fix: allow dropping into itself if the drop target is reparented outside of self (#148)

Author: lukasbach

packages/core/src/drag/DraggingPositionEvaluation.ts

@@ -127,12 +127,22 @@ export class DraggingPositionEvaluation {
       return undefined;
     }
 
-    // this.targetItem = newParent.parent;
     const reparentedChildIndex =
       this.env.items[newParent.parent.item].children!.indexOf(
         insertionItemAbove.parent.item
       ) + 1;
 
+    if (
+      this.draggingItems &&
+      this.isDescendant(
+        this.treeId,
+        newParent.parentLinearIndex + 1,
+        this.draggingItems
+      )
+    ) {
+      return undefined;
+    }
+
     return {
       targetType: 'between-items',
       treeId: this.treeId,
@@ -232,10 +242,6 @@ export class DraggingPositionEvaluation {
 
     this.maybeRedirectToParent();
 
-    if (this.areDraggingItemsDescendantOfTarget()) {
-      return undefined;
-    }
-
     this.maybeRedirectInsideOpenFolder();
     this.maybeMapToBottomOffset();
 
@@ -244,6 +250,10 @@ export class DraggingPositionEvaluation {
       return reparented;
     }
 
+    if (this.areDraggingItemsDescendantOfTarget()) {
+      return undefined;
+    }
+
     if (!this.canDropAtCurrentTarget()) {
       return undefined;
     }
@@ -282,6 +292,7 @@ export class DraggingPositionEvaluation {
     itemLinearIndex: number,
     potentialParents: TreeItem[]
   ) {
+    // console.log('descendant check', itemLinearIndex, potentialParents);
     const { parentLinearIndex, parent } = this.getParentOfLinearItem(
       itemLinearIndex,
       treeId

packages/core/test/dnd-basics.spec.tsx

@@ -446,6 +446,14 @@ describe('dnd basics', () => {
         ]);
       });
 
+      it('doesnt reparent into itself', async () => {
+        const test = await new TestUtil().renderOpenTree();
+        await test.startDrag('a');
+        await test.dragOver('aad', 'bottom', 3);
+        await test.drop();
+        await test.expectTreeUnchanged();
+      });
+
       it('reparents inner level', async () => {
         const test = await new TestUtil().renderOpenTree();
         await test.startDrag('bbb');
@@ -487,6 +495,41 @@ describe('dnd basics', () => {
         ]);
       });
 
+      it('reparents bottom-most nested item', async () => {
+        const test = await new TestUtil().renderOpenTree();
+        await test.startDrag('special');
+        await test.dragOver('deep5', 'bottom', 10);
+        await test.drop();
+        await test.expectVisibleItemContents('deep4', ['deep5', 'special']);
+
+        await new Promise(r => {
+          setTimeout(r);
+        });
+
+        await test.startDrag('special');
+        await test.dragOver('cannot-rename', 'bottom', 3);
+        await test.drop();
+        await test.expectVisibleItemContents('deep4', ['deep5']);
+        await test.expectVisibleItemContents('deep3', ['deep4', 'special']);
+
+        await new Promise(r => {
+          setTimeout(r);
+        });
+
+        await test.startDrag('special');
+        await test.dragOver('cannot-rename', 'bottom', 0);
+        await test.drop();
+        await test.expectVisibleItemContents('deep3', ['deep4']);
+        await test.expectItemContents('root', [
+          'target-parent',
+          'a',
+          'b',
+          'c',
+          'deep1',
+          'special',
+        ]);
+      });
+
       describe('reparent upwards when dragging at top of item below subtree', () => {
         it('reparents inner level', async () => {
           const test = await new TestUtil().renderOpenTree();