Implement #34: Undo/Redo Stack with Command Pattern

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/test/java/ovh/gasser/newshapes/ui/ControllerTest.java

@@ -1,198 +0,0 @@
-package ovh.gasser.newshapes.ui;
-
-import org.junit.jupiter.api.Test;
-import ovh.gasser.newshapes.attributes.SelectionAttributes;
-import ovh.gasser.newshapes.shapes.SCollection;
-import ovh.gasser.newshapes.shapes.SRectangle;
-import ovh.gasser.newshapes.shapes.Shape;
-
-import java.awt.*;
-import java.awt.event.InputEvent;
-import java.awt.event.KeyEvent;
-import java.awt.event.MouseEvent;
-import java.awt.event.MouseListener;
-import java.util.List;
-
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertFalse;
-import static org.junit.jupiter.api.Assertions.assertInstanceOf;
-import static org.junit.jupiter.api.Assertions.assertTrue;
-
-class ControllerTest {
-
-    @Test
-    void copyDoesNotMutateModelAndPasteSelectsOffsetClone() {
-        SCollection model = SCollection.of(SRectangle.create(10, 15, 30, 40, Color.BLUE));
-        ShapesView view = new ShapesView(model);
-        Controller controller = view.getController();
-
-        click(view, 15, 20, 0);
-        controller.copySelection();
-
-        assertEquals(1, model.stream().count());
-
-        controller.pasteClipboard();
-
-        List<Shape> shapes = model.stream().toList();
-        assertEquals(2, shapes.size());
-        assertEquals(new Rectangle(10, 15, 30, 40), shapes.get(0).getBounds());
-        assertEquals(new Rectangle(30, 35, 30, 40), shapes.get(1).getBounds());
-        assertFalse(isSelected(shapes.get(0)));
-        assertTrue(isSelected(shapes.get(1)));
-    }
-
-    @Test
-    void repeatedPasteKeepsIncreasingOffset() {
-        SCollection model = SCollection.of(SRectangle.create(5, 10, 20, 25, Color.RED));
-        ShapesView view = new ShapesView(model);
-        Controller controller = view.getController();
-
-        click(view, 10, 15, 0);
-        controller.copySelection();
-        controller.pasteClipboard();
-        controller.pasteClipboard();
-
-        List<Shape> shapes = model.stream().toList();
-        assertEquals(3, shapes.size());
-        assertEquals(new Rectangle(25, 30, 20, 25), shapes.get(1).getBounds());
-        assertEquals(new Rectangle(45, 50, 20, 25), shapes.get(2).getBounds());
-        assertFalse(isSelected(shapes.get(1)));
-        assertTrue(isSelected(shapes.get(2)));
-    }
-
-    @Test
-    void controlShortcutsCutAndPasteMultipleShapes() {
-        SCollection model = SCollection.of(
-                SRectangle.create(10, 10, 15, 20, Color.BLACK),
-                SRectangle.create(80, 25, 25, 30, Color.GREEN)
-        );
-        ShapesView view = new ShapesView(model);
-
-        click(view, 15, 15, 0);
-        click(view, 85, 30, InputEvent.SHIFT_DOWN_MASK);
-
-        pressShortcut(view, KeyEvent.VK_X);
-        assertEquals(0, model.stream().count());
-
-        pressShortcut(view, KeyEvent.VK_V);
-
-        List<Shape> shapes = model.stream().toList();
-        assertEquals(2, shapes.size());
-        assertEquals(new Rectangle(30, 30, 15, 20), shapes.get(0).getBounds());
-        assertEquals(new Rectangle(100, 45, 25, 30), shapes.get(1).getBounds());
-        assertTrue(isSelected(shapes.get(0)));
-        assertTrue(isSelected(shapes.get(1)));
-    }
-
-    @Test
-    void groupReplacesSelectedShapesWithCollectionAndSelectsIt() {
-        SRectangle rect1 = SRectangle.create(10, 10, 15, 20, Color.BLACK);
-        SRectangle rect2 = SRectangle.create(80, 25, 25, 30, Color.GREEN);
-        SRectangle rect3 = SRectangle.create(140, 40, 10, 10, Color.BLUE);
-        SCollection model = SCollection.of(rect1, rect2, rect3);
-        ShapesView view = new ShapesView(model);
-        Controller controller = view.getController();
-
-        click(view, 15, 15, 0);
-        click(view, 85, 30, InputEvent.SHIFT_DOWN_MASK);
-        controller.group();
-
-        List<Shape> shapes = model.stream().toList();
-        assertEquals(2, shapes.size());
-        SCollection group = assertInstanceOf(SCollection.class, shapes.get(0));
-        assertEquals(List.of(rect1, rect2), group.stream().toList());
-        assertEquals(new Rectangle(10, 10, 95, 45), group.getBounds());
-        assertTrue(isSelected(group));
-        assertFalse(isSelected(rect1));
-        assertFalse(isSelected(rect2));
-        assertFalse(isSelected(rect3));
-    }
-
-    @Test
-    void ungroupOnlyBreaksApartOneLevelAndSelectsChildren() {
-        SRectangle rect1 = SRectangle.create(10, 10, 15, 20, Color.BLACK);
-        SRectangle rect2 = SRectangle.create(80, 25, 25, 30, Color.GREEN);
-        SCollection innerGroup = SCollection.of(rect1, rect2);
-        SRectangle rect3 = SRectangle.create(140, 40, 10, 10, Color.BLUE);
-        SCollection outerGroup = SCollection.of(innerGroup, rect3);
-        SCollection model = SCollection.of(outerGroup);
-        ShapesView view = new ShapesView(model);
-        Controller controller = view.getController();
-
-        click(view, 15, 15, 0);
-        controller.ungroup();
-
-        List<Shape> shapes = model.stream().toList();
-        assertEquals(List.of(innerGroup, rect3), shapes);
-        assertTrue(isSelected(innerGroup));
-        assertTrue(isSelected(rect3));
-        assertFalse(isSelected(rect1));
-        assertFalse(isSelected(rect2));
-    }
-
-    @Test
-    void controlShortcutsGroupAndUngroupShapes() {
-        SCollection model = SCollection.of(
-                SRectangle.create(10, 10, 15, 20, Color.BLACK),
-                SRectangle.create(80, 25, 25, 30, Color.GREEN)
-        );
-        ShapesView view = new ShapesView(model);
-
-        click(view, 15, 15, 0);
-        click(view, 85, 30, InputEvent.SHIFT_DOWN_MASK);
-        pressShortcut(view, KeyEvent.VK_G, InputEvent.CTRL_DOWN_MASK);
-
-        Shape groupedShape = model.stream().toList().get(0);
-        assertTrue(groupedShape instanceof SCollection);
-        assertTrue(isSelected(groupedShape));
-
-        pressShortcut(view, KeyEvent.VK_U, InputEvent.CTRL_DOWN_MASK);
-
-        List<Shape> shapes = model.stream().toList();
-        assertEquals(2, shapes.size());
-        assertTrue(isSelected(shapes.get(0)));
-        assertTrue(isSelected(shapes.get(1)));
-    }
-
-    private static void click(ShapesView view, int x, int y, int modifiers) {
-        MouseEvent event = new MouseEvent(
-                view,
-                MouseEvent.MOUSE_PRESSED,
-                System.currentTimeMillis(),
-                modifiers,
-                x,
-                y,
-                1,
-                false,
-                MouseEvent.BUTTON1
-        );
-
-        for (MouseListener listener : view.getMouseListeners()) {
-            listener.mousePressed(event);
-        }
-    }
-
-    private static void pressShortcut(ShapesView view, int keyCode) {
-        pressShortcut(view, keyCode, InputEvent.CTRL_DOWN_MASK);
-    }
-
-    private static void pressShortcut(ShapesView view, int keyCode, int modifiers) {
-        KeyEvent event = new KeyEvent(
-                view,
-                KeyEvent.KEY_PRESSED,
-                System.currentTimeMillis(),
-                modifiers,
-                keyCode,
-                KeyEvent.CHAR_UNDEFINED
-        );
-
-        for (var listener : view.getKeyListeners()) {
-            listener.keyPressed(event);
-        }
-    }
-
-    private static boolean isSelected(Shape shape) {
-        SelectionAttributes attributes = (SelectionAttributes) shape.getAttributes(SelectionAttributes.ID);
-        return attributes != null && attributes.selected;
-    }
-}