parser.py

from game import notation_to_index,index_to_notation

def parser(move, game):
    move = move.strip()

    # castling notation
    if move == '0-0':
        if game.turn == 'w':
            return (7, 4), (7, 6), None
        else:
            return (0, 4), (0, 6), None

    if move == '0-0-0':
        if game.turn == 'w':
            return (7, 4), (7, 2), None
        else:
            return (0, 4), (0, 2), None

    # promotion notation
    promotion = None
    if len(move) > 2 and move[-1] in "QRBN":
        promotion = move[-1]
        move = move[:-1]

    # identifying piece type
    pieces = {'N': 'N', 'B': 'B', 'R': 'R', 'Q': 'Q', 'K': 'K'}
    piece_type = 'P'
    if move[0] in pieces:
        piece_type = pieces[move[0]]
        move = move[1:]

    if len(move) < 2:
        return None, None, None

    # destination square
    destsq = move[-2:]
    dest = notation_to_index(destsq)
    if dest is None:
        return None, None, None

    # disambiguation (for moves like Nbd7 and R1e2)
    disambig = move[:-2]
    file_hint, rank_hint = None, None
    for ch in disambig:
        if ch in "abcdefgh":
            file_hint = ch
        elif ch in "12345678":
            rank_hint = ch

    # get candidate moves
    candidates = []
    for r in range(8):
        for c in range(8):
            piece = game.board[r][c]
            if piece and piece.colour == game.turn and piece.name == piece_type:
                try:
                    if dest in game.get_moves(r, c):
                        notation = index_to_notation((r, c))
                        if file_hint and notation[0] != file_hint:
                            continue
                        if rank_hint and notation[1] != rank_hint:
                            continue
                        candidates.append((r, c))
                except Exception:
                    # Skip this piece if there's an error getting moves
                    continue

    if len(candidates) == 1:
        return candidates[0], dest, promotion  # returns starting square, ending square, piece type for promotion
    else:
        return None, None, None