Method restore

app/src/Misc/BackupManager.cpp:174–219

* @brief Load a snapshot file back into ProjectModel; returns true on success. */

 * @brief Load a snapshot file back into ProjectModel; returns true on success.
 */
bool Misc::BackupManager::restore(const QString& path)
{
  if (path.isEmpty())
    return false;

  QFile in(path);
  if (!in.open(QIODevice::ReadOnly))
    return false;

  const auto bytes = in.readAll();
  in.close();

  QJsonParseError err{};
  const auto doc = QJsonDocument::fromJson(bytes, &err);
  if (err.error != QJsonParseError::NoError || !doc.isObject())
    return false;

  auto obj = doc.object();
  if (obj.contains(kBackupMetaKey)) {
    const auto meta = obj.value(kBackupMetaKey).toObject();
    const int fmt   = meta.value(QStringLiteral("format")).toInt(0);
    if (fmt > kSnapshotFormat) {
      qWarning() << "[BackupManager] Refusing snapshot with format" << fmt
                 << "(this build understands up to" << kSnapshotFormat << ")";
      return false;
    }
    obj.remove(kBackupMetaKey);
  }
  const QJsonDocument projectDoc(obj);

  auto& pm = DataModel::ProjectModel::instance();

  const auto originalPath = pm.jsonFilePath();

  (void)snapshot(QStringLiteral("pre-restore"));

  pm.setSuppressMessageBoxes(true);
  const bool ok = pm.loadFromJsonDocument(projectDoc, originalPath);
  pm.setSuppressMessageBoxes(false);
  if (!ok)
    return false;

  pm.setModified(true);
  Q_EMIT restored(path);
  return true;
}

/**
 * @brief Enumerate snapshot files for the current project, newest first.