cinny/src/app/hooks/useThreadNotifications.ts

import { useCallback } from 'react';
import { useAtomValue } from 'jotai';
import { MatrixClient } from 'matrix-js-sdk';
import { AccountDataEvent } from '../../types/matrix/accountData';
import { threadNotificationsAtom } from '../state/threadNotifications';
import {
  getThreadNotificationMode,
  pruneThreadNotifications,
  ThreadNotificationEntry,
  ThreadNotificationMode,
  ThreadNotificationsContent,
} from '../utils/threadNotifications';
import { useMatrixClient } from './useMatrixClient';
import { AsyncState, useAsyncCallback } from './useAsyncCallback';
import { getAccountData, setAccountData } from '../utils/accountData';

/** Read the current notification mode for a thread from the bound atom. */
export function useThreadNotificationMode(
  roomId: string,
  threadRootId: string,
): ThreadNotificationMode {
  const content = useAtomValue(threadNotificationsAtom);
  return getThreadNotificationMode(content, roomId, threadRootId);
}

const readContent = (mx: MatrixClient): ThreadNotificationsContent =>
  getAccountData<ThreadNotificationsContent>(mx, AccountDataEvent.LotusThreadNotifications) ?? {};

const getJoinedRoomIds = (mx: MatrixClient): Set<string> => {
  const joined = new Set<string>();
  mx.getRooms().forEach((room) => {
    if (room.getMyMembership() === 'join') {
      joined.add(room.roomId);
    }
  });
  return joined;
};

const writeThreadNotificationMode = async (
  mx: MatrixClient,
  roomId: string,
  threadRootId: string,
  mode: ThreadNotificationMode,
): Promise<void> => {
  const current = readContent(mx);
  const now = Date.now();

  // Work on a mutable clone; prune produces a fresh object so the mutations
  // below never touch the atom's/account-data's current content.
  const next: ThreadNotificationsContent = {
    ...current,
    rooms: Object.fromEntries(
      Object.entries(current.rooms ?? {}).map(([rid, entries]) => [rid, { ...entries }]),
    ),
  };

  const rooms = next.rooms as Record<string, Record<string, ThreadNotificationEntry>>;

  if (mode === ThreadNotificationMode.Default) {
    if (rooms[roomId]) {
      delete rooms[roomId][threadRootId];
      if (Object.keys(rooms[roomId]).length === 0) {
        delete rooms[roomId];
      }
    }
  } else {
    if (!rooms[roomId]) {
      rooms[roomId] = {};
    }
    rooms[roomId][threadRootId] = { mode, ts: now };
  }

  // ALWAYS prune before persisting to keep account data bounded.
  const finalContent = pruneThreadNotifications(next, getJoinedRoomIds(mx), now);

  await setAccountData(mx, AccountDataEvent.LotusThreadNotifications, finalContent);
};

export function useSetThreadNotificationMode(
  roomId: string,
  threadRootId: string,
): {
  modeState: AsyncState<void, Error>;
  setMode: (mode: ThreadNotificationMode) => Promise<void>;
} {
  const mx = useMatrixClient();

  const [modeState, setMode] = useAsyncCallback<void, Error, [ThreadNotificationMode]>(
    useCallback(
      (mode: ThreadNotificationMode) => writeThreadNotificationMode(mx, roomId, threadRootId, mode),
      [mx, roomId, threadRootId],
    ),
  );

  return { modeState, setMode };
}