// TODO: run dbBot()

sclass ConceptsLoadedOnDemand {
  new Map<S, Concepts> loaded; // key = just the case ID. value can be null in case of error
  L onCaseLoaded; // L<voidfunc(S caseID, Concepts concepts)>
  Lock lock = lock();
  
  Concepts get(S caseID) { ret conceptsForCase(caseID); }
  
  Concepts conceptsForCase(S caseID) {
    lock lock;
    assertNempty(+caseID);
    
    if (loaded.containsKey(caseID))
      ret assertNotNull("Concepts load error", loaded.get(caseID));

    S id = combineWithSlash(getDBProgramID(), caseID);
    print("Loading concepts for case " + id);
    Concepts c = new Concepts(id);
    loaded.put(caseID, c);
    pcallFAll(onCaseLoaded, caseID, c);
    ret c;
  }
  
  void cleanMeUp {
    cleanUpAndClear(loaded);
  }
  
  void onLoad(VF2<S, Concepts> f) {
    onLoad = listCreateAndAdd(onLoad, f);
  }
}