// Note: renderUIUrl etc are called in Swing thread

srecord noeq UIURLSystem(Enterable owner, SimpleLiveValue<S> uiURL) {

  // key:   ui URL

  // value: component maker

  transient Map<S, IF0<? extends JComponent>> uiMap = syncCIMap();

  // these are additionally displayed at the top of the list

  LS preferredURLs = syncList();

  settable transient SingleComponentPanel scp;

  JComboBox comboBox;

  JComponent urlBar() {

    ret withLabel("Show",

      comboBoxAndButton(

        onSelectedItem(

          bindComboBoxToLiveValue(centerComboBox(

            comboBox = autoComboBox(url(), urlsForComboBox())), uiURL),

          url -> showUIURL(url)

        ),

        "Go", url -> showUIURL(url)));

  }

  JComponent renderUIUrl aka renderUIURL aka uiGet(S url) {

    try {

      temp tempEnter(owner);

      var maker = uiMap.get(url);

      var component = callF(maker);

      if (component != null) ret component;

      ret jCenteredLabel("URL not found: " + url);

    } catch print e {

      ret jErrorView(e);

    }

  }

  void showUIURL(S url) {

    temp tempEnter(owner);

    setURL(trim(url));

    go();

  }

  void go {

    setComponent(scp, renderUIUrl(url()));

  }

  S url() { ret uiURL!; }

  void setURL(S url) { uiURL.set(url); }

  selfType put(S url, IF0<? extends JComponent> maker) {

    uiMap.put(url, maker);

    this;

  }

  LS urlsForComboBox() {

    var sorted = cloneKeys(uiMap);

    ret concatLists(listSetIntersection(preferredURLs, sorted), sorted);

  }

  void addPreferredUIURL(S uiURL) {

    preferredURLs.add(uiURL);

  }

}