private List polygonize()

in baremaps-dem/src/main/java/org/apache/baremaps/dem/ContourTracer.java [110:171]
45 lines of code
9 McCabe index (conditional complexity)

  private List<Geometry> polygonize(List<Geometry> geometries) {
    var polygons = new ArrayList<>(geometries.stream()
        .map(Geometry::getCoordinates)
        .map(GEOMETRY_FACTORY::createPolygon)
        .map(polygon -> new GeometryFixer(polygon).getResult())
        .map(Polygon.class::cast)
        .sorted((a, b) -> Double.compare(b.getArea(), a.getArea()))
        .toList());

    List<Geometry> polygonized = new ArrayList<>();
    for (int i = 0; i < polygons.size(); i++) {
      // Skip null polygons
      if (polygons.get(i) == null) {
        continue;
      }

      // Extract the shell and holes
      Polygon shell = polygons.get(i);
      List<Polygon> holes = new ArrayList<>();
      for (int j = i + 1; j < polygons.size(); j++) {
        // Skip null polygons
        if (polygons.get(j) == null) {
          continue;
        }

        Polygon polygon = polygons.get(j);
        if (shell.contains(polygon)) {

          // Check if the hole is within a previously found hole
          boolean within = false;
          for (Polygon hole : holes) {
            if (hole.contains(polygon)) {
              within = true;
              break;
            }
          }
          if (within) {
            continue;
          }

          // Add the hole to the list
          holes.add(polygon);

          // Set the used polygon to null
          polygons.set(j, null);
        }
      }

      // Combine the shell and holes
      Polygon combinedPolygon = GEOMETRY_FACTORY.createPolygon(
          shell.getExteriorRing(),
          holes.stream()
              .map(Polygon::getExteriorRing)
              .toArray(LinearRing[]::new));
      polygonized.add(combinedPolygon);

      // Set the used polygon to null
      polygons.set(i, null);
    }

    return polygonized;
  }