function viewProcessorApplyUserOverwrite()

in packages/database/src/core/view/ViewProcessor.ts [427:514]

• 84 lines of code
• 8 McCabe index (conditional complexity)

function viewProcessorApplyUserOverwrite(
  viewProcessor: ViewProcessor,
  oldViewCache: ViewCache,
  changePath: Path,
  changedSnap: Node,
  writesCache: WriteTreeRef,
  completeCache: Node | null,
  accumulator: ChildChangeAccumulator
): ViewCache {
  const oldEventSnap = oldViewCache.eventCache;
  let newViewCache, newEventCache;
  const source = new WriteTreeCompleteChildSource(
    writesCache,
    oldViewCache,
    completeCache
  );
  if (pathIsEmpty(changePath)) {
    newEventCache = viewProcessor.filter.updateFullNode(
      oldViewCache.eventCache.getNode(),
      changedSnap,
      accumulator
    );
    newViewCache = viewCacheUpdateEventSnap(
      oldViewCache,
      newEventCache,
      true,
      viewProcessor.filter.filtersNodes()
    );
  } else {
    const childKey = pathGetFront(changePath);
    if (childKey === '.priority') {
      newEventCache = viewProcessor.filter.updatePriority(
        oldViewCache.eventCache.getNode(),
        changedSnap
      );
      newViewCache = viewCacheUpdateEventSnap(
        oldViewCache,
        newEventCache,
        oldEventSnap.isFullyInitialized(),
        oldEventSnap.isFiltered()
      );
    } else {
      const childChangePath = pathPopFront(changePath);
      const oldChild = oldEventSnap.getNode().getImmediateChild(childKey);
      let newChild;
      if (pathIsEmpty(childChangePath)) {
        // Child overwrite, we can replace the child
        newChild = changedSnap;
      } else {
        const childNode = source.getCompleteChild(childKey);
        if (childNode != null) {
          if (
            pathGetBack(childChangePath) === '.priority' &&
            childNode.getChild(pathParent(childChangePath)).isEmpty()
          ) {
            // This is a priority update on an empty node. If this node exists on the server, the
            // server will send down the priority in the update, so ignore for now
            newChild = childNode;
          } else {
            newChild = childNode.updateChild(childChangePath, changedSnap);
          }
        } else {
          // There is no complete child node available
          newChild = ChildrenNode.EMPTY_NODE;
        }
      }
      if (!oldChild.equals(newChild)) {
        const newEventSnap = viewProcessor.filter.updateChild(
          oldEventSnap.getNode(),
          childKey,
          newChild,
          childChangePath,
          source,
          accumulator
        );
        newViewCache = viewCacheUpdateEventSnap(
          oldViewCache,
          newEventSnap,
          oldEventSnap.isFullyInitialized(),
          viewProcessor.filter.filtersNodes()
        );
      } else {
        newViewCache = oldViewCache;
      }
    }
  }
  return newViewCache;
}