withSubscriptionEvent method

QuerySnapshot<T> withSubscriptionEvent({ required SubscriptionEvent<T> event, })

Returns a new QuerySnapshot with the event applied

Takes the existing snapshots QueryPredicate and QuerySortBy conditions into consideration when applying the event

If the event does not result in a change to the QuerySnapshot, the current snapshot is returned

Implementation

QuerySnapshot<T> withSubscriptionEvent({
  required SubscriptionEvent<T> event,
}) {
  SortedList<T> sortedListCopy = SortedList.from(_sortedList);
  SortedList<T>? updatedSortedList;

  T newItem = event.item;
  bool newItemMatchesPredicate = where == null || where!.evaluate(newItem);
  int currentItemIndex =
      sortedListCopy.indexWhere((item) => item.getId() == newItem.getId());
  T? currentItem =
      currentItemIndex == -1 ? null : sortedListCopy[currentItemIndex];
  bool currentItemMatchesPredicate =
      currentItem != null && (where == null || where!.evaluate(currentItem));

  if (event.eventType == EventType.create &&
      newItemMatchesPredicate &&
      currentItem == null) {
    updatedSortedList = sortedListCopy..addSorted(newItem);
  } else if (event.eventType == EventType.delete && currentItem != null) {
    updatedSortedList = sortedListCopy..removeAt(currentItemIndex);
  } else if (event.eventType == EventType.update) {
    if (currentItemMatchesPredicate &&
        newItemMatchesPredicate &&
        currentItem != newItem) {
      updatedSortedList = sortedListCopy
        ..updateAtSorted(currentItemIndex, newItem);
    } else if (currentItemMatchesPredicate && !newItemMatchesPredicate) {
      updatedSortedList = sortedListCopy..removeAt(currentItemIndex);
    } else if (currentItem == null && newItemMatchesPredicate) {
      updatedSortedList = sortedListCopy..addSorted(newItem);
    }
  }
  if (updatedSortedList != null) {
    return QuerySnapshot._(
      sortedList: updatedSortedList,
      isSynced: isSynced,
      where: where,
      sortBy: sortBy,
    );
  }
  return this;
}