import { Bookmark } from '../hooks/useBookmarks';

export type BookmarkSort = 'newest' | 'oldest' | 'room';

const BOOKMARK_SORTS: readonly BookmarkSort[] = ['newest', 'oldest', 'room'];

/** Type guard for persisted/untrusted sort values (localStorage can hold stale/corrupt data). */
export function isBookmarkSort(value: unknown): value is BookmarkSort {
  return typeof value === 'string' && (BOOKMARK_SORTS as readonly string[]).includes(value);
}

export type BookmarkRoomGroup = {
  roomId: string;
  roomName: string;
  items: Bookmark[];
};

// Deterministic newest-first comparator: most recently saved first, ties broken
// by eventId so the order is stable regardless of input order (keeps tests and
// re-renders from shuffling equal-timestamp entries).
const byNewest = (a: Bookmark, b: Bookmark): number =>
  b.savedAt - a.savedAt || (a.eventId < b.eventId ? -1 : a.eventId > b.eventId ? 1 : 0);

/**
 * Return a new array of bookmarks ordered per the selected sort. `room` has no
 * flat ordering of its own (grouping is a render concern) and falls back to
 * newest-first so callers can still render a sensible flat list if they want.
 */
export function sortBookmarks(bookmarks: Bookmark[], sort: BookmarkSort): Bookmark[] {
  const copy = [...bookmarks];
  if (sort === 'oldest') {
    // Oldest-first is the reverse ordering; keep the same eventId tie-break shape.
    return copy.sort(
      (a, b) =>
        a.savedAt - b.savedAt || (a.eventId < b.eventId ? -1 : a.eventId > b.eventId ? 1 : 0),
    );
  }
  return copy.sort(byNewest);
}

/**
 * Bucket bookmarks by room. Items within a group are newest-first; groups are
 * ordered by each group's most-recently-saved bookmark (active rooms float up),
 * with the room's stored name (the panel overrides with the live name when the
 * room is joined). Deterministic tie-breaks keep the output stable.
 */
export function groupBookmarksByRoom(bookmarks: Bookmark[]): BookmarkRoomGroup[] {
  const groups = new Map<string, BookmarkRoomGroup>();
  bookmarks.forEach((bk) => {
    const existing = groups.get(bk.roomId);
    if (existing) {
      existing.items.push(bk);
    } else {
      groups.set(bk.roomId, { roomId: bk.roomId, roomName: bk.roomName, items: [bk] });
    }
  });

  const result = [...groups.values()];
  result.forEach((group) => group.items.sort(byNewest));
  // Order groups by their newest item's savedAt (desc); tie-break by roomId.
  result.sort((a, b) => {
    const diff = b.items[0].savedAt - a.items[0].savedAt;
    if (diff !== 0) return diff;
    return a.roomId < b.roomId ? -1 : a.roomId > b.roomId ? 1 : 0;
  });
  return result;
}