From: Steinar H. Gunderson <sgunderson@bigfoot.com>
Date: Mon, 26 Nov 2018 22:50:53 +0000 (+0100)
Subject: Fix an issue where we would lose the history after Chess960-style castling, since... 
X-Git-Url: https://git.sesse.net/?p=remoteglot;a=commitdiff_plain;h=82620f45773509d6cb29f1df0f12bab1e3bbb63e

Fix an issue where we would lose the history after Chess960-style castling, since we wrongly had it reset the 50-move rule.
---

diff --git a/Position.pm b/Position.pm
index 3e3e84f..3e39e46 100644
--- a/Position.pm
+++ b/Position.pm
@@ -275,8 +275,11 @@ sub make_move {
 		$np->{'black_castle_k'} = undef;
 	}
 
-	# 50-move rule.
-	if (lc($piece) eq 'p' || $dest_piece ne '-') {
+	# 50-move rule. Note that castle does not reset the counter, per FIDE rules.
+	my $castling = (lc($piece) eq 'k' && abs($from_col - $to_col) > 1) ||  # King moves two squares.
+		($piece eq 'K' && $dest_piece eq 'R') ||  # Chess960-style king-takes-rook.
+		($piece eq 'k' && $dest_piece eq 'r');
+	if (!$castling && (lc($piece) eq 'p' || $dest_piece ne '-')) {
 		$np->{'time_since_100move_rule_reset'} = 0;
 	} else {
 		$np->{'time_since_100move_rule_reset'} = $pos->{'time_since_100move_rule_reset'} + 1;