Photoshop Scripting | Quick Save PNG By Layer/Group Name

I am trying to write a script that will quick save a PNG file by adding the selected Layer/Group name to the file. For instance if my photoshop file is called "Test.psd" and my selected Layer/Group is "2", when I run the script it would auto save with the name of "Test-2.png". Here is where I currently have the script, but I am having problems with getting the selected Layer/Group name properly because currently it adds "[LayerSet-2]" or "[ArtLayer-2]", etc. Any tips? Thanks!

#target photoshop
if (app.documents.length > 0) {
  var docRef = app.activeDocument;

  var docName = docRef.name;
  if (docName.indexOf(".") != -1) {
    var basename = docName.match(/(.*)\.[^\.]+$/)[1];
  } else {
    var basename = docName;
  }

  //getting the location, if unsaved save to desktop;
  try {
    var docPath = docRef.path;
  } catch (e) {
    var docPath = "~/Desktop";
  }

    var opts, file;
    opts = new ExportOptionsSaveForWeb();
    opts.format = SaveDocumentType.PNG;
    opts.PNG8 = false;
    opts.quality = 100;

  var layername = docRef.activeLayer;
  var filename = docPath + '/' + basename + '-' + layername + '.png';

  pngFile = new File(filename);
  app.activeDocument.exportDocument(pngFile, ExportType.SAVEFORWEB, opts);
};