feat: add star rating to metadata editor with write support to audio tags

- ClickableStarRating widget — 5 stars with hover preview, toggle to unrate
- Rating field in MetadataEditorDialog (0–5 stars), saved to LibraryCache (0–100)
- MetadataHandler writes rating to MP3 (POPM), M4A (\xa9rt), FLAC/Ogg (RATING)

src/ui/metadata_editor.py

@@ -31,6 +31,8 @@ from PyQt6.QtGui import QPixmap, QDragEnterEvent, QDropEvent
 from metadata_handler import MetadataHandler
 from artwork.cache import cover_cache
 from services.itunes_search import search_itunes
+from library_cache import get_library_cache, save_library_cache
+from .star_rating import ClickableStarRating
 
 
 COVER_SIZE = 250
@@ -72,6 +74,8 @@ class MetadataEditorDialog(QDialog):
         self._original_tags = dict(first_tags)
         self._existing_cover_data = self._extract_cover_from_path(self.file_paths[0])
 
+        self._load_ratings_from_cache()
+
         if self._batch_mode:
             all_tags = [first_tags]
             all_different = False
@@ -84,6 +88,31 @@ class MetadataEditorDialog(QDialog):
                     if tags.get(key) != self._original_tags.get(key):
                         self._mixed_fields.add(key)
 
+    def _load_ratings_from_cache(self):
+        """Load rating from LibraryCache for all selected files.
+
+        Stores the rating (0–5 stars) in ``self._original_tags['rating']``
+        (only when cache has a value; file‑tag rating takes precedence if
+        cache is empty).  In batch mode, marks ``rating`` as mixed when
+        values differ.
+        """
+        cache = get_library_cache()
+        ratings = []
+        for p in self.file_paths:
+            entry = cache.get(p)
+            r = entry.get("rating", 0) if entry else 0
+            ratings.append(max(0, min(5, round(r / 20))))
+
+        cache_val = ratings[0]
+        if cache_val > 0 or "rating" not in self._original_tags:
+            self._original_tags["rating"] = cache_val
+
+        if self._batch_mode and len(set(ratings)) > 1:
+            self._mixed_fields.add("rating")
+            self._ratings = {p: r for p, r in zip(self.file_paths, ratings)}
+        else:
+            self._ratings = {}
+
     def _load_single_file(self, file_path: str, skip_cover: bool = False) -> Dict[str, Any]:
         """Load tags from a single file. Returns dict of tag_key -> value."""
         result: Dict[str, Any] = {}
@@ -110,12 +139,40 @@ class MetadataEditorDialog(QDialog):
                     result[our_key] = val
 
             result.update(self._load_track_disc(tags))
+            result.update(self._load_rating_from_tags(tags, ext))
 
         except Exception:
             pass
 
         return result
 
+    @staticmethod
+    def _load_rating_from_tags(tags, ext: str) -> dict:
+        """Read rating (0–5 stars) from audio file tags, if present."""
+        if tags is None:
+            return {}
+        try:
+            if ext in ('.m4a', '.aac', '.mp4') and '\xa9rt' in tags:
+                rt = tags['\xa9rt']
+                if isinstance(rt, list) and rt:
+                    val = int(rt[0]) // 20  # 0-100 → 0-5
+                    return {"rating": max(0, min(5, val))}
+            elif ext == '.mp3':
+                for frame in tags.getall('POPM'):
+                    if frame.rating > 0:
+                        pops = [0, 64, 128, 192, 224, 255]
+                        stars = max(i for i, v in enumerate(pops) if v <= frame.rating)
+                        return {"rating": stars}
+            elif ext in ('.flac', '.ogg', '.opus') and 'RATING' in tags:
+                raw = tags['RATING']
+                if isinstance(raw, list):
+                    raw = raw[0]
+                val = int(str(raw)) // 20
+                return {"rating": max(0, min(5, val))}
+        except Exception:
+            pass
+        return {}
+
     def _load_track_disc(self, tags) -> Dict[str, Any]:
         result = {}
         if tags is None:
@@ -366,6 +423,11 @@ class MetadataEditorDialog(QDialog):
         self._genre_label = QLabel("Genre:")
         form_layout.addRow(self._genre_label, self.genre_edit)
 
+        self.rating_widget = ClickableStarRating()
+        self.rating_widget.rating_changed.connect(self._on_rating_changed)
+        self._rating_label = QLabel("Rating:")
+        form_layout.addRow(self._rating_label, self.rating_widget)
+
         self._year_label = QLabel("Year:")
         form_layout.addRow(self._year_label, self.year_spin)
 
@@ -429,6 +491,10 @@ class MetadataEditorDialog(QDialog):
         for key in self._mixed_fields:
             self._set_mixed(key)
 
+        if "rating" in self._mixed_fields:
+            self.rating_widget.set_rating(0)
+            self._rating_label.setText("Rating: (mixed)")
+
     def _set_mixed(self, key: str):
         placeholders = {
             'title': "(different values)",
@@ -488,8 +554,12 @@ class MetadataEditorDialog(QDialog):
         self.disc_num_spin.setValue(t.get('disc_number', 0))
         self.disc_total_spin.setValue(t.get('disc_total', 0))
 
+        self.rating_widget.set_rating(t.get("rating", 0))
         self._update_cover_display()
 
+    def _on_rating_changed(self, stars: int) -> None:
+        pass  # placeholder for future live-preview
+
     def _update_cover_display(self):
         if self._cover_removed:
             self.cover_label.setText("No cover")
@@ -629,6 +699,7 @@ class MetadataEditorDialog(QDialog):
             'disc_number': self.disc_num_spin.value(),
             'disc_total': self.disc_total_spin.value(),
             'comment': self.comment_edit.text().strip(),
+            'rating': self.rating_widget.rating(),
         }
 
     def _collect_changes(self) -> Dict[str, Any]:
@@ -709,6 +780,9 @@ class MetadataEditorDialog(QDialog):
                 else:
                     self._invalidate_cover_cache(path, changes, cover_arg)
 
+            if not failed:
+                self._persist_rating(paths, changes)
+
             if failed == len(paths):
                 QMessageBox.warning(self, "Error", "Failed to save metadata changes.")
             elif failed:
@@ -722,6 +796,21 @@ class MetadataEditorDialog(QDialog):
         except Exception as e:
             QMessageBox.critical(self, "Error", f"Failed to save metadata:\n{e}")
 
+    def _persist_rating(self, paths: list[str], changes: dict[str, Any]) -> None:
+        if "rating" not in changes:
+            return
+        try:
+            cache = get_library_cache()
+            for p in paths:
+                entry = cache.get(p)
+                if entry is None:
+                    continue
+                entry["rating"] = changes["rating"] * 20
+                cache.put(p, entry)
+            save_library_cache()
+        except Exception:
+            logger.exception("Failed to persist rating to LibraryCache")
+
     def _invalidate_cover_cache(self, file_path: str, changes: Dict[str, Any],
                                 cover_arg: Optional[str]) -> None:
         """Update cover cache after successful save."""

src/ui/star_rating.py

@@ -0,0 +1,107 @@
+#!/usr/bin/env python3
+"""
+Clickable 5‑star rating widget.
+
+Scale: 0 (unrated) … 5 (★★★★★).  Stored internally as stars;
+callers convert to/from the iPod 0–100 scale as needed.
+"""
+
+import math
+
+from PyQt6.QtCore import Qt, QRectF, pyqtSignal
+from PyQt6.QtGui import QPainter, QColor, QPainterPath, QBrush, QPen
+from PyQt6.QtWidgets import QWidget
+
+
+class ClickableStarRating(QWidget):
+    """Five clickable stars with hover preview and toggle-to-unrate."""
+
+    rating_changed = pyqtSignal(int)
+
+    STAR_COUNT = 5
+    STAR_SIZE = 22          # diameter of each star
+    PADDING = 4
+    FILLED_COLOR = QColor("#ffb347")   # warm amber
+    EMPTY_COLOR = QColor("#555555")
+    HOVER_COLOR = QColor("#ffd700")    # gold
+
+    def __init__(self, parent=None):
+        super().__init__(parent)
+        self._rating = 0
+        self._hover_idx = -1
+        w = self.STAR_COUNT * self.STAR_SIZE + (self.STAR_COUNT - 1) * self.PADDING
+        self.setFixedSize(w, self.STAR_SIZE + 8)
+        self.setMouseTracking(True)
+
+    # ── public API ────────────────────────────────────────────────
+
+    def set_rating(self, stars: int) -> None:
+        self._rating = max(0, min(self.STAR_COUNT, stars))
+        self.update()
+
+    def rating(self) -> int:
+        return self._rating
+
+    # ── painting ───────────────────────────────────────────────────
+
+    def paintEvent(self, event):                                # noqa: N802
+        painter = QPainter(self)
+        painter.setRenderHint(QPainter.RenderHint.Antialiasing)
+        painter.setPen(Qt.PenStyle.NoPen)
+
+        hovering = self._hover_idx >= 0
+        for i in range(self.STAR_COUNT):
+            if hovering:
+                filled = i <= self._hover_idx
+            else:
+                filled = i < self._rating
+
+            color = (
+                self.HOVER_COLOR if hovering and filled
+                else self.FILLED_COLOR if filled
+                else self.EMPTY_COLOR
+            )
+            painter.setBrush(QBrush(color))
+
+            cx = self.STAR_SIZE // 2 + i * (self.STAR_SIZE + self.PADDING)
+            cy = self.height() // 2
+            self._draw_star(painter, cx, cy, self.STAR_SIZE // 2 - 1)
+
+    @staticmethod
+    def _draw_star(painter: QPainter, cx: int, cy: int, r: int) -> None:
+        """Draw a five-pointed star centred at (cx, cy) with outer radius *r*."""
+        path = QPainterPath()
+        inner_r = r * 0.4
+        points = []
+        for i in range(10):
+            angle = math.pi / 2 + i * math.pi / 5
+            radius = r if i % 2 == 0 else inner_r
+            x = cx + radius * math.cos(angle)
+            y = cy - radius * math.sin(angle)
+            points.append((x, y))
+        path.moveTo(points[0][0], points[0][1])
+        for x, y in points[1:]:
+            path.lineTo(x, y)
+        path.closeSubpath()
+        painter.drawPath(path)
+
+    # ── mouse interaction ──────────────────────────────────────────
+
+    def _star_at(self, x: int) -> int:
+        idx = x // (self.STAR_SIZE + self.PADDING)
+        return min(max(idx, 0), self.STAR_COUNT - 1)
+
+    def mousePressEvent(self, event):                            # noqa: N802
+        star = self._star_at(int(event.position().x()))
+        new_val = star + 1 if self._rating != star + 1 else 0
+        self._rating = new_val
+        self.rating_changed.emit(new_val)
+        self.update()
+
+    def mouseMoveEvent(self, event):                             # noqa: N802
+        self._hover_idx = self._star_at(int(event.position().x()))
+        self.update()
+
+    def leaveEvent(self, event):                                 # noqa: N802
+        self._hover_idx = -1
+        self.update()