Pos = tuple[int, int]
Board = dict[Pos, str]  # Only "X", "O" and "_" are valid.


def read_board_from_file(filename: str) -> Board:
    """Return a `Board` from a simple text file which contains the current
    playing field, for example, as follows:

    XOX
    OXX
    ___
    """
    with open(filename, "r") as f:
        board = dict()

        for row, line in enumerate(f):
            for col, char in enumerate(line):
                board[(row, col)] = char if char in "XO_" else "_"

    return board


def read_board_from_str(string: str) -> Board:
    """Return a `Board` from a simple string, which contains the current
    playing field in a continous form, for example, as follows:

    XOXOXX___
    """
    assert 9 == string.count("X") + string.count("O") + string.count("_")

    board = dict()
    for row in range(3):
        for col in range(3):
            board[(row, col)] = string[row * 3 + col]

    return board


def print_board(board: Board):
    for row in range(3):
        for col in range(3):
            print(board[(row, col)], end="")
        print()


def calculate_score(board: Board, depth: int) -> int:
    """
    Return 10 if X wins, -10 if O wins or 0 if it is a draw or not
    decideable yet.
    """

    pass


def minimax(board: Board, depth: int, max_mode: bool) -> int:
    """
    Use the minimax algorithm to determine if a current game state will
    (possibly) lead to a win, a lose or a draw.
    """

    pass


def return_best_move(board: Board) -> Pos:

    pass


if __name__ == "__main__":
    board: Board = read_board_from_file("game.txt")
    print(return_best_move(board))