// 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, O extraInfo, Concepts concepts)>
  L onUnloadingCase; // L<voidfunc(S caseID, Concepts concepts)>
  Lock lock = lock();
  
  Concepts get(S caseID, O extraInfo) { ret conceptsForCase(caseID, extraInfo); }
  
  Concepts getIfLoaded(S caseID) {
    lock lock;
    ret loaded.get(unnull(caseID));
  }
  
  // caseID may be empty, then you get the program's main DB
  Concepts conceptsForCase(S caseID, O extraInfo) {
    lock lock;
    //assertNempty(+caseID);
    caseID = unnull(caseID);
    
    if (loaded.containsKey(caseID))
      ret assertNotNull("Concepts load error", loaded.get(caseID));

    S id = dbID(caseID);
    print("Loading concepts for case " + id);
    Concepts cc = new Concepts(id);
    cc.persist();
    loaded.put(caseID, cc);
    pcallFAll(onCaseLoaded, caseID, extraInfo, cc);
    ret cc;
  }
  
  S dbID(S caseID) {
    ret combineWithSlash(getDBProgramID(), caseID);
  }
  
  void cleanMeUp {
    cleanUpAndClear(loaded);
  }
  
  void onCaseLoaded(VF3<S, O, Concepts> f) {
    onCaseLoaded = listCreateAndAdd(onCaseLoaded, f);
  }
  
  void onUnloadingCase(VF2<S, Concepts> f) {
    onUnloadingCase = listCreateAndAdd(onUnloadingCase, f);
  }
  
  void unloadCase(S caseID) {
    lock lock;
    caseID = unnull(caseID);
    Concepts cc = loaded.get(caseID);
    if (cc != null) {
      pcallFAll(onUnloadingCase, caseID, cc);
      cleanUp(cc);
      loaded.remove(caseID);
    }
  }
}