v0.1.6: highlight the folder a dragged playlist would drop into

TASKS.md

@@ -3,6 +3,24 @@
 Legend: `[ ]` todo · `[~]` in progress · `[x]` done.
 When a round closes, move its finished items to `tasks-done.md`.
 
+## Round 25 — folder highlight while dragging a playlist (v0.1.6)
+
+Tests in `tests/test_round25.py`. Fix round → patch bump **0.1.6**.
+
+Dragging a playlist over a folder gave no indication the drop would land
+inside it. `PlaylistTree` now highlights the hovered folder mid-drag with the
+same treatment track drops give playlist rows, via a shared
+`_highlight_drop_target(pos, kind)` helper ("folder" for internal moves,
+"playlist" for track drops). A folder in the dragged row's own branch is
+never highlighted — `move_playlist` rejects that drop as a cycle, so lighting
+it up would lie. The Round 24 autoscroll tick's highlight refresh became
+kind-aware (`_drag_target_kind`) so a folder highlight survives edge
+auto-scrolling instead of being cleared by the track-only check.
+
+- [x] `lintunes/gui/sidebar.py` — `_highlight_drop_target` /
+      `_is_own_branch` helpers; `_drag_target_kind` tracked through
+      `dragMoveEvent`, reset in `_stop_autoscroll`.
+
 ## Round 24 — sidebar drag auto-scroll (v0.1.5)
 
 Tests in `tests/test_round24.py`. Fix round → patch bump **0.1.5**.

lintunes/__init__.py

@@ -1,3 +1,3 @@
 """LinTunes — iTunes-style music library manager and player for Linux."""
 
-__version__ = "0.1.5"
+__version__ = "0.1.6"

lintunes/gui/sidebar.py

@@ -157,6 +157,9 @@ class PlaylistTree(QTreeWidget):
         super().__init__(parent)
         self._manager = manager
         self._drop_target: QTreeWidgetItem | None = None
+        # KIND_ROLE value a drop during the active drag would land on
+        # ("folder" for internal playlist moves, "playlist" for track drops).
+        self._drag_target_kind: str | None = None
 
         self.setHeaderHidden(True)
         self.setIndentation(14)
@@ -396,13 +399,14 @@ class PlaylistTree(QTreeWidget):
             # so edge auto-scroll stays live even over non-folder rows —
             # otherwise scrolling down to a distant folder would be nearly
             # impossible past the playlists in between.
-            self._clear_drop_target()
+            self._drag_target_kind = "folder"
             target = self.itemAt(pos)
             kind = target.data(0, KIND_ROLE) if target else ""
             if kind in ("folder", "") or target is None:
                 event.acceptProposedAction()
             else:
                 event.ignore()
+            self._highlight_drop_target(pos, "folder")
             self._update_autoscroll(pos, accepted=True)
             return
         if not event.mimeData().hasFormat(TRACKS_MIME):
@@ -410,23 +414,48 @@ class PlaylistTree(QTreeWidget):
             self._update_autoscroll(pos, accepted=False)
             event.ignore()
             return
+        self._drag_target_kind = "playlist"
         target = self.itemAt(pos)
         if target and target.data(0, KIND_ROLE) == "playlist":
-            self._set_drop_target(target)
             event.acceptProposedAction()
             self._update_autoscroll(pos, accepted=True)
         else:
-            self._clear_drop_target()
             event.ignore()
             self._update_autoscroll(pos, accepted=False)
+        self._highlight_drop_target(pos, "playlist")
 
     def dragLeaveEvent(self, event):
         self._clear_drop_target()
         self._stop_autoscroll()
         super().dragLeaveEvent(event)
 
+    def _highlight_drop_target(self, pos: QPoint, kind: str):
+        """Highlight the row at ``pos`` if it's a valid target for the active
+        drag — a folder for internal playlist moves, a playlist for track
+        drops — so the user can see where the drop would land. Clears any
+        stale highlight otherwise. A folder inside the dragged row's own
+        branch is never highlighted: the manager would reject that drop as a
+        cycle, so lighting it up would lie."""
+        target = self.itemAt(pos)
+        ok = target is not None and target.data(0, KIND_ROLE) == kind
+        if ok and kind == "folder":
+            ok = not self._is_own_branch(self.currentItem(), target)
+        if ok:
+            self._set_drop_target(target)
+        else:
+            self._clear_drop_target()
+
+    @staticmethod
+    def _is_own_branch(dragged, item) -> bool:
+        """True if ``item`` is the dragged row or inside its subtree."""
+        while item is not None:
+            if item is dragged:
+                return True
+            item = item.parent()
+        return False
+
     def _set_drop_target(self, item):
-        """Highlight the playlist row a drop would land on (cleared on the way
+        """Highlight the row a drop would land on (cleared on the way
         out). Foreground is set too so the name stays legible on the highlight."""
         if item is self._drop_target:
             return
@@ -463,18 +492,16 @@ class PlaylistTree(QTreeWidget):
             self._autoscroll_timer.stop()
             return
         # The cursor may be held still while rows scroll under it, so keep the
-        # drop-target highlight on the row now beneath it (track drags only;
-        # internal playlist moves never set a drop target).
-        if self._autoscroll_pos is not None and self._drop_target is not None:
-            target = self.itemAt(self._autoscroll_pos)
-            if target and target.data(0, KIND_ROLE) == "playlist":
-                self._set_drop_target(target)
-            else:
-                self._clear_drop_target()
+        # drop-target highlight on the row now beneath it.
+        if (self._autoscroll_pos is not None
+                and self._drag_target_kind is not None):
+            self._highlight_drop_target(self._autoscroll_pos,
+                                        self._drag_target_kind)
 
     def _stop_autoscroll(self):
         self._autoscroll_dir = 0
         self._autoscroll_pos = None
+        self._drag_target_kind = None
         self._autoscroll_timer.stop()
 
     def dropEvent(self, event):

tests/test_round25.py

@@ -0,0 +1,135 @@
+"""Round 25: folder highlight while dragging a playlist.
+
+Hovering a folder mid-drag lights it up so the user can see the drop would
+land inside it (previously there was no indication at all). A folder in the
+dragged row's own branch is never highlighted — the manager rejects that drop
+as a cycle, so lighting it up would lie. The autoscroll tick's highlight
+refresh is now kind-aware so a folder highlight survives edge auto-scrolling.
+
+Synthetic QDropEvents report source() == None, so the internal-move branch of
+dragMoveEvent can't be driven directly; _highlight_drop_target carries the
+logic and is what gets tested.
+"""
+
+from PyQt6.QtCore import QPoint
+
+from lintunes.models import Library, Track
+from lintunes.library_manager import LibraryManager
+from lintunes.gui.sidebar import PlaylistTree
+
+
+def _tree(qapp, tmp_path, height=400):
+    library = Library(tracks={1: Track(track_id=1, name="One")})
+    manager = LibraryManager(library, tmp_path)
+    tree = PlaylistTree(manager)
+    tree.resize(200, height)
+    tree.show()
+    return manager, tree
+
+
+def _pos_over(tree, item) -> QPoint:
+    return tree.visualItemRect(item).center()
+
+
+class TestFolderHighlight:
+    def test_folder_highlighted_while_dragging_playlist(self, qapp, tmp_path):
+        manager, tree = _tree(qapp, tmp_path)
+        folder = manager.create_folder("a folder")
+        playlist = manager.create_playlist("a playlist")
+        folder_item = tree._find_item(folder.persistent_id)
+        tree.setCurrentItem(tree._find_item(playlist.persistent_id))
+
+        tree._highlight_drop_target(_pos_over(tree, folder_item), "folder")
+        assert tree._drop_target is folder_item
+
+    def test_leaving_the_folder_clears_the_highlight(self, qapp, tmp_path):
+        manager, tree = _tree(qapp, tmp_path)
+        folder = manager.create_folder("a folder")
+        playlist = manager.create_playlist("a playlist")
+        folder_item = tree._find_item(folder.persistent_id)
+        tree.setCurrentItem(tree._find_item(playlist.persistent_id))
+
+        tree._highlight_drop_target(_pos_over(tree, folder_item), "folder")
+        assert tree._drop_target is not None
+        # Hover empty space below the rows (drop there = top level).
+        tree._highlight_drop_target(
+            QPoint(10, tree.viewport().height() - 2), "folder")
+        assert tree._drop_target is None
+
+    def test_playlist_row_is_not_a_folder_target(self, qapp, tmp_path):
+        manager, tree = _tree(qapp, tmp_path)
+        playlist = manager.create_playlist("a playlist")
+        other = manager.create_playlist("another playlist")
+        tree.setCurrentItem(tree._find_item(other.persistent_id))
+
+        tree._highlight_drop_target(
+            _pos_over(tree, tree._find_item(playlist.persistent_id)), "folder")
+        assert tree._drop_target is None
+
+    def test_dragged_folder_cannot_drop_into_its_own_branch(
+            self, qapp, tmp_path):
+        manager, tree = _tree(qapp, tmp_path)
+        outer = manager.create_folder("a outer")
+        inner = manager.create_folder("b inner", outer.persistent_id)
+        other = manager.create_folder("c other")
+        outer_item = tree._find_item(outer.persistent_id)
+        inner_item = tree._find_item(inner.persistent_id)
+        other_item = tree._find_item(other.persistent_id)
+        outer_item.setExpanded(True)
+        tree.setCurrentItem(outer_item)  # dragging "outer"
+
+        # Onto itself: no highlight (manager would no-op the drop).
+        tree._highlight_drop_target(_pos_over(tree, outer_item), "folder")
+        assert tree._drop_target is None
+        # Into its own subfolder: no highlight (manager rejects the cycle).
+        tree._highlight_drop_target(_pos_over(tree, inner_item), "folder")
+        assert tree._drop_target is None
+        # Into an unrelated folder: highlighted.
+        tree._highlight_drop_target(_pos_over(tree, other_item), "folder")
+        assert tree._drop_target is other_item
+
+    def test_track_drag_still_highlights_playlists(self, qapp, tmp_path):
+        manager, tree = _tree(qapp, tmp_path)
+        folder = manager.create_folder("a folder")
+        playlist = manager.create_playlist("a playlist")
+        folder_item = tree._find_item(folder.persistent_id)
+        playlist_item = tree._find_item(playlist.persistent_id)
+
+        tree._highlight_drop_target(_pos_over(tree, playlist_item), "playlist")
+        assert tree._drop_target is playlist_item
+        # Folders are not track-drop targets.
+        tree._highlight_drop_target(_pos_over(tree, folder_item), "playlist")
+        assert tree._drop_target is None
+
+
+class TestKindAwareTick:
+    def test_tick_clears_folder_highlight_scrolled_out_from_under_cursor(
+            self, qapp, tmp_path):
+        manager, tree = _tree(qapp, tmp_path, height=100)
+        folder = manager.create_folder("aaa folder")  # sorts to the top row
+        dragged = None
+        for i in range(60):
+            dragged = manager.create_playlist(f"playlist {i}")
+        tree.setCurrentItem(tree._find_item(dragged.persistent_id))
+        tree.scrollToTop()  # setCurrentItem scrolled the dragged row into view
+
+        pos = _pos_over(tree, tree._find_item(folder.persistent_id))
+        tree._highlight_drop_target(pos, "folder")
+        assert tree._drop_target is not None
+
+        # Cursor held still over that spot while the edge auto-scroll rolls:
+        # the folder scrolls away and a non-target row takes its place.
+        tree._drag_target_kind = "folder"
+        tree._autoscroll_pos = pos
+        tree._autoscroll_dir = 1
+        assert tree.verticalScrollBar().value() == 0
+        tree._autoscroll_tick()
+
+        assert tree.verticalScrollBar().value() == 1
+        assert tree._drop_target is None
+
+    def test_stop_autoscroll_resets_drag_target_kind(self, qapp, tmp_path):
+        _manager, tree = _tree(qapp, tmp_path)
+        tree._drag_target_kind = "folder"
+        tree._stop_autoscroll()
+        assert tree._drag_target_kind is None