From aa09674791e7ec47f90ee5d6abdc350d01b59fd6 Mon Sep 17 00:00:00 2001
From: kske <kai@kske.dev>
Date: Tue, 29 Oct 2019 06:24:44 +0100
Subject: [PATCH] Fully implemented castling conditions

Closes #8
---
 src/dev/kske/chess/board/Board.java | 15 +++++++--
 src/dev/kske/chess/board/King.java  | 48 +++++++++++++++++------------
 2 files changed, 40 insertions(+), 23 deletions(-)

diff --git a/src/dev/kske/chess/board/Board.java b/src/dev/kske/chess/board/Board.java
index 93fa907..3de825a 100644
--- a/src/dev/kske/chess/board/Board.java
+++ b/src/dev/kske/chess/board/Board.java
@@ -227,7 +227,7 @@ public class Board {
 	}
 
 	/**
-	 * Reverts the last move.
+	 * Reverts the last move and removes it from the log.
 	 */
 	public void revert() {
 		MoveNode	moveNode		= log.getLast();
@@ -294,11 +294,20 @@ public class Board {
 	 * @param color The color of the king to check
 	 * @return {@code true}, if the king is in check
 	 */
-	public boolean checkCheck(Color color) {
+	public boolean checkCheck(Color color) { return isAttacked(kingPos.get(color), color.opposite()); }
+
+	/**
+	 * Checks, if a field can be attacked by pieces of a certain color.
+	 * 
+	 * @param dest  the field to check
+	 * @param color the color of a potential attacker piece
+	 * @return {@code true} if a move with the destination {@code dest}
+	 */
+	public boolean isAttacked(Position dest, Color color) {
 		for (int i = 0; i < 8; i++)
 			for (int j = 0; j < 8; j++) {
 				Position pos = new Position(i, j);
-				if (get(pos) != null && get(pos).getColor() != color && get(pos).isValidMove(new Move(pos, kingPos.get(color)))) return true;
+				if (get(pos) != null && get(pos).getColor() == color && get(pos).isValidMove(new Move(pos, dest))) return true;
 			}
 		return false;
 	}
diff --git a/src/dev/kske/chess/board/King.java b/src/dev/kske/chess/board/King.java
index 3e0c913..a864171 100644
--- a/src/dev/kske/chess/board/King.java
+++ b/src/dev/kske/chess/board/King.java
@@ -28,28 +28,9 @@ public class King extends Piece {
 				return true;
 			}
 		}
-
 		return move.xDist <= 1 && move.yDist <= 1 && checkDestination(move);
 	}
 
-	public boolean canCastleKingside() {
-		if (board.getLog().getCastlingRights()[getColor() == Color.WHITE ? MoveNode.WHITE_KINGSIDE : MoveNode.BLACK_KINGSIDE]) {
-			int			y		= getColor() == Color.WHITE ? 7 : 0;
-			Position	rookPos	= new Position(7, y);
-			Piece		rook	= board.get(rookPos);
-			return rook != null && rook.getType() == Type.ROOK && isFreePath(new Move(new Position(4, y), new Position(6, y)));
-		} else return false;
-	}
-
-	public boolean canCastleQueenside() {
-		if (board.getLog().getCastlingRights()[getColor() == Color.WHITE ? MoveNode.WHITE_QUEENSIDE : MoveNode.BLACK_QUEENSIDE]) {
-			int			y		= getColor() == Color.WHITE ? 7 : 0;
-			Position	rookPos	= new Position(0, y);
-			Piece		rook	= board.get(rookPos);
-			return rook != null && rook.getType() == Type.ROOK && isFreePath(new Move(new Position(4, y), new Position(1, y)));
-		} else return false;
-	}
-
 	@Override
 	protected List<Move> getPseudolegalMoves(Position pos) {
 		List<Move> moves = new ArrayList<>();
@@ -61,13 +42,40 @@ public class King extends Piece {
 				}
 
 		// Castling
-		// TODO: Condition: cannot castle out of, through or into check
 		if (canCastleKingside()) moves.add(new Move(pos, new Position(6, pos.y), Move.Type.CASTLING));
 		if (canCastleQueenside()) moves.add(new Move(pos, new Position(2, pos.y), Move.Type.CASTLING));
 
 		return moves;
 	}
 
+	private boolean canCastleKingside() {
+		if (board.getLog().getCastlingRights()[getColor() == Color.WHITE ? MoveNode.WHITE_KINGSIDE : MoveNode.BLACK_KINGSIDE]) {
+			int			y			= getColor() == Color.WHITE ? 7 : 0;
+			Position	kingPos		= new Position(4, y);
+			Position	jumpPos		= new Position(5, y);
+			Position	kingDest	= new Position(6, y);
+			Position	rookPos		= new Position(7, y);
+			return canCastle(kingPos, kingDest, rookPos, jumpPos);
+		} else return false;
+	}
+
+	private boolean canCastleQueenside() {
+		if (board.getLog().getCastlingRights()[getColor() == Color.WHITE ? MoveNode.WHITE_QUEENSIDE : MoveNode.BLACK_QUEENSIDE]) {
+			int			y			= getColor() == Color.WHITE ? 7 : 0;
+			Position	kingPos		= new Position(4, y);
+			Position	jumpPos		= new Position(3, y);
+			Position	freeDest	= new Position(1, y);
+			Position	rookPos		= new Position(0, y);
+			return canCastle(kingPos, freeDest, rookPos, jumpPos);
+		} else return false;
+	}
+
+	private boolean canCastle(Position kingPos, Position freeDest, Position rookPos, Position jumpPos) {
+		Piece rook = board.get(rookPos);
+		return rook != null && rook.getType() == Type.ROOK && isFreePath(new Move(kingPos, freeDest))
+				&& !board.isAttacked(kingPos, getColor().opposite()) && !board.isAttacked(jumpPos, getColor().opposite());
+	}
+
 	@Override
 	public Type getType() { return Type.KING; }
 }