streamyfin/hooks/useTwoWaySync.ts

import { getItemsApi, getUserLibraryApi } from "@jellyfin/sdk/lib/utils/api";
import { useNetInfo } from "@react-native-community/netinfo";
import { useAtomValue } from "jotai";
import { useDownload } from "@/providers/DownloadProvider";
import { apiAtom, userAtom } from "../providers/JellyfinProvider";

/**
 * This hook is used to sync the playback state of a downloaded item with the server
 * when the application comes back online after being used offline.
 */
export const useTwoWaySync = () => {
  const api = useAtomValue(apiAtom);
  const user = useAtomValue(userAtom);
  const netInfo = useNetInfo();
  const { getDownloadedItemById, updateDownloadedItem } = useDownload();

  /**
   * Syncs the playback state of an offline item with the server.
   * It determines if the local or remote state is more recent and applies the necessary update.
   *
   * @returns A Promise<boolean> indicating whether a server update was made (true) or not (false).
   */
  const syncPlaybackState = async (itemId: string): Promise<boolean> => {
    if (!api || !user || !netInfo.isConnected) {
      // Cannot sync if offline or not logged in
      return false;
    }

    const localItem = getDownloadedItemById(itemId);
    if (!localItem) return false;

    const remoteItem = (
      await getUserLibraryApi(api).getItem({ itemId, userId: user.Id })
    ).data;
    if (!remoteItem) return false;

    const localLastPlayed = localItem.item.UserData?.LastPlayedDate
      ? new Date(localItem.item.UserData.LastPlayedDate)
      : new Date(0);
    const remoteLastPlayed = remoteItem.UserData?.LastPlayedDate
      ? new Date(remoteItem.UserData.LastPlayedDate)
      : new Date(0);

    // If the remote item has been played more recently, we take the server's version as the source of truth.
    if (remoteLastPlayed > localLastPlayed) {
      updateDownloadedItem(itemId, {
        ...localItem,
        item: {
          ...localItem.item,
          UserData: {
            ...localItem.item.UserData,
            LastPlayedDate: remoteItem.UserData?.LastPlayedDate,
            PlaybackPositionTicks: remoteItem.UserData?.PlaybackPositionTicks,
            Played: remoteItem.UserData?.Played,
            PlayedPercentage: remoteItem.UserData?.PlayedPercentage,
          },
        },
      });
      return false;
    } else if (remoteLastPlayed < localLastPlayed) {
      // Since we're this is the source of truth, essentially need to make sure the played status matches the local item.
      try {
        await getItemsApi(api).updateItemUserData({
          itemId: localItem.item.Id!,
          userId: user.Id,
          updateUserItemDataDto: {
            Played: localItem.item.UserData?.Played,
            PlaybackPositionTicks:
              localItem.item.UserData?.PlaybackPositionTicks,
            PlayedPercentage: localItem.item.UserData?.PlayedPercentage,
            LastPlayedDate: localItem.item.UserData?.LastPlayedDate,
          },
        });
      } catch (error) {
        console.error(
          "Failed to update item user data during syncPlaybackState:",
          error,
        );
      }
      return true;
    }
    return false;
  };

  return { syncPlaybackState };
};