""" Evaluate a tictactoe board """

def evaluate_board(board):
    """
    Test the board for the 8 possible winning combinations
    and return the winner as soon as it's found.
    """

    status = _check_horizontals(board[:])
    if status:
        return status

    status = _check_verticals(board[:])
    if status:
        return status

    status = _check_diagonal(_left_rotate(board[:]))
    if status:
        return status

    status = _check_diagonal(_right_rotate(board[:]))
    if status:
        return status

    return "no winner"

def _check_horizontals(board):
    status = None

    for row in board:
        if row[0] == row[1] == row[2]:
            if row[0] is not None:
                return f'{row[0]} wins'

    return status

def _check_verticals(board):
    transposed_board = _transpose_board(board)

    return _check_horizontals(transposed_board)

def _check_diagonal(board):
    status = _check_verticals(board)
    if status:
        return status

def _right_rotate(board):
    """
    'rotates' the top and center rows so that a diagonal winnder
    can be evaluated as a vertical winner

    the top-left to bottom-right diagonal is being evaluated in this
    rotation
    """

    rotated_board = board
    rotated_board[0] = _rotate_board(2, board[0][:])
    rotated_board[1] = _rotate_board(1, board[1][:])

    return rotated_board

def _left_rotate(board):
    """
    'rotates' the center and bottom rows so that a diagonal winner
    an be evaluated as a vertical winner

    the top-right to bottom-left diagonal is being evaluated in this
    rotation
    """
    rotated_board = board
    rotated_board[1] = _rotate_board(1, board[1][:])
    rotated_board[2] = _rotate_board(2, board[2][:])

    return rotated_board

def _rotate_board(positions, row):
    for _ in range(positions):
        row.pop(0)

    for _ in range(positions):
        row.append(None)

    return row

def _transpose_board(board):
    new_board = [[None, None, None],
                 [None, None, None],
                 [None, None, None]]

    for row_i, row in enumerate(board):
        for cell_i, value in enumerate(row):
            new_board[cell_i][row_i] = value

    return new_board