sclass SimpleCRUD<A extends Concept> {
  Class<A> cc;
  JTable table;
  JPanel buttons, panel;
  O renderer; // optional, func(A) -> Map
  *(Class<A> *cc) {}
  
  SimpleCRUD<A> show(S frameTitle) {
    make();
    showFrame(frameTitle, panel);
    this;
  }
  
  SimpleCRUD<A> show() {
    ret show(plural(shortClassName(cc)));
  }
  
  JPanel make() {
    db();
    swing {
      table = makeConceptsTable(cc, wrapRenderer(renderer));
      panel = centerAndSouth(table, buttons = jRightAlignedLine(
        jbutton("Add...", r { newConcept() }),
        tableDependButton(table, jbutton("Edit", r {
          editConcept(selectedConcept())
        })),
        tableDependButton(table, jbutton("Delete", r {
          final A c = selectedConcept();
          withDBLock(r { c.delete() });
        }))));
      
      O fEdit = voidfunc(int row) {
        editConcept((A) getConcept(toLong(getTableCell(table, row, 0))))
      };
      tablePopupMenuItem(table, "Edit...", fEdit);
      onDoubleClick(table, fEdit);
    }
    ret panel;
  }
  
  O wrapRenderer(fO renderer) {
    ret renderer == null ? null : func(A a) {
      putAll(litorderedmap("ID" := str(a.id)), (Map) callF(renderer, a))
    };
  }
  
  void newConcept {
    final A c = unlisted(cc);
    final Map<S, JComponent> map = makeComponents(c);
    Runnable r = r {
      register(c);
      saveData(c, map);
    };
    showFormTitled("New " + shortClassName(cc), arrayPlus(mapToObjectArray(map), r));
  }

  void editConcept(final A c) {
    if (c == null) ret;
    final Map<S, JComponent> map = makeComponents(c);
    Runnable r = r { saveData(c, map) };
    showFormTitled("Edit " + shortClassName(cc) + " #" + c.id, arrayPlus(mapToObjectArray(map), r));
  }
  
  A selectedConcept() {
    ret (A) getConcept(toLong(selectedTableCell(table, 0)));
  }
  
  Map<S, JComponent> makeComponents(A c) {
    Map<S, JComponent> map = litorderedmap();
    makeComponents(c, map);
    ret map;
  }
  
  JComponent fieldComponent(A c, S field) {
    Class type = getFieldType(cc, field);
    O value = getOpt(c, field);
    //print("Field type: " + field + " => " + type);
    if (type == bool.class)
      ret jCenteredCheckBox(isTrue(value));
    else
      ret jTextField(structureOrText_crud(value));
  }
  
  void saveComponent(A c, S field, JComponent comp) {
    comp = unwrap(comp);
    if (comp instanceof JTextComponent)
      cset(c, field, convertToField(getTextTrim((JTextComponent) comp), cc, field));
    else if (comp instanceof JCheckBox)
      cset(c, field, isChecked((JCheckBox) comp));
    ifclass ImageChooser
      else if (comp instanceof ImageChooser)
        cUpdatePNGFile(c, field, comp/ImageChooser.getImage(), false);
    endif
  }
  
  // override the following two methods to customize edit window
  
  void makeComponents(A c, Map<S, JComponent> map) {
    for (S field : conceptFieldsInOrder(cc))
      map.put(field, fieldComponent(c, field));
  }
  
  void saveData(A c, Map<S, JComponent> components) {
    for (S field : keys(components))
      saveComponent(c, field, components.get(field));
  }
}