Function sanitizeFolderTree

app/src/DataModel/ProjectModel.cpp:109–141

 */
template<typename Folder, typename Entity>
static void sanitizeFolderTree(std::vector<Folder>& folders, std::vector<Entity>& entities)
{
  QHash<int, int> parentOf;
  QSet<int> validFolders;
  for (const auto& f : std::as_const(folders)) {
    validFolders.insert(f.folderId);
    parentOf.insert(f.folderId, f.parentFolderId);
  }

  for (auto& f : folders) {
    if (f.parentFolderId != -1 && !validFolders.contains(f.parentFolderId)) {
      f.parentFolderId = -1;
      continue;
    }

    QSet<int> seen;
    int p          = f.parentFolderId;
    const int kMax = static_cast<int>(folders.size());
    for (int i = 0; i < kMax && p != -1; ++i) {
      if (p == f.folderId || seen.contains(p)) {
        f.parentFolderId = -1;
        break;
      }

      seen.insert(p);
      p = parentOf.value(p, -1);
    }
  }

  for (auto& e : entities)
    if (e.parentFolderId != -1 && !validFolders.contains(e.parentFolderId))
      e.parentFolderId = -1;
}

/**
 * @brief Serializes any folder vector to a JSON array.