fix: NCS-32 Queenside Castle doesn't care about pieces in the way (#23)

Reviewed-on: #23
Co-authored-by: Janis <janis.e.20@gmx.de>
Co-committed-by: Janis <janis.e.20@gmx.de>

modules/io/CHANGELOG.md

@@ -1,2 +1,7 @@
 ##  (2026-04-06)
 ##  (2026-04-07)
+##  (2026-04-07)
+
+### Features
+
+* NCS-30 FEN Parser using ParserCombinators ([#21](https://git.janis-eccarius.de/NowChess/NowChessSystems/issues/21)) ([b4bc72f](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/b4bc72f7e49f94d6e1bc805c68680e5fe8ef8e36))

modules/io/versions.env

@@ -1,3 +1,3 @@
 MAJOR=0
-MINOR=0
-PATCH=2
+MINOR=1
+PATCH=0

modules/rule/src/main/scala/de/nowchess/rules/sets/DefaultRules.scala

@@ -163,6 +163,12 @@ object DefaultRules extends RuleSet:
         CastlingMove("e8", "c8", "d8", "a8", MoveType.CastleQueenside))
       moves.toList
 
+  private def queensideBSquare(kingToAlg: String): List[String] =
+    kingToAlg match
+      case "c1" => List("b1")
+      case "c8" => List("b8")
+      case _    => List.empty
+
   private def addCastleMove(
     context: GameContext,
     moves: scala.collection.mutable.ListBuffer[Move],
@@ -170,7 +176,8 @@ object DefaultRules extends RuleSet:
     castlingMove: CastlingMove
   ): Unit =
     if castlingRight then
-      val clearSqs = List(castlingMove.middleAlg, castlingMove.kingToAlg).flatMap(Square.fromAlgebraic)
+      val clearSqs = (List(castlingMove.middleAlg, castlingMove.kingToAlg) ++ queensideBSquare(castlingMove.kingToAlg))
+        .flatMap(Square.fromAlgebraic)
       if squaresEmpty(context.board, clearSqs) then
         for
           kf <- Square.fromAlgebraic(castlingMove.kingFromAlg)

modules/rule/src/test/scala/de/nowchess/rule/DefaultRulesTest.scala

@@ -52,7 +52,7 @@ class DefaultRulesTest extends AnyFunSuite with Matchers:
     val moves = rules.allLegalMoves(context)
 
     // King must move; e2 should be valid but d1 might be blocked by rook if still on same file
-    moves.filter(m => m.from == Square(File.E, Rank.R1)).nonEmpty shouldBe true
+    moves.exists(m => m.from == Square(File.E, Rank.R1)) shouldBe true
 
   test("king cannot move to square attacked by opponent"):
     // FEN: white king e1, black rook e2 defended by black king e3
@@ -109,6 +109,28 @@ class DefaultRulesTest extends AnyFunSuite with Matchers:
     val castles = moves.filter(m => m.moveType == MoveType.CastleKingside)
     castles.isEmpty shouldBe true
 
+  test("castling queenside is illegal when knight blocks on b8"):
+    // Black king e8, black rook a8, black knight b8 (blocks queenside path)
+    val board = Board(Map(
+      Square(File.A, Rank.R8) -> Piece(Color.Black, PieceType.Rook),
+      Square(File.B, Rank.R8) -> Piece(Color.Black, PieceType.Knight),
+      Square(File.E, Rank.R8) -> Piece(Color.Black, PieceType.King),
+      Square(File.A, Rank.R1) -> Piece(Color.White, PieceType.Rook),
+      Square(File.E, Rank.R1) -> Piece(Color.White, PieceType.King)
+    ))
+    val context = GameContext(
+      board = board,
+      turn = Color.Black,
+      castlingRights = CastlingRights(whiteKingSide = true, whiteQueenSide = true, blackKingSide = true, blackQueenSide = true),
+      enPassantSquare = None,
+      halfMoveClock = 0,
+      moves = List.empty
+    )
+    val moves = rules.allLegalMoves(context)
+
+    val castles = moves.filter(m => m.moveType == MoveType.CastleQueenside)
+    castles.isEmpty shouldBe true
+
   // ── En passant legality ──────────────────────────────────────────
 
   test("en passant is legal when en passant square is set"):

modules/ui/CHANGELOG.md

@@ -41,3 +41,11 @@
 * NCS-16 Core Separation via Patterns ([#10](https://git.janis-eccarius.de/NowChess/NowChessSystems/issues/10)) ([1361dfc](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/1361dfc89553b146864fb8ff3526cf12cf3f293a))
 * NCS-17 Implement basic ScalaFX UI ([#14](https://git.janis-eccarius.de/NowChess/NowChessSystems/issues/14)) ([3ff8031](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/3ff80318b4f16c59733a46498581a5c27f048287))
 * NCS-21 Write Scripts to automate certain tasks ([#15](https://git.janis-eccarius.de/NowChess/NowChessSystems/issues/15)) ([8051871](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/80518719d536a087d339fe02530825dc07f8b388))
+##  (2026-04-07)
+
+### Features
+
+* NCS-10 Implement Pawn Promotion ([#12](https://git.janis-eccarius.de/NowChess/NowChessSystems/issues/12)) ([13bfc16](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/13bfc16cfe25db78ec607db523ca6d993c13430c))
+* NCS-16 Core Separation via Patterns ([#10](https://git.janis-eccarius.de/NowChess/NowChessSystems/issues/10)) ([1361dfc](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/1361dfc89553b146864fb8ff3526cf12cf3f293a))
+* NCS-17 Implement basic ScalaFX UI ([#14](https://git.janis-eccarius.de/NowChess/NowChessSystems/issues/14)) ([3ff8031](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/3ff80318b4f16c59733a46498581a5c27f048287))
+* NCS-21 Write Scripts to automate certain tasks ([#15](https://git.janis-eccarius.de/NowChess/NowChessSystems/issues/15)) ([8051871](https://git.janis-eccarius.de/NowChess/NowChessSystems/commit/80518719d536a087d339fe02530825dc07f8b388))

modules/ui/versions.env

@@ -1,3 +1,3 @@
 MAJOR=0
-MINOR=6
+MINOR=7
 PATCH=0