utils_chess.py

import chess

SELECT_A_PIECE = 0
SELECT_INVALID_GRID = 1
RESELECT_SAME_GRID = 2
VALID_MOVE = 3


def get_grid_id(x, y):  # get the grid id from x and y
    return 8 * y + x


def get_grid_coord(id):  # get x and y from grid id defined in python-chess
    return (id % 8, id // 8)


def peices_position(board):  # get the positions where pieces exist

    def isupper(string):
        return string.isupper()

    def islower(string):
        return string.islower()

    creteria = isupper if board.turn == chess.WHITE else islower
    result = []
    current_state = board.__str__().split('\n')
    for i in range(8):
        pieces = current_state[i].split(' ')
        for j in range(len(pieces)):
            piece = pieces[j]
            if creteria(piece):
                result.append(8 * (7 - i) + j)

    return result


def king_position(board):  # get the position of the king belongs to current player

    creteria = 'K' if board.turn == chess.WHITE else 'k'
    current_state = board.__str__().split('\n')
    for i in range(8):
        pieces = current_state[i].split(' ')
        for j in range(len(pieces)):
            piece = pieces[j]
            if creteria == piece:
                return 8 * (7 - i) + j


def move_type(board, x, y, last_x, last_y, selection_flag):  # check whether a move is valid, etc.
    if not selection_flag:  # now no grid has been selected
        if get_grid_id(x, y) in peices_position(board):
            return SELECT_A_PIECE
        return SELECT_INVALID_GRID

    else:
        if x == last_x and y == last_y:
            return RESELECT_SAME_GRID
        if get_grid_id(x, y) in peices_position(board):
            return SELECT_A_PIECE
        if chess.Move(get_grid_id(last_x, last_y), get_grid_id(x, y)) in board.legal_moves or chess.Move(
                get_grid_id(last_x, last_y), get_grid_id(x, y), promotion=chess.QUEEN) in board.legal_moves:
            return VALID_MOVE
        return SELECT_INVALID_GRID


def make_move(board, x, y, last_x, last_y, promotion_type):  # make a move. Move must be valid
    if promotion_type != 0:
        board.push(chess.Move(get_grid_id(last_x, last_y), get_grid_id(x, y), promotion_type))
    else:
        board.push(chess.Move(get_grid_id(last_x, last_y), get_grid_id(x, y)))

    return board.is_game_over(), board.result()


def bottom_line(board):  # the row id of bottom row
    return 7 if board.turn == chess.WHITE else 0