computeAndScheduleDiff method

void computeAndScheduleDiff(String id, String collectionName)

Compute diff vs baseline and schedule if non-empty. If empty, calls onNoDiff.

Implementation

void computeAndScheduleDiff(String id, String collectionName) {
  final map = toSyncMapForId(id);
  if (map == null) return;
  final current = sanitize(map);

  Map<String, dynamic> last = _lastSyncedById[id] ?? <String, dynamic>{};

  Map<String, dynamic> patch = {};

  // collectionType & userProvider are non-null by signature; always attempt cached diff first
  final key = '$userId|${collectionName}|$id';
  final dbCache = realm.find<SyncDBCache>(key);
  if (dbCache != null) {
    try {
      final raw = jsonDecode(dbCache.diffJson) as Map<String, dynamic>;
      patch = rehydratePatch(raw);
      // Diff consumed: remove the cache entry so we don't resend stale patches after baseline update.
      try {
        realm.write(() {
          realm.delete(dbCache);
        });
      } catch (e) {
        AppLogger.log(
          'SyncHelper: failed to delete consumed DBCache $key: $e',
        );
      }
    } catch (e) {
      // Malformed JSON in DBCache, fall back to computing diff
      AppLogger.log(
        'SyncHelper: malformed DBCache $key, recomputing diff: $e',
      );
      patch = diff(last, current);
      // Clean up corrupted entry
      try {
        realm.write(() => realm.delete(dbCache));
      } catch (_) {}
    }
  } else {
    // Fallback to computing on the fly if cache not present
    patch = diff(last, current);
  }

  // Create a check if there already same thing exists in queue or outbox patch and we dont overflow the queue

  if (patch.isEmpty) {
    if (onNoDiff != null) onNoDiff!(id);
    return;
  }

  _schedule(id, patch);
}