#!/usr/bin/python3

"""This is a Sudoku Solver."""

from board import Board


def main():
    """Provided a string representing a Sudoku game, solve it."""

    string = (
        ".....6...\n"
        "..2.35.8.\n"
        "....2..13\n"
        ".2....19.\n"
        "93....7..\n"
        "5....4...\n"
        "1......7.\n"
        ".7...142.\n"
        ".9.4.3...\n"
    )

    iterations = 0
    while '.' in string:
        iterations += 1
        new_string = iterate_board(string, debug=True)
        assert new_string != string
        string = new_string
    print(f"Solved in {iterations} iterations.")


def iterate_board(string, debug=False):
    """This function consists of one iteration through the solving process.

    Return an updated string.
    """

    board = Board(string, debug=debug)
    iterations = 0
    while '.' in string:
        iterations += 1
        print(board)
        board.compute_possible_values()
        board.compute_obligated_in_each_line()
        board.compute_obligated_in_each_column()
        print(board)
        board.update_board()


if __name__ == '__main__':
    main()