Merge pull request #16 from CyB3RC0nN0R/f/pgn_save

Implemented game serialization to the PGN format

.classpath

@@ -7,11 +7,12 @@
 			<attribute name="test" value="true"/>
 		</attributes>
 	</classpathentry>
-	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER">
+	<classpathentry kind="src" output="bin_test" path="test_res">
 		<attributes>
-			<attribute name="module" value="true"/>
+			<attribute name="test" value="true"/>
 		</attributes>
 	</classpathentry>
 	<classpathentry kind="con" path="org.eclipse.jdt.junit.JUNIT_CONTAINER/5"/>
+	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.8"/>
 	<classpathentry kind="output" path="bin"/>
 </classpath>

.gitignore

@@ -22,3 +22,4 @@ local.properties
 
 # Annotation Processing
 .apt_generated/
+/engine_infos.ser

src/dev/kske/chess/board/Bishop.java

@@ -7,7 +7,9 @@ import java.util.List;
  * Project: <strong>Chess</strong><br>
  * File: <strong>Bishop.java</strong><br>
  * Created: <strong>01.07.2019</strong><br>
- * Author: <strong>Kai S. K. Engelbart</strong>
+ * 
+ * @since Chess v0.1-alpha
+ * @author Kai S. K. Engelbart
  */
 public class Bishop extends Piece {
 
@@ -20,14 +22,6 @@ public class Bishop extends Piece {
 		return move.isDiagonal() && isFreePath(move);
 	}
 
-	@Override
-	protected boolean isFreePath(Move move) {
-		for (int i = move.pos.x + move.xSign, j = move.pos.y
-				+ move.ySign; i != move.dest.x; i += move.xSign, j += move.ySign)
-			if (board.getBoardArr()[i][j] != null) return false;
-		return checkDestination(move);
-	}
-
 	@Override
 	protected List<Move> getPseudolegalMoves(Position pos) {
 		List<Move> moves = new ArrayList<>();
@@ -71,5 +65,5 @@ public class Bishop extends Piece {
 	}
 
 	@Override
-	public Type getType() { return Type.BISHOP; }
+	public int getValue() { return 30; }
 }

src/dev/kske/chess/board/Board.java

@@ -1,68 +1,55 @@
 package dev.kske.chess.board;
 
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 
-import dev.kske.chess.board.Log.LoggedMove;
 import dev.kske.chess.board.Piece.Color;
-import dev.kske.chess.board.Piece.Type;
 
 /**
  * Project: <strong>Chess</strong><br>
  * File: <strong>Board.java</strong><br>
  * Created: <strong>01.07.2019</strong><br>
- * Author: <strong>Kai S. K. Engelbart</strong>
+ *
+ * @since Chess v0.1-alpha
+ * @author Kai S. K. Engelbart
  */
-public class Board implements Cloneable {
+public class Board {
 
-	private Piece[][]				boardArr;
+	private Piece[][]				boardArr	= new Piece[8][8];
-	private Map<Color, Position>	kingPos;
+	private Map<Color, Position>	kingPos		= new HashMap<>();
-	private Log						log;
+	private Log						log			= new Log();
 
-	private static final Map<Type, int[][]> positionScores;
+	/**
+	 * Initializes the board with the default chess starting position.
+	 */
+	public Board() { initDefaultPositions(); }
 
-	static {
+	/**
-		positionScores = new HashMap<>();
+	 * Creates a copy of another {@link Board} instance.<br>
-		positionScores.put(Type.KING,
+	 * The created object is a deep copy, but does not contain any move history
-				new int[][] { new int[] { -3, -4, -4, -5, -5, -4, -4, -3 },
+	 * apart from the current {@link MoveNode}.
-						new int[] { -3, -4, -4, -5, -4, -4, -4, -3 }, new int[] { -3, -4, -4, -5, -4, -4, -4, -3 },
+	 *
-						new int[] { -3, -4, -4, -5, -4, -4, -4, -3 }, new int[] { -2, -3, -3, -2, -2, -2, -2, -1 },
+	 * @param other The {@link Board} instance to copy
-						new int[] { -1, -2, -2, -2, -2, -2, -2, -1 }, new int[] { 2, 2, 0, 0, 0, 0, 2, 2 },
+	 * @param copyVariations TODO
-						new int[] { 2, 3, 1, 0, 0, 1, 3, 2 } });
+	 */
-		positionScores.put(Type.QUEEN,
+	public Board(Board other, boolean copyVariations) {
-				new int[][] { new int[] { -2, -1, -1, -1, -1, -1, -1, -2 }, new int[] { -1, 0, 0, 0, 0, 0, 0, -1 },
+		for (int i = 0; i < 8; i++)
-						new int[] { -1, 0, 1, 1, 1, 1, 0, -1 }, new int[] { -1, 0, 1, 1, 1, 1, 0, -1 },
+			for (int j = 0; j < 8; j++) {
-						new int[] { 0, 0, 1, 1, 1, 1, 0, -1 }, new int[] { -1, 1, 1, 1, 1, 1, 0, -1 },
+				if (other.boardArr[i][j] == null) continue;
-						new int[] { -1, 0, 1, 0, 0, 0, 0, -1 }, new int[] { -2, -1, -1, -1, -1, -1, -1, -2 } });
+				boardArr[i][j]			= (Piece) other.boardArr[i][j].clone();
-		positionScores.put(Type.ROOK,
+				boardArr[i][j].board	= this;
-				new int[][] { new int[] { 0, 0, 0, 0, 0, 0, 0, 0 }, new int[] { 1, 1, 1, 1, 1, 1, 1, 1 },
-						new int[] { -1, 0, 0, 0, 0, 0, 0, -1 }, new int[] { -1, 0, 0, 0, 0, 0, 0, -1 },
-						new int[] { -1, 0, 0, 0, 0, 0, 0, -1 }, new int[] { -1, 0, 0, 0, 0, 0, 0, -1 },
-						new int[] { -1, 0, 0, 0, 0, 0, 0, -1 }, new int[] { 0, 0, 0, 1, 1, 0, 0, 0 } });
-		positionScores.put(Type.KNIGHT,
-				new int[][] { new int[] { -5, -4, -3, -3, -3, -3, -4, -5 }, new int[] { -4, -2, 0, 0, 0, 0, -2, -4 },
-						new int[] { -3, 0, 1, 2, 2, 1, 0, -3 }, new int[] { -3, 1, 2, 2, 2, 2, 1, -3 },
-						new int[] { -3, 0, 2, 2, 2, 2, 0, -1 }, new int[] { -3, 1, 1, 2, 2, 1, 1, -3 },
-						new int[] { -4, -2, 0, 1, 1, 0, -2, -4 }, new int[] { -5, -4, -3, -3, -3, -3, -4, -5 } });
-		positionScores.put(Type.BISHOP,
-				new int[][] { new int[] { -2, -1, -1, -1, -1, -1, -1, 2 }, new int[] { -1, 0, 0, 0, 0, 0, 0, -1 },
-						new int[] { -1, 0, 1, 1, 1, 1, 0, -1 }, new int[] { -1, 1, 1, 1, 1, 1, 1, -1 },
-						new int[] { -1, 0, 1, 1, 1, 1, 0, -1 }, new int[] { -1, 1, 1, 1, 1, 1, 1, -1 },
-						new int[] { -1, 1, 0, 0, 0, 0, 1, -1 }, new int[] { -2, -1, -1, -1, -1, -1, -1, -2 } });
-		positionScores.put(Type.PAWN,
-				new int[][] { new int[] { 0, 0, 0, 0, 0, 0, 0, 0 }, new int[] { 5, 5, 5, 5, 5, 5, 5, 5 },
-						new int[] { 1, 1, 2, 3, 3, 2, 1, 1 }, new int[] { 0, 0, 1, 3, 3, 1, 0, 0 },
-						new int[] { 0, 0, 0, 2, 2, 0, 0, 0 }, new int[] { 0, 0, -1, 0, 0, -1, 0, 0 },
-						new int[] { 0, 1, 1, -2, -2, 1, 1, 0 }, new int[] { 0, 0, 0, 0, 0, 0, 0, 0 } });
 			}
 
-	public Board() {
+		kingPos.putAll(other.kingPos);
-		boardArr	= new Piece[8][8];
+		log = new Log(other.log, copyVariations);
-		kingPos		= new HashMap<>();
+
-		log			= new Log();
+		// Synchronize the current move node with the board
-		initializeDefaultPositions();
+		while (log.getLast().hasVariations())
+			log.selectNextNode(0);
 	}
 
 	/**
@@ -75,9 +62,6 @@ public class Board implements Cloneable {
 		Piece piece = getPos(move);
 		if (piece == null || !piece.isValidMove(move)) return false;
 		else {
-			// Set type after validation
-			if (move.type == Move.Type.UNKNOWN) move.type = Move.Type.NORMAL;
-
 			// Move piece
 			move(move);
 
@@ -95,96 +79,42 @@ public class Board implements Cloneable {
 	 * Moves a piece across the board without checking if the move is legal.
 	 *
 	 * @param move The move to execute
-	 * @return The captures piece, or null if the move's destination was empty
 	 */
 	public void move(Move move) {
 		Piece	piece			= getPos(move);
 		Piece	capturePiece	= getDest(move);
 
-		switch (move.type) {
+		// Execute the move
-			case PAWN_PROMOTION:
+		move.execute(this);
-				setPos(move, null);
-				// TODO: Select promotion
-				setDest(move, new Queen(piece.getColor(), this));
-				break;
-			case CASTLING:
-				// Move the king
-				setDest(move, piece);
-				setPos(move, null);
-
-				// Move the rook
-				Move rookMove = move.dest.x == 6 ? new Move(7, move.pos.y, 5, move.pos.y) // Kingside
-						: new Move(0, move.pos.y, 3, move.pos.y); // Queenside
-
-				// Move the rook
-				setDest(rookMove, getPos(rookMove));
-				setPos(rookMove, null);
-
-				getDest(rookMove).incMoveCounter();
-				break;
-			case UNKNOWN:
-				System.err.printf("Move of unknown type %s found!%n", move);
-			case NORMAL:
-				setDest(move, piece);
-				setPos(move, null);
-				break;
-			default:
-				System.err.printf("Move %s of unimplemented type found!%n", move);
-		}
-
-		// Increment move counter
-		getDest(move).incMoveCounter();
 
 		// Update the king's position if the moved piece is the king
-		if (piece.getType() == Type.KING) kingPos.put(piece.getColor(), move.dest);
+		if (piece instanceof King) kingPos.put(piece.getColor(), move.getDest());
 
 		// Update log
-		log.add(move, capturePiece);
+		log.add(move, piece, capturePiece);
 	}
 
 	/**
-	 * Reverts the last move.
+	 * Moves a piece across the board without checking if the move is legal.
+	 *
+	 * @param sanMove The move to execute in SAN (Standard Algebraic Notation)
 	 */
-	public void revert() {
+	public void move(String sanMove) {
-		LoggedMove	loggedMove		= log.getLast();
+		move(Move.fromSAN(sanMove, this));
-		Move		move			= loggedMove.move;
-		Piece		capturedPiece	= loggedMove.capturedPiece;
-
-		switch (move.type) {
-			case PAWN_PROMOTION:
-				setPos(move, new Pawn(getDest(move).getColor(), this));
-				setDest(move, capturedPiece);
-				break;
-			case CASTLING:
-				// Move the king
-				setPos(move, getDest(move));
-				setDest(move, null);
-
-				// Move the rook
-				Move rookMove = move.dest.x == 6 ? new Move(5, move.pos.y, 7, move.pos.y) // Kingside
-						: new Move(3, move.pos.y, 0, move.pos.y); // Queenside
-
-				// Move the rook
-				setDest(rookMove, getPos(rookMove));
-				setPos(rookMove, null);
-
-				getDest(rookMove).decMoveCounter();
-				break;
-			case UNKNOWN:
-				System.err.printf("Move of unknown type %s found!%n", move);
-			case NORMAL:
-				setPos(move, getDest(move));
-				setDest(move, capturedPiece);
-				break;
-			default:
-				System.err.printf("Move %s of unimplemented type found!%n", move);
 	}
 
-		// Decrement move counter
+	/**
-		getPos(move).decMoveCounter();
+	 * Reverts the last move and removes it from the log.
+	 */
+	public void revert() {
+		MoveNode	moveNode	= log.getLast();
+		Move		move		= moveNode.move;
+
+		// Revert the move
+		move.revert(this, moveNode.capturedPiece);
 
 		// Update the king's position if the moved piece is the king
-		if (getPos(move).getType() == Type.KING) kingPos.put(getPos(move).getColor(), move.pos);
+		if (getPos(move) instanceof King) kingPos.put(getPos(move).getColor(), move.getPos());
 
 		// Update log
 		log.removeLast();
@@ -200,14 +130,11 @@ public class Board implements Cloneable {
 		List<Move> moves = new ArrayList<>();
 		for (int i = 0; i < 8; i++)
 			for (int j = 0; j < 8; j++)
-				if (boardArr[i][j] != null && boardArr[i][j].getColor() == color)
+				if (boardArr[i][j] != null && boardArr[i][j].getColor() == color) moves.addAll(boardArr[i][j].getMoves(new Position(i, j)));
-					moves.addAll(boardArr[i][j].getMoves(new Position(i, j)));
 		return moves;
 	}
 
-	public List<Move> getMoves(Position pos) {
+	public List<Move> getMoves(Position pos) { return get(pos).getMoves(pos); }
-		return get(pos).getMoves(pos);
-	}
 
 	/**
 	 * Checks, if the king is in check.
@@ -215,13 +142,20 @@ public class Board implements Cloneable {
 	 * @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
+				if (get(pos) != null && get(pos).getColor() == color && get(pos).isValidMove(new Move(pos, dest))) return true;
-						&& get(pos).isValidMove(new Move(pos, kingPos.get(color))))
-					return true;
 			}
 		return false;
 	}
@@ -247,49 +181,15 @@ public class Board implements Cloneable {
 		}
 	}
 
-	public GameState getGameEventType(Color color) {
+	public BoardState getGameEventType(Color color) {
-		return checkCheck(color) ? checkCheckmate(color) ? GameState.CHECKMATE : GameState.CHECK
+		return checkCheck(color) ? checkCheckmate(color) ? BoardState.CHECKMATE : BoardState.CHECK
-				: getMoves(color).isEmpty() ? GameState.STALEMATE : GameState.NORMAL;
+				: getMoves(color).isEmpty() || log.getLast().halfmoveClock >= 50 ? BoardState.STALEMATE : BoardState.NORMAL;
-	}
-
-	/**
-	 * Evaluated the board.
-	 * 
-	 * @param color The color to evaluate for
-	 * @return An positive number representing how good the position is
-	 */
-	public int evaluate(Color color) {
-		int score = 0;
-		for (int i = 0; i < 8; i++)
-			for (int j = 0; j < 8; j++)
-				if (boardArr[i][j] != null && boardArr[i][j].getColor() == color) {
-					switch (boardArr[i][j].getType()) {
-						case QUEEN:
-							score += 90;
-							break;
-						case ROOK:
-							score += 50;
-							break;
-						case KNIGHT:
-							score += 30;
-							break;
-						case BISHOP:
-							score += 30;
-							break;
-						case PAWN:
-							score += 10;
-							break;
-					}
-					if (positionScores.containsKey(boardArr[i][j].getType()))
-						score += positionScores.get(boardArr[i][j].getType())[i][color == Color.WHITE ? j : 7 - j];
-				}
-		return score;
 	}
 
 	/**
 	 * Initialized the board array with the default chess pieces and positions.
 	 */
-	public void initializeDefaultPositions() {
+	public void initDefaultPositions() {
 		// Initialize pawns
 		for (int i = 0; i < 8; i++) {
 			boardArr[i][1]	= new Pawn(Color.BLACK, this);
@@ -330,62 +230,125 @@ public class Board implements Cloneable {
 		for (int i = 0; i < 8; i++)
 			for (int j = 2; j < 6; j++)
 				boardArr[i][j] = null;
+
+		log.reset();
+	}
+
+	@Override
+	public int hashCode() {
+		final int	prime	= 31;
+		int			result	= 1;
+		result	= prime * result + Arrays.deepHashCode(boardArr);
+		result	= prime * result + Objects.hash(kingPos, log);
+		return result;
+	}
+
+	@Override
+	public boolean equals(Object obj) {
+		if (this == obj) return true;
+		if (obj == null) return false;
+		if (getClass() != obj.getClass()) return false;
+		Board other = (Board) obj;
+		return Arrays.deepEquals(boardArr, other.boardArr) && Objects.equals(kingPos, other.kingPos) && Objects.equals(log, other.log);
 	}
 
 	/**
-	 * @return A new instance of this class with a shallow copy of both
+	 * @param pos The position from which to return a piece
-	 *         {@code kingPos} and {code boardArr}
+	 * @return The piece at the position
 	 */
-	@Override
+	public Piece get(Position pos) { return boardArr[pos.x][pos.y]; }
-	public Object clone() {
+
-		Board board = null;
+	/**
-		try {
+	 * Searches for a {@link Piece} inside a file (A - H).
-			board = (Board) super.clone();
+	 *
-		} catch (CloneNotSupportedException ex) {
+	 * @param pieceClass The class of the piece to search for
-			ex.printStackTrace();
+	 * @param file       The file in which to search for the piece
-		}
+	 * @return The rank (1 - 8) of the first piece with the specified type and
-		board.boardArr = new Piece[8][8];
+	 *         current color in the file, or {@code -1} if there isn't any
+	 */
+	public int get(Class<? extends Piece> pieceClass, char file) {
+		int x = file - 97;
 		for (int i = 0; i < 8; i++)
-			for (int j = 0; j < 8; j++) {
+			if (boardArr[x][i] != null && boardArr[x][i].getClass() == pieceClass && boardArr[x][i].getColor() == log.getActiveColor()) return 8 - i;
-				if (boardArr[i][j] == null) continue;
+		return -1;
-				board.boardArr[i][j]		= (Piece) boardArr[i][j].clone();
-				board.boardArr[i][j].board	= board;
 	}
 
-		board.kingPos = new HashMap<>();
+	/**
-		board.kingPos.putAll(kingPos);
+	 * Searches for a {@link Piece} inside a rank (1 - 8).
-
+	 *
-		board.log = (Log) log.clone();
+	 * @param pieceClass The class of the piece to search for
-
+	 * @param rank       The rank in which to search for the piece
-		return board;
+	 * @return The file (A - H) of the first piece with the specified type and
+	 *         current color in the file, or {@code -} if there isn't any
+	 */
+	public char get(Class<? extends Piece> pieceClass, int rank) {
+		int y = rank - 1;
+		for (int i = 0; i < 8; i++)
+			if (boardArr[i][y] != null && boardArr[i][y].getClass() == pieceClass && boardArr[i][y].getColor() == log.getActiveColor())
+				return (char) (i + 97);
+		return '-';
 	}
 
-	public Piece get(Position pos) {
+	/**
-		return boardArr[pos.x][pos.y];
+	 * Searches for a {@link Piece} that can move to a {@link Position}.
+	 *
+	 * @param pieceClass The class of the piece to search for
+	 * @param dest       The destination that the piece is required to reach
+	 * @return The position of a piece that can move to the specified destination
+	 */
+	public Position get(Class<? extends Piece> pieceClass, Position dest) {
+		for (int i = 0; i < 8; i++)
+			for (int j = 0; j < 8; j++)
+				if (boardArr[i][j] != null && boardArr[i][j].getClass() == pieceClass && boardArr[i][j].getColor() == log.getActiveColor()) {
+					Position pos = new Position(i, j);
+					if (boardArr[i][j].isValidMove(new Move(pos, dest))) return pos;
+				}
+		return null;
 	}
 
-	public void set(Position pos, Piece piece) {
+	/**
-		boardArr[pos.x][pos.y] = piece;
+	 * Places a piece at a position.
-	}
+	 *
+	 * @param pos   The position to place the piece at
+	 * @param piece The piece to place
+	 */
+	public void set(Position pos, Piece piece) { boardArr[pos.x][pos.y] = piece; }
 
-	public Piece getPos(Move move) {
+	/**
-		return get(move.pos);
+	 * @param move The move from which position to return a piece
-	}
+	 * @return The piece at the position of the move
+	 */
+	public Piece getPos(Move move) { return get(move.getPos()); }
 
-	public Piece getDest(Move move) {
+	/**
-		return get(move.dest);
+	 * @param move The move from which destination to return a piece
-	}
+	 * @return The piece at the destination of the move
+	 */
+	public Piece getDest(Move move) { return get(move.getDest()); }
 
-	public void setPos(Move move, Piece piece) {
+	/**
-		set(move.pos, piece);
+	 * Places a piece at the position of a move.
-	}
+	 *
+	 * @param move  The move at which position to place the piece
+	 * @param piece The piece to place
+	 */
+	public void setPos(Move move, Piece piece) { set(move.getPos(), piece); }
 
-	public void setDest(Move move, Piece piece) {
+	/**
-		set(move.dest, piece);
+	 * Places a piece at the destination of a move.
-	}
+	 *
+	 * @param move  The move at which destination to place the piece
+	 * @param piece The piece to place
+	 */
+	public void setDest(Move move, Piece piece) { set(move.getDest(), piece); }
 
 	/**
 	 * @return The board array
 	 */
 	public Piece[][] getBoardArr() { return boardArr; }
+
+	/**
+	 * @return The move log
+	 */
+	public Log getLog() { return log; }
 }

src/dev/kske/chess/board/BoardState.java

@@ -2,10 +2,12 @@ package dev.kske.chess.board;
 
 /**
  * Project: <strong>Chess</strong><br>
- * File: <strong>GameState.java</strong><br>
+ * File: <strong>BoardState.java</strong><br>
  * Created: <strong>07.07.2019</strong><br>
- * Author: <strong>Kai S. K. Engelbart</strong>
+ * 
+ * @since Chess v0.1-alpha
+ * @author Kai S. K. Engelbart
  */
-public enum GameState {
+public enum BoardState {
 	CHECK, CHECKMATE, STALEMATE, NORMAL;
 }

src/dev/kske/chess/board/Castling.java

@@ -0,0 +1,44 @@
+package dev.kske.chess.board;
+
+/**
+ * Project: <strong>Chess</strong><br>
+ * File: <strong>Castling.java</strong><br>
+ * Created: <strong>2 Nov 2019</strong><br>
+ *
+ * @since Chess v0.5-alpha
+ * @author Kai S. K. Engelbart
+ */
+public class Castling extends Move {
+
+	private final Move rookMove;
+
+	public Castling(Position pos, Position dest) {
+		super(pos, dest);
+		rookMove = dest.x == 6 ? new Move(7, pos.y, 5, pos.y) : new Move(0, pos.y, 3, pos.y);
+	}
+
+	public Castling(int xPos, int yPos, int xDest, int yDest) { this(new Position(xPos, yPos), new Position(xDest, yDest)); }
+
+	@Override
+	public void execute(Board board) {
+		// Move the king and the rook
+		super.execute(board);
+		rookMove.execute(board);
+	}
+
+	@Override
+	public void revert(Board board, Piece capturedPiece) {
+		// Move the king and the rook
+		super.revert(board, capturedPiece);
+		rookMove.revert(board, null);
+	}
+
+	/**
+	 * @return {@code O-O-O} for a queenside castling or {@code O-O} for a kingside
+	 *         castling
+	 */
+	@Override
+	public String toSAN(Board board) {
+		return rookMove.pos.x == 0 ? "O-O-O" : "O-O";
+	}
+}

src/dev/kske/chess/board/EnPassant.java

@@ -0,0 +1,35 @@
+package dev.kske.chess.board;
+
+/**
+ * Project: <strong>Chess</strong><br>
+ * File: <strong>EnPassant.java</strong><br>
+ * Created: <strong>2 Nov 2019</strong><br>
+ * 
+ * @since Chess v0.5-alpha
+ * @author Kai S. K. Engelbart
+ */
+public class EnPassant extends Move {
+
+	private final Position capturePos;
+
+	public EnPassant(Position pos, Position dest) {
+		super(pos, dest);
+		capturePos = new Position(dest.x, dest.y - ySign);
+	}
+
+	public EnPassant(int xPos, int yPos, int xDest, int yDest) { this(new Position(xPos, yPos), new Position(xDest, yDest)); }
+
+	@Override
+	public void execute(Board board) {
+		super.execute(board);
+		board.set(capturePos, null);
+	}
+
+	@Override
+	public void revert(Board board, Piece capturedPiece) {
+		super.revert(board, capturedPiece);
+		board.set(capturePos, new Pawn(board.get(pos).getColor().opposite(), board));
+	}
+
+	public Position getCapturePos() { return capturePos; }
+}

src/dev/kske/chess/board/FENString.java

@@ -0,0 +1,212 @@
+package dev.kske.chess.board;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import dev.kske.chess.board.Piece.Color;
+import dev.kske.chess.exception.ChessException;
+
+/**
+ * Project: <strong>Chess</strong><br>
+ * File: <strong>FENString.java</strong><br>
+ * Created: <strong>20 Oct 2019</strong><br>
+ * <br>
+ * Represents a FEN string and enables parsing an existing FEN string or
+ * serializing a {@link Board} to one.
+ * 
+ * @since Chess v0.5-alpha
+ * @author Kai S. K. Engelbart
+ */
+public class FENString {
+
+	private Board		board;
+	private String		piecePlacement, castlingAvailability;
+	private int			halfmoveClock, fullmoveNumber;
+	private Color		activeColor;
+	private Position	enPassantTargetSquare;
+
+	/**
+	 * Constructs a {@link FENString} representing the starting position
+	 * {@code rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1}.
+	 */
+	public FENString() {
+		board					= new Board();
+		piecePlacement			= "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR";
+		activeColor				= Color.WHITE;
+		castlingAvailability	= "KQkq";
+		halfmoveClock			= 0;
+		fullmoveNumber			= 1;
+	}
+
+	/**
+	 * Constructs a {@link FENString} by parsing an existing string.
+	 * 
+	 * @param fen the FEN string to parse
+	 * @throws ChessException
+	 */
+	public FENString(String fen) throws ChessException {
+		// Check fen string against regex
+		Pattern	fenPattern	= Pattern.compile(
+				"^(?<piecePlacement>(?:[1-8nbrqkpNBRQKP]{1,8}\\/){7}[1-8nbrqkpNBRQKP]{1,8}) (?<activeColor>[wb]) (?<castlingAvailability>-|[KQkq]{1,4}) (?<enPassantTargetSquare>-|[a-h][1-8]) (?<halfmoveClock>\\d+) (?<fullmoveNumber>\\d+)$");
+		Matcher	matcher		= fenPattern.matcher(fen);
+		if (!matcher.find()) throw new ChessException("FEN string does not match pattern " + fenPattern.pattern());
+
+		// Initialize data fields
+		piecePlacement			= matcher.group("piecePlacement");
+		activeColor				= Color.fromFirstChar(matcher.group("activeColor").charAt(0));
+		castlingAvailability	= matcher.group("castlingAvailability");
+		if (!matcher.group("enPassantTargetSquare").equals("-")) enPassantTargetSquare = Position.fromLAN(matcher.group("enPassantTargetSquare"));
+		halfmoveClock	= Integer.parseInt(matcher.group("halfmoveClock"));
+		fullmoveNumber	= Integer.parseInt(matcher.group("fullmoveNumber"));
+
+		// Initialize and clean board
+		board = new Board();
+		for (int i = 0; i < 8; i++)
+			for (int j = 0; j < 8; j++)
+				board.getBoardArr()[i][j] = null;
+
+		// Parse individual fields
+
+		// Piece placement
+		final String[] rows = piecePlacement.split("/");
+		if (rows.length != 8) throw new ChessException("FEN string contains invalid piece placement");
+		for (int i = 0; i < 8; i++) {
+			final char[]	cols	= rows[i].toCharArray();
+			int				j		= 0;
+			for (char c : cols) {
+
+				// Empty space
+				if (Character.isDigit(c)) {
+					j += Character.getNumericValue(c);
+				} else {
+					Color color = Character.isUpperCase(c) ? Color.WHITE : Color.BLACK;
+					try {
+						Constructor<? extends Piece> pieceConstructor = Piece.fromFirstChar(c).getDeclaredConstructor(Color.class, Board.class);
+						pieceConstructor.setAccessible(true);
+						board.getBoardArr()[j][i] = pieceConstructor.newInstance(color, board);
+					} catch (InstantiationException | IllegalAccessException | IllegalArgumentException | InvocationTargetException
+							| NoSuchMethodException | SecurityException e) {
+						e.printStackTrace();
+					}
+					++j;
+				}
+			}
+		}
+
+		// Active color
+		board.getLog().setActiveColor(activeColor);
+
+		// Castling availability
+		boolean castlingRights[] = new boolean[4];
+		for (char c : castlingAvailability.toCharArray())
+			switch (c) {
+				case 'K':
+					castlingRights[MoveNode.WHITE_KINGSIDE] = true;
+					break;
+				case 'Q':
+					castlingRights[MoveNode.WHITE_QUEENSIDE] = true;
+					break;
+				case 'k':
+					castlingRights[MoveNode.BLACK_KINGSIDE] = true;
+					break;
+				case 'q':
+					castlingRights[MoveNode.BLACK_QUEENSIDE] = true;
+					break;
+			}
+		board.getLog().setCastlingRights(castlingRights);
+
+		// En passant square
+		board.getLog().setEnPassant(enPassantTargetSquare);
+
+		// Halfmove clock
+		board.getLog().setHalfmoveClock(halfmoveClock);
+
+		// Fullmove number
+		board.getLog().setFullmoveNumber(fullmoveNumber);
+	}
+
+	/**
+	 * Constructs a {@link FENString} form a {@link Board} object.
+	 * 
+	 * @param board the {@link Board} object to encode in this {@link FENString}
+	 */
+	public FENString(Board board) {
+		this.board = board;
+
+		// Serialize individual fields
+
+		// Piece placement
+		StringBuilder sb = new StringBuilder();
+		for (int i = 0; i < 8; i++) {
+			int empty = 0;
+			for (int j = 0; j < 8; j++) {
+				final Piece piece = board.getBoardArr()[j][i];
+
+				if (piece == null) ++empty;
+				else {
+
+					// Write empty field count
+					if (empty > 0) {
+						sb.append(empty);
+						empty = 0;
+					}
+
+					// Write piece character
+					char p = piece.firstChar();
+					sb.append(piece.getColor() == Color.WHITE ? Character.toUpperCase(p) : p);
+				}
+			}
+
+			// Write empty field count
+			if (empty > 0) {
+				sb.append(empty);
+				empty = 0;
+			}
+
+			if (i < 7) sb.append('/');
+		}
+		piecePlacement = sb.toString();
+
+		// Active color
+		activeColor = board.getLog().getActiveColor();
+
+		// Castling availability
+		castlingAvailability = "";
+		final char castlingRightsChars[] = new char[] { 'K', 'Q', 'k', 'q' };
+		for (int i = 0; i < 4; i++)
+			if (board.getLog().getCastlingRights()[i]) castlingAvailability += castlingRightsChars[i];
+		if (castlingAvailability.isEmpty()) castlingAvailability = "-";
+
+		// En passant availability
+		enPassantTargetSquare = board.getLog().getEnPassant();
+
+		// Halfmove clock
+		halfmoveClock = board.getLog().getHalfmoveClock();
+
+		// Fullmove counter
+		fullmoveNumber = board.getLog().getFullmoveNumber();
+	}
+
+	/**
+	 * Exports this {@link FENString} object to a FEN string.
+	 * 
+	 * @return a FEN string representing the board
+	 */
+	@Override
+	public String toString() {
+		return String.format("%s %c %s %s %d %d",
+				piecePlacement,
+				activeColor.firstChar(),
+				castlingAvailability,
+				enPassantTargetSquare == null ? "-" : enPassantTargetSquare.toLAN(),
+				halfmoveClock,
+				fullmoveNumber);
+	}
+
+	/**
+	 * @return a {@link Board} object corresponding to this {@link FENString}
+	 */
+	public Board getBoard() { return board; }
+}

src/dev/kske/chess/board/King.java

@@ -7,36 +7,19 @@ import java.util.List;
  * Project: <strong>Chess</strong><br>
  * File: <strong>King.java</strong><br>
  * Created: <strong>01.07.2019</strong><br>
- * Author: <strong>Kai S. K. Engelbart</strong>
+ * 
+ * @since Chess v0.1-alpha
+ * @author Kai S. K. Engelbart
  */
 public class King extends Piece {
 
-	public King(Color color, Board board) {
+	public King(Color color, Board board) { super(color, board); }
-		super(color, board);
-	}
 
 	@Override
 	public boolean isValidMove(Move move) {
-		// Castling
+		return (move.getxDist() == 2 && move.getyDist() == 0
-		if (getMoveCounter() == 0 && move.xDist == 2 && move.yDist == 0) {
+				&& (move.getDest().x == 6 && canCastleKingside() || move.getDest().x == 2 && canCastleQueenside()))
-
+				|| move.getxDist() <= 1 && move.getyDist() <= 1 && checkDestination(move);
-			// Kingside
-			if (board.getBoardArr()[7][move.pos.y] != null && board.getBoardArr()[7][move.pos.y].getType() == Type.ROOK
-					&& isFreePath(new Move(new Position(5, move.pos.y), new Position(7, move.pos.y)))) {
-				move.type = Move.Type.CASTLING;
-				return true;
-			}
-
-			// Queenside
-			if (board.getBoardArr()[0][move.pos.y] != null && board.getBoardArr()[0][move.pos.y].getType() == Type.ROOK
-					&& isFreePath(new Move(new Position(1, move.pos.y), new Position(4, move.pos.y)))) {
-				move.type = Move.Type.CASTLING;
-				return true;
-			}
-
-		}
-
-		return move.xDist <= 1 && move.yDist <= 1 && checkDestination(move);
 	}
 
 	@Override
@@ -50,31 +33,40 @@ public class King extends Piece {
 				}
 
 		// Castling
-		// TODO: Check attacked squares in between
+		if (canCastleKingside()) moves.add(new Castling(pos, new Position(6, pos.y)));
-		// TODO: Castling out of check?
+		if (canCastleQueenside()) moves.add(new Castling(pos, new Position(2, pos.y)));
-		if (getMoveCounter() == 0) {
-
-			// Kingside
-			if (board.getBoardArr()[7][pos.y] != null && board.getBoardArr()[7][pos.y].getType() == Type.ROOK
-					&& isFreePath(new Move(new Position(5, pos.y), new Position(7, pos.y))))
-				moves.add(new Move(pos, new Position(6, pos.y), Move.Type.CASTLING));
-
-			// Queenside
-			if (board.getBoardArr()[0][pos.y] != null && board.getBoardArr()[0][pos.y].getType() == Type.ROOK
-					&& isFreePath(new Move(new Position(1, pos.y), new Position(4, pos.y))))
-				moves.add(new Move(pos, new Position(2, pos.y), Move.Type.CASTLING));
-		}
 
 		return moves;
 	}
 
-	@Override
+	private boolean canCastleKingside() {
-	protected boolean isFreePath(Move move) {
+		if (board.getLog().getCastlingRights()[getColor() == Color.WHITE ? MoveNode.WHITE_KINGSIDE : MoveNode.BLACK_KINGSIDE]) {
-		for (int i = move.pos.x, j = move.pos.y; i != move.dest.x || j != move.dest.y; i += move.xSign, j += move.ySign)
+			int			y			= getColor() == Color.WHITE ? 7 : 0;
-			if (board.getBoardArr()[i][j] != null) return false;
+			Position	kingPos		= new Position(4, y);
-		return true;
+			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 instanceof Rook && isFreePath(new Move(kingPos, freeDest)) && !board.isAttacked(kingPos, getColor().opposite())
+				&& !board.isAttacked(jumpPos, getColor().opposite());
 	}
 
 	@Override
-	public Type getType() { return Type.KING; }
+	public int getValue() { return 0; }
 }

src/dev/kske/chess/board/Knight.java

@@ -7,7 +7,9 @@ import java.util.List;
  * Project: <strong>Chess</strong><br>
  * File: <strong>Knight.java</strong><br>
  * Created: <strong>01.07.2019</strong><br>
- * Author: <strong>Kai S. K. Engelbart</strong>
+ * 
+ * @since Chess v0.1-alpha
+ * @author Kai S. K. Engelbart
  */
 public class Knight extends Piece {
 
@@ -17,8 +19,8 @@ public class Knight extends Piece {
 
 	@Override
 	public boolean isValidMove(Move move) {
-		return Math.abs(move.xDist - move.yDist) == 1
+		return Math.abs(move.getxDist() - move.getyDist()) == 1
-				&& (move.xDist == 1 && move.yDist == 2 || move.xDist == 2 && move.yDist == 1) && checkDestination(move);
+				&& (move.getxDist() == 1 && move.getyDist() == 2 || move.getxDist() == 2 && move.getyDist() == 1) && checkDestination(move);
 	}
 
 	private void checkAndInsertMove(List<Move> moves, Position pos, int offsetX, int offsetY) {
@@ -43,5 +45,8 @@ public class Knight extends Piece {
 	}
 
 	@Override
-	public Type getType() { return Type.KNIGHT; }
+	public int getValue() { return 35; }
+
+	@Override
+	public char firstChar() { return 'n'; }
 }

src/dev/kske/chess/board/Log.java

@@ -1,55 +1,252 @@
 package dev.kske.chess.board;
 
-import java.util.ArrayList;
+import java.util.Arrays;
-import java.util.List;
+import java.util.Iterator;
+import java.util.Objects;
+
+import dev.kske.chess.board.Piece.Color;
 
 /**
  * Project: <strong>Chess</strong><br>
  * File: <strong>Log.java</strong><br>
  * Created: <strong>09.07.2019</strong><br>
- * Author: <strong>Kai S. K. Engelbart</strong>
+ *
+ * @since Chess v0.1-alpha
+ * @author Kai S. K. Engelbart
  */
-public class Log implements Cloneable {
+public class Log implements Iterable<MoveNode> {
 
-	private List<LoggedMove> moves;
+	private MoveNode root, current;
 
-	public Log() {
+	private Color		activeColor;
-		moves = new ArrayList<>();
+	private boolean[]	castlingRights;
+	private Position	enPassant;
+	private int			fullmoveNumber, halfmoveClock;
+
+	public Log() { reset(); }
+
+	/**
+	 * Creates a (partially deep) copy of another {@link Log} instance which begins
+	 * with the current {@link MoveNode}.
+	 *
+	 * @param other          The {@link Log} instance to copy
+	 * @param copyVariations If set to {@code true}, subsequent variations of the
+	 *                       current {@link MoveNode} are copied with the
+	 *                       {@link Log}
+	 */
+	public Log(Log other, boolean copyVariations) {
+		enPassant		= other.enPassant;
+		castlingRights	= other.castlingRights.clone();
+		activeColor		= other.activeColor;
+		fullmoveNumber	= other.fullmoveNumber;
+		halfmoveClock	= other.halfmoveClock;
+
+		// The new root is the current node of the copied instance
+		if (!other.isEmpty()) {
+			root = new MoveNode(other.root, copyVariations);
+			root.setParent(null);
+			current = root;
+		}
 	}
 
-	public void add(Move move, Piece capturedPiece) {
+	/**
-		moves.add(new LoggedMove(move, capturedPiece));
+	 * @return an iterator over all {@link MoveNode} objects that are either the
+	 *         root node or a first variation of another node, starting from the
+	 *         root node
+	 */
+	@Override
+	public Iterator<MoveNode> iterator() {
+		return new Iterator<MoveNode>() {
+
+			private MoveNode	current	= root;
+			private boolean		hasNext	= !isEmpty();
+
+			@Override
+			public boolean hasNext() { return hasNext; }
+
+			@Override
+			public MoveNode next() {
+				MoveNode result = current;
+				if (current.hasVariations()) current = current.getVariations().get(0);
+				else hasNext = false;
+				return result;
+			}
+		};
 	}
 
-	public LoggedMove getLast() {
+	/**
-		return moves.get(moves.size() - 1);
+	 * Adds a move to the move history and adjusts the log to the new position.
+	 *
+	 * @param move          The move to log
+	 * @param piece         The piece that performed the move
+	 * @param capturedPiece The piece captured with the move
+	 */
+	public void add(Move move, Piece piece, Piece capturedPiece) {
+		enPassant = piece instanceof Pawn && move.getyDist() == 2 ? new Position(move.getPos().x, move.getPos().y + move.getySign()) : null;
+		if (activeColor == Color.BLACK) ++fullmoveNumber;
+		if (piece instanceof Pawn || capturedPiece != null) halfmoveClock = 0;
+		else++halfmoveClock;
+		activeColor = activeColor.opposite();
+
+		// Disable castling rights if a king or a rook has been moved
+		if (piece instanceof King || piece instanceof Rook) disableCastlingRights(piece, move.getPos());
+
+		final MoveNode leaf = new MoveNode(move, capturedPiece, castlingRights.clone(), enPassant, activeColor, fullmoveNumber, halfmoveClock);
+
+		if (isEmpty()) {
+			root	= leaf;
+			current	= leaf;
+		} else {
+			current.addVariation(leaf);
+			current = leaf;
+		}
 	}
 
+	/**
+	 * Removes the last move from the log and adjusts its state to the previous
+	 * move.
+	 */
 	public void removeLast() {
-		if (!moves.isEmpty()) moves.remove(moves.size() - 1);
+		if (hasParent()) {
+			current.getParent().getVariations().remove(current);
+			current = current.getParent();
+			update();
+		} else reset();
+	}
+
+	/**
+	 * @return {@code true} if the root node exists
+	 */
+	public boolean isEmpty() { return root == null; }
+
+	/**
+	 * @return {@code true} if the current node has a parent node
+	 */
+	public boolean hasParent() { return !isEmpty() && current.hasParent(); }
+
+	/**
+	 * Reverts the log to its initial state corresponding to the default board
+	 * position.
+	 */
+	public void reset() {
+		root			= null;
+		current			= null;
+		castlingRights	= new boolean[] { true, true, true, true };
+		enPassant		= null;
+		activeColor		= Color.WHITE;
+		fullmoveNumber	= 1;
+		halfmoveClock	= 0;
+	}
+
+	/**
+	 * Changes the current node to one of its children (variations).
+	 *
+	 * @param index the index of the variation to select
+	 */
+	public void selectNextNode(int index) {
+		if (!isEmpty() && current.hasVariations() && index < current.getVariations().size()) {
+			current = current.getVariations().get(index);
+			update();
+		}
+	}
+
+	/**
+	 * Selects the parent of the current {@link MoveNode} as the current node.
+	 */
+	public void selectPreviousNode() {
+		if (hasParent()) {
+			current = current.getParent();
+			update();
+		}
+	}
+
+	/**
+	 * Selects the root {@link MoveNode} as the current node.
+	 */
+	public void selectRootNode() {
+		if (!isEmpty()) {
+			current = root;
+			update();
+		}
+	}
+
+	/**
+	 * Sets the active color, castling rights, en passant target square, fullmove
+	 * number and halfmove clock to those of the current {@link MoveNode}.
+	 */
+	private void update() {
+		activeColor		= current.activeColor;
+		castlingRights	= current.castlingRights.clone();
+		enPassant		= current.enPassant;
+		fullmoveNumber	= current.fullmoveCounter;
+		halfmoveClock	= current.halfmoveClock;
+	}
+
+	/**
+	 * Removed the castling rights bound to a rook or king for the rest of the game.
+	 * This method should be called once the piece has been moved, as a castling
+	 * move involving this piece is forbidden afterwards.
+	 *
+	 * @param piece           the rook or king to disable the castling rights for
+	 * @param initialPosition the initial position of the piece during the start of
+	 *                        the game
+	 */
+	private void disableCastlingRights(Piece piece, Position initialPosition) {
+		// Kingside
+		if (piece instanceof King || piece instanceof Rook && initialPosition.x == 7)
+			castlingRights[piece.getColor() == Color.WHITE ? MoveNode.WHITE_KINGSIDE : MoveNode.BLACK_KINGSIDE] = false;
+
+		// Queenside
+		if (piece instanceof King || piece instanceof Rook && initialPosition.x == 0)
+			castlingRights[piece.getColor() == Color.WHITE ? MoveNode.WHITE_QUEENSIDE : MoveNode.BLACK_QUEENSIDE] = false;
 	}
 
 	@Override
-	public Object clone() {
+	public int hashCode() {
-		Log log = null;
+		final int	prime	= 31;
-		try {
+		int			result	= 1;
-			log = (Log) super.clone();
+		result	= prime * result + Arrays.hashCode(castlingRights);
-		} catch (CloneNotSupportedException e) {
+		result	= prime * result + Objects.hash(activeColor, current, enPassant, fullmoveNumber, halfmoveClock);
-			e.printStackTrace();
+		return result;
-		}
-		log.moves = new ArrayList<>();
-		log.moves.addAll(this.moves);
-		return log;
 	}
 
-	public static class LoggedMove {
+	@Override
+	public boolean equals(Object obj) {
+		if (this == obj) return true;
+		if (obj == null) return false;
+		if (getClass() != obj.getClass()) return false;
+		Log other = (Log) obj;
+		return activeColor == other.activeColor && Arrays.equals(castlingRights, other.castlingRights) && Objects.equals(current, other.current)
+				&& Objects.equals(enPassant, other.enPassant) && fullmoveNumber == other.fullmoveNumber && halfmoveClock == other.halfmoveClock;
+	}
 
-		public final Move		move;
+	/**
-		public final Piece	capturedPiece;
+	 * @return The first logged move, or {@code null} if there is none
+	 */
+	public MoveNode getRoot() { return root; }
 
-		public LoggedMove(Move move, Piece capturedPiece) {
+	/**
-			this.move		= move;
+	 * @return the last logged move, or {@code null} if there is none
-			this.capturedPiece	= capturedPiece;
+	 */
-		}
+	public MoveNode getLast() { return current; }
-	}
+
+	public boolean[] getCastlingRights() { return castlingRights; }
+
+	public void setCastlingRights(boolean[] castlingRights) { this.castlingRights = castlingRights; }
+
+	public Position getEnPassant() { return enPassant; }
+
+	public void setEnPassant(Position enPassant) { this.enPassant = enPassant; }
+
+	public Color getActiveColor() { return activeColor; }
+
+	public void setActiveColor(Color activeColor) { this.activeColor = activeColor; }
+
+	public int getFullmoveNumber() { return fullmoveNumber; }
+
+	public void setFullmoveNumber(int fullmoveNumber) { this.fullmoveNumber = fullmoveNumber; }
+
+	public int getHalfmoveClock() { return halfmoveClock; }
+
+	public void setHalfmoveClock(int halfmoveClock) { this.halfmoveClock = halfmoveClock; }
 }

src/dev/kske/chess/board/Move.java

@@ -1,47 +1,205 @@
 package dev.kske.chess.board;
 
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Objects;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import dev.kske.chess.board.Piece.Color;
+
 /**
  * Project: <strong>Chess</strong><br>
  * File: <strong>Move.java</strong><br>
  * Created: <strong>02.07.2019</strong><br>
- * Author: <strong>Kai S. K. Engelbart</strong>
+ *
+ * @since Chess v0.1-alpha
+ * @author Kai S. K. Engelbart
  */
 public class Move {
 
-	public final Position	pos, dest;
+	protected final Position	pos, dest;
-	public final int		xDist, yDist, xSign, ySign;
+	protected final int			xDist, yDist, xSign, ySign;
-	public Type				type;
 
-	public Move(Position pos, Position dest, Type type) {
+	public Move(Position pos, Position dest) {
 		this.pos	= pos;
 		this.dest	= dest;
-		this.type	= type;
 		xDist		= Math.abs(dest.x - pos.x);
 		yDist		= Math.abs(dest.y - pos.y);
 		xSign		= (int) Math.signum(dest.x - pos.x);
 		ySign		= (int) Math.signum(dest.y - pos.y);
 	}
 
-	public Move(Position pos, Position dest) {
+	public Move(int xPos, int yPos, int xDest, int yDest) { this(new Position(xPos, yPos), new Position(xDest, yDest)); }
-		this(pos, dest, Type.NORMAL);
+
+	public void execute(Board board) {
+		// Move the piece to the move's destination square and clean the old position
+		board.set(dest, board.get(pos));
+		board.set(pos, null);
 	}
 
-	public Move(int xPos, int yPos, int xDest, int yDest) {
+	public void revert(Board board, Piece capturedPiece) {
-		this(new Position(xPos, yPos), new Position(xDest, yDest));
+		// Move the piece to the move's position square and clean the destination
+		board.set(pos, board.get(dest));
+		board.set(dest, capturedPiece);
 	}
 
-	public boolean isHorizontal() { return yDist == 0; }
+	public static Move fromLAN(String move) {
+		Position	pos		= Position.fromLAN(move.substring(0, 2));
+		Position	dest	= Position.fromLAN(move.substring(2));
+		if (move.length() == 5) {
+			try {
+				return new PawnPromotion(pos, dest, Piece.fromFirstChar(move.charAt(4)));
+			} catch (Exception e) {
+				e.printStackTrace();
+				return null;
+			}
+		} else return new Move(pos, dest);
+	}
 
-	public boolean isVertical() { return xDist == 0; }
+	public String toLAN() { return getPos().toLAN() + getDest().toLAN(); }
 
-	public boolean isDiagonal() { return xDist == yDist; }
+	/**
+	 * Converts a move string from standard algebraic notation to a {@link Move}
+	 * object.
+	 *
+	 * @param sanMove the move string to convert from
+	 * @param board   the board on which the move has to be executed
+	 * @return the converted {@link Move} object
+	 */
+	public static Move fromSAN(String sanMove, Board board) {
+		Map<String, Pattern> patterns = new HashMap<>();
+		patterns.put("pieceMove",
+				Pattern.compile(
+						"^(?<pieceType>[NBRQK])(?:(?<fromFile>[a-h])|(?<fromRank>[1-8])|(?<fromSquare>[a-h][1-8]))?x?(?<toSquare>[a-h][1-8])(?:\\+{0,2}|\\#)$"));
+		patterns.put("pawnCapture",
+				Pattern.compile("^(?<fromFile>[a-h])(?<fromRank>[1-8])?x(?<toSquare>[a-h][1-8])(?<promotedTo>[NBRQ])?(?:\\+{0,2}|\\#)?$"));
+		patterns.put("pawnPush", Pattern.compile("^(?<toSquare>[a-h][1-8])(?<promotedTo>[NBRQ])?(?:\\+{0,2}|\\#)$"));
+		patterns.put("castling", Pattern.compile("^(?<queenside>O-O-O)|(?<kingside>O-O)(?:\\+{0,2}|\\#)?$"));
+
+		for (Map.Entry<String, Pattern> entry : patterns.entrySet()) {
+			Matcher m = entry.getValue().matcher(sanMove);
+			if (m.find()) {
+				Position	pos		= null, dest = null;
+				Move		move	= null;
+				switch (entry.getKey()) {
+					case "pieceMove":
+						dest = Position.fromLAN(m.group("toSquare"));
+						if (m.group("fromSquare") != null) pos = Position.fromLAN(m.group("fromSquare"));
+						else {
+							Class<? extends Piece>	pieceClass	= Piece.fromFirstChar(m.group("pieceType").charAt(0));
+							char					file;
+							int						rank;
+							if (m.group("fromFile") != null) {
+								file	= m.group("fromFile").charAt(0);
+								rank	= board.get(pieceClass, file);
+								pos		= Position.fromLAN(String.format("%c%d", file, rank));
+							} else if (m.group("fromRank") != null) {
+								rank	= Integer.parseInt(m.group("fromRank").substring(0, 1));
+								file	= board.get(pieceClass, rank);
+								pos		= Position.fromLAN(String.format("%c%d", file, rank));
+							} else pos = board.get(pieceClass, dest);
+						}
+						move = new Move(pos, dest);
+						break;
+					case "pawnCapture":
+						char file = m.group("fromFile").charAt(0);
+						int rank = m.group("fromRank") == null ? board.get(Pawn.class, file) : Integer.parseInt(m.group("fromRank"));
+
+						dest = Position.fromLAN(m.group("toSquare"));
+						pos = Position.fromLAN(String.format("%c%d", file, rank));
+
+						if (m.group("promotedTo") != null) {
+							try {
+								move = new PawnPromotion(pos, dest, Piece.fromFirstChar(m.group("promotedTo").charAt(0)));
+							} catch (Exception e) {
+								e.printStackTrace();
+							}
+						} else move = new Move(pos, dest);
+						break;
+					case "pawnPush":
+						dest = Position.fromLAN(m.group("toSquare"));
+						int step = board.getLog().getActiveColor() == Color.WHITE ? 1 : -1;
+
+						// One step forward
+						if (board.getBoardArr()[dest.x][dest.y + step] != null) pos = new Position(dest.x, dest.y + step);
+
+						// Double step forward
+						else pos = new Position(dest.x, dest.y + 2 * step);
+
+						if (m.group("promotedTo") != null) {
+							try {
+								move = new PawnPromotion(pos, dest, Piece.fromFirstChar(m.group("promotedTo").charAt(0)));
+							} catch (Exception e) {
+								e.printStackTrace();
+							}
+						} else move = new Move(pos, dest);
+						break;
+					case "castling":
+						pos = new Position(4, board.getLog().getActiveColor() == Color.WHITE ? 7 : 0);
+						dest = new Position(m.group("kingside") != null ? 6 : 2, pos.y);
+						move = new Castling(pos, dest);
+						break;
+				}
+				return move;
+			}
+		}
+		return null;
+	}
+
+	public String toSAN(Board board) {
+		final Piece		piece	= board.get(pos);
+		StringBuilder	sb		= new StringBuilder(8);
+
+		// Piece symbol
+		if(!(piece instanceof Pawn))
+			sb.append(Character.toUpperCase(piece.firstChar()));
+
+		// Position
+		// TODO: Deconstruct position into optional file or rank
+		// Omit position if the move is a pawn push
+		if (!(piece instanceof Pawn && xDist == 0)) sb.append(pos.toLAN());
+
+		// Capture indicator
+		if (board.get(dest) != null) sb.append('x');
+
+		// Destination
+		sb.append(dest.toLAN());
+
+		return sb.toString();
+	}
+
+	public boolean isHorizontal() { return getyDist() == 0; }
+
+	public boolean isVertical() { return getxDist() == 0; }
+
+	public boolean isDiagonal() { return getxDist() == getyDist(); }
 
 	@Override
-	public String toString() {
+	public String toString() { return toLAN(); }
-		return String.format("%s -> %s", pos, dest);
+
+	@Override
+	public int hashCode() { return Objects.hash(getDest(), getPos(), getxDist(), getxSign(), getyDist(), getySign()); }
+
+	@Override
+	public boolean equals(Object obj) {
+		if (this == obj) return true;
+		if (obj == null) return false;
+		if (getClass() != obj.getClass()) return false;
+		Move other = (Move) obj;
+		return Objects.equals(getDest(), other.getDest()) && Objects.equals(getPos(), other.getPos()) && getxDist() == other.getxDist()
+				&& getxSign() == other.getxSign() && getyDist() == other.getyDist() && getySign() == other.getySign();
 	}
 
-	public static enum Type {
+	public Position getPos() { return pos; }
-		NORMAL, PAWN_PROMOTION, CASTLING, EN_PASSANT, UNKNOWN
+
-	}
+	public Position getDest() { return dest; }
+
+	public int getxDist() { return xDist; }
+
+	public int getyDist() { return yDist; }
+
+	public int getxSign() { return xSign; }
+
+	public int getySign() { return ySign; }
 }

src/dev/kske/chess/board/MoveNode.java

@@ -0,0 +1,126 @@
+package dev.kske.chess.board;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Objects;
+
+import dev.kske.chess.board.Piece.Color;
+
+/**
+ * Project: <strong>Chess</strong><br>
+ * File: <strong>MoveNode.java</strong><br>
+ * Created: <strong>02.10.2019</strong><br>
+ *
+ * @since Chess v0.5-alpha
+ * @author Kai S. K. Engelbart
+ */
+public class MoveNode {
+
+	public static final int WHITE_KINGSIDE = 0, WHITE_QUEENSIDE = 1, BLACK_KINGSIDE = 2, BLACK_QUEENSIDE = 3;
+
+	public final Move		move;
+	public final Piece		capturedPiece;
+	public final boolean[]	castlingRights;
+	public final Position	enPassant;
+	public final Color		activeColor;
+	public final int		fullmoveCounter, halfmoveClock;
+
+	private MoveNode		parent;
+	private List<MoveNode>	variations;
+
+	/**
+	 * Creates a new {@link MoveNode}.
+	 *
+	 * @param move            The logged {@link Move}
+	 * @param capturedPiece   The {@link Piece} captures by the logged {@link Move}
+	 * @param enPassant       The en passant {@link Position} valid after the logged
+	 *                        {@link Move}, or {@code null} if there is none
+	 * @param activeColor     The {@link Color} active after the logged {@link Move}
+	 * @param fullmoveCounter
+	 * @param halfmoveClock
+	 */
+	public MoveNode(Move move, Piece capturedPiece, boolean castlingRights[], Position enPassant, Color activeColor,
+			int fullmoveCounter, int halfmoveClock) {
+		this.move				= move;
+		this.capturedPiece		= capturedPiece;
+		this.castlingRights		= castlingRights;
+		this.enPassant			= enPassant;
+		this.activeColor		= activeColor;
+		this.fullmoveCounter	= fullmoveCounter;
+		this.halfmoveClock		= halfmoveClock;
+	}
+
+	/**
+	 * Creates a (deep) copy of another {@link MoveNode}.
+	 *
+	 * @param other          The {@link MoveNode} to copy
+	 * @param copyVariations When this is set to {@code true} a deep copy is
+	 *                       created, which
+	 *                       considers subsequent variations
+	 */
+	public MoveNode(MoveNode other, boolean copyVariations) {
+		this(other.move, other.capturedPiece, other.castlingRights.clone(), other.enPassant, other.activeColor,
+				other.fullmoveCounter, other.halfmoveClock);
+		if (copyVariations && other.variations != null) {
+			if (variations == null) variations = new ArrayList<>();
+			for (MoveNode variation : other.variations) {
+				MoveNode copy = new MoveNode(variation, true);
+				copy.parent = this;
+				variations.add(copy);
+			}
+		}
+	}
+
+	/**
+	 * Adds another {@link MoveNode} as a child node.
+	 *
+	 * @param variation The {@link MoveNode} to append to this {@link MoveNode}
+	 */
+	public void addVariation(MoveNode variation) {
+		if (variations == null) variations = new ArrayList<>();
+		if (!variations.contains(variation)) {
+			variations.add(variation);
+			variation.parent = this;
+		}
+	}
+
+	/**
+	 * @return A list of all variations associated with this {@link MoveNode}
+	 */
+	public List<MoveNode> getVariations() { return variations; }
+
+	public boolean hasVariations() {
+		return variations != null && variations.size() > 0;
+	}
+
+	public MoveNode getParent() { return parent; }
+
+	public void setParent(MoveNode parent) { this.parent = parent; }
+
+	public boolean hasParent() {
+		return parent != null;
+	}
+
+	@Override
+	public int hashCode() {
+		final int	prime	= 31;
+		int			result	= 1;
+		result	= prime * result + Arrays.hashCode(castlingRights);
+		result	= prime * result
+				+ Objects.hash(activeColor, capturedPiece, enPassant, fullmoveCounter, halfmoveClock, move);
+		return result;
+	}
+
+	@Override
+	public boolean equals(Object obj) {
+		if (this == obj) return true;
+		if (obj == null) return false;
+		if (getClass() != obj.getClass()) return false;
+		MoveNode other = (MoveNode) obj;
+		return activeColor == other.activeColor && Objects.equals(capturedPiece, other.capturedPiece)
+				&& Arrays.equals(castlingRights, other.castlingRights) && Objects.equals(enPassant, other.enPassant)
+				&& fullmoveCounter == other.fullmoveCounter && halfmoveClock == other.halfmoveClock
+				&& Objects.equals(move, other.move);
+	}
+}

src/dev/kske/chess/board/Pawn.java

@@ -7,37 +7,33 @@ import java.util.List;
  * Project: <strong>Chess</strong><br>
  * File: <strong>Pawn.java</strong><br>
  * Created: <strong>01.07.2019</strong><br>
- * Author: <strong>Kai S. K. Engelbart</strong>
+ *
+ * @since Chess v0.1-alpha
+ * @author Kai S. K. Engelbart
  */
 public class Pawn extends Piece {
 
-	public Pawn(Color color, Board board) {
+	public Pawn(Color color, Board board) { super(color, board); }
-		super(color, board);
-	}
 
 	@Override
 	public boolean isValidMove(Move move) {
-		// TODO: en passant
+		boolean	step		= move.isVertical() && move.getyDist() == 1;
-		boolean	step		= move.isVertical() && move.yDist == 1;
+		boolean	doubleStep	= move.isVertical() && move.getyDist() == 2;
-		boolean	doubleStep	= move.isVertical() && move.yDist == 2;
+		boolean	strafe		= move.isDiagonal() && move.getxDist() == 1;
-		boolean	strafe		= move.isDiagonal() && move.xDist == 1;
+		boolean	enPassant	= strafe && move.getDest().equals(board.getLog().getEnPassant());
-		if (getColor() == Color.WHITE) doubleStep &= move.pos.y == 6;
+		if (getColor() == Color.WHITE) doubleStep &= move.getPos().y == 6;
-		else doubleStep &= move.pos.y == 1;
+		else doubleStep &= move.getPos().y == 1;
 
-		// Mark move as pawn promotion if necessary
+		return enPassant || (step ^ doubleStep ^ strafe) && move.getySign() == (getColor() == Color.WHITE ? -1 : 1) && isFreePath(move);
-		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);
 	}
 
 	@Override
 	protected boolean isFreePath(Move move) {
 		// Two steps forward
-		if (move.yDist == 2)
+		if (move.getyDist() == 2)
-			return board.getBoardArr()[move.pos.x][move.dest.y - move.ySign] == null && board.getDest(move) == null;
+			return board.getBoardArr()[move.getPos().x][move.getDest().y - move.getySign()] == null && board.getDest(move) == null;
 		// One step forward
-		else if (move.xDist == 0) return board.getDest(move) == null;
+		else if (move.getxDist() == 0) return board.getDest(move) == null;
 		// Capture move
 		else return board.getDest(move) != null && board.getDest(move).getColor() != getColor();
 	}
@@ -45,40 +41,46 @@ public class Pawn extends Piece {
 	@Override
 	protected List<Move> getPseudolegalMoves(Position pos) {
 		List<Move>	moves			= new ArrayList<>();
-
 		int			sign			= getColor() == Color.WHITE ? -1 : 1;
+		boolean		pawnPromotion	= sign == 1 && pos.y == 6 || sign == -1 && pos.y == 1;
 
 		// Strafe left
-		if (pos.x > 0) {
+		if (pos.x > 0) addMoveIfValid(moves, pos, new Position(pos.x - 1, pos.y + sign), pawnPromotion);
-			Move move = new Move(pos, new Position(pos.x - 1, pos.y + sign));
-			if (isFreePath(move)) moves.add(move);
-		}
 
 		// Strafe right
-		if (pos.x < 7) {
+		if (pos.x < 7) addMoveIfValid(moves, pos, new Position(pos.x + 1, pos.y + sign), pawnPromotion);
-			Move move = new Move(pos, new Position(pos.x + 1, pos.y + sign));
-			if (isFreePath(move)) moves.add(move);
-		}
 
 		// Step forward
-		if (sign == 1 && pos.y < 7 || sign == -1 && pos.y > 0) {
+		if (sign == 1 && pos.y < 7 || sign == -1 && pos.y > 0) addMoveIfValid(moves, pos, new Position(pos.x, pos.y + sign), pawnPromotion);
-			Move move = new Move(pos, new Position(pos.x, pos.y + sign));
-			if (isFreePath(move)) moves.add(move);
-		}
 
 		// Double step forward
-		if (sign == 1 && pos.y == 1 || sign == -1 && pos.y == 6) {
+		if (sign == 1 && pos.y == 1 || sign == -1 && pos.y == 6) addMoveIfValid(moves, pos, new Position(pos.x, pos.y + 2 * sign), pawnPromotion);
-			Move move = new Move(pos, new Position(pos.x, pos.y + 2 * sign));
-			if (isFreePath(move)) moves.add(move);
-		}
 
-		// Mark moves as pawn promotions if necessary
+		// Add en passant move if necessary
-		if (sign == 1 && pos.y == 6 || sign == -1 && pos.y == 1)
+		if (board.getLog().getEnPassant() != null) {
-			moves.parallelStream().forEach(m -> m.type = Move.Type.PAWN_PROMOTION);
+			Move move = new EnPassant(pos, board.getLog().getEnPassant());
+			if (move.isDiagonal() && move.getxDist() == 1) moves.add(move);
+		}
 
 		return moves;
 	}
 
-	@Override
+	private void addMoveIfValid(List<Move> moves, Position pos, Position dest, boolean pawnPromotion) {
-	public Type getType() { return Type.PAWN; }
+		Move move = new Move(pos, dest);
+		if (isFreePath(move)) {
+			if (pawnPromotion) {
+				try {
+					moves.add(new PawnPromotion(pos, dest, Queen.class));
+					moves.add(new PawnPromotion(pos, dest, Rook.class));
+					moves.add(new PawnPromotion(pos, dest, Knight.class));
+					moves.add(new PawnPromotion(pos, dest, Bishop.class));
+				} catch (Exception e) {
+					e.printStackTrace();
+				}
+			} else moves.add(move);
+		}
+	}
+
+	@Override
+	public int getValue() { return 10; }
 }

src/dev/kske/chess/board/PawnPromotion.java

@@ -0,0 +1,80 @@
+package dev.kske.chess.board;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
+import java.util.Objects;
+
+import dev.kske.chess.board.Piece.Color;
+
+/**
+ * Project: <strong>Chess</strong><br>
+ * File: <strong>PawnPromotion.java</strong><br>
+ * Created: <strong>2 Nov 2019</strong><br>
+ *
+ * @since Chess v0.5-alpha
+ * @author Kai S. K. Engelbart
+ */
+public class PawnPromotion extends Move {
+
+	private final Constructor<? extends Piece>	promotionPieceConstructor;
+	private final char							promotionPieceChar;
+
+	public PawnPromotion(Position pos, Position dest, Class<? extends Piece> promotionPieceClass)
+			throws ReflectiveOperationException, RuntimeException {
+		super(pos, dest);
+
+		// Cache piece constructor
+		promotionPieceConstructor = promotionPieceClass.getDeclaredConstructor(Color.class, Board.class);
+		promotionPieceConstructor.setAccessible(true);
+
+		// Get piece char
+		promotionPieceChar = (char) promotionPieceClass.getMethod("firstChar").invoke(promotionPieceConstructor.newInstance(null, null));
+	}
+
+	public PawnPromotion(int xPos, int yPos, int xDest, int yDest, Class<? extends Piece> promotionPiece)
+			throws ReflectiveOperationException, RuntimeException {
+		this(new Position(xPos, yPos), new Position(xDest, yDest), promotionPiece);
+	}
+
+	@Override
+	public void execute(Board board) {
+		try {
+			board.set(pos, promotionPieceConstructor.newInstance(board.get(pos).getColor(), board));
+			super.execute(board);
+		} catch (InstantiationException | IllegalAccessException | IllegalArgumentException | InvocationTargetException | SecurityException e) {
+			e.printStackTrace();
+		}
+	}
+
+	@Override
+	public void revert(Board board, Piece capturedPiece) {
+		board.set(dest, new Pawn(board.get(dest).getColor(), board));
+		super.revert(board, capturedPiece);
+	}
+
+	@Override
+	public String toLAN() { return pos.toLAN() + dest.toLAN() + promotionPieceChar; }
+
+	@Override
+	public String toSAN(Board board) {
+		String san = super.toSAN(board);
+		return san + Character.toUpperCase(promotionPieceChar);
+	}
+
+	@Override
+	public int hashCode() {
+		final int	prime	= 31;
+		int			result	= super.hashCode();
+		result = prime * result + Objects.hash(promotionPieceChar, promotionPieceConstructor);
+		return result;
+	}
+
+	@Override
+	public boolean equals(Object obj) {
+		if (this == obj) return true;
+		if (!super.equals(obj)) return false;
+		if (!(obj instanceof PawnPromotion)) return false;
+		PawnPromotion other = (PawnPromotion) obj;
+		return promotionPieceChar == other.promotionPieceChar && Objects.equals(promotionPieceConstructor, other.promotionPieceConstructor);
+	}
+}

src/dev/kske/chess/board/Piece.java

@@ -2,18 +2,20 @@ package dev.kske.chess.board;
 
 import java.util.Iterator;
 import java.util.List;
+import java.util.Objects;
 
 /**
  * Project: <strong>Chess</strong><br>
  * File: <strong>Piece.java</strong><br>
  * Created: <strong>01.07.2019</strong><br>
- * Author: <strong>Kai S. K. Engelbart</strong>
+ * 
+ * @since Chess v0.1-alpha
+ * @author Kai S. K. Engelbart
  */
 public abstract class Piece implements Cloneable {
 
 	private final Color	color;
 	protected Board		board;
-	private int			moveCounter;
 
 	public Piece(Color color, Board board) {
 		this.color	= color;
@@ -35,8 +37,16 @@ public abstract class Piece implements Cloneable {
 
 	public abstract boolean isValidMove(Move move);
 
+	/**
+	 * Checks, if the squares between the position and the destination of a move are
+	 * free.
+	 * 
+	 * @param move The move to check
+	 */
 	protected boolean isFreePath(Move move) {
-		// Only check destination by default
+		for (int i = move.getPos().x + move.getxSign(), j = move.getPos().y + move.getySign(); i != move.getDest().x
+				|| j != move.getDest().y; i += move.getxSign(), j += move.getySign())
+			if (board.getBoardArr()[i][j] != null) return false;
 		return checkDestination(move);
 	}
 
@@ -47,9 +57,7 @@ public abstract class Piece implements Cloneable {
 	 * @param move The move to check
 	 * @return {@code false} if the move's destination is from the same team
 	 */
-	protected final boolean checkDestination(Move move) {
+	protected final boolean checkDestination(Move move) { return board.getDest(move) == null || board.getDest(move).getColor() != getColor(); }
-		return board.getDest(move) == null || board.getDest(move).getColor() != getColor();
-	}
 
 	@Override
 	public Object clone() {
@@ -62,29 +70,65 @@ public abstract class Piece implements Cloneable {
 		return piece;
 	}
 
-	public abstract Type getType();
+	@Override
+	public String toString() { return getClass().getSimpleName(); }
 
+	@Override
+	public int hashCode() { return Objects.hash(color); }
+
+	@Override
+	public boolean equals(Object obj) {
+		if (this == obj) return true;
+		if (obj == null) return false;
+		if (getClass() != obj.getClass()) return false;
+		Piece other = (Piece) obj;
+		return color == other.color;
+	}
+
+	/**
+	 * @return the standard value of this {@link Piece} that can be used for board
+	 *         evaluation
+	 */
+	public abstract int getValue();
+
+	/**
+	 * @return The first character of this {@link Piece} in algebraic notation and
+	 *         lower case
+	 */
+	public char firstChar() { return Character.toLowerCase(toString().charAt(0)); }
+
+	public static Class<? extends Piece> fromFirstChar(char firstChar) {
+		switch (Character.toLowerCase(firstChar)) {
+			case 'k':
+				return King.class;
+			case 'q':
+				return Queen.class;
+			case 'r':
+				return Rook.class;
+			case 'n':
+				return Knight.class;
+			case 'b':
+				return Bishop.class;
+			case 'p':
+				return Pawn.class;
+			default:
+				return null;
+		}
+	}
+
+	/**
+	 * @return the {@link Color} of this {@link Piece}
+	 */
 	public Color getColor() { return color; }
 
-	public int getMoveCounter() { return moveCounter; }
-
-	public void incMoveCounter() {
-		++moveCounter;
-	}
-
-	public void decMoveCounter() {
-		--moveCounter;
-	}
-
-	public static enum Type {
-		KING, QUEEN, ROOK, KNIGHT, BISHOP, PAWN
-	}
-
 	public static enum Color {
+
 		WHITE, BLACK;
 
-		public Color opposite() {
+		public static Color fromFirstChar(char c) { return Character.toLowerCase(c) == 'w' ? WHITE : BLACK; }
-			return this == WHITE ? BLACK : WHITE;
+
-		}
+		public char firstChar() { return this == WHITE ? 'w' : 'b'; }
+
+		public Color opposite() { return this == WHITE ? BLACK : WHITE; }
 	}
 }

src/dev/kske/chess/board/Position.java

@@ -4,7 +4,9 @@ package dev.kske.chess.board;
  * Project: <strong>Chess</strong><br>
  * File: <strong>Position.java</strong><br>
  * Created: <strong>02.07.2019</strong><br>
- * Author: <strong>Kai S. K. Engelbart</strong>
+ * 
+ * @since Chess v0.1-alpha
+ * @author Kai S. K. Engelbart
  */
 public class Position {
 
@@ -15,8 +17,36 @@ public class Position {
 		this.y	= y;
 	}
 
+	public static Position fromLAN(String pos) {
+		return new Position(pos.charAt(0) - 97, 8 - Character.getNumericValue(pos.charAt(1)));
+	}
+
+	public String toLAN() {
+		return String.valueOf((char) (x + 97)) + String.valueOf(8 - y);
+	}
+
 	@Override
 	public String toString() {
 		return String.format("[%d, %d]", x, y);
 	}
+
+	@Override
+	public int hashCode() {
+		final int	prime	= 31;
+		int			result	= 1;
+		result	= prime * result + x;
+		result	= prime * result + y;
+		return result;
+	}
+
+	@Override
+	public boolean equals(Object obj) {
+		if (this == obj) return true;
+		if (obj == null) return false;
+		if (getClass() != obj.getClass()) return false;
+		Position other = (Position) obj;
+		if (x != other.x) return false;
+		if (y != other.y) return false;
+		return true;
+	}
 }

src/dev/kske/chess/board/Queen.java

@@ -7,7 +7,9 @@ import java.util.List;
  * Project: <strong>Chess</strong><br>
  * File: <strong>Queen.java</strong><br>
  * Created: <strong>01.07.2019</strong><br>
- * Author: <strong>Kai S. K. Engelbart</strong>
+ * 
+ * @since Chess v0.1-alpha
+ * @author Kai S. K. Engelbart
  */
 public class Queen extends Piece {
 
@@ -20,22 +22,6 @@ public class Queen extends Piece {
 		return ((move.isHorizontal() || move.isVertical()) || move.isDiagonal()) && isFreePath(move);
 	}
 
-	@Override
-	protected boolean isFreePath(Move move) {
-		if (move.isHorizontal()) {
-			for (int i = move.pos.x + move.xSign; i != move.dest.x; i += move.xSign)
-				if (board.getBoardArr()[i][move.pos.y] != null) return false;
-		} else if (move.isVertical()) {
-			for (int i = move.pos.y + move.ySign; i != move.dest.y; i += move.ySign)
-				if (board.getBoardArr()[move.pos.x][i] != null) return false;
-		} else {
-			for (int i = move.pos.x + move.xSign, j = move.pos.y
-					+ move.ySign; i != move.dest.x; i += move.xSign, j += move.ySign)
-				if (board.getBoardArr()[i][j] != null) return false;
-		}
-		return checkDestination(move);
-	}
-
 	@Override
 	protected List<Move> getPseudolegalMoves(Position pos) {
 		List<Move> moves = new ArrayList<>();
@@ -115,5 +101,5 @@ public class Queen extends Piece {
 	}
 
 	@Override
-	public Type getType() { return Type.QUEEN; }
+	public int getValue() { return 90; }
 }

src/dev/kske/chess/board/Rook.java

@@ -7,7 +7,9 @@ import java.util.List;
  * Project: <strong>Chess</strong><br>
  * File: <strong>Rook.java</strong><br>
  * Created: <strong>01.07.2019</strong><br>
- * Author: <strong>Kai S. K. Engelbart</strong>
+ * 
+ * @since Chess v0.1-alpha
+ * @author Kai S. K. Engelbart
  */
 public class Rook extends Piece {
 
@@ -20,18 +22,6 @@ public class Rook extends Piece {
 		return (move.isHorizontal() || move.isVertical()) && isFreePath(move);
 	}
 
-	@Override
-	protected boolean isFreePath(Move move) {
-		if (move.isHorizontal()) {
-			for (int i = move.pos.x + move.xSign; i != move.dest.x; i += move.xSign)
-				if (board.getBoardArr()[i][move.pos.y] != null) return false;
-		} else {
-			for (int i = move.pos.y + move.ySign; i != move.dest.y; i += move.ySign)
-				if (board.getBoardArr()[move.pos.x][i] != null) return false;
-		}
-		return checkDestination(move);
-	}
-
 	@Override
 	protected List<Move> getPseudolegalMoves(Position pos) {
 		List<Move> moves = new ArrayList<>();
@@ -75,5 +65,5 @@ public class Rook extends Piece {
 	}
 
 	@Override
-	public Type getType() { return Type.ROOK; }
+	public int getValue() { return 50; }
 }

src/dev/kske/chess/event/Event.java

@@ -0,0 +1,17 @@
+package dev.kske.chess.event;
+
+/**
+ * Project: <strong>Chess</strong><br>
+ * File: <strong>Event.java</strong><br>
+ * Created: <strong>7 Aug 2019</strong><br>
+ * 
+ * @since Chess v0.4-alpha
+ * @author Kai S. K. Engelbart
+ */
+public interface Event<T> {
+
+	/**
+	 * @return The data associated with the event
+	 */
+	T getData();
+}

src/dev/kske/chess/event/EventBus.java

@@ -0,0 +1,38 @@
+package dev.kske.chess.event;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Project: <strong>Chess</strong><br>
+ * File: <strong>EventBus.java</strong><br>
+ * Created: <strong>7 Aug 2019</strong><br>
+ * 
+ * @since Chess v0.4-alpha
+ * @author Kai S. K. Engelbart
+ */
+public class EventBus {
+
+	private List<Subscribable> subscribers;
+
+	private static EventBus instance;
+
+	public static EventBus getInstance() {
+		if (instance == null) instance = new EventBus();
+		return instance;
+	}
+
+	private EventBus() {
+		subscribers = new ArrayList<>();
+	}
+
+	public void register(Subscribable subscribable) {
+		subscribers.add(subscribable);
+	}
+
+	public void dispatch(Event<?> event) {
+		subscribers.stream().filter(e -> e.supports().contains(event.getClass())).forEach(e -> e.handle(event));
+	}
+
+	public List<Subscribable> getSubscribers() { return subscribers; }
+}

src/dev/kske/chess/event/GameStartEvent.java

@@ -0,0 +1,21 @@
+package dev.kske.chess.event;
+
+import dev.kske.chess.game.Game;
+
+/**
+ * Project: <strong>Chess</strong><br>
+ * File: <strong>GameStartEvent.java</strong><br>
+ * Created: <strong>30 Oct 2019</strong><br>
+ * 
+ * @since Chess v0.5-alpha
+ * @author Kai S. K. Engelbart
+ */
+public class GameStartEvent implements Event<Game> {
+
+	private final Game game;
+
+	public GameStartEvent(Game source) { game = source; }
+
+	@Override
+	public Game getData() { return game; }
+}

src/dev/kske/chess/event/MoveEvent.java

@@ -0,0 +1,28 @@
+package dev.kske.chess.event;
+
+import dev.kske.chess.board.BoardState;
+import dev.kske.chess.board.Move;
+
+/**
+ * Project: <strong>Chess</strong><br>
+ * File: <strong>MoveEvent.java</strong><br>
+ * Created: <strong>7 Aug 2019</strong><br>
+ * 
+ * @since Chess v0.4-alpha
+ * @author Kai S. K. Engelbart
+ */
+public class MoveEvent implements Event<Move> {
+
+	private final Move move;
+	private final BoardState	boardState;
+
+	public MoveEvent(Move move, BoardState boardState) {
+		this.move = move;
+		this.boardState	= boardState;
+	}
+
+	@Override
+	public Move getData() { return move; }
+
+	public BoardState getBoardState() { return boardState; }
+}

src/dev/kske/chess/event/Subscribable.java

@@ -0,0 +1,26 @@
+package dev.kske.chess.event;
+
+import java.util.Set;
+
+/**
+ * Project: <strong>Chess</strong><br>
+ * File: <strong>Subscribable.java</strong><br>
+ * Created: <strong>7 Aug 2019</strong><br>
+ * 
+ * @since Chess v0.4-alpha
+ * @author Kai S. K. Engelbart
+ */
+public interface Subscribable {
+
+	/**
+	 * Consumes an event dispatched by an event bus.
+	 * 
+	 * @param event The event dispatched by the event bus, only of supported type
+	 */
+	void handle(Event<?> event);
+
+	/**
+	 * @return A set of classes this class is supposed to handle in events
+	 */
+	Set<Class<?>> supports();
+}

src/dev/kske/chess/exception/ChessException.java

@@ -0,0 +1,26 @@
+package dev.kske.chess.exception;
+
+/**
+ * Project: <strong>Chess</strong><br>
+ * File: <strong>ChessException.java</strong><br>
+ * Created: <strong>22 Sep 2019</strong><br>
+ * 
+ * @since Chess v0.5-alpha
+ * @author Kai S. K. Engelbart
+ */
+public class ChessException extends Exception {
+
+	private static final long serialVersionUID = -2208596063548245189L;
+
+	public ChessException(String message, Throwable cause) {
+		super(message, cause);
+	}
+
+	public ChessException(String message) {
+		super(message);
+	}
+
+	public ChessException(Throwable cause) {
+		super(cause);
+	}
+}

src/dev/kske/chess/game/Game.java

@@ -3,11 +3,18 @@ package dev.kske.chess.game;
 import java.util.HashMap;
 import java.util.Map;
 
+import javax.swing.JOptionPane;
+
 import dev.kske.chess.board.Board;
-import dev.kske.chess.board.GameState;
+import dev.kske.chess.board.BoardState;
 import dev.kske.chess.board.Move;
 import dev.kske.chess.board.Piece.Color;
+import dev.kske.chess.event.EventBus;
+import dev.kske.chess.event.GameStartEvent;
+import dev.kske.chess.event.MoveEvent;
 import dev.kske.chess.game.ai.AIPlayer;
+import dev.kske.chess.io.EngineUtil;
+import dev.kske.chess.io.EngineUtil.EngineInfo;
 import dev.kske.chess.ui.BoardComponent;
 import dev.kske.chess.ui.BoardPane;
 import dev.kske.chess.ui.OverlayComponent;
@@ -16,89 +23,124 @@ import dev.kske.chess.ui.OverlayComponent;
  * Project: <strong>Chess</strong><br>
  * File: <strong>Game.java</strong><br>
  * Created: <strong>06.07.2019</strong><br>
- * Author: <strong>Kai S. K. Engelbart</strong>
+ * 
+ * @since Chess v0.1-alpha
+ * @author Kai S. K. Engelbart
  */
 public class Game {
 
-	private Map<Color, Player>	players;
+	private Map<Color, Player>	players	= new HashMap<>();
 	private Board				board;
 	private OverlayComponent	overlayComponent;
 	private BoardComponent		boardComponent;
 
-	public Game(Map<Color, Player> players, BoardPane boardPane) {
+	public Game(BoardPane boardPane, String whiteName, String blackName) {
-		this.players			= players;
+		board = new Board();
-		this.overlayComponent	= boardPane.getOverlayComponent();
+		init(boardPane, whiteName, blackName);
-		this.boardComponent		= boardPane.getBoardComponent();
+	}
-		this.board				= new Board();
+
+	public Game(BoardPane boardPane, String whiteName, String blackName, Board board) {
+		this.board = board;
+		init(boardPane, whiteName, blackName);
+	}
+
+	private void init(BoardPane boardPane, String whiteName, String blackName) {
+
+		// Initialize / synchronize UI
+		overlayComponent	= boardPane.getOverlayComponent();
+		boardComponent		= boardPane.getBoardComponent();
 		boardComponent.setBoard(board);
 
+		// Initialize players
+		players.put(Color.WHITE, getPlayer(whiteName, Color.WHITE));
+		players.put(Color.BLACK, getPlayer(blackName, Color.BLACK));
+
 		// Initialize the game variable in each player
 		players.values().forEach(player -> player.setGame(this));
 	}
 
-	public static Game createNatural(BoardPane boardPane) {
+	private Player getPlayer(String name, Color color) {
-		Map<Color, Player>	players	= new HashMap<>();
+		switch (name) {
-		OverlayComponent	overlay	= boardPane.getOverlayComponent();
+			case "Natural Player":
-
+				return new NaturalPlayer(color, overlayComponent);
-		players.put(Color.WHITE, new NaturalPlayer(Color.WHITE, overlay));
+			case "AI Player":
-		players.put(Color.BLACK, new NaturalPlayer(Color.BLACK, overlay));
+				return new AIPlayer(color, 4, -10);
-		return new Game(players, boardPane);
+			default:
+				for (EngineInfo info : EngineUtil.getEngineInfos())
+					if (info.name.equals(name)) return new UCIPlayer(color, info.path);
+				System.err.println("Invalid player name: " + name);
+				return null;
 		}
-
-	public static Game createNaturalVsAI(BoardPane boardPane, int maxDepth, int alphaBeta) {
-		Map<Color, Player>	players	= new HashMap<>();
-		OverlayComponent	overlay	= boardPane.getOverlayComponent();
-
-		players.put(Color.WHITE, new NaturalPlayer(Color.WHITE, overlay));
-		players.put(Color.BLACK, new AIPlayer(Color.BLACK, maxDepth, alphaBeta));
-		return new Game(players, boardPane);
-	}
-
-	public static Game createAIVsAI(BoardPane boardPane, int maxDepthW, int maxDepthB, int alphaBetaW, int alphaBetaB) {
-		Map<Color, Player> players = new HashMap<>();
-
-		players.put(Color.WHITE, new AIPlayer(Color.WHITE, maxDepthW, alphaBetaW));
-		players.put(Color.BLACK, new AIPlayer(Color.BLACK, maxDepthB, alphaBetaB));
-		return new Game(players, boardPane);
 	}
 
 	public void onMove(Player player, Move move) {
 		if (board.getPos(move).getColor() == player.color && board.attemptMove(move)) {
-			System.out.printf("%s: %s%n", player.color, move);
+
-			GameState eventType = board.getGameEventType(board.getDest(move).getColor().opposite());
+			// Redraw
-			switch (eventType) {
+			boardComponent.repaint();
+			overlayComponent.displayArrow(move);
+
+			// Run garbage collection
+			System.gc();
+
+			BoardState boardState = board.getGameEventType(board.getDest(move).getColor().opposite());
+			EventBus.getInstance().dispatch(new MoveEvent(move, boardState));
+			switch (boardState) {
 				case CHECKMATE:
 				case STALEMATE:
-					System.out.printf("%s in %s!%n", player.color.opposite(), eventType);
+					String result = String.format("%s in %s!%n", player.color.opposite(), boardState);
+					System.out.print(result);
+					JOptionPane.showMessageDialog(boardComponent, result);
 					break;
 				case CHECK:
 					System.out.printf("%s in check!%n", player.color.opposite());
 				default:
-					boardComponent.repaint();
+					players.get(board.getLog().getActiveColor()).requestMove();
-					players.get(player.color.opposite()).requestMove();
 			}
-			overlayComponent.displayArrow(move);
 		} else player.requestMove();
 	}
 
 	public void start() {
-		players.get(Color.WHITE).requestMove();
+		EventBus.getInstance().dispatch(new GameStartEvent(this));
+		players.get(board.getLog().getActiveColor()).requestMove();
 	}
 
 	public void reset() {
-		players.forEach((k, v) -> v.cancelMove());
+		players.values().forEach(Player::cancelMove);
-		board.initializeDefaultPositions();
+		board.initDefaultPositions();
 		boardComponent.repaint();
 		overlayComponent.clearDots();
 		overlayComponent.clearArrow();
 	}
 
 	/**
-	 * Removed all connections between the game and the ui.
+	 * Stops the game by disconnecting its players form the UI.
 	 */
-	public void disconnect() {
+	public void stop() {
 		players.values().forEach(Player::disconnect);
 	}
 
-	public Board getBoard() { return board; }
+	/**
+	 * Assigns the players their opposite colors.
+	 */
+	public void swapColors() {
+		players.values().forEach(Player::cancelMove);
+		Player	white	= players.get(Color.WHITE);
+		Player	black	= players.get(Color.BLACK);
+		white.setColor(Color.BLACK);
+		black.setColor(Color.WHITE);
+		players.put(Color.WHITE, black);
+		players.put(Color.BLACK, white);
+		players.get(board.getLog().getActiveColor()).requestMove();
+	}
+
+	/**
+	 * @return The board on which this game's moves are made
+	 */
+	public Board getBoard() { return board; }
+
+	/**
+	 * @return The players participating in this game
+	 */
+	public Map<Color, Player> getPlayers() { return players; }
 }

src/dev/kske/chess/game/NaturalPlayer.java

@@ -5,9 +5,11 @@ import java.awt.event.MouseListener;
 import java.util.List;
 import java.util.stream.Collectors;
 
-import dev.kske.chess.board.Board;
+import javax.swing.JComboBox;
+import javax.swing.JOptionPane;
+
 import dev.kske.chess.board.Move;
-import dev.kske.chess.board.Move.Type;
+import dev.kske.chess.board.Piece;
 import dev.kske.chess.board.Piece.Color;
 import dev.kske.chess.board.Position;
 import dev.kske.chess.ui.OverlayComponent;
@@ -16,61 +18,85 @@ import dev.kske.chess.ui.OverlayComponent;
  * Project: <strong>Chess</strong><br>
  * File: <strong>NaturalPlayer.java</strong><br>
  * Created: <strong>06.07.2019</strong><br>
- * Author: <strong>Kai S. K. Engelbart</strong>
+ * 
+ * @since Chess v0.1-alpha
+ * @author Kai S. K. Engelbart
  */
 public class NaturalPlayer extends Player implements MouseListener {
 
 	private final OverlayComponent overlayComponent;
 
 	private boolean		moveRequested;
-	private Position	pos;
+	private Piece		selectedPiece;
+	private List<Move>	possibleMoves;
 
 	public NaturalPlayer(Color color, OverlayComponent overlayComponent) {
 		super(color);
 		this.overlayComponent	= overlayComponent;
+		name					= "Player";
 		moveRequested			= false;
 
 		overlayComponent.addMouseListener(this);
 	}
 
 	@Override
-	public void requestMove() {
+	public void requestMove() { moveRequested = true; }
-		moveRequested = true;
-	}
 
 	@Override
-	public void cancelMove() {
+	public void cancelMove() { moveRequested = false; }
-		moveRequested = false;
-	}
 
 	@Override
-	public void disconnect() {
+	public void disconnect() { overlayComponent.removeMouseListener(this); }
-		overlayComponent.removeMouseListener(this);
-	}
 
 	@Override
 	public void mousePressed(MouseEvent evt) {
 		if (!moveRequested) return;
-		if (pos == null) {
+		if (selectedPiece == null) {
-			pos = new Position(evt.getPoint().x / overlayComponent.getTileSize(),
-					evt.getPoint().y / overlayComponent.getTileSize());
 
-			Board board = (Board) NaturalPlayer.this.board.clone();
+			// Get selected Piece
-			if (board.get(pos) != null && board.get(pos).getColor() == color) {
+			final Position pos = new Position(evt.getPoint().x / overlayComponent.getTileSize(), evt.getPoint().y / overlayComponent.getTileSize());
-				List<Position> positions = board.getMoves(pos)
+			selectedPiece = board.get(pos);
-					.stream()
+
-					.map(move -> move.dest)
+			// Check if a piece was selected
-					.collect(Collectors.toList());
+			if (selectedPiece != null) {
-				overlayComponent.displayDots(positions);
+
-			} else pos = null;
+				// Discard selection if the piece has the wrong color
+				if (selectedPiece.getColor() == color.opposite()) selectedPiece = null;
+				else {
+
+					// Generate all moves possible with the selected piece and display their
+					// destinations
+					possibleMoves = selectedPiece.getMoves(pos);
+					overlayComponent.displayDots(possibleMoves.stream().map(move -> move.getDest()).collect(Collectors.toList()));
+				}
+			}
 		} else {
-			Position dest = new Position(evt.getPoint().x / overlayComponent.getTileSize(),
+			Position dest = new Position(evt.getPoint().x / overlayComponent.getTileSize(), evt.getPoint().y / overlayComponent.getTileSize());
-					evt.getPoint().y / overlayComponent.getTileSize());
 
-			overlayComponent.clearDots();
+			// Get all moves leading to the specified destination
+			List<Move> selectedMoves = possibleMoves.stream().filter(m -> m.getDest().equals(dest)).collect(Collectors.toList());
+			if (!selectedMoves.isEmpty()) {
+				Move move;
+
+				// Process pawn promotion if necessary
+				if (selectedMoves.size() > 1) {
+
+					// Let the user select a promotion piece
+					JComboBox<Move> comboBox = new JComboBox<Move>(selectedMoves.toArray(new Move[0]));
+					JOptionPane.showMessageDialog(overlayComponent, comboBox, "Select a promotion", JOptionPane.QUESTION_MESSAGE);
+
+					move = selectedMoves.get(comboBox.getSelectedIndex());
+				} else move = selectedMoves.get(0);
+
+				// Tell the game to execute the move
 				moveRequested = false;
-			game.onMove(NaturalPlayer.this, new Move(pos, dest, Type.UNKNOWN));
+				game.onMove(NaturalPlayer.this, move);
-			pos = null;
+			}
+
+			// Discard the selection
+			overlayComponent.clearDots();
+			selectedPiece	= null;
+			possibleMoves	= null;
 		}
 	}
 

src/dev/kske/chess/game/Player.java

@@ -7,13 +7,16 @@ import dev.kske.chess.board.Piece.Color;
  * Project: <strong>Chess</strong><br>
  * File: <strong>Player.java</strong><br>
  * Created: <strong>06.07.2019</strong><br>
- * Author: <strong>Kai S. K. Engelbart</strong>
+ * 
+ * @since Chess v0.1-alpha
+ * @author Kai S. K. Engelbart
  */
 public abstract class Player {
 
 	protected Game		game;
 	protected Board		board;
 	protected Color		color;
+	protected String	name;
 
 	public Player(Color color) {
 		this.color = color;
@@ -39,4 +42,8 @@ public abstract class Player {
 	public Color getColor() { return color; }
 
 	public void setColor(Color color) { this.color = color; }
+
+	public String getName() { return name; }
+
+	public void setName(String name) { this.name = name; }
 }

src/dev/kske/chess/game/UCIPlayer.java

@@ -0,0 +1,95 @@
+package dev.kske.chess.game;
+
+import java.io.IOException;
+
+import dev.kske.chess.board.FENString;
+import dev.kske.chess.board.Move;
+import dev.kske.chess.board.Piece.Color;
+import dev.kske.chess.uci.UCIHandle;
+import dev.kske.chess.uci.UCIListener;
+
+/**
+ * Project: <strong>Chess</strong><br>
+ * File: <strong>UCIPlayer.java</strong><br>
+ * Created: <strong>18.07.2019</strong><br>
+ * 
+ * @since Chess v0.3-alpha
+ * @author Kai S. K. Engelbart
+ */
+public class UCIPlayer extends Player implements UCIListener {
+
+	private UCIHandle		handle;
+
+	public UCIPlayer(Color color, String enginePath) {
+		super(color);
+		try {
+			handle = new UCIHandle(enginePath);
+			handle.setListener(this);
+			handle.start();
+		} catch (IOException ex) {
+			ex.printStackTrace();
+		}
+	}
+
+	@Override
+	public void requestMove() {
+		handle.positionFEN(new FENString(board).toString());
+		handle.go();
+	}
+
+	@Override
+	public void cancelMove() {
+		handle.stop();
+	}
+
+	@Override
+	public void disconnect() {
+		handle.quit();
+	}
+
+	@Override
+	public void onIdName(String name) {
+		this.name = name;
+	}
+
+	@Override
+	public void onBestMove(String move) {
+		Move moveObj = Move.fromLAN(move);
+		game.onMove(this, moveObj);
+	}
+
+	@Override
+	public void onBestMove(String move, Move ponderMove) {
+		onBestMove(move);
+	}
+
+	@Override
+	public void onCopyProtectionChecking() {
+		System.out.println("Copy protection checking...");
+	}
+
+	@Override
+	public void onCopyProtectionOk() {
+		System.out.println("Copy protection ok");
+	}
+
+	@Override
+	public void onCopyProtectionError() {
+		System.err.println("Copy protection error!");
+	}
+
+	@Override
+	public void onRegistrationChecking() {
+		System.out.println("Registration checking...");
+	}
+
+	@Override
+	public void onRegistrationOk() {
+		System.out.println("Registration ok");
+	}
+
+	@Override
+	public void onRegistrationError() {
+		System.err.println("Registration error!");
+	}
+}

src/dev/kske/chess/game/ai/AIPlayer.java

@@ -19,7 +19,9 @@ import dev.kske.chess.game.Player;
  * Project: <strong>Chess</strong><br>
  * File: <strong>AIPlayer.java</strong><br>
  * Created: <strong>06.07.2019</strong><br>
- * Author: <strong>Kai S. K. Engelbart</strong>
+ * 
+ * @since Chess v0.1-alpha
+ * @author Kai S. K. Engelbart
  */
 public class AIPlayer extends Player {
 
@@ -32,6 +34,7 @@ public class AIPlayer extends Player {
 
 	public AIPlayer(Color color, int maxDepth, int alphaBetaThreshold) {
 		super(color);
+		name					= "AIPlayer";
 		availableProcessors		= Runtime.getRuntime().availableProcessors();
 		this.maxDepth			= maxDepth;
 		this.alphaBetaThreshold	= alphaBetaThreshold;
@@ -49,7 +52,7 @@ public class AIPlayer extends Player {
 			/*
 			 * Get a copy of the board and the available moves.
 			 */
-			Board		board	= (Board) AIPlayer.this.board.clone();
+			Board		board	= new Board(this.board, false);
 			List<Move>	moves	= board.getMoves(color);
 
 			/*
@@ -63,7 +66,7 @@ public class AIPlayer extends Player {
 			for (int i = 0; i < numThreads; i++) {
 				if (rem-- > 0) ++endIndex;
 				endIndex += step;
-				processors.add(new MoveProcessor((Board) board.clone(), moves.subList(beginIndex, endIndex), color,
+				processors.add(new MoveProcessor(new Board(board, false), moves.subList(beginIndex, endIndex), color,
 						maxDepth, alphaBetaThreshold));
 				beginIndex = endIndex;
 			}

src/dev/kske/chess/game/ai/MoveProcessor.java

@@ -1,17 +1,28 @@
 package dev.kske.chess.game.ai;
 
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 import java.util.concurrent.Callable;
 
+import dev.kske.chess.board.Bishop;
 import dev.kske.chess.board.Board;
+import dev.kske.chess.board.King;
+import dev.kske.chess.board.Knight;
 import dev.kske.chess.board.Move;
+import dev.kske.chess.board.Pawn;
+import dev.kske.chess.board.Piece;
 import dev.kske.chess.board.Piece.Color;
+import dev.kske.chess.board.Queen;
+import dev.kske.chess.board.Rook;
 
 /**
  * Project: <strong>Chess</strong><br>
  * File: <strong>MoveProcessor.java</strong><br>
  * Created: <strong>08.07.2019</strong><br>
- * Author: <strong>Kai S. K. Engelbart</strong>
+ * 
+ * @since Chess v0.1-alpha
+ * @author Kai S. K. Engelbart
  */
 public class MoveProcessor implements Callable<ProcessingResult> {
 
@@ -23,6 +34,40 @@ public class MoveProcessor implements Callable<ProcessingResult> {
 
 	private Move bestMove;
 
+	private static final Map<Class<? extends Piece>, int[][]> positionScores;
+
+	static {
+		positionScores = new HashMap<>();
+		positionScores.put(King.class,
+				new int[][] { new int[] { -3, -4, -4, -5, -5, -4, -4, -3 }, new int[] { -3, -4, -4, -5, -4, -4, -4, -3 },
+						new int[] { -3, -4, -4, -5, -4, -4, -4, -3 }, new int[] { -3, -4, -4, -5, -4, -4, -4, -3 },
+						new int[] { -2, -3, -3, -2, -2, -2, -2, -1 }, new int[] { -1, -2, -2, -2, -2, -2, -2, -1 },
+						new int[] { 2, 2, 0, 0, 0, 0, 2, 2 }, new int[] { 2, 3, 1, 0, 0, 1, 3, 2 } });
+		positionScores.put(Queen.class,
+				new int[][] { new int[] { -2, -1, -1, -1, -1, -1, -1, -2 }, new int[] { -1, 0, 0, 0, 0, 0, 0, -1 },
+						new int[] { -1, 0, 1, 1, 1, 1, 0, -1 }, new int[] { -1, 0, 1, 1, 1, 1, 0, -1 }, new int[] { 0, 0, 1, 1, 1, 1, 0, -1 },
+						new int[] { -1, 1, 1, 1, 1, 1, 0, -1 }, new int[] { -1, 0, 1, 0, 0, 0, 0, -1 },
+						new int[] { -2, -1, -1, -1, -1, -1, -1, -2 } });
+		positionScores.put(Rook.class,
+				new int[][] { new int[] { 0, 0, 0, 0, 0, 0, 0, 0 }, new int[] { 1, 1, 1, 1, 1, 1, 1, 1 }, new int[] { -1, 0, 0, 0, 0, 0, 0, -1 },
+						new int[] { -1, 0, 0, 0, 0, 0, 0, -1 }, new int[] { -1, 0, 0, 0, 0, 0, 0, -1 }, new int[] { -1, 0, 0, 0, 0, 0, 0, -1 },
+						new int[] { -1, 0, 0, 0, 0, 0, 0, -1 }, new int[] { 0, 0, 0, 1, 1, 0, 0, 0 } });
+		positionScores.put(Knight.class,
+				new int[][] { new int[] { -5, -4, -3, -3, -3, -3, -4, -5 }, new int[] { -4, -2, 0, 0, 0, 0, -2, -4 },
+						new int[] { -3, 0, 1, 2, 2, 1, 0, -3 }, new int[] { -3, 1, 2, 2, 2, 2, 1, -3 }, new int[] { -3, 0, 2, 2, 2, 2, 0, -1 },
+						new int[] { -3, 1, 1, 2, 2, 1, 1, -3 }, new int[] { -4, -2, 0, 1, 1, 0, -2, -4 },
+						new int[] { -5, -4, -3, -3, -3, -3, -4, -5 } });
+		positionScores.put(Bishop.class,
+				new int[][] { new int[] { -2, -1, -1, -1, -1, -1, -1, 2 }, new int[] { -1, 0, 0, 0, 0, 0, 0, -1 },
+						new int[] { -1, 0, 1, 1, 1, 1, 0, -1 }, new int[] { -1, 1, 1, 1, 1, 1, 1, -1 }, new int[] { -1, 0, 1, 1, 1, 1, 0, -1 },
+						new int[] { -1, 1, 1, 1, 1, 1, 1, -1 }, new int[] { -1, 1, 0, 0, 0, 0, 1, -1 },
+						new int[] { -2, -1, -1, -1, -1, -1, -1, -2 } });
+		positionScores.put(Pawn.class,
+				new int[][] { new int[] { 0, 0, 0, 0, 0, 0, 0, 0 }, new int[] { 5, 5, 5, 5, 5, 5, 5, 5 }, new int[] { 1, 1, 2, 3, 3, 2, 1, 1 },
+						new int[] { 0, 0, 1, 3, 3, 1, 0, 0 }, new int[] { 0, 0, 0, 2, 2, 0, 0, 0 }, new int[] { 0, 0, -1, 0, 0, -1, 0, 0 },
+						new int[] { 0, 1, 1, -2, -2, 1, 1, 0 }, new int[] { 0, 0, 0, 0, 0, 0, 0, 0 } });
+	}
+
 	public MoveProcessor(Board board, List<Move> rootMoves, Color color, int maxDepth, int alphaBetaThreshold) {
 		this.board				= board;
 		this.rootMoves			= rootMoves;
@@ -41,8 +86,8 @@ public class MoveProcessor implements Callable<ProcessingResult> {
 		int bestValue = Integer.MIN_VALUE;
 		for (Move move : moves) {
 			board.move(move);
-			int		teamValue		= board.evaluate(color);
+			int	teamValue	= evaluate(board, color);
-			int		enemyValue		= board.evaluate(color.opposite());
+			int	enemyValue	= evaluate(board, color.opposite());
 			int	valueChange	= teamValue - enemyValue;
 
 			if (depth < maxDepth && valueChange >= alphaBetaThreshold)
@@ -57,4 +102,22 @@ public class MoveProcessor implements Callable<ProcessingResult> {
 		}
 		return bestValue;
 	}
+
+	/**
+	 * Evaluated a board.
+	 * 
+	 * @param color The color to evaluate for
+	 * @return An positive number representing how good the position is
+	 */
+	private int evaluate(Board board, Color color) {
+		int score = 0;
+		for (int i = 0; i < 8; i++)
+			for (int j = 0; j < 8; j++)
+				if (board.getBoardArr()[i][j] != null && board.getBoardArr()[i][j].getColor() == color) {
+					score += board.getBoardArr()[i][j].getValue();
+					if (positionScores.containsKey(board.getBoardArr()[i][j].getClass()))
+						score += positionScores.get(board.getBoardArr()[i][j].getClass())[i][color == Color.WHITE ? j : 7 - j];
+				}
+		return score;
+	}
 }

src/dev/kske/chess/game/ai/ProcessingResult.java

@@ -6,7 +6,9 @@ import dev.kske.chess.board.Move;
  * Project: <strong>Chess</strong><br>
  * File: <strong>ProcessingResult.java</strong><br>
  * Created: <strong>08.07.2019</strong><br>
- * Author: <strong>Kai S. K. Engelbart</strong>
+ * 
+ * @since Chess v0.1-alpha
+ * @author Kai S. K. Engelbart
  */
 public class ProcessingResult {
 

src/dev/kske/chess/io/EngineUtil.java

@@ -0,0 +1,101 @@
+package dev.kske.chess.io;
+
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.io.Serializable;
+import java.util.ArrayList;
+import java.util.List;
+
+import dev.kske.chess.uci.UCIHandle;
+import dev.kske.chess.uci.UCIListener;
+
+/**
+ * Project: <strong>Chess</strong><br>
+ * File: <strong>MenuBar.java</strong><br>
+ * Created: <strong>23.07.2019</strong><br>
+ * 
+ * @since Chess v0.2-alpha
+ * @author Kai S. K. Engelbart
+ * @author Leon Hofmeister
+ */
+public class EngineUtil {
+
+	private static volatile List<EngineInfo> engineInfos;
+
+	private static final String engineInfoFile = "engine_infos.ser";
+
+	static {
+		loadEngineInfos();
+	}
+
+	private EngineUtil() {}
+
+	public static void addEngine(String enginePath) {
+		try {
+			EngineInfo	info	= new EngineInfo(enginePath);
+			UCIHandle	handle	= new UCIHandle(enginePath);
+			handle.setListener(new UCIListener() {
+
+				@Override
+				public void onIdName(String name) {
+					info.name = name;
+				}
+
+				@Override
+				public void onIdAuthor(String author) {
+					info.author = author;
+				}
+
+				@Override
+				public void onUCIOk() {
+					engineInfos.add(info);
+					handle.quit();
+					saveEngineInfos();
+				}
+			});
+			handle.start();
+		} catch (IOException ex) {
+			ex.printStackTrace();
+		}
+	}
+
+	@SuppressWarnings("unchecked")
+	private static void loadEngineInfos() {
+		try (ObjectInputStream in = new ObjectInputStream(new FileInputStream(engineInfoFile))) {
+			Object obj = in.readObject();
+			if (obj instanceof ArrayList<?>) engineInfos = (ArrayList<EngineInfo>) obj;
+			else throw new IOException("Serialized object has the wrong class.");
+		} catch (ClassNotFoundException | IOException ex) {
+			engineInfos = new ArrayList<>();
+		}
+	}
+
+	private static void saveEngineInfos() {
+		try (ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream(engineInfoFile))) {
+			out.writeObject(engineInfos);
+		} catch (IOException ex) {
+			ex.printStackTrace();
+		}
+	}
+
+	public static class EngineInfo implements Serializable {
+
+		private static final long serialVersionUID = -474177108900833005L;
+
+		public String path, name, author;
+
+		public EngineInfo(String path) {
+			this.path = path;
+		}
+
+		@Override
+		public String toString() {
+			return name + " by " + author + " at " + path;
+		}
+	}
+
+	public static List<EngineInfo> getEngineInfos() { return engineInfos; }
+}

src/dev/kske/chess/io/TextureUtil.java

@@ -1,4 +1,4 @@
-package dev.kske.chess.ui;
+package dev.kske.chess.io;
 
 import java.awt.Image;
 import java.awt.image.BufferedImage;
@@ -15,15 +15,15 @@ import dev.kske.chess.board.Piece;
  * Project: <strong>Chess</strong><br>
  * File: <strong>TextureUtil.java</strong><br>
  * Created: <strong>01.07.2019</strong><br>
- * Author: <strong>Kai S. K. Engelbart</strong>
+ * 
+ * @since Chess v0.1-alpha
+ * @author Kai S. K. Engelbart
  */
 public class TextureUtil {
 
-	private static Map<String, Image> textures, scaledTextures;
+	private static Map<String, Image> textures = new HashMap<>(), scaledTextures = new HashMap<>();
 
 	static {
-		textures = new HashMap<>();
-		scaledTextures	= new HashMap<>();
 		loadPieceTextures();
 		scaledTextures.putAll(textures);
 	}
@@ -31,23 +31,24 @@ public class TextureUtil {
 	private TextureUtil() {}
 
 	/**
-	 * Loads a piece texture fitting to a piece object
+	 * Loads a piece texture fitting to a piece object.
 	 * 
 	 * @param piece The piece from which the texture properties are taken
 	 * @return The fitting texture
 	 */
 	public static Image getPieceTexture(Piece piece) {
-		String key = piece.getType().toString().toLowerCase() + "_" + piece.getColor().toString().toLowerCase();
+		String key = piece.toString().toLowerCase() + "_" + piece.getColor().toString().toLowerCase();
 		return scaledTextures.get(key);
 	}
 
 	/**
-	 * Scales all piece textures to fit the current tile size
+	 * Scales all piece textures to fit the current tile size.
+	 * 
+	 * @param tileSize the new width and height of the piece textures
 	 */
-	public static void scalePieceTextures(int scale) {
+	public static void scalePieceTextures(int tileSize) {
 		scaledTextures.clear();
-		textures
+		textures.forEach((key, img) -> scaledTextures.put(key, img.getScaledInstance(tileSize, tileSize, Image.SCALE_SMOOTH)));
-			.forEach((key, img) -> scaledTextures.put(key, img.getScaledInstance(scale, scale, Image.SCALE_SMOOTH)));
 	}
 
 	/**
@@ -86,5 +87,4 @@ public class TextureUtil {
 					"pawn_black")
 			.forEach(name -> textures.put(name, loadImage("/pieces/" + name + ".png")));
 	}
-
 }

src/dev/kske/chess/pgn/PGNDatabase.java

@@ -0,0 +1,56 @@
+package dev.kske.chess.pgn;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Scanner;
+
+import dev.kske.chess.exception.ChessException;
+
+/**
+ * Project: <strong>Chess</strong><br>
+ * File: <strong>PGNDatabase.java</strong><br>
+ * Created: <strong>4 Oct 2019</strong><br>
+ * <br>
+ * Contains a series of {@link PGNGame} objects that can be stored inside a PGN
+ * file.
+ * 
+ * @since Chess v0.5-alpha
+ * @author Kai S. K. Engelbart
+ */
+public class PGNDatabase {
+
+	private final List<PGNGame> games = new ArrayList<>();
+
+	/**
+	 * Loads PGN games from a file.
+	 * 
+	 * @param pgnFile the file to load the games from
+	 * @throws FileNotFoundException if the specified file is not found
+	 * @throws ChessException        if an error occurs while parsing the file
+	 */
+	public void load(File pgnFile) throws FileNotFoundException, ChessException {
+		Scanner sc = new Scanner(pgnFile);
+		while (sc.hasNext())
+			games.add(PGNGame.parse(sc));
+		sc.close();
+	}
+
+	/**
+	 * Saves PGN games to a file.
+	 * 
+	 * @param pgnFile the file to save the games to.
+	 * @throws IOException if the file could not be created
+	 */
+	public void save(File pgnFile) throws IOException {
+		pgnFile.getParentFile().mkdirs();
+		PrintWriter pw = new PrintWriter(pgnFile);
+		games.forEach(g -> g.writePGN(pw));
+		pw.close();
+	}
+
+	public List<PGNGame> getGames() { return games; }
+}

src/dev/kske/chess/pgn/PGNGame.java

@@ -0,0 +1,121 @@
+package dev.kske.chess.pgn;
+
+import java.io.PrintWriter;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Scanner;
+import java.util.regex.MatchResult;
+import java.util.regex.Pattern;
+
+import dev.kske.chess.board.Board;
+import dev.kske.chess.board.FENString;
+import dev.kske.chess.board.Move;
+import dev.kske.chess.board.Piece.Color;
+import dev.kske.chess.exception.ChessException;
+
+/**
+ * Project: <strong>Chess</strong><br>
+ * File: <strong>PGNGame.java</strong><br>
+ * Created: <strong>22 Sep 2019</strong><br>
+ *
+ * @since Chess v0.5-alpha
+ * @author Kai S. K. Engelbart
+ */
+public class PGNGame {
+
+	private final Map<String, String>	tagPairs	= new HashMap<>(7);
+	private final Board					board;
+
+	public PGNGame() { board = new Board(); }
+
+	public PGNGame(Board board) { this.board = board; }
+
+	public static PGNGame parse(Scanner sc) throws ChessException {
+		PGNGame game = new PGNGame();
+
+		MatchResult	matchResult;
+		Pattern		tagPairPattern	= Pattern.compile("\\[(\\w+) \"(.*)\"]"),
+				movePattern = Pattern.compile("\\d+\\.\\s+(?:(?:(\\S+)\\s+(\\S+))|(?:O-O-O)|(?:O-O))(?:\\+{0,2}|\\#)"),
+				nagPattern = Pattern.compile("(\\$\\d{1,3})*"), terminationMarkerPattern = Pattern.compile("1-0|0-1|1\\/2-1\\/2|\\*");
+
+		// Parse tag pairs
+		while (sc.findInLine(tagPairPattern) != null) {
+			matchResult = sc.match();
+			if (matchResult.groupCount() == 2) game.setTag(matchResult.group(1), matchResult.group(2));
+			else break;
+			sc.nextLine();
+		}
+
+		// Parse movetext
+		while (true) {
+			// Skip NAG (Numeric Annotation Glyph)
+			sc.skip(nagPattern);
+
+			// TODO: Parse RAV (Recursive Annotation Variation)
+
+			if (sc.findWithinHorizon(movePattern, 20) != null) {
+				matchResult = sc.match();
+				if (matchResult.groupCount() > 0) for (int i = 1; i < matchResult.groupCount() + 1; i++) {
+					game.board.move(matchResult.group(i));
+					System.out.println(game.getBoard().getLog().getLast().move.toLAN() + ": " + new FENString(game.board).toString());
+				}
+				else break;
+			} else break;
+		}
+
+		// Parse game termination marker
+		if (sc.findWithinHorizon(terminationMarkerPattern, 20) == null) System.err.println("Termination marker expected");
+
+		return game;
+	}
+
+	public void writePGN(PrintWriter pw) {
+		// Set the unknown result tag if no result tag is specified
+		tagPairs.putIfAbsent("Result", "*");
+
+		// Write tag pairs
+		tagPairs.forEach((k, v) -> pw.printf("[%s \"%s\"]%n", k, v));
+
+		// Insert newline if tags were printed
+		if (!tagPairs.isEmpty()) pw.println();
+
+		if (!board.getLog().isEmpty()) {
+			// Collect SAN moves
+			Board			clone	= new Board(board, true);
+			List<String>	chunks	= new ArrayList<>();
+			boolean			flag	= true;
+			while (flag) {
+				Move move = clone.getLog().getLast().move;
+				flag = clone.getLog().hasParent();
+				clone.revert();
+				String chunk = clone.getLog().getActiveColor() == Color.WHITE ? String.format(" %d. ", clone.getLog().getFullmoveNumber()) : " ";
+				chunk += move.toSAN(clone);
+				chunks.add(chunk);
+			}
+			Collections.reverse(chunks);
+
+			// Write movetext
+			String line = "";
+			for (String chunk : chunks)
+				if (line.length() + chunk.length() <= 80) line += chunk;
+				else {
+					pw.println(line);
+					line = chunk;
+				}
+			if (!line.isEmpty()) pw.println(line);
+		}
+		// Write game termination marker
+		pw.print(tagPairs.get("Result"));
+	}
+
+	public String getTag(String tagName) { return tagPairs.get(tagName); }
+
+	public boolean hasTag(String tagName) { return tagPairs.containsKey(tagName); }
+
+	public void setTag(String tagName, String tagValue) { tagPairs.put(tagName, tagValue); }
+
+	public Board getBoard() { return board; }
+}

src/dev/kske/chess/uci/UCIHandle.java

@@ -0,0 +1,200 @@
+package dev.kske.chess.uci;
+
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.util.List;
+import java.util.StringJoiner;
+
+import dev.kske.chess.board.Move;
+
+/**
+ * Project: <strong>Chess</strong><br>
+ * File: <strong>UCIHandle.java</strong><br>
+ * Created: <strong>18.07.2019</strong><br>
+ * 
+ * @since Chess v0.3-alpha
+ * @author Kai S. K. Engelbart
+ */
+public class UCIHandle {
+
+	private final Process		process;
+	private final PrintWriter	out;
+	private final UCIReceiver	receiver;
+
+	public UCIHandle(String enginePath) throws IOException {
+		process		= new ProcessBuilder(enginePath).start();
+		out			= new PrintWriter(process.getOutputStream(), true);
+		receiver	= new UCIReceiver(process.getInputStream());
+	}
+
+	public void start() {
+		new Thread(receiver, "UCI Receiver").start();
+		uci();
+	}
+
+	/**
+	 * Tells the engine to use UCI.
+	 */
+	public void uci() { out.println("uci"); }
+
+	/**
+	 * Switches the debug mode of the engine on or off.
+	 * 
+	 * @param debug Enables debugging if set to {@code true}, disables it otherwise
+	 */
+	public void debug(boolean debug) { out.println("debug " + (debug ? "on" : "off")); }
+
+	/**
+	 * Synchronized the engine with the GUI
+	 */
+	public void isready() { out.println("isready"); }
+
+	/**
+	 * Signifies a button press to the engine.
+	 * 
+	 * @param name The name of the button
+	 */
+	public void setOption(String name) { out.println("setoption name " + name); }
+
+	/**
+	 * Changes an internal parameter of the engine.
+	 * 
+	 * @param name  The name of the parameter
+	 * @param value The value of the parameter
+	 */
+	public void setOption(String name, String value) { out.printf("setoption name %s value %s%n", name, value); }
+
+	/**
+	 * Registers the engine
+	 * 
+	 * @param name The name the engine should be registered with
+	 * @param code The code the engine should be registered with
+	 */
+	public void register(String name, String code) { out.printf("register %s %s%n", name, code); }
+
+	/**
+	 * Tells the engine to postpone the registration.
+	 */
+	public void registerLater() { out.println("register later"); }
+
+	/**
+	 * Tells the engine that the next search will be from a different game.
+	 */
+	public void uciNewGame() { out.println("ucinewgame"); }
+
+	/**
+	 * Sets up the position in its initial state.
+	 */
+	public void positionStartpos() { out.println("position startpos"); }
+
+	/**
+	 * Sets up the position described in the FEN string.
+	 * 
+	 * @param fen FEN representation of the current board
+	 */
+	public void positionFEN(String fen) { out.println("position fen " + fen); }
+
+	/**
+	 * Sets up the position described by a list of moves.
+	 * 
+	 * @param moves the moves to execute from the starting position to reach the
+	 *              desired position
+	 */
+	public void positionMoves(List<Move> moves) {
+		StringJoiner joiner = new StringJoiner(" ");
+		moves.forEach(m -> joiner.add(m.toLAN()));
+		out.println("position moves " + joiner);
+	}
+
+	/**
+	 * Starts calculating on the current position.
+	 */
+	public void go() { out.println("go"); }
+
+	/**
+	 * Starts calculating on the current position.
+	 * This command has multiple optional parameters which will only be included in
+	 * the call if they are not {@code null}, greater than zero or {@code true} for
+	 * {@code searchMoves}, all integer parameters and all boolean parameters
+	 * respectively.
+	 * 
+	 * @param searchMoves restrict the search to these moves only
+	 * @param ponder      start the search in ponder mode
+	 * @param wTime       the amount of milliseconds left on white's clock
+	 * @param bTime       the amount of milliseconds left on black's clocks
+	 * @param wInc        white's increment per move in milliseconds
+	 * @param bInc        black's increment per move in milliseconds
+	 * @param movesToGo   the number of moves left until the next time control
+	 * @param depth       the maximal amount of plies to search
+	 * @param nodes       the maximal amount of nodes to search
+	 * @param mate        the amount of moves in which to search for a mate
+	 * @param moveTime    the exact search time
+	 * @param infinite    search until the {@code stop} command
+	 */
+	public void go(List<Move> searchMoves, boolean ponder, int wTime, int bTime, int wInc, int bInc, int movesToGo, int depth, int nodes, int mate,
+			int moveTime, boolean infinite) {
+		StringJoiner joiner = new StringJoiner(" ");
+		joiner.add("go");
+
+		if (searchMoves != null && !searchMoves.isEmpty()) {
+			joiner.add("searchmoves");
+			searchMoves.forEach(m -> joiner.add(m.toLAN()));
+		}
+		if (ponder) joiner.add("ponder");
+		if (wTime > 0) {
+			joiner.add("wtime");
+			joiner.add(String.valueOf(wTime));
+		}
+		if (bTime > 0) {
+			joiner.add("btime");
+			joiner.add(String.valueOf(bTime));
+		}
+		if (wInc > 0) {
+			joiner.add("winc");
+			joiner.add(String.valueOf(wInc));
+		}
+		if (bInc > 0) {
+			joiner.add("bind");
+			joiner.add(String.valueOf(bInc));
+		}
+		if (movesToGo > 0) {
+			joiner.add("movestogo");
+			joiner.add(String.valueOf(movesToGo));
+		}
+		if (depth > 0) {
+			joiner.add("depth");
+			joiner.add(String.valueOf(depth));
+		}
+		if (nodes > 0) {
+			joiner.add("nodes");
+			joiner.add(String.valueOf(nodes));
+		}
+		if (mate > 0) {
+			joiner.add("mate");
+			joiner.add(String.valueOf(mate));
+		}
+		if (moveTime > 0) {
+			joiner.add("movetime");
+			joiner.add(String.valueOf(moveTime));
+		}
+		if (infinite) joiner.add("infinite");
+		out.println(joiner);
+	}
+
+	/**
+	 * Stops calculation as soon as possible.
+	 */
+	public void stop() { out.println("stop"); }
+
+	/**
+	 * Tells the engine that the user has played the expected move.
+	 */
+	public void ponderHit() { out.println("ponderhit"); }
+
+	/**
+	 * Quits the engine process as soon as possible.
+	 */
+	public void quit() { out.println("quit"); }
+
+	public void setListener(UCIListener listener) { receiver.addListener(listener); }
+}

src/dev/kske/chess/uci/UCIInfo.java

@@ -0,0 +1,202 @@
+package dev.kske.chess.uci;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import dev.kske.chess.board.Move;
+
+/**
+ * Project: <strong>Chess</strong><br>
+ * File: <strong>UCIInfo.java</strong><br>
+ * Created: <strong>28.07.2019</strong><br>
+ * 
+ * @since Chess v0.3-alpha
+ * @author Kai S. K. Engelbart
+ */
+public class UCIInfo {
+
+	private int							depth, seldepth, time, nodes, multipv, currmovenumber, hashfull, nps, tbhits, sbhits, cpuload, cpunr;
+	private List<Move>					pv			= new ArrayList<>(), refutation = new ArrayList<>();
+	private Map<Integer, List<Move>>	currline	= new HashMap<>();
+	private Move						currmove;
+	private Score						score;
+	private String						displayString;
+
+	/**
+	 * Contains every parameter for the UCI info command. Helpful for parsing
+	 * multi-value parameters.
+	 */
+	private static final List<String> params = Arrays.asList("depth",
+			"seldepth",
+			"time",
+			"nodes",
+			"multipv",
+			"currmove",
+			"currmovenumber",
+			"hashfull",
+			"nps",
+			"tbhits",
+			"sbhits",
+			"cpuload",
+			"string",
+			"score",
+			"pv",
+			"refutation",
+			"currline");
+
+	public UCIInfo(String line) {
+		String[] tokens = line.split(" ");
+
+		for (int i = 0; i < tokens.length; i++)
+			switch (tokens[i]) {
+				// Single parameter info
+				case "depth":
+					depth = Integer.parseInt(tokens[++i]);
+					break;
+				case "seldepth":
+					seldepth = Integer.parseInt(tokens[++i]);
+					break;
+				case "time":
+					time = Integer.parseInt(tokens[++i]);
+					break;
+				case "nodes":
+					nodes = Integer.parseInt(tokens[++i]);
+					break;
+				case "multipv":
+					multipv = Integer.parseInt(tokens[++i]);
+					break;
+				case "currmove":
+					currmove = Move.fromLAN(tokens[++i]);
+					break;
+				case "currmovenumber":
+					currmovenumber = Integer.parseInt(tokens[++i]);
+					break;
+				case "hashfull":
+					hashfull = Integer.parseInt(tokens[++i]);
+					break;
+				case "nps":
+					nps = Integer.parseInt(tokens[++i]);
+					break;
+				case "tbhits":
+					tbhits = Integer.parseInt(tokens[++i]);
+					break;
+				case "sbhits":
+					sbhits = Integer.parseInt(tokens[++i]);
+					break;
+				case "cpuload":
+					cpuload = Integer.parseInt(tokens[++i]);
+					break;
+				case "string":
+					displayString = tokens[++i];
+					break;
+				case "score":
+					score = new Score(line.substring(line.indexOf("score") + tokens[i].length() + 1));
+					i += score.getLength() + 1;
+					break;
+				case "pv":
+					while (++i < tokens.length && !params.contains(tokens[i]))
+						pv.add(Move.fromLAN(tokens[i]));
+					break;
+				case "refutation":
+					while (++i < tokens.length && !params.contains(tokens[i]))
+						refutation.add(Move.fromLAN(tokens[i]));
+					break;
+				case "currline":
+					// A CPU number of 1 can be omitted
+					final Integer cpu = tokens[i].matches("\\d+") ? Integer.valueOf(tokens[i++]) : 1;
+					final ArrayList<Move> moves = new ArrayList<>();
+					while (i < tokens.length && !params.contains(tokens[i]))
+						moves.add(Move.fromLAN(tokens[i++]));
+					currline.put(cpu, moves);
+					System.err.println("The parameter 'currline' for command 'info' is not yet implemented");
+					break;
+				default:
+					System.err.printf("Unknown parameter '%s' for command 'info' found!%n", tokens[i]);
+			}
+	}
+
+	public int getDepth() { return depth; }
+
+	public int getSeldepth() { return seldepth; }
+
+	public int getTime() { return time; }
+
+	public int getNodes() { return nodes; }
+
+	public int getMultipv() { return multipv; }
+
+	public int getCurrmovenumber() { return currmovenumber; }
+
+	public int getHashfull() { return hashfull; }
+
+	public int getNps() { return nps; }
+
+	public int getTbhits() { return tbhits; }
+
+	public int getSbhits() { return sbhits; }
+
+	public int getCpuload() { return cpuload; }
+
+	public int getCpunr() { return cpunr; }
+
+	public List<Move> getPv() { return pv; }
+
+	public List<Move> getRefutation() { return refutation; }
+
+	public Map<Integer, List<Move>> getCurrline() { return currline; }
+
+	public Move getCurrmove() { return currmove; }
+
+	public Score getScore() { return score; }
+
+	public String getDisplayString() { return displayString; }
+
+	public static class Score {
+
+		private int		cp, mate;
+		private boolean	lowerbound, upperbound;
+		private int		length;
+
+		public Score(String line) {
+			String[]	tokens	= line.split(" ");
+			int			i		= 0;
+			for (; i < tokens.length; i++) {
+				if (params.contains(tokens[i])) break;
+				switch (tokens[i]) {
+					case "cp":
+						cp = Integer.parseInt(tokens[++i]);
+						break;
+					case "mate":
+						mate = Integer.parseInt(tokens[++i]);
+						break;
+					case "lowerbound":
+						lowerbound = true;
+						break;
+					case "upperbound":
+						upperbound = true;
+						break;
+					default:
+						System.err.printf("Unknown parameter '%s' for command 'score' found!%n", tokens[i]);
+				}
+			}
+			length = i + 1;
+		}
+
+		public int getCp() { return cp; }
+
+		public int getMate() { return mate; }
+
+		public boolean isLowerbound() { return lowerbound; }
+
+		public boolean isUpperbound() { return upperbound; }
+
+		/**
+		 * @return The number of tokens this 'score' command contains (including
+		 *         itself).
+		 */
+		public int getLength() { return length; }
+	}
+}

src/dev/kske/chess/uci/UCIListener.java

@@ -0,0 +1,97 @@
+package dev.kske.chess.uci;
+
+import dev.kske.chess.board.Move;
+
+/**
+ * Project: <strong>Chess</strong><br>
+ * File: <strong>UCIListener.java</strong><br>
+ * Created: <strong>19.07.2019</strong><br>
+ * 
+ * @since Chess v0.3-alpha
+ * @author Kai S. K. Engelbart
+ */
+public interface UCIListener {
+
+	/**
+	 * Identifies the name of the engine.
+	 * 
+	 * @param name The name of the engine
+	 */
+	default void onIdName(String name) {}
+
+	/**
+	 * Identifies the author of the engine.
+	 * 
+	 * @param author The name of the engine's author
+	 */
+	default void onIdAuthor(String author) {}
+
+	/**
+	 * The engine is ready in UCI mode.
+	 */
+	default void onUCIOk() {}
+
+	/**
+	 * The engine has processed all inputs and is ready for new commands.
+	 */
+	default void onReadyOk() {}
+
+	/**
+	 * The engine has stopped searching and has found the best move.
+	 * 
+	 * @param move The best moves the engine has found
+	 */
+	default void onBestMove(String move) {}
+
+	/**
+	 * The engine has stopped searching and has found the best move.
+	 * 
+	 * @param move       The best move the engine has found
+	 * @param ponderMove The move the engine likes to ponder on
+	 */
+	default void onBestMove(String move, Move ponderMove) {}
+
+	/**
+	 * The engine will check the copy protection now.
+	 */
+	default void onCopyProtectionChecking() {}
+
+	/**
+	 * The engine has successfully checked the copy protection.
+	 */
+	default void onCopyProtectionOk() {}
+
+	/**
+	 * The engine has encountered an error during copy protection checking.
+	 */
+	default void onCopyProtectionError() {}
+
+	/**
+	 * The engine will check the registration now.
+	 */
+	default void onRegistrationChecking() {}
+
+	/**
+	 * The engine has successfully checked the registration.
+	 */
+	default void onRegistrationOk() {}
+
+	/**
+	 * The engine has encountered an error during registration checking.
+	 */
+	default void onRegistrationError() {}
+
+	/**
+	 * The engine sends information to the GUI.
+	 * 
+	 * @param info Contains all pieces of information to be sent
+	 */
+	default void onInfo(UCIInfo info) {}
+
+	/**
+	 * Tells the GUI which parameters can be changed in the engine.
+	 * 
+	 * @param option Option object describing the parameter
+	 */
+	default void onOption(UCIOption option) {}
+}

src/dev/kske/chess/uci/UCIOption.java

@@ -0,0 +1,70 @@
+package dev.kske.chess.uci;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.StringJoiner;
+
+/**
+ * Project: <strong>Chess</strong><br>
+ * File: <strong>UCIOption.java</strong><br>
+ * Created: <strong>22.07.2019</strong><br>
+ * 
+ * @since Chess v0.3-alpha
+ * @author Kai S. K. Engelbart
+ */
+public class UCIOption {
+
+	private String			name, defaultVal, minVal, maxVal;
+	private GUIType			type;
+	private List<String>	varList;
+
+	public UCIOption(String line) {
+		varList = new ArrayList<>();
+		String[] tokens = line.split(" ");
+
+		for (int i = 0; i < tokens.length; i++)
+			switch (tokens[i]) {
+				case "name":
+					StringJoiner nameJoiner = new StringJoiner(" ");
+					while (!Arrays.asList("type", "default", "min", "max", "var").contains(tokens[i + 1]))
+						nameJoiner.add(tokens[++i]);
+					name = nameJoiner.toString();
+					break;
+				case "type":
+					type = GUIType.valueOf(tokens[++i].toUpperCase());
+					break;
+				case "default":
+					// Default string may be empty
+					defaultVal = i == tokens.length - 1 ? "" : tokens[++i];
+					break;
+				case "min":
+					minVal = tokens[++i];
+					break;
+				case "max":
+					maxVal = tokens[++i];
+					break;
+				case "var":
+					varList.add(tokens[++i]);
+					break;
+				default:
+					System.err.printf("Unknown parameter '%s' for command 'option' found!%n", tokens[i]);
+			}
+	}
+
+	public String getName() { return name; }
+
+	public String getDefaultVal() { return defaultVal; }
+
+	public String getMinVal() { return minVal; }
+
+	public String getMaxVal() { return maxVal; }
+
+	public GUIType getType() { return type; }
+
+	public List<String> getVarList() { return varList; }
+
+	public static enum GUIType {
+		CHECK, SPIN, COMBO, BUTTON, STRING
+	}
+}

src/dev/kske/chess/uci/UCIReceiver.java

@@ -0,0 +1,139 @@
+package dev.kske.chess.uci;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.util.ArrayList;
+import java.util.List;
+
+import dev.kske.chess.board.Move;
+
+/**
+ * Project: <strong>Chess</strong><br>
+ * File: <strong>UCIReceiver.java</strong><br>
+ * Created: <strong>19.07.2019</strong><br>
+ * 
+ * @since Chess v0.3-alpha
+ * @author Kai S. K. Engelbart
+ */
+public class UCIReceiver implements Runnable {
+
+	private final BufferedReader in;
+
+	private List<UCIListener> listeners;
+
+	public UCIReceiver(InputStream in) {
+		this.in		= new BufferedReader(new InputStreamReader(in));
+		listeners	= new ArrayList<>();
+	}
+
+	@Override
+	public void run() {
+		String line;
+		while (!Thread.currentThread().isInterrupted())
+			try {
+				if ((line = in.readLine()) != null && !line.isEmpty()) parse(line);
+			} catch (IndexOutOfBoundsException ex) {
+				System.err.println("Too few arguments were provided!");
+				ex.printStackTrace();
+			} catch (IOException ex) {
+				ex.printStackTrace();
+			}
+	}
+
+	private void parse(String line) {
+		int		spaceIndex	= line.indexOf(' ');
+		String	command		= spaceIndex == -1 ? line : line.substring(0, spaceIndex);
+		switch (command) {
+			case "id":
+				parseId(line.substring(command.length() + 1));
+				break;
+			case "uciok":
+				listeners.forEach(UCIListener::onUCIOk);
+				break;
+			case "readyok":
+				listeners.forEach(UCIListener::onReadyOk);
+				break;
+			case "bestmove":
+				parseBestMove(line.substring(command.length() + 1));
+				break;
+			case "copyprotection":
+				parseCopyProtection(line.substring(command.length() + 1));
+				break;
+			case "registration":
+				parseRegistration(line.substring(command.length() + 1));
+				break;
+			case "info":
+				parseInfo(line.substring(command.length() + 1));
+				break;
+			case "option":
+				parseOption(line.substring(command.length() + 1));
+				break;
+			default:
+				System.err.printf("Unknown command '%s' found!%n", command);
+		}
+	}
+
+	private void parseId(String line) {
+		String	param	= line.substring(0, line.indexOf(' '));
+		String	arg		= line.substring(param.length() + 1);
+		switch (param) {
+			case "name":
+				listeners.forEach(l -> l.onIdName(arg));
+				break;
+			case "author":
+				listeners.forEach(l -> l.onIdAuthor(arg));
+				break;
+			default:
+				System.err.printf("Unknown parameter '%s' for command 'id' found!%n", param);
+		}
+	}
+
+	private void parseBestMove(String line) {
+		String[]	tokens	= line.split(" ");
+		String		move	= tokens[0];
+
+		// Ponder move
+		if (tokens.length == 3) listeners.forEach(l -> l.onBestMove(move, Move.fromLAN(tokens[2])));
+		else listeners.forEach(l -> l.onBestMove(move));
+	}
+
+	private void parseCopyProtection(String line) {
+		switch (line) {
+			case "checking":
+				listeners.forEach(UCIListener::onCopyProtectionChecking);
+				break;
+			case "ok":
+				listeners.forEach(UCIListener::onCopyProtectionOk);
+				break;
+			case "error":
+				listeners.forEach(UCIListener::onCopyProtectionError);
+				break;
+			default:
+				System.err.printf("Unknown parameter '%s' for command 'copyprotection' found!%n", line);
+		}
+	}
+
+	private void parseRegistration(String line) {
+		switch (line) {
+			case "checking":
+				listeners.forEach(UCIListener::onRegistrationChecking);
+				break;
+			case "ok":
+				listeners.forEach(UCIListener::onRegistrationOk);
+				break;
+			case "error":
+				listeners.forEach(UCIListener::onRegistrationError);
+				break;
+			default:
+				System.err.printf("Unknown parameter '%s' for command 'registration' found!%n", line);
+		}
+	}
+
+	private void parseInfo(String line) { listeners.forEach(l -> l.onInfo(new UCIInfo(line))); }
+
+	private void parseOption(String line) { listeners.forEach(l -> l.onOption(new UCIOption((line)))); }
+
+	public void addListener(UCIListener listener) { listeners.add(listener); }
+}

src/dev/kske/chess/ui/AIConfigDialog.java

@@ -12,8 +12,11 @@ import javax.swing.SpinnerNumberModel;
  * Project: <strong>Chess</strong><br>
  * File: <strong>AIConfigDialog.java</strong><br>
  * Created: <strong>16.07.2019</strong><br>
- * Author: <strong>Kai S. K. Engelbart</strong>
+ * 
+ * @since Chess v0.1-alpha
+ * @author Kai S. K. Engelbart
  */
+@Deprecated
 public class AIConfigDialog extends JDialog {
 
 	private static final long serialVersionUID = -8047984368152479992L;
@@ -78,5 +81,4 @@ public class AIConfigDialog extends JDialog {
 	public boolean isStartGame() { return startGame; }
 
 	public void setStartGame(boolean startGame) { this.startGame = startGame; }
-
 }

src/dev/kske/chess/ui/BoardComponent.java

@@ -6,16 +6,19 @@ import java.awt.Graphics;
 import javax.swing.JComponent;
 
 import dev.kske.chess.board.Board;
+import dev.kske.chess.io.TextureUtil;
 
 /**
  * Project: <strong>Chess</strong><br>
  * File: <strong>BoardComponent.java</strong><br>
  * Created: <strong>01.07.2019</strong><br>
- * Author: <strong>Kai S. K. Engelbart</strong><br>
  * <br>
  * A square panel for rendering the chess board. To work correctly,
  * this must be added to a parent component that allows the child to decide the
  * size.
+ * 
+ * @since Chess v0.1-alpha
+ * @author Kai S. K. Engelbart
  */
 public class BoardComponent extends JComponent {
 
@@ -47,8 +50,8 @@ public class BoardComponent extends JComponent {
 		// Draw the pieces if a board is present
 		if (board != null) for (int i = 0; i < 8; i++)
 			for (int j = 0; j < 8; j++)
-				if (board.getBoardArr()[i][j] != null) g.drawImage(TextureUtil
+				if (board.getBoardArr()[i][j] != null)
-					.getPieceTexture(board.getBoardArr()[i][j]), i * tileSize, j * tileSize, this);
+					g.drawImage(TextureUtil.getPieceTexture(board.getBoardArr()[i][j]), i * tileSize, j * tileSize, this);
 	}
 
 	public int getTileSize() { return boardPane.getTileSize(); }

src/dev/kske/chess/ui/BoardPane.java

@@ -1,8 +1,6 @@
 package dev.kske.chess.ui;
 
 import java.awt.Dimension;
-import java.awt.event.ComponentAdapter;
-import java.awt.event.ComponentEvent;
 
 import javax.swing.JLayeredPane;
 
@@ -10,7 +8,9 @@ import javax.swing.JLayeredPane;
  * Project: <strong>Chess</strong><br>
  * File: <strong>BoardPane.java</strong><br>
  * Created: <strong>08.07.2019</strong><br>
- * Author: <strong>Kai S. K. Engelbart</strong>
+ * 
+ * @since Chess v0.1-alpha
+ * @author Kai S. K. Engelbart
  */
 public class BoardPane extends JLayeredPane {
 
@@ -24,23 +24,13 @@ public class BoardPane extends JLayeredPane {
 	public BoardPane() {
 		boardComponent		= new BoardComponent(this);
 		overlayComponent	= new OverlayComponent(this);
+		setLayer(overlayComponent, 1);
+		setLayout(null);
 
-		add(boardComponent, Integer.valueOf(1));
+		add(boardComponent);
-		add(overlayComponent, Integer.valueOf(2));
+		add(overlayComponent);
 
-		/*
+		tileSize = 60;
-		 * Add a component listener for adjusting the tile size on resizing.
-		 * The size of the board is assumed to be 8x8, as well as the both the board and
-		 * the tiles being square.
-		 */
-		addComponentListener(new ComponentAdapter() {
-
-			@Override
-			public void componentResized(ComponentEvent e) {
-				tileSize = getWidth() / 8;
-				TextureUtil.scalePieceTextures(tileSize);
-			}
-		});
 		setSize(getPreferredSize());
 	}
 

src/dev/kske/chess/ui/DialogUtil.java

@@ -0,0 +1,82 @@
+package dev.kske.chess.ui;
+
+import java.awt.Component;
+import java.awt.Font;
+import java.io.File;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.List;
+import java.util.function.BiConsumer;
+import java.util.function.Consumer;
+
+import javax.swing.DefaultComboBoxModel;
+import javax.swing.JComboBox;
+import javax.swing.JFileChooser;
+import javax.swing.JLabel;
+import javax.swing.JOptionPane;
+import javax.swing.JPanel;
+import javax.swing.filechooser.FileNameExtensionFilter;
+
+import dev.kske.chess.io.EngineUtil;
+
+/**
+ * Project: <strong>Chess</strong><br>
+ * File: <strong>DialogUtil.java</strong><br>
+ * Created: <strong>24.07.2019</strong><br>
+ *
+ * @since Chess v0.3-alpha
+ * @author Kai S. K. Engelbart
+ */
+public class DialogUtil {
+
+	private DialogUtil() {}
+
+	public static void showFileSelectionDialog(Component parent, Consumer<List<File>> action, Collection<FileNameExtensionFilter> filters) {
+		JFileChooser fileChooser = new JFileChooser();
+		fileChooser.setCurrentDirectory(new File(System.getProperty("user.home")));
+		fileChooser.setAcceptAllFileFilterUsed(false);
+		filters.forEach(fileChooser::addChoosableFileFilter);
+		if (fileChooser.showOpenDialog(parent) == JFileChooser.APPROVE_OPTION) action.accept(Arrays.asList(fileChooser.getSelectedFile()));
+	}
+
+	public static void showFileSaveDialog(Component parent, Consumer<File> action, Collection<FileNameExtensionFilter> filters) {
+		JFileChooser fileChooser = new JFileChooser();
+		fileChooser.setCurrentDirectory(new File(System.getProperty("user.home")));
+		fileChooser.setAcceptAllFileFilterUsed(false);
+		filters.forEach(fileChooser::addChoosableFileFilter);
+		if (fileChooser.showSaveDialog(parent) == JFileChooser.APPROVE_OPTION) action.accept(
+				new File(fileChooser.getSelectedFile().getAbsolutePath() + "."
+						+ ((FileNameExtensionFilter) fileChooser.getFileFilter()).getExtensions()[0]));
+	}
+
+	public static void showGameConfigurationDialog(Component parent, BiConsumer<String, String> action) {
+		JPanel dialogPanel = new JPanel();
+
+		List<String> options = new ArrayList<>(Arrays.asList("Natural Player", "AI Player"));
+		EngineUtil.getEngineInfos().forEach(info -> options.add(info.name));
+
+		JLabel lblWhite = new JLabel("White:");
+		lblWhite.setFont(new Font("Tahoma", Font.PLAIN, 14));
+		lblWhite.setBounds(10, 11, 49, 14);
+		dialogPanel.add(lblWhite);
+
+		JComboBox<Object> cbWhite = new JComboBox<>();
+		cbWhite.setModel(new DefaultComboBoxModel<>(options.toArray()));
+		cbWhite.setBounds(98, 9, 159, 22);
+		dialogPanel.add(cbWhite);
+
+		JLabel lblBlack = new JLabel("Black:");
+		lblBlack.setFont(new Font("Tahoma", Font.PLAIN, 14));
+		lblBlack.setBounds(10, 38, 49, 14);
+		dialogPanel.add(lblBlack);
+
+		JComboBox<Object> cbBlack = new JComboBox<>();
+		cbBlack.setModel(new DefaultComboBoxModel<>(options.toArray()));
+		cbBlack.setBounds(98, 36, 159, 22);
+		dialogPanel.add(cbBlack);
+
+		JOptionPane.showMessageDialog(parent, dialogPanel, "Game configuration", JOptionPane.QUESTION_MESSAGE);
+		action.accept(options.get(cbWhite.getSelectedIndex()), options.get(cbBlack.getSelectedIndex()));
+	}
+}

src/dev/kske/chess/ui/GameDropTarget.java

@@ -0,0 +1,37 @@
+package dev.kske.chess.ui;
+
+import java.awt.datatransfer.DataFlavor;
+import java.awt.datatransfer.UnsupportedFlavorException;
+import java.awt.dnd.DnDConstants;
+import java.awt.dnd.DropTargetAdapter;
+import java.awt.dnd.DropTargetDropEvent;
+import java.io.File;
+import java.io.IOException;
+import java.util.List;
+
+/**
+ * Project: <strong>Chess</strong><br>
+ * File: <strong>GameDropTarget.java</strong><br>
+ * Created: <strong>13 Aug 2019</strong><br>
+ * 
+ * @since Chess v0.3-alpha
+ * @author Kai S. K. Engelbart
+ */
+public class GameDropTarget extends DropTargetAdapter {
+
+	private MainWindow mainWindow;
+
+	public GameDropTarget(MainWindow mainWindow) { this.mainWindow = mainWindow; }
+
+	@SuppressWarnings("unchecked")
+	@Override
+	public void drop(DropTargetDropEvent evt) {
+		try {
+			evt.acceptDrop(DnDConstants.ACTION_COPY_OR_MOVE);
+			mainWindow.loadFiles((List<File>) evt.getTransferable().getTransferData(DataFlavor.javaFileListFlavor));
+		} catch (UnsupportedFlavorException | IOException ex) {
+			ex.printStackTrace();
+			evt.rejectDrop();
+		}
+	}
+}

src/dev/kske/chess/ui/GamePane.java

@@ -0,0 +1,199 @@
+package dev.kske.chess.ui;
+
+import java.awt.GridBagConstraints;
+import java.awt.GridBagLayout;
+import java.awt.GridLayout;
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.Set;
+
+import javax.swing.DefaultListModel;
+import javax.swing.JButton;
+import javax.swing.JComponent;
+import javax.swing.JLabel;
+import javax.swing.JList;
+import javax.swing.JPanel;
+import javax.swing.JScrollPane;
+import javax.swing.ListSelectionModel;
+
+import dev.kske.chess.board.BoardState;
+import dev.kske.chess.board.MoveNode;
+import dev.kske.chess.board.Piece.Color;
+import dev.kske.chess.event.Event;
+import dev.kske.chess.event.EventBus;
+import dev.kske.chess.event.GameStartEvent;
+import dev.kske.chess.event.MoveEvent;
+import dev.kske.chess.event.Subscribable;
+import dev.kske.chess.game.Game;
+import dev.kske.chess.game.NaturalPlayer;
+
+/**
+ * Project: <strong>Chess</strong><br>
+ * File: <strong>GamePane.java</strong><br>
+ * Created: <strong>23.08.2019</strong><br>
+ * 
+ * @since Chess v0.4-alpha
+ * @author Kai S. K. Engelbart
+ */
+public class GamePane extends JComponent {
+
+	private static final long serialVersionUID = 4349772338239617477L;
+
+	private JButton		btnRestart, btnSwapColors;
+	private BoardPane	boardPane;
+	private Game		game;
+	private Color		activeColor;
+	private JPanel		moveSelectionPanel;
+	private JButton		btnNext;
+	private JButton		btnFirst;
+	private JButton		btnLast;
+
+	public GamePane() {
+		activeColor = Color.WHITE;
+
+		GridBagLayout gridBagLayout = new GridBagLayout();
+		gridBagLayout.columnWidths	= new int[] { 450, 1, 0 };
+		gridBagLayout.rowHeights	= new int[] { 33, 267, 1, 0 };
+		gridBagLayout.columnWeights	= new double[] { 0.0, 1.0, 1.0 };
+		gridBagLayout.rowWeights	= new double[] { 1.0, 1.0, 1.0, Double.MIN_VALUE };
+		setLayout(gridBagLayout);
+
+		JPanel toolPanel = new JPanel();
+		btnRestart = new JButton("Restart");
+		btnRestart.addActionListener((evt) -> {
+			if (game != null) {
+				game.reset();
+				game.start();
+			}
+		});
+
+		btnSwapColors = new JButton("Play as black");
+		btnSwapColors.addActionListener((evt) -> {
+			game.swapColors();
+			btnSwapColors.setText("Play as " + activeColor.toString().toLowerCase());
+			activeColor = activeColor.opposite();
+		});
+
+		toolPanel.add(btnRestart);
+		toolPanel.add(btnSwapColors);
+
+		GridBagConstraints gbc_toolPanel = new GridBagConstraints();
+		gbc_toolPanel.anchor	= GridBagConstraints.NORTH;
+		gbc_toolPanel.fill		= GridBagConstraints.HORIZONTAL;
+		gbc_toolPanel.gridx		= 0;
+		gbc_toolPanel.gridy		= 0;
+		gbc_toolPanel.gridwidth	= 2;
+		add(toolPanel, gbc_toolPanel);
+
+		moveSelectionPanel = new JPanel();
+		GridBagConstraints gbc_moveSelectionPanel = new GridBagConstraints();
+		gbc_moveSelectionPanel.fill		= GridBagConstraints.BOTH;
+		gbc_moveSelectionPanel.gridx	= 2;
+		gbc_moveSelectionPanel.gridy	= 0;
+		add(moveSelectionPanel, gbc_moveSelectionPanel);
+
+		btnFirst = new JButton("First");
+		btnFirst.setEnabled(false);
+		moveSelectionPanel.add(btnFirst);
+
+		JButton btnPreviousMove = new JButton("Previous");
+		btnPreviousMove.setEnabled(false);
+		moveSelectionPanel.add(btnPreviousMove);
+
+		btnNext = new JButton("Next");
+		btnNext.setEnabled(false);
+		moveSelectionPanel.add(btnNext);
+
+		btnLast = new JButton("Last");
+		btnLast.setEnabled(false);
+		moveSelectionPanel.add(btnLast);
+		boardPane = new BoardPane();
+		GridBagConstraints gbc_boardPane = new GridBagConstraints();
+		gbc_boardPane.fill	= GridBagConstraints.BOTH;
+		gbc_boardPane.gridx	= 0;
+		gbc_boardPane.gridy	= 1;
+		add(boardPane, gbc_boardPane);
+
+		JPanel				numberPanel		= new JPanel(new GridLayout(8, 1));
+		GridBagConstraints	gbc_numberPanel	= new GridBagConstraints();
+		gbc_numberPanel.anchor	= GridBagConstraints.WEST;
+		gbc_numberPanel.fill	= GridBagConstraints.VERTICAL;
+		gbc_numberPanel.gridx	= 1;
+		gbc_numberPanel.gridy	= 1;
+		add(numberPanel, gbc_numberPanel);
+
+		JPanel				letterPanel		= new JPanel(new GridLayout(1, 8));
+		GridBagConstraints	gbc_letterPanel	= new GridBagConstraints();
+		gbc_letterPanel.anchor	= GridBagConstraints.NORTH;
+		gbc_letterPanel.fill	= GridBagConstraints.HORIZONTAL;
+		gbc_letterPanel.gridx	= 0;
+		gbc_letterPanel.gridy	= 2;
+		add(letterPanel, gbc_letterPanel);
+
+		// Initialize board coordinates
+		for (int i = 0; i < 8; i++) {
+			numberPanel.add(new JLabel(String.valueOf(8 - i)));
+			JLabel letterLabel = new JLabel(String.valueOf((char) (65 + i)));
+			letterLabel.setHorizontalAlignment(JLabel.CENTER);
+			letterPanel.add(letterLabel);
+		}
+
+		JScrollPane			scrollPane		= new JScrollPane();
+		GridBagConstraints	gbc_scrollPane	= new GridBagConstraints();
+		gbc_scrollPane.fill		= GridBagConstraints.BOTH;
+		gbc_scrollPane.gridx	= 2;
+		gbc_scrollPane.gridy	= 1;
+		add(scrollPane, gbc_scrollPane);
+
+		JList<MoveNode> pgnList = new JList<>();
+		pgnList.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
+		pgnList.setLayoutOrientation(JList.HORIZONTAL_WRAP);
+		pgnList.setVisibleRowCount(0);
+		pgnList.setCellRenderer(new MoveNodeRenderer());
+		scrollPane.setViewportView(pgnList);
+
+		// Listen to moves and game (re-)starts and update the move list or disable the
+		// color switching buttons if necessary
+		EventBus.getInstance().register(new Subscribable() {
+
+			@Override
+			public void handle(Event<?> event) {
+				if (event instanceof MoveEvent && (((MoveEvent) event).getBoardState() == BoardState.CHECKMATE
+						|| ((MoveEvent) event).getBoardState() == BoardState.STALEMATE))
+					btnSwapColors.setEnabled(false);
+				else if (event instanceof GameStartEvent) btnSwapColors.setEnabled(
+						game.getPlayers().get(Color.WHITE) instanceof NaturalPlayer ^ game.getPlayers().get(Color.BLACK) instanceof NaturalPlayer);
+
+				if (game.getBoard().getLog() == null) return;
+
+				DefaultListModel<MoveNode> model = new DefaultListModel<>();
+				game.getBoard().getLog().forEach(node -> model.addElement(node));
+				pgnList.setModel(model);
+			}
+
+			@Override
+			public Set<Class<?>> supports() { return new HashSet<>(Arrays.asList(MoveEvent.class, GameStartEvent.class)); }
+		});
+	}
+
+	/**
+	 * @return The {@link BoardPane} instance associated with this game pane
+	 */
+	public BoardPane getBoardPane() { return boardPane; }
+
+	/**
+	 * @return The {@link Game} instance associated with this game pane
+	 */
+	public Game getGame() { return game; }
+
+	/**
+	 * Assigns a new {@link Game} instance to this game pane. If exactly one of the
+	 * players is natural, color swapping functionality is enabled.
+	 * 
+	 * @param game The {@link Game} to assign to this game pane.
+	 */
+	public void setGame(Game game) {
+		if (this.game != null) this.game.stop();
+		this.game = game;
+	}
+}

src/dev/kske/chess/ui/MainWindow.java

@@ -1,40 +1,50 @@
 package dev.kske.chess.ui;
 
-import java.awt.BorderLayout;
+import java.awt.Desktop;
 import java.awt.EventQueue;
 import java.awt.Toolkit;
+import java.awt.dnd.DropTarget;
+import java.io.File;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.util.List;
 
-import javax.swing.JButton;
+import javax.swing.JComboBox;
 import javax.swing.JFrame;
-import javax.swing.JPanel;
+import javax.swing.JOptionPane;
+import javax.swing.JTabbedPane;
 
+import dev.kske.chess.board.Board;
+import dev.kske.chess.board.FENString;
+import dev.kske.chess.exception.ChessException;
 import dev.kske.chess.game.Game;
+import dev.kske.chess.pgn.PGNDatabase;
+import dev.kske.chess.pgn.PGNGame;
 
 /**
  * Project: <strong>Chess</strong><br>
  * File: <strong>MainWindow.java</strong><br>
  * Created: <strong>01.07.2019</strong><br>
- * Author: <strong>Kai S. K. Engelbart</strong>
+ * 
+ * @since Chess v0.1-alpha
+ * @author Kai S. K. Engelbart
  */
-public class MainWindow {
+public class MainWindow extends JFrame {
 
-	private JFrame		mframe;
+	private static final long serialVersionUID = -3100939302567978977L;
-	private BoardPane	boardPane;
+
-	private Game		game;
+	private JTabbedPane tabbedPane;
 
 	/**
 	 * Launch the application.
 	 */
 	public static void main(String[] args) {
-		EventQueue.invokeLater(new Runnable() {
+		EventQueue.invokeLater(() -> {
-
-			public void run() {
 			try {
-					MainWindow window = new MainWindow();
+				new MainWindow();
-					window.mframe.setVisible(true);
+			} catch (Exception ex) {
-				} catch (Exception e) {
+				ex.printStackTrace();
-					e.printStackTrace();
-				}
 			}
 		});
 	}
@@ -43,6 +53,7 @@ public class MainWindow {
 	 * Create the application.
 	 */
 	public MainWindow() {
+		super("Chess by Kai S. K. Engelbart");
 		initialize();
 	}
 
@@ -50,31 +61,135 @@ public class MainWindow {
 	 * Initialize the contents of the frame.
 	 */
 	private void initialize() {
-		mframe = new JFrame();
+		// Configure frame
-		mframe.setResizable(false);
+		setResizable(false);
-		mframe.setBounds(100, 100, 494, 565);
+		setBounds(100, 100, 494, 565);
-		mframe.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+		setIconImage(Toolkit.getDefaultToolkit().getImage(getClass().getResource("/pieces/queen_white.png")));
 
-		mframe.setIconImage(Toolkit.getDefaultToolkit().getImage(getClass().getResource("/pieces/king_white.png")));
+		// Add frame content
+		tabbedPane = new JTabbedPane();
+		getContentPane().add(tabbedPane);
 
-		boardPane = new BoardPane();
+		setJMenuBar(new MenuBar(this));
-		mframe.getContentPane().add(boardPane, BorderLayout.CENTER);
+		new DropTarget(this, new GameDropTarget(this));
 
-		mframe.setJMenuBar(new MenuBar(this));
+		// Update position and dimensions
-
+		pack();
-		JPanel toolPanel = new JPanel();
+		setLocationRelativeTo(null);
-		mframe.getContentPane().add(toolPanel, BorderLayout.NORTH);
+		setVisible(true);
-
-		JButton btnRestart = new JButton("Restart");
-		btnRestart.addActionListener((evt) -> { if (game != null) game.reset(); game.start(); });
-		toolPanel.add(btnRestart);
-		mframe.pack();
-		mframe.setLocationRelativeTo(null);
 	}
 
-	public BoardPane getBoardPane() { return boardPane; }
+	/**
+	 * @return The currently selected {@link GamePane} component
+	 */
+	public GamePane getSelectedGamePane() { return (GamePane) tabbedPane.getSelectedComponent(); }
 
-	public Game getGame() { return game; }
+	/**
+	 * Creates a new {@link GamePane}, adds it to the tabbed pane and opens it.
+	 * The new tab has the title {@code Game n} where {@code n} is its number.
+	 * 
+	 * @return The new {@link GamePane}
+	 */
+	public GamePane addGamePane() { return addGamePane("Game " + (tabbedPane.getComponentCount() + 1)); }
 
-	public void setGame(Game game) { this.game = game; }
+	/**
+	 * Creates a new {@link GamePane}, adds it to the tabbed pane and opens it.
+	 * 
+	 * @param title The title of the {@link GamePane}
+	 * @return The new {@link GamePane}
+	 */
+	public GamePane addGamePane(String title) {
+		GamePane gamePane = new GamePane();
+		tabbedPane.add(title, gamePane);
+		tabbedPane.setSelectedIndex(tabbedPane.getComponentCount() - 1);
+		return gamePane;
+	}
+
+	public GamePane addGamePane(String title, Board board) {
+		GamePane gamePane = addGamePane(title);
+		DialogUtil.showGameConfigurationDialog(this,
+				(whiteName, blackName) -> {
+					Game game = new Game(gamePane.getBoardPane(), whiteName, blackName, board);
+					gamePane.setGame(game);
+					game.start();
+				});
+		return gamePane;
+	}
+
+	/**
+	 * Removes a {@link GamePane} form the tabbed pane.
+	 * 
+	 * @param index The index of the {@link GamePane} to remove
+	 */
+	public void removeGamePane(int index) { tabbedPane.remove(index); }
+
+	/**
+	 * Loads a game file (FEN or PGN) and adds it to a new {@link GamePane}.
+	 * 
+	 * @param files the files to load the game from
+	 */
+	public void loadFiles(List<File> files) {
+		files.forEach(file -> {
+			final String	name		= file.getName().substring(0, file.getName().lastIndexOf('.'));
+			final String	extension	= file.getName().substring(file.getName().lastIndexOf('.')).toLowerCase();
+			try {
+				Board board;
+				switch (extension) {
+					case ".fen":
+						board = new FENString(new String(Files.readAllBytes(file.toPath()), StandardCharsets.UTF_8)).getBoard();
+						break;
+					case ".pgn":
+						PGNDatabase pgnDB = new PGNDatabase();
+						pgnDB.load(file);
+						if (pgnDB.getGames().size() > 0) {
+							String[] gameNames = new String[pgnDB.getGames().size()];
+							for (int i = 0; i < gameNames.length; i++) {
+								final PGNGame game = pgnDB.getGames().get(i);
+								gameNames[i] = String.format("%s vs %s: %s", game.getTag("White"), game.getTag("Black"), game.getTag("Result"));
+							}
+							JComboBox<String> comboBox = new JComboBox<>(gameNames);
+							JOptionPane.showMessageDialog(this, comboBox, "Select a game", JOptionPane.QUESTION_MESSAGE);
+							board = pgnDB.getGames().get(comboBox.getSelectedIndex()).getBoard();
+						} else throw new ChessException("The PGN database '" + name + "' is empty!");
+						break;
+					default:
+						throw new ChessException("The file extension '" + extension + "' is not supported!");
+				}
+				addGamePane(name, board);
+			} catch (Exception e) {
+				e.printStackTrace();
+				JOptionPane.showMessageDialog(this,
+						"Failed to load the file " + file.getName() + ": " + e.toString(),
+						"File loading error",
+						JOptionPane.ERROR_MESSAGE);
+			}
+		});
+	}
+
+	public void saveFile(File file) {
+		final int		dotIndex	= file.getName().lastIndexOf('.');
+		final String	extension	= file.getName().substring(dotIndex).toLowerCase();
+
+		if (extension.equals(".pgn")) try {
+			PGNGame pgnGame = new PGNGame(getSelectedGamePane().getGame().getBoard());
+			pgnGame.setTag("Event", tabbedPane.getTitleAt(tabbedPane.getSelectedIndex()));
+			pgnGame.setTag("Result", "*");
+			PGNDatabase pgnDB = new PGNDatabase();
+			pgnDB.getGames().add(pgnGame);
+			pgnDB.save(file);
+
+			if (JOptionPane.showConfirmDialog(this,
+					"Game export finished. Do you want to view the created file?",
+					"Game export finished",
+					JOptionPane.YES_NO_OPTION) == JOptionPane.YES_OPTION)
+				Desktop.getDesktop().open(file);
+		} catch (IOException e) {
+			e.printStackTrace();
+			JOptionPane.showMessageDialog(this,
+					"Failed to save the file " + file.getName() + ": " + e.toString(),
+					"File saving error",
+					JOptionPane.ERROR_MESSAGE);
+		}
+	}
 }

src/dev/kske/chess/ui/MenuBar.java

@@ -1,64 +1,118 @@
 package dev.kske.chess.ui;
 
+import java.awt.Toolkit;
+import java.awt.datatransfer.StringSelection;
+import java.util.Arrays;
+
 import javax.swing.JMenu;
 import javax.swing.JMenuBar;
 import javax.swing.JMenuItem;
+import javax.swing.JOptionPane;
+import javax.swing.filechooser.FileNameExtensionFilter;
 
+import dev.kske.chess.board.FENString;
+import dev.kske.chess.exception.ChessException;
 import dev.kske.chess.game.Game;
+import dev.kske.chess.io.EngineUtil;
 
 /**
  * Project: <strong>Chess</strong><br>
  * File: <strong>MenuBar.java</strong><br>
  * Created: <strong>16.07.2019</strong><br>
- * Author: <strong>Kai S. K. Engelbart</strong>
+ * 
+ * @since Chess v0.1-alpha
+ * @author Kai S. K. Engelbart
  */
 public class MenuBar extends JMenuBar {
 
 	private static final long serialVersionUID = -7221583703531248228L;
 
 	private final MainWindow mainWindow;
-	private final BoardPane		boardPane;
 
 	public MenuBar(MainWindow mainWindow) {
 		this.mainWindow = mainWindow;
-		boardPane		= mainWindow.getBoardPane();
 
 		initGameMenu();
+		initEngineMenu();
+		initToolsMenu();
 	}
 
 	private void initGameMenu() {
 		JMenu gameMenu = new JMenu("Game");
 
-		JMenuItem	naturalMenuItem	= new JMenuItem("Game against natural opponent");
+		JMenuItem newGameMenuItem = new JMenuItem("New Game");
-		JMenuItem	aiMenuItem		= new JMenuItem("Game against artificial opponent");
+		newGameMenuItem.addActionListener((evt) -> DialogUtil.showGameConfigurationDialog(mainWindow, (whiteName, blackName) -> {
-		JMenuItem	aiVsAiMenuItem	= new JMenuItem("Watch AI vs. AI");
+			GamePane	gamePane	= mainWindow.addGamePane();
+			Game		game		= new Game(gamePane.getBoardPane(), whiteName, blackName);
+			gamePane.setGame(game);
+			game.start();
+		}));
+		gameMenu.add(newGameMenuItem);
 
-		naturalMenuItem.addActionListener((evt) -> startGame(Game.createNatural(boardPane)));
+		JMenuItem loadFileMenu = new JMenuItem("Load game file");
+		loadFileMenu.addActionListener((evt) -> DialogUtil
+			.showFileSelectionDialog(mainWindow,
+					mainWindow::loadFiles,
+					Arrays.asList(new FileNameExtensionFilter("FEN and PGN files", "fen", "pgn"))));
+		gameMenu.add(loadFileMenu);
 
-		aiMenuItem.addActionListener((evt) -> {
+		JMenuItem saveFileMenu = new JMenuItem("Save game file");
-			AIConfigDialog dialog = new AIConfigDialog();
+		saveFileMenu
-			dialog.setVisible(true);
+			.addActionListener((evt) -> DialogUtil
-			if (dialog.isStartGame())
+				.showFileSaveDialog(mainWindow, mainWindow::saveFile, Arrays.asList(new FileNameExtensionFilter("PGN file", "pgn"))));
-				startGame(Game.createNaturalVsAI(boardPane, dialog.getMaxDepth(), dialog.getAlphaBetaThreshold()));
+		gameMenu.add(saveFileMenu);
-		});
-
-		aiVsAiMenuItem.addActionListener((evt) -> startGame(Game.createAIVsAI(boardPane, 4, 3, -10, -10)));
-
-		gameMenu.add(naturalMenuItem);
-		gameMenu.add(aiMenuItem);
-		gameMenu.add(aiVsAiMenuItem);
 
 		add(gameMenu);
-
+		newGameMenuItem.doClick();
-		// Start a game
-		naturalMenuItem.doClick();
 	}
 
-	private void startGame(Game game) {
+	private void initEngineMenu() {
-		mainWindow.setGame(game);
+		JMenu engineMenu = new JMenu("Engine");
 
-		// Update board and board component
+		JMenuItem addEngineMenuItem = new JMenuItem("Add engine");
-		game.reset();
+		addEngineMenuItem.addActionListener((evt) -> {
+			String enginePath = JOptionPane
+				.showInputDialog(getParent(), "Enter the path to a UCI-compatible chess engine:", "Engine selection", JOptionPane.QUESTION_MESSAGE);
+			if (enginePath != null) EngineUtil.addEngine(enginePath);
+		});
+
+		JMenuItem showInfoMenuItem = new JMenuItem("Show engine info");
+
+		engineMenu.add(addEngineMenuItem);
+		engineMenu.add(showInfoMenuItem);
+		add(engineMenu);
+	}
+
+	private void initToolsMenu() {
+		JMenu toolsMenu = new JMenu("Tools");
+
+		JMenuItem exportFENMenuItem = new JMenuItem("Export board to FEN");
+		exportFENMenuItem.addActionListener((evt) -> {
+			final String fen = new FENString(mainWindow.getSelectedGamePane().getGame().getBoard()).toString();
+			Toolkit.getDefaultToolkit().getSystemClipboard().setContents(new StringSelection(fen), null);
+			JOptionPane.showMessageDialog(mainWindow, String.format("FEN-string copied to clipboard!%n%s", fen));
+		});
+		toolsMenu.add(exportFENMenuItem);
+
+		JMenuItem loadFromFENMenuItem = new JMenuItem("Load board from FEN");
+		loadFromFENMenuItem.addActionListener((evt) -> {
+			final GamePane	gamePane	= mainWindow.addGamePane();
+			final String	fen			= JOptionPane.showInputDialog("Enter a FEN string: ");
+			DialogUtil.showGameConfigurationDialog(mainWindow, (whiteName, blackName) -> {
+				Game game;
+				try {
+					game = new Game(gamePane.getBoardPane(), whiteName, blackName, new FENString(fen).getBoard());
+					gamePane.setGame(game);
 					game.start();
+				} catch (ChessException e) {
+					e.printStackTrace();
+					JOptionPane
+						.showMessageDialog(mainWindow, "Failed to load FEN string: " + e.toString(), "FEN loading error", JOptionPane.ERROR_MESSAGE);
+				}
+			});
+		});
+		toolsMenu.add(loadFromFENMenuItem);
+
+		add(toolsMenu);
 	}
 }

src/dev/kske/chess/ui/MoveNodeRenderer.java

@@ -0,0 +1,34 @@
+package dev.kske.chess.ui;
+
+import java.awt.Color;
+import java.awt.Component;
+
+import javax.swing.JLabel;
+import javax.swing.JList;
+import javax.swing.ListCellRenderer;
+import javax.swing.border.EmptyBorder;
+
+import dev.kske.chess.board.MoveNode;
+
+/**
+ * Project: <strong>Chess</strong><br>
+ * File: <strong>MoveNodeRenderer.java</strong><br>
+ * Created: <strong>9 Oct 2019</strong><br>
+ * 
+ * @since Chess v0.5-alpha
+ * @author Kai S. K. Engelbart
+ */
+public class MoveNodeRenderer extends JLabel implements ListCellRenderer<MoveNode> {
+
+	private static final long serialVersionUID = 5242015788752442446L;
+
+	@Override
+	public Component getListCellRendererComponent(JList<? extends MoveNode> list, MoveNode node, int index,
+			boolean isSelected, boolean cellHasFocus) {
+		setBorder(new EmptyBorder(5, 5, 5, 5));
+		setText(node.move.toLAN());
+		setBackground(isSelected ? Color.red : Color.white);
+		setOpaque(true);
+		return this;
+	}
+}

src/dev/kske/chess/ui/OverlayComponent.java

@@ -1,5 +1,6 @@
 package dev.kske.chess.ui;
 
+import java.awt.BasicStroke;
 import java.awt.Color;
 import java.awt.Graphics;
 import java.awt.Graphics2D;
@@ -19,7 +20,9 @@ import dev.kske.chess.board.Position;
  * Project: <strong>Chess</strong><br>
  * File: <strong>OverlayComponent.java</strong><br>
  * Created: <strong>08.07.2019</strong><br>
- * Author: <strong>Kai S. K. Engelbart</strong>
+ * 
+ * @since Chess v0.1-alpha
+ * @author Kai S. K. Engelbart
  */
 public class OverlayComponent extends JComponent {
 
@@ -32,8 +35,8 @@ public class OverlayComponent extends JComponent {
 
 	public OverlayComponent(BoardPane boardPane) {
 		this.boardPane = boardPane;
-		setSize(boardPane.getPreferredSize());
 		dots = new ArrayList<>();
+		setSize(boardPane.getPreferredSize());
 	}
 
 	@Override
@@ -42,6 +45,26 @@ public class OverlayComponent extends JComponent {
 
 		final int tileSize = getTileSize();
 
+		// Draw an arrow representing the last move and mark its position and
+		// destination
+		if (arrow != null) {
+			Point	pos		= new Point(arrow.getPos().x * tileSize + tileSize / 2, arrow.getPos().y * tileSize + tileSize / 2);
+			Point	dest	= new Point(arrow.getDest().x * tileSize + tileSize / 2, arrow.getDest().y * tileSize + tileSize / 2);
+
+			Graphics2D g2d = (Graphics2D) g;
+			g2d.setStroke(new BasicStroke(3));
+
+			g2d.setColor(Color.yellow);
+			g2d.drawRect(arrow.getPos().x * tileSize, arrow.getPos().y * tileSize, tileSize, tileSize);
+			g2d.drawRect(arrow.getDest().x * tileSize, arrow.getDest().y * tileSize, tileSize, tileSize);
+
+			Shape arrowShape = createArrowShape(pos, dest);
+			g.setColor(new Color(255, 0, 0, 127));
+			g2d.fill(arrowShape);
+			g2d.setColor(Color.black);
+			g2d.draw(arrowShape);
+		}
+
 		// Draw possible moves if a piece was selected
 		if (!dots.isEmpty()) {
 			g.setColor(Color.green);
@@ -52,13 +75,6 @@ public class OverlayComponent extends JComponent {
 						radius,
 						radius);
 		}
-
-		if (arrow != null) {
-			g.setColor(new Color(255, 0, 0, 127));
-			Point	pos		= new Point(arrow.pos.x * tileSize + tileSize / 2, arrow.pos.y * tileSize + tileSize / 2);
-			Point	dest	= new Point(arrow.dest.x * tileSize + tileSize / 2, arrow.dest.y * tileSize + tileSize / 2);
-			((Graphics2D) g).fill(createArrowShape(pos, dest));
-		}
 	}
 
 	private Shape createArrowShape(Point pos, Point dest) {

test/dev/kske/chess/board/BoardTest.java

@@ -1,4 +1,4 @@
-package dev.kske.chess.test;
+package dev.kske.chess.board;
 
 import static org.junit.Assert.assertNotEquals;
 import static org.junit.Assert.assertNotSame;
@@ -6,9 +6,7 @@ import static org.junit.Assert.assertNotSame;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
-import dev.kske.chess.board.Board;
 import dev.kske.chess.board.Piece.Color;
-import dev.kske.chess.board.Queen;
 
 /**
  * Project: <strong>Chess</strong><br>
@@ -33,11 +31,13 @@ class BoardTest {
 	 */
 	@Test
 	void testClone() {
-		Board clone = (Board) board.clone();
+		Board clone = new Board(board, false);
 		assertNotSame(clone, board);
 		assertNotSame(clone.getBoardArr(), board.getBoardArr());
 
 		clone.getBoardArr()[0][0] = new Queen(Color.BLACK, clone);
+		clone.move(new Move(1, 1, 1, 2));
 		assertNotEquals(clone.getBoardArr()[0][0], board.getBoardArr()[0][0]);
+		assertNotEquals(clone.getLog().getActiveColor(), board.getLog().getActiveColor());
 	}
 }

test/dev/kske/chess/board/FENStringTest.java

@@ -0,0 +1,72 @@
+package dev.kske.chess.board;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import dev.kske.chess.board.Piece.Color;
+import dev.kske.chess.exception.ChessException;
+
+/**
+ * Project: <strong>Chess</strong><br>
+ * File: <strong>FENStringTest.java</strong><br>
+ * Created: <strong>24 Oct 2019</strong><br>
+ * 
+ * @author Kai S. K. Engelbart
+ */
+class FENStringTest {
+
+	List<String>	fenStrings	= new ArrayList<>();
+	List<Board>		boards		= new ArrayList<>();
+
+	void cleanBoard(Board board) {
+		for (int i = 0; i < 8; i++)
+			for (int j = 0; j < 8; j++)
+				board.getBoardArr()[i][j] = null;
+	}
+
+	/**
+	 * @throws java.lang.Exception
+	 */
+	@BeforeEach
+	void setUp() throws Exception {
+		fenStrings.addAll(Arrays.asList("rnbqkbnr/pp1ppppp/8/2p5/4P3/5N2/PPPP1PPP/RNBQKB1R b KQkq - 1 2"));
+		Board board = new Board();
+		board.set(Position.fromLAN("c7"), null);
+		board.set(Position.fromLAN("c5"), new Pawn(Color.BLACK, board));
+		board.set(Position.fromLAN("e4"), new Pawn(Color.WHITE, board));
+		board.set(Position.fromLAN("f3"), new Knight(Color.WHITE, board));
+		board.set(Position.fromLAN("e2"), null);
+		board.set(Position.fromLAN("g1"), null);
+
+		board.getLog().setActiveColor(Color.BLACK);
+		board.getLog().setHalfmoveClock(1);
+		board.getLog().setFullmoveNumber(2);
+		boards.add(board);
+	}
+
+	/**
+	 * Test method for {@link dev.kske.chess.board.FENString#toString()}.
+	 */
+	@Test
+	void testToString() {
+		for (int i = 0; i < fenStrings.size(); i++)
+			assertEquals(fenStrings.get(i), new FENString(boards.get(i)).toString());
+	}
+
+	/**
+	 * Test method for {@link dev.kske.chess.board.FENString#getBoard()}.
+	 * 
+	 * @throws ChessException
+	 */
+	@Test
+	void testGetBoard() throws ChessException {
+		for (int i = 0; i < boards.size(); i++)
+			assertEquals(boards.get(i), new FENString(fenStrings.get(i)).getBoard());
+	}
+}

test/dev/kske/chess/board/LogTest.java

@@ -0,0 +1,165 @@
+package dev.kske.chess.board;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assertions.fail;
+
+import org.junit.jupiter.api.Test;
+
+import dev.kske.chess.board.Piece.Color;
+
+/**
+ * Project: <strong>Chess</strong><br>
+ * File: <strong>LogTest.java</strong><br>
+ * Created: <strong>13 Sep 2019</strong><br>
+ * Author: <strong>Kai S. K. Engelbart</strong>
+ */
+class LogTest {
+
+	Log log = new Log();
+
+	/**
+	 * Test method for {@link dev.kske.chess.board.Log#Log()}.
+	 */
+	@Test
+	void testLog() {
+		assertTrue(log.isEmpty());
+		assertNull(log.getLast());
+		assertNull(log.getRoot());
+		assertEquals(log.getActiveColor(), Color.WHITE);
+		assertNull(log.getEnPassant());
+		assertEquals(log.getFullmoveNumber(), 1);
+		assertEquals(log.getHalfmoveClock(), 0);
+	}
+
+	/**
+	 * Test method for {@link dev.kske.chess.board.Log#clone()}.
+	 */
+	@Test
+	void testClone() {
+		Log other = new Log(log, false);
+		log.setActiveColor(Color.WHITE);
+		other.setActiveColor(Color.BLACK);
+		assertNotEquals(log.getActiveColor(), other.getActiveColor());
+		log.add(Move.fromLAN("a2a4"), new Pawn(Color.WHITE, null), null);
+		log.add(Move.fromLAN("a4a5"), new Pawn(Color.WHITE, null), null);
+		other.add(Move.fromLAN("a2a4"), new Pawn(Color.WHITE, null), null);
+		other.add(Move.fromLAN("a4a5"), new Pawn(Color.WHITE, null), null);
+		assertNotEquals(log.getRoot(), other.getRoot());
+		assertNotEquals(log.getRoot().getVariations(), other.getRoot().getVariations());
+	}
+
+	/**
+	 * Test method for {@link dev.kske.chess.board.Log#add(dev.kske.chess.board.Move, dev.kske.chess.board.Piece, boolean)}.
+	 */
+	@Test
+	void testAdd() {
+		fail("Not yet implemented");
+	}
+
+	/**
+	 * Test method for {@link dev.kske.chess.board.Log#removeLast()}.
+	 */
+	@Test
+	void testRemoveLast() {
+		fail("Not yet implemented");
+	}
+
+	/**
+	 * Test method for {@link dev.kske.chess.board.Log#isEmpty()}.
+	 */
+	@Test
+	void testIsEmpty() {
+		fail("Not yet implemented");
+	}
+
+	/**
+	 * Test method for {@link dev.kske.chess.board.Log#reset()}.
+	 */
+	@Test
+	void testReset() {
+		fail("Not yet implemented");
+	}
+
+	/**
+	 * Test method for {@link dev.kske.chess.board.Log#getRoot()}.
+	 */
+	@Test
+	void testGetRoot() {
+		fail("Not yet implemented");
+	}
+
+	/**
+	 * Test method for {@link dev.kske.chess.board.Log#getLast()}.
+	 */
+	@Test
+	void testGetLast() {
+		fail("Not yet implemented");
+	}
+
+	/**
+	 * Test method for {@link dev.kske.chess.board.Log#getEnPassant()}.
+	 */
+	@Test
+	void testGetEnPassant() {
+		fail("Not yet implemented");
+	}
+
+	/**
+	 * Test method for {@link dev.kske.chess.board.Log#setEnPassant(dev.kske.chess.board.Position)}.
+	 */
+	@Test
+	void testSetEnPassant() {
+		fail("Not yet implemented");
+	}
+
+	/**
+	 * Test method for {@link dev.kske.chess.board.Log#getActiveColor()}.
+	 */
+	@Test
+	void testGetActiveColor() {
+		fail("Not yet implemented");
+	}
+
+	/**
+	 * Test method for {@link dev.kske.chess.board.Log#setActiveColor(dev.kske.chess.board.Piece.Color)}.
+	 */
+	@Test
+	void testSetActiveColor() {
+		fail("Not yet implemented");
+	}
+
+	/**
+	 * Test method for {@link dev.kske.chess.board.Log#getFullmoveNumber()}.
+	 */
+	@Test
+	void testGetFullmoveCounter() {
+		fail("Not yet implemented");
+	}
+
+	/**
+	 * Test method for {@link dev.kske.chess.board.Log#setFullmoveNumber(int)}.
+	 */
+	@Test
+	void testSetFullmoveCounter() {
+		fail("Not yet implemented");
+	}
+
+	/**
+	 * Test method for {@link dev.kske.chess.board.Log#getHalfmoveClock()}.
+	 */
+	@Test
+	void testGetHalfmoveClock() {
+		fail("Not yet implemented");
+	}
+
+	/**
+	 * Test method for {@link dev.kske.chess.board.Log#setHalfmoveClock(int)}.
+	 */
+	@Test
+	void testSetHalfmoveClock() {
+		fail("Not yet implemented");
+	}
+}

test/dev/kske/chess/board/PositionTest.java

@@ -0,0 +1,47 @@
+package dev.kske.chess.board;
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+/**
+ * Project: <strong>Chess</strong><br>
+ * File: <strong>PositionTest.java</strong><br>
+ * Created: <strong>24.07.2019</strong><br>
+ * Author: <strong>Kai S. K. Engelbart</strong>
+ */
+class PositionTest {
+
+	final int	n			= 4;
+	Position[]	positions	= new Position[] { new Position(0, 0), new Position(7, 7), new Position(0, 7), new Position(7, 0) };
+	String[]	sans		= new String[] { "a8", "h1", "a1", "h8" };
+	String[]	strings		= new String[] { "[0, 0]", "[7, 7]", "[0, 7]", "[7, 0]" };
+
+	/**
+	 * Test method for
+	 * {@link dev.kske.chess.board.Position#fromLAN(java.lang.String)}.
+	 */
+	@Test
+	void testFromSAN() {
+		for (int i = 0; i < n; i++)
+			assertEquals(positions[i], Position.fromLAN(sans[i]));
+	}
+
+	/**
+	 * Test method for {@link dev.kske.chess.board.Position#toLAN()}.
+	 */
+	@Test
+	void testToSAN() {
+		for (int i = 0; i < n; i++)
+			assertEquals(sans[i], positions[i].toLAN());
+	}
+
+	/**
+	 * Test method for {@link dev.kske.chess.board.Position#toString()}.
+	 */
+	@Test
+	void testToString() {
+		for (int i = 0; i < n; i++)
+			assertEquals(strings[i], positions[i].toString());
+	}
+}

test/dev/kske/chess/pgn/PGNDatabaseTest.java

@@ -0,0 +1,36 @@
+package dev.kske.chess.pgn;
+
+import static org.junit.jupiter.api.Assertions.fail;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+
+import org.junit.jupiter.api.Test;
+
+import dev.kske.chess.exception.ChessException;
+
+/**
+ * Project: <strong>Chess</strong><br>
+ * File: <strong>PGNDatabaseTest.java</strong><br>
+ * Created: <strong>4 Oct 2019</strong><br>
+ * Author: <strong>Kai S. K. Engelbart</strong>
+ */
+class PGNDatabaseTest {
+
+	/**
+	 * Test method for {@link dev.kske.chess.pgn.PGNDatabase#load(java.io.File)}.
+	 * 
+	 * @throws ChessException
+	 * @throws FileNotFoundException
+	 */
+	@Test
+	void testLoad() {
+		PGNDatabase db = new PGNDatabase();
+		try {
+			db.load(new File(getClass().getClassLoader().getResource("test.pgn").getFile()));
+		} catch (FileNotFoundException | ChessException e) {
+			e.printStackTrace();
+			fail(e);
+		}
+	}
+}

test_res/test.pgn

@@ -0,0 +1,18 @@
+[Event "Test Game"]
+[Site "Test Environment"]
+[Date "2019.10.04"]
+[Round "1"]
+[Result "1-0"]
+[White "Kai Engelbart"]
+[Black "Kai Engelbart 2"]
+
+1. e4 c5 2. Nf3 e6 3. d4 cxd4 4. Nxd4 a6 5. Bd3 Nf6 6. O-O d6
+7. c4 Bd7 8. Nc3 Nc6 9. Be3 Be7 10. h3 Ne5 11. Be2 Rc8 12. Qb3
+Qc7 13. Rac1 O-O 14. f4 Nc6 15. Nf3 Qb8 16. Qd1 Be8 17. Qd2
+Na5 18. b3 b6 19. Bd3 Nc6 20. Qf2 b5 21. Rfd1 Nb4 22. Bf1 bxc4
+23. bxc4 a5 24. Nd4 Qa8 25. Qf3 Na6 26. Ndb5 Nc5 27. e5 dxe5
+28. Qxa8 Rxa8 29. fxe5 Nfe4 30. Nd6 Bc6 31. Ncxe4 Nxe4 32. c5
+Ng3 33. Bc4 h5 34. Bf2 h4 35. Bxg3 hxg3 36. Bb5 Bxb5 37. Nxb5
+f6 38. Rd7 Bd8 39. Rc3 fxe5 40. Rxg3 Rf7 41. Rxf7 Kxf7 42. c6
+Bb6+ 43. Kf1 Kf8 44. c7 Rc8 45. a4 e4 46. Ke2 e5 47. Rg6 Bd4
+48. h4 Bb2 1-0