Python Tic Tac Toe Game Project

"""A two-player command-line Tic-Tac-Toe game."""

from __future__ import annotations


WINNING_LINES = (
    (0, 1, 2),
    (3, 4, 5),
    (6, 7, 8),
    (0, 3, 6),
    (1, 4, 7),
    (2, 5, 8),
    (0, 4, 8),
    (2, 4, 6),
)


def display_board(board: list[str]) -> None:
    cells = [value if value else str(index + 1) for index, value in enumerate(board)]
    print(f"\n {cells[0]} | {cells[1]} | {cells[2]}")
    print("---+---+---")
    print(f" {cells[3]} | {cells[4]} | {cells[5]}")
    print("---+---+---")
    print(f" {cells[6]} | {cells[7]} | {cells[8]}\n")


def winner(board: list[str]) -> str | None:
    for first, second, third in WINNING_LINES:
        if board[first] and board[first] == board[second] == board[third]:
            return board[first]
    return None


def read_move(board: list[str], player: str) -> int:
    while True:
        value = input(f"Player {player}, choose an empty square [1-9]: ").strip()
        if not value.isdigit() or not 1 <= int(value) <= 9:
            print("Enter a number from 1 to 9.")
            continue
        index = int(value) - 1
        if board[index]:
            print("That square is already occupied.")
            continue
        return index


def play_game() -> str | None:
    board = [""] * 9
    player = "X"

    for _ in range(9):
        display_board(board)
        board[read_move(board, player)] = player
        if winner(board):
            display_board(board)
            print(f"Player {player} wins!")
            return player
        player = "O" if player == "X" else "X"

    display_board(board)
    print("The game is a draw.")
    return None


def main() -> None:
    print("Python Tic-Tac-Toe")
    while True:
        play_game()
        if input("Play again? [y/N]: ").strip().lower() != "y":
            break


if __name__ == "__main__":
    main()