feat(dees-dashboardgrid): implement collision detection during widget swap to prevent overlaps

test/test.dashboardgrid-layout.node.ts

@@ -0,0 +1,28 @@
+import { tap, expect } from '@push.rocks/tapbundle';
+
+import {
+  resolveWidgetPlacement,
+  collectCollisions,
+} from '../ts_web/elements/dees-dashboardgrid/layout.ts';
+import type { DashboardWidget } from '../ts_web/elements/dees-dashboardgrid/types.ts';
+
+tap.test('dashboardgrid does not overlap widgets after swap attempt', async () => {
+  const widgets: DashboardWidget[] = [
+    { id: 'w0', x: 6, y: 5, w: 1, h: 3 },
+    { id: 'w1', x: 6, y: 1, w: 1, h: 3 },
+    { id: 'w2', x: 3, y: 0, w: 2, h: 2 },
+    { id: 'w3', x: 9, y: 0, w: 1, h: 2 },
+    { id: 'w4', x: 4, y: 3, w: 1, h: 2 },
+  ];
+
+  const placement = resolveWidgetPlacement(widgets, 'w0', { x: 6, y: 3 }, 12);
+  expect(placement).toBeTruthy();
+
+  const layout = placement!.widgets;
+  for (const widget of layout) {
+    const collisions = collectCollisions(layout, widget, widget.x, widget.y, widget.w, widget.h);
+    expect(collisions).toBeEmptyArray();
+  }
+});
+
+export default tap.start();

ts_web/elements/dees-dashboardgrid/layout.ts

@@ -164,9 +164,20 @@ export const resolveWidgetPlacement = (
         // Use the original position of the moving widget for a clean swap
         // This prevents the "snapping together" issue where both widgets end up at the same position
         const swapTarget = original;
+        const previousOtherPosition = { x: otherClone.x, y: otherClone.y };
         otherClone.x = swapTarget.x;
         otherClone.y = swapTarget.y;
-        return { widgets: sourceWidgets, movedWidgets: [moving.id, otherClone.id], swappedWith: otherClone.id };
+
+        const swapValid =
+          collectCollisions(sourceWidgets, moving, moving.x, moving.y, moving.w, moving.h).length === 0 &&
+          collectCollisions(sourceWidgets, otherClone, otherClone.x, otherClone.y, otherClone.w, otherClone.h).length === 0;
+
+        if (swapValid) {
+          return { widgets: sourceWidgets, movedWidgets: [moving.id, otherClone.id], swappedWith: otherClone.id };
+        }
+
+        otherClone.x = previousOtherPosition.x;
+        otherClone.y = previousOtherPosition.y;
       }
     }
   }