Error? Losing the castling for no apparent reason

[boulayo]

Try this code:

$a = "d4 Nc6 c4 Nf6 d5 Na5 b3 c6 dxc6 bxc6 Nf3 g6 Nc3 Bg7 Bb2 Ne4 Qc2 Nxc3 Bxc3 Bxc3+ Nd2 Bxa1 b4 Nb7 e3 Bg7 Bd3 a5 bxa5 Rxa5 O-O Qc7 Nb3 Rh5 h3 d6 Be2 Rh6 f4 O-O Rd1 e5 fxe5 dxe5 e4 f5 Bf3 fxe4 Bxe4 Bf5 Rf1 Bxe4 Rxf8+ Bxf8 Qxe4 Nd6 Qd3 e4 Qe2 Rh5 c5 Nf5 Qxe4 Qa7 Qe6+ Kh8 Qxc6 Ne7 Qf6+ Bg7 Qf2 Rf5 Qc2 Qa4 Nd4 Qxd4+ Kh2 Be5+ g3 Rf2+ Qxf2 Qxf2+ Kh1 Bd4 c6 Qg1#";
$pgn = new Onspli\Chess\PGN($a);
for ($i=0; $i < $pgn->get_last_halfmove_number(); $i++) {
$fen = new Onspli\Chess\FEN($pgn->get_fen_after_halfmove($i));
$move = $pgn->get_halfmove($i+1);
$resultingfen = new Onspli\Chess\FEN($pgn->get_fen_after_halfmove($i+1));
}

In this game at move 19 the fen is this:
2b1k2r/1nq1ppbp/2pp2p1/7r/2P5/1N2P2P/P1Q1BPP1/5RK1 b k -
From there I move "Rh6" and it loses the possibility to castle for no apparent reason. The new fen is this:
2b1k2r/1nq1ppbp/2pp2pr/8/2P5/1N2P2P/P1Q1BPP1/5RK1 w - -

Is it a bug?
Thank you

[boulayo]

I'm pretty sure that the error is here.

private function after_move_update_castling_availability(string $piece_type, Square $origin_square) : void
{
$origin_file = $origin_square->get_file();
if ($piece_type == 'R' && $origin_file == 'a') {
$this->set_castling_availability($this->get_active_piece('Q'), false);
} else if ($piece_type == 'R' && $origin_file == 'h') {
$this->set_castling_availability($this->get_active_piece('K'), false);
} else if ($piece_type == 'K' && $origin_file == 'e') {
$this->set_castling_availability($this->get_active_piece('Q'), false);
$this->set_castling_availability($this->get_active_piece('K'), false);
}
}

It seems that you assume that if a rock is on a file it has to be the same rock that starts on that file.

Maybe this would fix it but I'm not 100% sure

private function after_move_update_castling_availability(string $piece_type, Square $origin_square) : void
{
$origin_file = $origin_square->get_file();
if ($piece_type == 'R' && (($origin_square=="a8" && $this->get_active_color()=="b") || ($origin_square=="a1" && $this->get_active_color()=="w")) {
$this->set_castling_availability($this->get_active_piece('Q'), false);
} else if ($piece_type == 'R' && (($origin_square=="h8" && $this->get_active_color()=="b") || ($origin_square=="h1" && $this->get_active_color()=="w")) {
$this->set_castling_availability($this->get_active_piece('K'), false);
} else if ($piece_type == 'K' && $origin_file == 'e') {
$this->set_castling_availability($this->get_active_piece('Q'), false);
$this->set_castling_availability($this->get_active_piece('K'), false);
}
}

[onspli]

Thanks for reporting the issue, I'll take a look. What version do you use - v0.1.0 or dev-master?

[boulayo]

v0.1.0

[onspli]

Fix was released in v0.2.0.

Offtopic: I noticed this piece of code in your sample

$fen = new Onspli\Chess\FEN($pgn->get_fen_after_halfmove($i));

It is not very efficient as it converts FEN -> String -> FEN. You can pass parameter bool $as_object (docs) to get FEN object directly (it creates a copy of FEN)

$fen = $pgn->get_fen_after_halfmove($i, true);

[boulayo]

Thanks for the suggestion!