7] and board[8] =='8':
        board[8]=comp_select
        a = 1
        post_move_stuff()
    if board[6]==board[8] and board[7] =='7':
        board[7]=comp_select
        a = 1
        post_move_stuff()
    if board[7]==board[8] and board[6] =='6':
        board[6]=comp_select
        a = 1
        post_move_stuff()
    if board[0]==board[4] and board[8] =='8':
        board[8]=comp_select
        a = 1
        post_move_stuff()
    if board[0]==board[8] and board[4] =='4':
        board[4]=comp_select
        a = 1
        post_move_stuff()
    if board[4]==board[8] and board[0] =='0':
        board[0]=comp_select
        a = 1
        post_move_stuff()
    if board[2]==board[4] and board[6] =='6':
        board[6]=comp_select
        a = 1
        post_move_stuff()
    if board[2]==board[6] and board[4] =='4':
        board[4]=comp_select
        a = 1
        post_move_stuff()
    if board[4]==board[6] and board[2] =='2':
        board[2]=comp_select
        a = 1
        post_move_stuff()
    if board[1]==board[3] == player_select and board[0] =='0':
        board[0]=comp_select
        a = 1
        post_move_stuff()
    if board[1]==board[5] == player_select and board[2] =='2':
        board[2]=comp_select
        a = 1
        post_move_stuff()
    if board[3]==board[7] == player_select and board[6] =='6':
        board[6]=comp_select
        a = 1
        post_move_stuff()
    if board[5]==board[7]==player_select and board[8] =='8':
        board[8]=comp_select
        a = 1
        post_move_stuff()
    if board[4] == '4':
        board[4] = comp_select
        a = 1
        post_move_stuff()

def AI_move_part_2():
    global a
    global board
    if board[0] == '0' or board[2] == '2' or board[6] == '6' or board[8] == '8':
        n = random.choice([0,2,6,8])
        if board[n] == str(n):
            board[n] = comp_select
            a = 1
            post_move_stuff()
        else:
            AI_move_part_2()
    if board[1] == '1' or board[5] == '5' or board[7] == '7' or board[3] == '3':
        m = random.choice([1,5,7,3])
        if board[m] == str(m):
            board[m] = comp_select
            a = 1
            post_move_stuff()
        else:
            AI_move_part_2()


def play_again():
    global board
    board = ['0','1','2','3','4','5','6','7','8']
    x = input('Do you want to play again? (y/n) \n' )
    if x in ['y','Y']:
        print('\n'*100)
        player_assign()
    else:
        exit()

def check_for_win():
    global board
    global player_select
    global comp_select
    if board[0] ==  board[1] ==  board[2] == player_select or board[3] ==  board[4] == board[5] == player_select or board[6] == board[7] == board[8] == player_select or board[0] == board[4] == board[8] == player_select or board[2] == board[4] == board[6] == player_select or board[0] == board[3] == board[6] == player_select or board[1] == board[4] == board[7] == player_select or board[2] == board[5] == board[8] == player_select:
        print("Player wins!\n")
        play_again()
    elif board[0] == board[1] == board[2] == comp_select or board[3] == board[4] == board[5] == comp_select or board[6] == board[7] == board[8] == comp_select or board[0] == board[4] == board[8] == comp_select or board[2] == board[4] == board[6] == comp_select or board[0] == board[3] == board[6] == comp_select or board[1] == board[4] == board[7] == comp_select or board[2] == board[5] == board[8] == comp_select:
        print(f'\n {board[0]} |  {board[1]}  | {board[2]} \n-------------\n {board[3]} |  {board[4]}  | {board[5]} \n-------------\n {board[6]} |  {board[7]}  | {board[8]} \n')
        print("The Computer wins!\n")
        play_again()

def player_moves():
    global board
    global comp_select
    global player_select
    global a
    if '1' not in board and '2' not in board and '3' not in board and '4' not in board and '5' not in board and '6' not in board and '7' not in board and '8' not in board and '0' not in board:
        print("Cat's Game!")
        play_again()
    while a == 1:
        print(f'\n {board[0]} |  {board[1]}  | {board[2]} \n-------------\n {board[3]} |  {board[4]}  | {board[5]} \n-------------\n {board[6]} |  {board[7]}  | {board[8]} \n')
        b = input("Player, where would you like to place? ")
        if b not in ['0','1','2','3','4','5','6','7','8'] or board[int(b)] in ['X','O']:
            print('\nInvalid Move!\n')
            player_moves()
        board[int(b)] = player_select
        print(f'\n {board[0]} |  {board[1]}  | {board[2]} \n-------------\n {board[3]} |  {board[4]}  | {board[5]} \n-------------\n {board[6]} |  {board[7]}  | {board[8]} \n')
        a = 0
        post_move_stuff()
    while a == 0:
        AI_move_part_1()
        AI_move_part_2()


def player_assign():
    global player_select
    global comp_select
    global a
    player_select = input("Let's play Tic Tac Toe!\n \nPlayer, do you want to be X's or O's? \n")
    print("These are the locations you can play.\n\n 0 |  1  | 2 \n-------------\n 3 |  4  | 5 \n-------------\n 6 |  7  | 8 \n")
    if player_select in ['x','X']:
        player_select = player_select.upper()
        comp_select = 'O'
        a = 1
        player_moves()
    elif player_select in ['o','O']:
        player_select = player_select.upper()
        comp_select = 'X'
        a = 0
        player_moves()
    else:
        print('\nInvalid Entry!\n')
        player_assign()

player_assign()