refactor(album): co-locate album feature into features/album

src/features/album/hooks/useAlbumTrackListSelection.ts

@@ -0,0 +1,108 @@
+import React, { useCallback, useEffect, useRef } from 'react';
+import type { SubsonicSong } from '@/api/subsonicTypes';
+import { useSelectionStore } from '@/store/selectionStore';
+import { useDragDrop } from '@/contexts/DragDropContext';
+import { songToTrack } from '@/utils/playback/songToTrack';
+
+interface UseAlbumTrackListSelectionArgs {
+  songs: SubsonicSong[];
+  tracklistRef: React.RefObject<HTMLDivElement | null>;
+}
+
+interface UseAlbumTrackListSelectionResult {
+  inSelectMode: boolean;
+  allSelected: boolean;
+  onToggleSelect: (id: string, globalIdx: number, shift: boolean) => void;
+  onDragStart: (song: SubsonicSong, me: MouseEvent) => void;
+  toggleAll: () => void;
+}
+
+/**
+ * Bulk selection + drag wiring for `AlbumTrackList`:
+ *  - Clears selection whenever the song list changes (album switch or
+ *    filter applied) and on mousedown outside the tracklist — but not when
+ *    the click lands on the bulk-action toolbar, which belongs to the selection.
+ *  - `onToggleSelect` supports shift-click ranges anchored against the
+ *    last toggled row.
+ *  - `onDragStart` promotes a single-row drag into a multi-row drag when
+ *    the dragged song is part of the active selection.
+ *
+ * Subscribes only to `selectedIds.size` so the host component re-renders
+ * once when select-mode flips on/off; per-row state stays inside
+ * `TrackRow`'s own primitive selector for O(1) toggles.
+ */
+export function useAlbumTrackListSelection({
+  songs,
+  tracklistRef,
+}: UseAlbumTrackListSelectionArgs): UseAlbumTrackListSelectionResult {
+  const psyDrag = useDragDrop();
+  const selectedCount = useSelectionStore(s => s.selectedIds.size);
+  const inSelectMode = selectedCount > 0;
+  const allSelected = selectedCount === songs.length && songs.length > 0;
+  const lastSelectedIdxRef = useRef<number | null>(null);
+
+  useEffect(() => {
+    useSelectionStore.getState().clearAll();
+    lastSelectedIdxRef.current = null;
+  }, [songs]);
+
+  useEffect(() => {
+    if (!inSelectMode) return;
+    const handler = (e: MouseEvent) => {
+      const target = e.target as HTMLElement;
+      if (!tracklistRef.current || tracklistRef.current.contains(target)) return;
+      // The bulk-action toolbar (filter, add-to-playlist picker, clear button)
+      // renders outside the tracklist DOM but belongs to the selection — a
+      // mousedown there must not wipe the selection before the button's own
+      // click handler runs (otherwise "Add to playlist" clears and never opens).
+      if (target.closest('.album-track-toolbar')) return;
+      useSelectionStore.getState().clearAll();
+    };
+    document.addEventListener('mousedown', handler);
+    return () => document.removeEventListener('mousedown', handler);
+  }, [inSelectMode, tracklistRef]);
+
+  const onToggleSelect = useCallback((id: string, globalIdx: number, shift: boolean) => {
+    useSelectionStore.getState().setSelectedIds(prev => {
+      const next = new Set(prev);
+      if (shift && lastSelectedIdxRef.current !== null) {
+        const from = Math.min(lastSelectedIdxRef.current, globalIdx);
+        const to   = Math.max(lastSelectedIdxRef.current, globalIdx);
+        songs.slice(from, to + 1).forEach(s => next.add(s.id));
+      } else {
+        if (next.has(id)) next.delete(id);
+        else next.add(id);
+      }
+      lastSelectedIdxRef.current = globalIdx;
+      return next;
+    });
+  }, [songs]);
+
+  const onDragStart = useCallback((song: SubsonicSong, me: MouseEvent) => {
+    const { selectedIds } = useSelectionStore.getState();
+    if (selectedIds.has(song.id) && selectedIds.size > 1) {
+      const tracks = songs
+        .filter(s => selectedIds.has(s.id))
+        .map(s => songToTrack(s));
+      psyDrag.startDrag(
+        { data: JSON.stringify({ type: 'songs', tracks }), label: `${tracks.length} Songs` },
+        me.clientX, me.clientY,
+      );
+    } else {
+      psyDrag.startDrag(
+        { data: JSON.stringify({ type: 'song', track: songToTrack(song) }), label: song.title },
+        me.clientX, me.clientY,
+      );
+    }
+  }, [songs, psyDrag]);
+
+  const toggleAll = useCallback(() => {
+    if (allSelected) {
+      useSelectionStore.getState().clearAll();
+    } else {
+      useSelectionStore.getState().setSelectedIds(() => new Set(songs.map(s => s.id)));
+    }
+  }, [allSelected, songs]);
+
+  return { inSelectMode, allSelected, onToggleSelect, onDragStart, toggleAll };
+}