import random
X = "X"
O = "O"
EMPTY = " "
TIE = "TIE"
human = X
computer = O
grid = 9
position = 0
def display_instructions():
    print("The tic tac toe you will be playing on will\n",
          "be a 3 by 3 grid and will look like this\n",
          " 0 | 1 | 2\n",
          " ---------\n",
          " 3 | 4 | 5\n",
          " ---------\n",
          " 6 | 7 | 8\n",
          "You will start off by going first as X's\n",
          "use 0-8 to position where you would like to go")

def display_board(board):
    print(board[0], "|", board[1], "|", board[2])
    print("---------")
    print(board[3], "|", board[4], "|", board[5])
    print("---------")
    print(board[6], "|", board[7], "|", board[8])

def new_board():
    board = []
    for position in range(grid):
        board.append(EMPTY)
    return board

def winner(board):
    winner = "none"
    while winner != X or O:
        if board[0] == board[1] == board[2] != EMPTY:
            winner = board[0]
            return winner
        elif board[3] == board[4] == board[5] != EMPTY:
            winner = board[3]
            return winner
        elif board[5] == board[6] == board[7] != EMPTY:
            winner = board[5]
            return winner
        elif board[0] == board[3] == board[6] != EMPTY:
            winner = board[0]
            return winner
        elif board[1] == board[4] == board[7] != EMPTY:
            winner = board[1]
            return winner
        elif board[2] == board[5] == board[8] != EMPTY:
            winner = board[2]
            return winner
        elif board[0] == board[4] == board[8] != EMPTY:
            winner = board[0]
            return winner
        elif board[2] == board[4] == board[6] != EMPTY:
            winner = board[2]
            return winner

        elif EMPTY not in board:
            return TIE
        return None

def next_turn(turn):
    if turn == X:
        return 0
    else:
        return X


def human_move(board):
    print("Where will you move?(0-8): ")
    move=int(input())
    turn = X
    while turn == X:
        if move in range(grid) and board[move] == EMPTY:
            board[move] = X
            turn = next_turn(turn)
        else:
            print("Move not valid, please choose an empty space using 0-8")
            move=int(input())
    return move

def computer_move(board):
    turn = O
    move = random.randint(0,8)
    while turn == O:
        if move in range(grid) and board[move] == EMPTY:
            board[move] = O
            turn = next_turn(turn)
        else:
            move = random.randint(0,8)
    return move


def legal_move(board):
    move = []
    if board[move] in range(grid):
            if board[move]== EMPTY:
                move.append(position)
    return move

def main():
    display_instructions()
    board = new_board()
    while not winner(board):
            human_move(board)
            computer_move(board)
            display_board(board)
    the_winner = winner(board)
    if the_winner == human:
        print("A winner is you!")
    if the_winner == computer:
        print("You Fail it! \n"
              "Your skill is not enough \n"
              "see you next time \n"
              "bye-bye!\n")
    import os
    os.system('pause')
main()