// Abstract base class for tiling an image (G22Tiling)

abstract srecord noeq G22AbstractTiler<Img extends WidthAndHeight>(Img image) is Runnable, Steppable {
  delegate Tile to G22Tiling.
  
  int w, h, runner;
  gettable int size; // =w*h
  
  // iterator that provides points to be looked at
  // (e.g. a WeightlessShuffledIterator)
  IndexIterator pointIterator;
  
  // Temporary stack of points to be looked at
  // (e.g. neighbors of a tile just discovered).
  // May or may not be used.
  new IntBuffer stack;

  G22Tiling<Img> tiling; // the tiling we are making
  
  int tileCounter;
  GrowTile growingTile; // tile currently being grown
  
  bool verbose;
  
  // The one method subclasses need to override.
  // The exact meaning of a "color" is not defined,
  // the tiler just treats different int value as different colors.
  abstract int getColor(int pos);
  
  // calculations for positions (pixel index)
  int x(int pos) { ret pos % w; }
  int y(int pos) { ret pos / w; }
  int pos(int x, int y) { ret y*w+x; }
  Pt pt(int pos) { ret Pt(x(pos), y(pos)); }
  bool validPos(int x, int y) { ret x >= 0 && y >= 0 && x < w && y < h; }
  
  class GrowTile is Steppable {
    Tile tile;
    
    // Still growing in each of the 4 directions?
    bool growingN = true;
    bool growingE = true;
    bool growingS = true;
    bool growingW = true;
    
    *(int pos) {
      int x = x(pos), y = y(pos);
      int iTile = tileCounter++;
      tile = new Tile;
      tile.position = rect(x, y, 1, 1);
      tiling.tiles.add(tile);
      tiling.tileMatrix[pos] = iTile+1;
    }
    
    public bool step() {
      false;
    }
  }
  
  run { stepAll(this); }
  
  public bool step() {
    init();
    
    // Currently growing a tile? Continue that
    if (growingTile != null) {
      if (growingTile.step()) true;
      growingTile = null; // Done growing this tile
    }
    
    int pos = pointIterator.nextIndex();
    if (pos < 0) false;
    
    // Is point already covered by a tile?
    if (tiling.tileMatrix[pos] != 0) true;
    
    // Create new tile
    growingTile = new GrowTile(pos);
    
    true;
  }
  
  void init {
    if (tiling != null) ret;
    w = image.getWidth(); h = image.getHeight();
    size = w*h;
    tiling = new G22Tiling(image);
    tiling.initTileMatrix();
    
    pointIterator = WeightlessShuffledIterator(size);
  }
  
  G22Tiling<Img> get() {
    if (tiling == null) run();
    ret tiling;
  }
}