// A is the user object associated with each mask (aka a "label").

persistable sclass G22HashedMasks<A> is IG22SimpleMasksHolder<A> {

  !include early #1035854 // Masks holder Include

  record noeq Mask(Image2B image) is IG22Mask<A> {

    settable A label;

    int hash;

    public bool equals(O o) {

      if (o cast G22HashedMasks.Mask)

        ret hashCode() == o.hashCode()

          && binaryImagesIdentical(image, o.image);

      false;

    }

    public int hashCode() {

      if (hash == 0)

        hash = (int) hashImage2B(image);

      ret hash;

    }

    public Image2B image() { ret image; }

  }

  new CompactHashSet<Mask> masks;

  // creating a sub-holder

  *(L<IG22Mask<A>> masks) {

    assertNempty(masks);

    maskSize(imageSize(first(masks).image()));

    fOr (mask : masks)

      this.masks.add(mask);

  }

  // same with pre-calculated ghost

  *(L<IG22Mask<A>> masks, G22GhostImage ghost) {

    this(masks);

    ghost_cache = ghost;

  }

  void addRegion(IImageRegion region, A label) {

    addMask(regionToMaskImage(region), label);

  }

  void addMask(IBinaryImage maskImage, A label default null) {

    var mask = new Mask(toImage2B(maskImage));

    var existingMask = masks.find(mask);

    if (existingMask != null) {

      mask = existingMask;

      mask.label = combineLabels(mask.label, label);

    } else {

      mask.label = label;

      masks.add(mask);

    }

    ghost_cache = null;

    certainty_cache = null;

    //this.labels.addAll(labels);

  }

  public L<Mask> masks() { ret asList(masks); }

  /*public LPair<Image2B, A> maskImagesWithLabels() {

    ret map(masks(), mask -> pair(mask.image, mask.labels));

  }*/

  A combineLabels(A label1, A label2) {

    if (eq(label1, label2)) ret label1;

    if (label1 == null) ret label2;

    if (label2 == null) ret label1;

    if (label1 cast MultiSet) {

      if (label2 cast MultiSet) {

        label1.addAll(label2);

        ret (A) label1;

      }

    }

    ret specialCombineLabels(label1, label2);

  }

  swappable A specialCombineLabels(A label1, A label2) {

    fail("Can't combine labels: " + label1 + " + " + label2);

  }

  public <B> IG22MasksHolder<B> cloneTreeWithLabelTransform(IF1<A, B> f) {

    new G22HashedMasks<B> clone;

    for (mask : masks) {

      G22HashedMasks<B>.Mask clonedMask = clone.new Mask;

      clonedMask.image = mask.image;

      clonedMask.hash = mask.hash;

      clonedMask.label = f.get(mask.label);

      clone.masks.add(clonedMask);

    }

    ret clone;

  }

}