Implement #34: Undo/Redo Stack with Command Pattern

pom.xml

@@ -68,12 +68,6 @@
     <version>1.0-SNAPSHOT</version>
 
     <dependencies>
-        <dependency>
-            <groupId>com.fasterxml.jackson.core</groupId>
-            <artifactId>jackson-databind</artifactId>
-            <version>2.18.3</version>
-        </dependency>
-
         <dependency>
             <groupId>org.slf4j</groupId>
             <artifactId>slf4j-api</artifactId>

src/main/java/ovh/gasser/newshapes/command/AddShapeCommand.java

@@ -0,0 +1,54 @@
+package ovh.gasser.newshapes.command;
+
+import ovh.gasser.newshapes.shapes.SCollection;
+import ovh.gasser.newshapes.shapes.Shape;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Comparator;
+import java.util.List;
+
+public class AddShapeCommand implements Command {
+    private final SCollection model;
+    private final List<IndexedShape> shapes;
+
+    public AddShapeCommand(SCollection model, Shape shape) {
+        this(model, List.of(shape));
+    }
+
+    public AddShapeCommand(SCollection model, Collection<? extends Shape> shapes) {
+        this.model = model;
+        int baseIndex = model.size();
+        List<IndexedShape> indexedShapes = new ArrayList<>();
+        int offset = 0;
+        for (Shape shape : shapes) {
+            indexedShapes.add(new IndexedShape(baseIndex + offset, shape));
+            offset++;
+        }
+        this.shapes = List.copyOf(indexedShapes);
+    }
+
+    @Override
+    public void execute() {
+        shapes.stream()
+                .sorted(Comparator.comparingInt(IndexedShape::index))
+                .forEach(entry -> {
+                    if (!model.contains(entry.shape())) {
+                        model.insert(entry.index(), entry.shape());
+                    }
+                });
+    }
+
+    @Override
+    public void undo() {
+        List<IndexedShape> reversed = new ArrayList<>(shapes);
+        reversed.sort(Comparator.comparingInt(IndexedShape::index).reversed());
+        reversed.forEach(entry -> {
+            if (model.contains(entry.shape())) {
+                model.remove(entry.shape());
+            }
+        });
+    }
+
+    private record IndexedShape(int index, Shape shape) {}
+}

src/main/java/ovh/gasser/newshapes/command/ChangeColorCommand.java

@@ -0,0 +1,44 @@
+package ovh.gasser.newshapes.command;
+
+import ovh.gasser.newshapes.attributes.ColorAttributes;
+import ovh.gasser.newshapes.shapes.Shape;
+
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+
+public class ChangeColorCommand implements Command {
+    private final List<ShapeColor> before;
+    private final List<ShapeColor> after;
+
+    public ChangeColorCommand(Collection<? extends Shape> shapes, Map<Shape, ColorAttributes> before, Map<Shape, ColorAttributes> after) {
+        this.before = snapshots(shapes, before);
+        this.after = snapshots(shapes, after);
+    }
+
+    @Override
+    public void execute() {
+        apply(after);
+    }
+
+    @Override
+    public void undo() {
+        apply(before);
+    }
+
+    private static List<ShapeColor> snapshots(Collection<? extends Shape> shapes, Map<Shape, ColorAttributes> colors) {
+        return shapes.stream()
+                .map(shape -> new ShapeColor(shape, copy(colors.get(shape))))
+                .toList();
+    }
+
+    private void apply(List<ShapeColor> colors) {
+        colors.forEach(shapeColor -> shapeColor.shape().addAttributes(shapeColor.attributes()));
+    }
+
+    private static ColorAttributes copy(ColorAttributes attrs) {
+        return new ColorAttributes(attrs.filled, attrs.stroked, attrs.filledColor, attrs.strokedColor);
+    }
+
+    private record ShapeColor(Shape shape, ColorAttributes attributes) {}
+}

src/main/java/ovh/gasser/newshapes/command/Command.java

@@ -0,0 +1,11 @@
+package ovh.gasser.newshapes.command;
+
+public interface Command {
+    void execute();
+
+    void undo();
+
+    default void redo() {
+        execute();
+    }
+}

src/main/java/ovh/gasser/newshapes/command/CommandHistory.java

@@ -0,0 +1,85 @@
+package ovh.gasser.newshapes.command;
+
+import java.util.ArrayDeque;
+import java.util.ArrayList;
+import java.util.Deque;
+import java.util.List;
+
+public class CommandHistory {
+    public static final int DEFAULT_LIMIT = 100;
+
+    private final Deque<Command> undoStack = new ArrayDeque<>();
+    private final Deque<Command> redoStack = new ArrayDeque<>();
+    private final List<CommandHistoryListener> listeners = new ArrayList<>();
+    private final int limit;
+
+    public CommandHistory() {
+        this(DEFAULT_LIMIT);
+    }
+
+    public CommandHistory(int limit) {
+        this.limit = Math.max(1, limit);
+    }
+
+    public void execute(Command command) {
+        command.execute();
+        undoStack.push(command);
+        trimUndoStack();
+        redoStack.clear();
+        notifyListeners();
+    }
+
+    public void undo() {
+        if (!canUndo()) {
+            return;
+        }
+
+        Command command = undoStack.pop();
+        command.undo();
+        redoStack.push(command);
+        notifyListeners();
+    }
+
+    public void redo() {
+        if (!canRedo()) {
+            return;
+        }
+
+        Command command = redoStack.pop();
+        command.redo();
+        undoStack.push(command);
+        trimUndoStack();
+        notifyListeners();
+    }
+
+    public boolean canUndo() {
+        return !undoStack.isEmpty();
+    }
+
+    public boolean canRedo() {
+        return !redoStack.isEmpty();
+    }
+
+    public void clear() {
+        undoStack.clear();
+        redoStack.clear();
+        notifyListeners();
+    }
+
+    public void addListener(CommandHistoryListener listener) {
+        listeners.add(listener);
+        listener.onHistoryChanged(canUndo(), canRedo());
+    }
+
+    private void trimUndoStack() {
+        while (undoStack.size() > limit) {
+            undoStack.removeLast();
+        }
+    }
+
+    private void notifyListeners() {
+        boolean canUndo = canUndo();
+        boolean canRedo = canRedo();
+        listeners.forEach(listener -> listener.onHistoryChanged(canUndo, canRedo));
+    }
+}

src/main/java/ovh/gasser/newshapes/command/CommandHistoryListener.java

@@ -0,0 +1,5 @@
+package ovh.gasser.newshapes.command;
+
+public interface CommandHistoryListener {
+    void onHistoryChanged(boolean canUndo, boolean canRedo);
+}

src/main/java/ovh/gasser/newshapes/command/MoveShapeCommand.java

@@ -0,0 +1,28 @@
+package ovh.gasser.newshapes.command;
+
+import ovh.gasser.newshapes.shapes.Shape;
+
+import java.util.Collection;
+import java.util.List;
+
+public class MoveShapeCommand implements Command {
+    private final List<Shape> shapes;
+    private final int dx;
+    private final int dy;
+
+    public MoveShapeCommand(Collection<? extends Shape> shapes, int dx, int dy) {
+        this.shapes = List.copyOf(shapes);
+        this.dx = dx;
+        this.dy = dy;
+    }
+
+    @Override
+    public void execute() {
+        shapes.forEach(shape -> shape.translate(dx, dy));
+    }
+
+    @Override
+    public void undo() {
+        shapes.forEach(shape -> shape.translate(-dx, -dy));
+    }
+}

src/main/java/ovh/gasser/newshapes/command/RemoveShapeCommand.java

@@ -0,0 +1,49 @@
+package ovh.gasser.newshapes.command;
+
+import ovh.gasser.newshapes.shapes.SCollection;
+import ovh.gasser.newshapes.shapes.Shape;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Comparator;
+import java.util.List;
+
+public class RemoveShapeCommand implements Command {
+    private final SCollection model;
+    private final List<IndexedShape> shapes;
+
+    public RemoveShapeCommand(SCollection model, Shape shape) {
+        this(model, List.of(shape));
+    }
+
+    public RemoveShapeCommand(SCollection model, Collection<? extends Shape> shapes) {
+        this.model = model;
+        this.shapes = shapes.stream()
+                .map(shape -> new IndexedShape(model.indexOf(shape), shape))
+                .filter(entry -> entry.index() >= 0)
+                .sorted(Comparator.comparingInt(IndexedShape::index))
+                .toList();
+    }
+
+    @Override
+    public void execute() {
+        List<IndexedShape> reversed = new ArrayList<>(shapes);
+        reversed.sort(Comparator.comparingInt(IndexedShape::index).reversed());
+        reversed.forEach(entry -> {
+            if (model.contains(entry.shape())) {
+                model.remove(entry.shape());
+            }
+        });
+    }
+
+    @Override
+    public void undo() {
+        shapes.forEach(entry -> {
+            if (!model.contains(entry.shape())) {
+                model.insert(entry.index(), entry.shape());
+            }
+        });
+    }
+
+    private record IndexedShape(int index, Shape shape) {}
+}

src/main/java/ovh/gasser/newshapes/command/ResizeShapeCommand.java

@@ -0,0 +1,51 @@
+package ovh.gasser.newshapes.command;
+
+import ovh.gasser.newshapes.shapes.AbstractShape;
+import ovh.gasser.newshapes.shapes.Shape;
+
+import java.awt.*;
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+
+public class ResizeShapeCommand implements Command {
+    private final List<ShapeBounds> before;
+    private final List<ShapeBounds> after;
+
+    public ResizeShapeCommand(Collection<? extends Shape> shapes, Map<Shape, Rectangle> before, Map<Shape, Rectangle> after) {
+        this.before = snapshots(shapes, before);
+        this.after = snapshots(shapes, after);
+    }
+
+    @Override
+    public void execute() {
+        apply(after);
+    }
+
+    @Override
+    public void undo() {
+        apply(before);
+    }
+
+    private static List<ShapeBounds> snapshots(Collection<? extends Shape> shapes, Map<Shape, Rectangle> states) {
+        return shapes.stream()
+                .map(shape -> new ShapeBounds(shape, states.get(shape)))
+                .toList();
+    }
+
+    private void apply(List<ShapeBounds> states) {
+        states.forEach(state -> {
+            if (!(state.shape() instanceof AbstractShape abstractShape)) {
+                throw new IllegalArgumentException("Resize commands support AbstractShape instances only");
+            }
+            abstractShape.setBounds(state.bounds());
+        });
+    }
+
+    private record ShapeBounds(Shape shape, Rectangle bounds) {
+        private ShapeBounds(Shape shape, Rectangle bounds) {
+            this.shape = shape;
+            this.bounds = new Rectangle(bounds);
+        }
+    }
+}

src/main/java/ovh/gasser/newshapes/persistence/DrawingSerializer.java

@@ -1,43 +0,0 @@
-package ovh.gasser.newshapes.persistence;
-
-import com.fasterxml.jackson.core.Version;
-import com.fasterxml.jackson.databind.ObjectMapper;
-import com.fasterxml.jackson.databind.module.SimpleModule;
-import ovh.gasser.newshapes.shapes.SCollection;
-import ovh.gasser.newshapes.shapes.Shape;
-
-import java.io.File;
-import java.io.IOException;
-
-public class DrawingSerializer {
-    private static final String VERSION = "1.0";
-    private final ObjectMapper mapper;
-
-    public DrawingSerializer() {
-        this.mapper = new ObjectMapper();
-        SimpleModule module = new SimpleModule("ShapeModule", new Version(1, 0, 0, null, null, null));
-        module.addSerializer(Shape.class, new ShapeSerializer());
-        module.addDeserializer(Shape.class, new ShapeDeserializer());
-        this.mapper.registerModule(module);
-    }
-
-    public void save(SCollection model, File file) throws IOException {
-        DrawingData data = new DrawingData();
-        data.version = VERSION;
-        data.shapes = new java.util.ArrayList<>();
-        for (Shape shape : model) {
-            data.shapes.add(shape);
-        }
-        mapper.writerWithDefaultPrettyPrinter().writeValue(file, data);
-    }
-
-    public SCollection load(File file) throws IOException {
-        DrawingData data = mapper.readValue(file, DrawingData.class);
-        return SCollection.of(data.shapes.toArray(new Shape[0]));
-    }
-
-    public static class DrawingData {
-        public String version;
-        public java.util.List<Shape> shapes;
-    }
-}

src/main/java/ovh/gasser/newshapes/persistence/ShapeDeserializer.java

@@ -1,159 +0,0 @@
-package ovh.gasser.newshapes.persistence;
-
-import com.fasterxml.jackson.core.JsonParser;
-import com.fasterxml.jackson.databind.DeserializationContext;
-import com.fasterxml.jackson.databind.JsonNode;
-import com.fasterxml.jackson.databind.deser.std.StdDeserializer;
-import ovh.gasser.newshapes.shapes.SCircle;
-import ovh.gasser.newshapes.shapes.SCollection;
-import ovh.gasser.newshapes.shapes.SPolygon;
-import ovh.gasser.newshapes.shapes.SRectangle;
-import ovh.gasser.newshapes.shapes.SText;
-import ovh.gasser.newshapes.shapes.STriangle;
-import ovh.gasser.newshapes.shapes.Shape;
-
-import java.awt.*;
-import java.io.IOException;
-import java.util.ArrayList;
-import java.util.List;
-
-public class ShapeDeserializer extends StdDeserializer<Shape> {
-
-    public ShapeDeserializer() {
-        super(Shape.class);
-    }
-
-    @Override
-    public Shape deserialize(JsonParser p, DeserializationContext ctxt) throws IOException {
-        JsonNode node = p.getCodec().readTree(p);
-        String type = node.get("type").asText();
-
-        return switch (type) {
-            case "rectangle" -> deserializeRectangle(node);
-            case "circle" -> deserializeCircle(node);
-            case "triangle" -> deserializeTriangle(node);
-            case "text" -> deserializeText(node);
-            case "polygon" -> deserializePolygon(node);
-            case "collection" -> deserializeCollection(node, p, ctxt);
-            default -> throw new IllegalArgumentException("Unknown shape type: " + type);
-        };
-    }
-
-    private SRectangle deserializeRectangle(JsonNode node) {
-        int x = node.get("x").asInt();
-        int y = node.get("y").asInt();
-        int width = node.get("width").asInt();
-        int height = node.get("height").asInt();
-
-        Color strokeColor = extractStrokeColor(node);
-        return SRectangle.create(x, y, width, height, strokeColor);
-    }
-
-    private SCircle deserializeCircle(JsonNode node) {
-        int x = node.get("x").asInt();
-        int y = node.get("y").asInt();
-        int radius = node.get("radius").asInt();
-
-        Color strokeColor = extractStrokeColor(node);
-        Color fillColor = extractFillColor(node);
-
-        SCircle circle = SCircle.create(x + radius, y + radius, radius);
-        circle.addAttributes(new ovh.gasser.newshapes.attributes.ColorAttributes(
-                fillColor != null, strokeColor != null, strokeColor, fillColor));
-        return circle;
-    }
-
-    private STriangle deserializeTriangle(JsonNode node) {
-        int x = node.get("x").asInt();
-        int y = node.get("y").asInt();
-        int size = node.get("size").asInt();
-
-        Color strokeColor = extractStrokeColor(node);
-        Color fillColor = extractFillColor(node);
-
-        return STriangle.create(x, y, size, fillColor != null ? fillColor : Color.YELLOW,
-                strokeColor != null ? strokeColor : Color.BLACK);
-    }
-
-    private SText deserializeText(JsonNode node) {
-        int x = node.get("x").asInt();
-        int y = node.get("y").asInt();
-        String text = node.get("text").asText();
-
-        Color strokeColor = extractStrokeColor(node);
-
-        SText sText = SText.create(x, y, text);
-        if (strokeColor != null) {
-            sText.addAttributes(new ovh.gasser.newshapes.attributes.ColorAttributes(
-                    true, true, strokeColor, strokeColor));
-        }
-        return sText;
-    }
-
-    private SPolygon deserializePolygon(JsonNode node) {
-        List<Point> points = new ArrayList<>();
-        JsonNode pointsNode = node.get("points");
-        for (JsonNode pointNode : pointsNode) {
-            int x = pointNode.get("x").asInt();
-            int y = pointNode.get("y").asInt();
-            points.add(new Point(x, y));
-        }
-
-        Color strokeColor = extractStrokeColor(node);
-        Color fillColor = extractFillColor(node);
-
-        SPolygon poly = SPolygon.create(points);
-        if (strokeColor != null || fillColor != null) {
-            poly.addAttributes(new ovh.gasser.newshapes.attributes.ColorAttributes(
-                    fillColor != null, strokeColor != null,
-                    strokeColor != null ? strokeColor : Color.BLACK,
-                    fillColor != null ? fillColor : Color.BLACK));
-        }
-        return poly;
-    }
-
-    private SCollection deserializeCollection(JsonNode node, JsonParser p, DeserializationContext ctxt) throws IOException {
-        List<Shape> children = new ArrayList<>();
-        JsonNode shapesNode = node.get("shapes");
-        if (shapesNode != null && shapesNode.isArray()) {
-            for (JsonNode childNode : shapesNode) {
-                JsonParser childParser = childNode.traverse(p.getCodec());
-                children.add(deserialize(childParser, ctxt));
-            }
-        }
-        return SCollection.of(children.toArray(new Shape[0]));
-    }
-
-    private Color extractStrokeColor(JsonNode node) {
-        if (node.has("color")) {
-            JsonNode colorNode = node.get("color");
-            if (colorNode.has("stroked") && colorNode.get("stroked").asBoolean()) {
-                return hexToColor(colorNode.get("strokedColor").asText());
-            }
-        }
-        return null;
-    }
-
-    private Color extractFillColor(JsonNode node) {
-        if (node.has("color")) {
-            JsonNode colorNode = node.get("color");
-            if (colorNode.has("filled") && colorNode.get("filled").asBoolean()) {
-                return hexToColor(colorNode.get("filledColor").asText());
-            }
-        }
-        return null;
-    }
-
-    private Color hexToColor(String hex) {
-        if (hex == null || hex.isEmpty()) return Color.BLACK;
-        try {
-            return new Color(
-                    Integer.parseInt(hex.substring(1, 3), 16),
-                    Integer.parseInt(hex.substring(3, 5), 16),
-                    Integer.parseInt(hex.substring(5, 7), 16)
-            );
-        } catch (Exception e) {
-            return Color.BLACK;
-        }
-    }
-}

src/main/java/ovh/gasser/newshapes/persistence/ShapeSerializer.java

@@ -1,121 +0,0 @@
-package ovh.gasser.newshapes.persistence;
-
-import com.fasterxml.jackson.core.JsonGenerator;
-import com.fasterxml.jackson.databind.JsonSerializer;
-import com.fasterxml.jackson.databind.SerializerProvider;
-import ovh.gasser.newshapes.attributes.ColorAttributes;
-import ovh.gasser.newshapes.shapes.SCircle;
-import ovh.gasser.newshapes.shapes.SCollection;
-import ovh.gasser.newshapes.shapes.SPolygon;
-import ovh.gasser.newshapes.shapes.SRectangle;
-import ovh.gasser.newshapes.shapes.SText;
-import ovh.gasser.newshapes.shapes.STriangle;
-import ovh.gasser.newshapes.shapes.Shape;
-
-import java.awt.*;
-import java.io.IOException;
-import java.util.ArrayList;
-import java.util.List;
-
-public class ShapeSerializer extends JsonSerializer<Shape> {
-
-    @Override
-    public void serialize(Shape shape, JsonGenerator gen, SerializerProvider serializers) throws IOException {
-        gen.writeStartObject();
-
-        if (shape instanceof SRectangle rect) {
-            gen.writeStringField("type", "rectangle");
-            writeRectangle(rect, gen);
-        } else if (shape instanceof SCircle circle) {
-            gen.writeStringField("type", "circle");
-            writeCircle(circle, gen);
-        } else if (shape instanceof STriangle tri) {
-            gen.writeStringField("type", "triangle");
-            writeTriangle(tri, gen);
-        } else if (shape instanceof SText text) {
-            gen.writeStringField("type", "text");
-            writeText(text, gen);
-        } else if (shape instanceof SPolygon poly) {
-            gen.writeStringField("type", "polygon");
-            writePolygon(poly, gen);
-        } else if (shape instanceof SCollection coll) {
-            gen.writeStringField("type", "collection");
-            writeCollection(coll, gen);
-        }
-
-        gen.writeEndObject();
-    }
-
-    private void writeRectangle(SRectangle rect, JsonGenerator gen) throws IOException {
-        Rectangle bounds = rect.getBounds();
-        gen.writeNumberField("x", bounds.x);
-        gen.writeNumberField("y", bounds.y);
-        gen.writeNumberField("width", bounds.width);
-        gen.writeNumberField("height", bounds.height);
-        writeColorAttributes(rect, gen);
-    }
-
-    private void writeCircle(SCircle circle, JsonGenerator gen) throws IOException {
-        Rectangle bounds = circle.getBounds();
-        gen.writeNumberField("x", bounds.x);
-        gen.writeNumberField("y", bounds.y);
-        gen.writeNumberField("radius", circle.getRadius());
-        writeColorAttributes(circle, gen);
-    }
-
-    private void writeTriangle(STriangle tri, JsonGenerator gen) throws IOException {
-        Rectangle bounds = tri.getBounds();
-        gen.writeNumberField("x", bounds.x);
-        gen.writeNumberField("y", bounds.y);
-        gen.writeNumberField("size", bounds.width);
-        writeColorAttributes(tri, gen);
-    }
-
-    private void writeText(SText text, JsonGenerator gen) throws IOException {
-        Rectangle bounds = text.getBounds();
-        gen.writeNumberField("x", bounds.x);
-        gen.writeNumberField("y", bounds.y);
-        gen.writeStringField("text", text.getText());
-        gen.writeStringField("fontName", text.getFontName());
-        gen.writeNumberField("fontSize", text.getFontSize());
-        gen.writeNumberField("fontStyle", text.getFontStyle());
-        writeColorAttributes(text, gen);
-    }
-
-    private void writePolygon(SPolygon poly, JsonGenerator gen) throws IOException {
-        gen.writeArrayFieldStart("points");
-        for (Point p : poly.getPoints()) {
-            gen.writeStartObject();
-            gen.writeNumberField("x", p.x);
-            gen.writeNumberField("y", p.y);
-            gen.writeEndObject();
-        }
-        gen.writeEndArray();
-        writeColorAttributes(poly, gen);
-    }
-
-    private void writeCollection(SCollection coll, JsonGenerator gen) throws IOException {
-        gen.writeArrayFieldStart("shapes");
-        for (Shape child : coll) {
-            serialize(child, gen, null);
-        }
-        gen.writeEndArray();
-    }
-
-    private void writeColorAttributes(Shape shape, JsonGenerator gen) throws IOException {
-        ColorAttributes attrs = (ColorAttributes) shape.getAttributes(ColorAttributes.ID);
-        if (attrs != null) {
-            gen.writeObjectFieldStart("color");
-            gen.writeBooleanField("filled", attrs.filled);
-            gen.writeBooleanField("stroked", attrs.stroked);
-            gen.writeStringField("filledColor", colorToHex(attrs.filledColor));
-            gen.writeStringField("strokedColor", colorToHex(attrs.strokedColor));
-            gen.writeEndObject();
-        }
-    }
-
-    private String colorToHex(Color c) {
-        if (c == null) return "#000000";
-        return String.format("#%02x%02x%02x", c.getRed(), c.getGreen(), c.getBlue());
-    }
-}