sclass FindURLBox1 {
  Color color = Color.white;
  int maxHeight = 50, minWidth = 100;
  int g = 2; // grid size
  double fullScanEvery = 10.0; // if we get stuck on a wrong box
  
  new L<Rect> encouragedBoxes;
  new L<Rect> discouragedBoxes;
  
  RGBImage img;
  L<Rect> clips;
  Rect bestClip;
  RGBImage bestImage;
  bool verbose;
  long recogTime; // includes shooting the screen
  long lastFullScan;
  
  // returns true if smth was found
  bool go() {
    long time = sysNow();
    try {
      if (lastFullScan >= now()-toMS(fullScanEvery)
        && stillThere())
        ret true;
      lastFullScan = now();
      img = shootScreen();
      ret calc();
    } finally {
      recogTime = sysNow()-time;
    }
  }

  bool calc() {
    clips = [Rect r : areasColored(img, color, g) | r.h <= maxHeight && r.w >= minWidth];
    if (verbose)
      print(n(clips, "areas") + " found for color " + new RGB(color) + ": " + struct(clips));
    
    bestClip = bestAccordingTo(clips, func(Rect r) { scoreClip(r) });
    bestImage = img.clip(bestClip);
    ret bestClip != null;
  }

  double scoreClip(Rect r) {
    int i = encouragedBoxes.indexOf(r);
    if (i >= 0) ret 1000-i;
    i = discouragedBoxes.indexOf(r);
    if (i >= 0) ret -1000+i;
    
    double width = min(1, r.w/(double) img.w()*2);
    double top = r.y/(double) img.h();
    double height = r.h/(double) img.h();
    ret width-(top+height)*2; // thin, wide, high up
  }
  
  RGBImage bestImage() {
    ret bestImage;
  }
  
  void reset() {
    bestClip = null;
  }
  
  bool stillThere() {
    if (bestClip == null) false;
    Rect r = intersectWithScreen(growRect(bestClip, g));
    RGBImage img = shootScreen(r);
    L<Rect> clips = areasColored(img, color, g);
    Rect r2 = translateRect(bestClip, -r.x, -r.y);
    //print("r2=" + r2 + ", clips=" + struct(clips));
    if (clips.contains(r2)) {
      bestImage = img.clip(r2);
      true;
    } else {
      bestClip = null;
      bestImage = null;
      false;
    }
  }
}