basic model

app/src/main/java/chess/model/visitor/PiecePathChecker.java

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+package chess.model.visitor;
+
+import chess.model.ChessBoard;
+import chess.model.Color;
+import chess.model.Coordinate;
+import chess.model.Direction;
+import chess.model.Move;
+import chess.model.Piece;
+import chess.model.PieceVisitor;
+import chess.model.pieces.Bishop;
+import chess.model.pieces.King;
+import chess.model.pieces.Knight;
+import chess.model.pieces.Pawn;
+import chess.model.pieces.Queen;
+import chess.model.pieces.Rook;
+
+public class PiecePathChecker implements PieceVisitor<Boolean> {
+
+	private final ChessBoard board;
+	private final Move move;
+
+	public PiecePathChecker(ChessBoard board, Move move) {
+		this.move = move;
+		this.board = board;
+	}
+
+	public boolean isValidForPiece(Piece piece) {
+		return visit(piece);
+	}
+
+	@Override
+	public Boolean visitPiece(Bishop bishop) {
+		if (!new PermissiveRuleChecker(this.move).isValidFor(bishop))
+			return false;
+		return testPath(bishop.getColor());
+	}
+
+	@Override
+	public Boolean visitPiece(King king) {
+		if (!new PermissiveRuleChecker(this.move).isValidFor(king))
+			return false;
+
+		Piece destPiece = board.pieceAt(this.move.getFinish());
+		if (destPiece == null)
+			return true;
+		return destPiece.getColor() != king.getColor();
+	}
+
+	@Override
+	public Boolean visitPiece(Knight knight) {
+		if (!new PermissiveRuleChecker(this.move).isValidFor(knight))
+			return false;
+
+		Piece destPiece = board.pieceAt(this.move.getFinish());
+		if (destPiece == null)
+			return true;
+		return destPiece.getColor() != knight.getColor();
+	}
+
+	@Override
+	public Boolean visitPiece(Pawn pawn) {
+		if (!new PermissiveRuleChecker(this.move).isValidFor(pawn))
+			return false;
+
+		Direction moveDirection = Direction.findDirection(this.move);
+		// ...
+		// moveDirection = Directions(int(findDirection(move)) * pawn.multiplier())
+
+		if (moveDirection == Direction.Front)
+			return testPath(pawn.getColor());
+
+		assert moveDirection == Direction.FrontLeft || moveDirection == Direction.FrontRight;
+
+		Piece destPiece = this.board.pieceAt(this.move.getFinish());
+		if (destPiece == null)
+			return true;
+
+		return destPiece.getColor() != pawn.getColor();
+	}
+
+	@Override
+	public Boolean visitPiece(Queen queen) {
+		if (!new PermissiveRuleChecker(this.move).isValidFor(queen))
+			return false;
+		return testPath(queen.getColor());
+	}
+
+	@Override
+	public Boolean visitPiece(Rook rook) {
+		if (!new PermissiveRuleChecker(this.move).isValidFor(rook))
+			return false;
+		return testPath(rook.getColor());
+	}
+
+	private boolean testPath(Color color) {
+		Direction moveDirection = Direction.findDirection(this.move);
+		int distance = this.move.traversedCells();
+		int stepIndex = move.getStart().toIndex();
+
+		for (int step = 0; step < distance; step++) {
+			stepIndex += moveDirection.getIndexOffset();
+
+			if (Coordinate.fromIndex(stepIndex).equals(move.getFinish())) {
+				Piece pieceDest = this.board.pieceAt(move.getFinish());
+				if (pieceDest == null)
+					return true;
+				return pieceDest.getColor() != color;
+			}
+
+			if (!this.board.isCellEmpty(Coordinate.fromIndex(stepIndex)))
+				return false;
+		}
+
+		return false;
+	}
+}