abstract sclass ChessOCR_DynChessBoardRecognizer extends DynModule {
  replace Segmenter with IF1<BufferedImage, L<Rect>>.
  
  S segmenterPreset;
  transient Iterator<? extends Segmenter> segmenters;
  L<Rect> segments;
  Rect boardLocation;
  double recognitionScore;
  S status;
  S selectedSquare;
  S piece;
  LPair<S, Double> recognized;
  S fen;

  switchable bool showSelectedSquare = true;
  switchable bool showSegmenterSection = true;
  switchable bool squareHeightAtBottom = true; // for YouTube videos
  transient int recreatedSquareSize = 32;
  transient ReliableSingleThread rst = dm_rst(module(), r recognize);
  transient BufferedImage img, board, square, recreated;
  transient LL<BufferedImage> squareImages;
  transient ImageSurface isInput, isBoard, isSquare, isRecreated;
  
  transient LS pieces = ai_chessPieces();
  transient Map<Bool, Map<S, BufferedImage>> recreateStock; // false = dark, true = light
  transient ChessPieceRecognizer pieceRecognizer;
  
  visualize {
    isBoard = jImageSurface();
    imageSurfaceOnHover(isBoard, voidfunc(Pt p) {
      if (board == null || p == null) ret with noToolTip(isBoard);
      setToolTip(isBoard, toolTipForSquare(boardPointToSquare(p));
    });
    imageSurfaceOnLeftClick(isBoard, voidfunc(Pt p) {
      selectSquare(boardPointToSquare(p))
    });
    
    isRecreated = jImageSurface(recreated);
    imageSurfaceOnHover(isRecreated, voidfunc(Pt p) {
      if (recreated == null || p == null) ret with noToolTip(isRecreated);
      setToolTip(isRecreated, toolTipForSquare(recreatedPointToSquare(p));
    });
    imageSurfaceOnLeftClick(isRecreated, voidfunc(Pt p) {
      selectSquare(recreatedPointToSquare(p))
    });
    
    isInput = jImageSurface(or_func(img, () -> whiteImage(100)));
    isInput.onNewImage = rst;
    isInput.zoomToWindow();
    
    JComponent recreatedSection = jCenteredSection("Recreated", jscroll_center(isRecreated)),
      boardSection = jCenteredSection("Chess board in image",
        centerAndSouthWithMargin(jscroll_center(isBoard),
        dm_centeredCalculatedLabel(() -> "Recognition score: " + formatDouble(recognitionScore, 2))
      ));
      
    JButton btnScreenshot = jbutton("Grab screenshot & recognize", rThread grabScreenshot);
    JButton popDownButton = jPopDownButton_noText(
      "Show possible chess boards found", rThread showSegments,
      "Publish training image...", rThread publishImage,
      //"---", null,
      //"Screenshot (hiding OS)", rThread grabScreenshot
    );
    
    ret withCalc(rst, jvsplit(
      jCenteredSection("Input image", jscroll_center(isInput)),
      northCenterAndSouthWithMargins(
        !showSegmenterSection ? centeredLine(btnScreenshot, popDownButton)
        : westCenterAndEastWithMargin(
          btnScreenshot,
          segmenterSection(),
          hstackWithSpacing(
            jbutton("Recognize", rst),
            popDownButton
          )),
          
        (!showSelectedSquare ? hgridWithSpacing(boardSection, recreatedSection) : hgridWithSpacing(
          recreatedSection,
          boardSection,
          jCenteredLiveValueSection(dm_calculatedLiveValue(S, () -> "Selected square" + (empty(selectedSquare) ? "" : " (" + selectedSquare + ")")), centerAndSouthWithMargin(
            jscroll_center(isSquare = jImageSurface(square)),
            rightAlignedLine(
              withLabel("Piece: ", dm_comboBox('piece, pieces)),
              jbutton("Save & upload", rThread saveAndUploadPiece))
        )))),
        vstackWithSpacing(
          dm_label('status),
          rightAlignedLine(withLabel("FEN (chess position):", dm_calculatedBoldLabel(() -> or2(fen, "-"))),
            jbutton("Copy", rThread copyFEN))
        )
      )));
  }
    
  void recognize {
    status("Recognizing...");
    segmenters = makeSegmenters();
    if (empty(segmenters)) ret with infoBox(status("No segmenter"));
    //img = dm_shootScreenHidingOS();
    if (isInput != null) img = isInput.getImage();
    
    if (pieceRecognizer == null)
      pieceRecognizer = chessOCR_pieceRecognizer();
    
    ChessOCR_TwoStageRecognizer rec = new(pieceRecognizer, img, segmenters);
    rec.verbose(true);

    clearImageSurfaces(isBoard, isRecreated);
    setField(fen := "");
          
    bool done = false;
    new Var<Rect> lastLocation;
    while (!done && !rst.triggered()) {
      done = !rec.step();
      
      Rect r = rec.bestBoardLocation();
      if (r != null)
        rec.tryRect(print("wiggling", wiggleRect(r)));
      
      r = rec.bestBoardLocation();
      if (r != null && setVar_trueIfChanged(lastLocation, r))
        newBestLocation(r, pieceRecognizer);
    }
    
    if (done && !lastLocation.has())
      status("No chess board found");
  }
  
  S status(S status) { setField(+status); ret status; }
  
  O _getReloadData() { ret img; }
  void _setReloadData(BufferedImage img) { this.img = img; }
 
  void setImage(BufferedImage img) {
    this.img = img;
    if (isInput != null) isInput.setImageAndZoomToDisplay(img);
    rst.trigger();
  }

  S boardPointToSquare(Pt p) {
    double space = imageMergeSpacing();
    double squareW = board.getWidth()/8.0+space;
    double squareH = board.getHeight()/8.0+space;
    int x = clamp(iratio_floor(p.x+space/2, squareW), 0, 7);
    int y = clamp(iratio_floor(p.y+space/2, squareH), 0, 7);
    ret strCharPlus('A', x) + (8-y);
  }
  
  S recreatedPointToSquare(Pt p) {
    int x = clamp(iratio_floor(p.x, recreatedSquareSize), 0, 7);
    int y = clamp(iratio_floor(p.y, recreatedSquareSize), 0, 7);
    ret strCharPlus('A', x) + (8-y);
  }
  
  void saveAndUploadPiece enter {
    if (square == null || empty(piece)) ret;
    chessOCR_uploadPieceImage(selectedSquare, piece, square);
    if (mapGet(mapGet(recreateStock, chess_isLightSquare(selectedSquare)), piece) == null) recreateStock = null;
    rst.trigger();
  }
  
  void recreate {
    if (recognized == null) ret;
    if (recreateStock == null)
      recreateStock = mapToValues(ll(false, true), light ->
        mapValues(pairsToMap(reversePairs(chessPieceImagesFromAGIBlue(light))), imageID -> resizeImage(loadImage2(imageID), recreatedSquareSize, recreatedSquareSize)));

    new L<BufferedImage> out;
    int i = 0;
    for (S piece : pairsA(recognized)) {
      bool light = even(i/8+i%8);
      out.add(or_func(mapGet(mapGet(recreateStock, light), piece), () -> whiteImage(recreatedSquareSize, recreatedSquareSize)));
      ++i;
    }
      
    new L<BufferedImage> rows;
    for (L<BufferedImage> row : listToChunks(out, 8))
      rows.add(mergeBufferedImagesHorizontally(row, spacing := 0));
    recreated = mergeBufferedImagesVertically(rows, spacing := 0);
    if (isRecreated != null) isRecreated.setImageAndZoomToDisplay(recreated);
  }
  
  Pair<S, Double> recognitionForSquare(S square) {
    int x, y = unpair chess_squareToPos(square);
    ret _get(recognized, y*8+x);
  }
  
  S toolTipForSquare(S square) {
    Pair<S, Double> rec = recognitionForSquare(square);
    ret square + " - " + (rec == null ? "?" : rec.a + " [" + iround(clamp(rec.b, 0, 100)) + "%]");
  }
  
  void selectSquare(S _square) {
    setField(selectedSquare := _square);
    S rec = pairA(recognitionForSquare(selectedSquare));
    if (rec != null) setField(piece := rec);
    int x, y = unpair chess_squareToPos(selectedSquare);
    square = _get(_get(squareImages, y), x);
    
    ChessPieceProfile1 profile = chessOCR_pieceProfileFromRawImage_1(square, withPreprocessedImages := true);
    isSquare.setImage(mergeBufferedImagesHorizontally(
      itemPlusList(square, map toBufferedImage(profile.preprocessedImages))));
    //printVars_str("leftClick", +p, +selectedSquare, +x, +y, +square);
  }
  
  void showSegments {
    L<Rect> segments = this.segments;
    showImage_centered(n2(segments, "segment") + " found",
      mergeBufferedImagesVertically(map(segments, r -> clipBufferedImage(img, r))));
  }
  
  void publishImage enter {
    BufferedImage img = this.img;
    S segmenterPreset = this.segmenterPreset;
    
    JCheckBox cbFound = jcheckbox(true), cbHasBoard = jcheckbox(true);
    JTextField tfFEN = jtextfield(fen), tfComments = jtextfield(),
      tfImageCredits = jtextfield();
    
    showFormTitled("Publish training image",
      "Image", jImageSurface(scaleImageToWidth(img, 500)),
      "Segmenter used", jlabel(segmenterPreset),
      "Is there a chess board in the image?", cbHasBoard,
      "FEN (empty if no board in image)", tfFEN,
      "Was the chess board found?", cbFound, // TODO: make clearer what this means if there is no board in image
      "Image credits (optional)", tfImageCredits,
      "Random comments", tfComments,
      "NOTE:", jMultiLineLabel("By clicking 'publish', you PUBLISH this image (fair use/public domain)."),
      "", jThreadedButton("Publish", r {
        temp tempInfoBox_noHide("Uploading training image...");
        S imageURL = uploadToImageServer("Chess board recognition training image", img);
        S desc = "Chess board recognition training image " + assertNempty("Parseable image URL", parseSnippetImageURL(imageURL));
        new LinkedHashMap<S> map;
        map.put("Input image", imageURL);
        mapPutIfNemptyValue(map, "Image credits", gtt(tfImageCredits));
        S fen = gtt(tfFEN);
        map.put("Image has chess board", yesNo_short_firstUpper(isChecked(cbHasBoard) || nempty(fen)));
        mapPutIfNemptyValue(map, "FEN", fen);
        map.put("Segmenter used", segmenterPreset);
        map.put("Chess board found", yesNo_short_firstUpper(isChecked(cbFound)));
        if (isChecked(cbFound))
          map.put("Board location", struct(boardLocation));
        S sliceID = agiBlue_chessBoardRecognitionTrainingImagesSliceID();
        new L<Map> toPost;
        S name = agiBlue_createUnusedNumberedPage(sliceID, desc + " #");
        for (S key, value : map)
          toPost.add(litmap(q := name, +key, +value));
        agiBot_postMulti(keyPairForProgram(), toPost, slice := sliceID);
        infoBox("Training image uploaded!");
        openURLInBrowser(agiBlue_linkForPhrase(name, slice := sliceID));
        disposeWindow(heldButton());
      })
    );
  }
  
  S makeFEN() {
    ret chess_makeFEN(listToChunks(pairsA(recognized), 8));
  }
  
  void newBestLocation(Rect r, ChessPieceRecognizer pieceRecognizer) {
    setField(segments := singletonUnlessNull(r));
    bool corrected = squareHeightAtBottom && abs(r.w-r.h) > 3;
    if (corrected) r.h = r.w;
    new LS comments;
    if (corrected) comments.add("height-corrected");
    status("Chess board found at: " + r + appendRoundBracketed(joinWithComma(comments)));
    setField(boardLocation := r);
    board = clipBufferedImage(img, r);
    
    squareImages = bufferedImageMNGrid(board, 8, 8);
    
    if (isBoard != null)
      isBoard.setImageAndZoomToDisplay(
        mergeBufferedImagesVertically(
          map(bufferedImageNVerticalSlices(8, board), i ->
            mergeBufferedImagesHorizontally(bufferedImageNHorizontalSlices(8, i)))));
            
    recognized = new L;
    for (BufferedImage img : concatLists(squareImages))
      recognized.add(pieceRecognizer.recognize(img));
    setField(recognitionScore := doubleAvg(pairsB(recognized));
    setField(fen := makeFEN());
    print(recognized);
    recreate();
  }
  
  Rect wiggleRect(Rect r) {
    if (r == null) null;
    int range = 1;
    ret intersectRects(imageRect(img),
      rectFromPoints(varyInt(range, r.x), varyInt(range, r.y),
        varyInt(range, r.x2()), varyInt(range, r.y2())));
  }
  
  void copyFEN {
    if (empty(fen)) ret;
    copyToClipboard(fen);
    infoBox("FEN copied to clipboard");
  }
  
  void grabScreenshot {
    isInput.setImageAndZoomToDisplay(dm_shootScreenHidingOS());
    rst.trigger();
  }

  abstract JComponent segmenterSection();
  abstract Iterator<? extends Segmenter> makeSegmenters();
}

Began life as a copy of #1024674