From 8077aaafdb8a88f92a089dc90de0e8702e2757b1 Mon Sep 17 00:00:00 2001
From: kske <kai@kske.dev>
Date: Sun, 28 Jul 2019 13:51:10 +0200
Subject: [PATCH] Implemented en passant

---
 src/dev/kske/chess/board/Board.java | 15 +++++++++++++++
 src/dev/kske/chess/board/Pawn.java  | 19 ++++++++++++++++---
 src/dev/kske/chess/game/Game.java   |  4 ++--
 3 files changed, 33 insertions(+), 5 deletions(-)

diff --git a/src/dev/kske/chess/board/Board.java b/src/dev/kske/chess/board/Board.java
index c57064b..e1d3c2d 100644
--- a/src/dev/kske/chess/board/Board.java
+++ b/src/dev/kske/chess/board/Board.java
@@ -109,6 +109,11 @@ public class Board implements Cloneable {
 				// TODO: Select promotion
 				setDest(move, new Queen(piece.getColor(), this));
 				break;
+			case EN_PASSANT:
+				setDest(move, piece);
+				setPos(move, null);
+				boardArr[move.dest.x][move.dest.y - move.ySign] = null;
+				break;
 			case CASTLING:
 				// Move the king
 				setDest(move, piece);
@@ -160,6 +165,11 @@ public class Board implements Cloneable {
 				setPos(move, new Pawn(getDest(move).getColor(), this));
 				setDest(move, capturedPiece);
 				break;
+			case EN_PASSANT:
+				setPos(move, getDest(move));
+				setDest(move, null);
+				boardArr[move.dest.x][move.dest.y - move.ySign] = new Pawn(getPos(move).getColor().opposite(), this);
+				break;
 			case CASTLING:
 				// Move the king
 				setPos(move, getDest(move));
@@ -504,4 +514,9 @@ public class Board implements Cloneable {
 	 * @return The active color for the next move
 	 */
 	public Color getActiveColor() { return log.getActiveColor(); }
+
+	/**
+	 * @return The current en passant square, or null if there isn't any
+	 */
+	public Position getEnPassantSquare() { return log.getLast() == null ? null : log.getLast().enPassant; }
 }
diff --git a/src/dev/kske/chess/board/Pawn.java b/src/dev/kske/chess/board/Pawn.java
index 1411e31..596dc38 100644
--- a/src/dev/kske/chess/board/Pawn.java
+++ b/src/dev/kske/chess/board/Pawn.java
@@ -17,10 +17,10 @@ public class Pawn extends Piece {
 
 	@Override
 	public boolean isValidMove(Move move) {
-		// TODO: en passant
 		boolean	step		= move.isVertical() && move.yDist == 1;
 		boolean	doubleStep	= move.isVertical() && move.yDist == 2;
 		boolean	strafe		= move.isDiagonal() && move.xDist == 1;
+		boolean	enPassant	= false;
 		if (getColor() == Color.WHITE) doubleStep &= move.pos.y == 6;
 		else doubleStep &= move.pos.y == 1;
 
@@ -28,7 +28,14 @@ public class Pawn extends Piece {
 		if (move.ySign == 1 && move.pos.y == 6 || move.ySign == -1 && move.pos.y == 1)
 			move.type = Move.Type.PAWN_PROMOTION;
 
-		return (step ^ doubleStep ^ strafe) && move.ySign == (getColor() == Color.WHITE ? -1 : 1) && isFreePath(move);
+		// Mark the move as en passant if necessary
+		if (strafe && move.dest.equals(board.getEnPassantSquare())) {
+			enPassant	= true;
+			move.type	= Move.Type.EN_PASSANT;
+		}
+
+		return enPassant || (step ^ doubleStep ^ strafe) && move.ySign == (getColor() == Color.WHITE ? -1 : 1)
+				&& isFreePath(move);
 	}
 
 	@Override
@@ -72,10 +79,16 @@ public class Pawn extends Piece {
 			if (isFreePath(move)) moves.add(move);
 		}
 
-		// Mark moves as pawn promotions if necessary
+		// Mark moves as pawn promotion if necessary
 		if (sign == 1 && pos.y == 6 || sign == -1 && pos.y == 1)
 			moves.parallelStream().forEach(m -> m.type = Move.Type.PAWN_PROMOTION);
 
+		// Add en passant move if necessary
+		if (board.getEnPassantSquare() != null) {
+			Move move = new Move(pos, board.getEnPassantSquare(), Move.Type.EN_PASSANT);
+			if (move.isDiagonal() && move.xDist == 1) moves.add(move);
+		}
+
 		return moves;
 	}
 
diff --git a/src/dev/kske/chess/game/Game.java b/src/dev/kske/chess/game/Game.java
index 8f33977..e7552a1 100644
--- a/src/dev/kske/chess/game/Game.java
+++ b/src/dev/kske/chess/game/Game.java
@@ -86,7 +86,7 @@ public class Game {
 	}
 
 	public void reset() {
-		players.forEach((k, v) -> v.cancelMove());
+		players.values().forEach(Player::cancelMove);
 		board.initializeDefaultPositions();
 		boardComponent.repaint();
 		overlayComponent.clearDots();
@@ -94,7 +94,7 @@ public class Game {
 	}
 
 	/**
-	 * Removed all connections between the game and the ui.
+	 * Removed all connections between the game and the UI.
 	 */
 	public void disconnect() {
 		players.values().forEach(Player::disconnect);