import { useCallback, useEffect, useState } from 'react';
import { MatrixClient } from 'matrix-js-sdk';
import { useMatrixClient } from './useMatrixClient';
import { useAccountDataCallback } from './useAccountDataCallback';

export type Bookmark = {
  roomId: string;
  eventId: string;
  savedAt: number;
  previewText: string;
  roomName: string;
};

const BOOKMARKS_KEY = 'io.lotus.bookmarks';
const MAX_BOOKMARKS = 500;

type BookmarksContent = {
  bookmarks: Bookmark[];
};

function readBookmarks(mx: MatrixClient): Bookmark[] {
  return (
    (mx.getAccountData(BOOKMARKS_KEY as any)?.getContent() as BookmarksContent | undefined)
      ?.bookmarks ?? []
  );
}

export function useBookmarks(): {
  bookmarks: Bookmark[];
  addBookmark: (b: Bookmark) => Promise<void>;
  removeBookmark: (eventId: string) => Promise<void>;
  isBookmarked: (eventId: string) => boolean;
} {
  const mx = useMatrixClient();
  const [bookmarks, setBookmarks] = useState<Bookmark[]>(() => readBookmarks(mx));

  useAccountDataCallback(
    mx,
    useCallback(
      (evt) => {
        if (evt.getType() === BOOKMARKS_KEY) {
          setBookmarks(evt.getContent<BookmarksContent>()?.bookmarks ?? []);
        }
      },
      [setBookmarks],
    ),
  );

  // Re-read on mx change
  useEffect(() => {
    setBookmarks(readBookmarks(mx));
  }, [mx]);

  const addBookmark = useCallback(
    async (b: Bookmark) => {
      const current = readBookmarks(mx);
      // Avoid duplicates
      const filtered = current.filter((bk) => bk.eventId !== b.eventId);
      let next = [b, ...filtered];
      if (next.length > MAX_BOOKMARKS) {
        next = next.slice(0, MAX_BOOKMARKS);
      }
      await (mx as any).setAccountData(BOOKMARKS_KEY, { bookmarks: next });
    },
    [mx],
  );

  const removeBookmark = useCallback(
    async (eventId: string) => {
      const current = readBookmarks(mx);
      const next = current.filter((bk) => bk.eventId !== eventId);
      await (mx as any).setAccountData(BOOKMARKS_KEY, { bookmarks: next });
    },
    [mx],
  );

  const isBookmarked = useCallback(
    (eventId: string) => bookmarks.some((bk) => bk.eventId === eventId),
    [bookmarks],
  );

  return { bookmarks, addBookmark, removeBookmark, isBookmarked };
}