code: /*
   * citygml-tools - Collection of tools for processing CityGML files
   * https://github.com/citygml4j/citygml-tools
   *
   * citygml-tools is part of the citygml4j project
   *
   * Copyright 2018-2023 Claus Nagel <claus.nagel@gmail.com>
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package org.citygml4j.tools.util;
  
  import org.citygml4j.core.model.common.GeometryInfo;
  import org.citygml4j.core.model.core.AbstractFeature;
  import org.citygml4j.core.model.core.AbstractSpaceBoundary;
  import org.citygml4j.core.visitor.ObjectWalker;
  import org.xmlobjects.gml.model.GMLObject;
  import org.xmlobjects.gml.model.geometry.AbstractGeometry;
  import org.xmlobjects.gml.model.geometry.GeometryProperty;
  import org.xmlobjects.gml.util.reference.ReferenceResolver;
  import org.xmlobjects.model.Child;
  
  import java.util.*;
  
  public class CrossLodReferenceResolver {
      private final CrossLodReferenceCollector lodReferenceCollector = new CrossLodReferenceCollector();
      private final GeometryCopyBuilder copyBuilder = GeometryCopyBuilder.newInstance().copyAppearance(true);
      private final Map<Mode, Integer> counter = new HashMap<>();
  
      private Mode mode = Mode.RESOLVE;
  
      public enum Mode {
          RESOLVE,
          REMOVE_LOD4_REFERENCES
      }
  
      private CrossLodReferenceResolver() {
      }
  
      public static CrossLodReferenceResolver newInstance() {
          return new CrossLodReferenceResolver();
      }
  
      public CrossLodReferenceResolver withGlobalAppearanceHelper(AppearanceHelper globalAppearanceHelper) {
          copyBuilder.withGlobalAppearanceHelper(globalAppearanceHelper);
          return this;
      }
  
      public CrossLodReferenceResolver withMode(Mode mode) {
          this.mode = mode;
          return this;
      }
  
      public CrossLodReferenceResolver copyAppearance(boolean copyAppearance) {
          copyBuilder.copyAppearance(copyAppearance);
          return this;
      }
  
      public Map<Mode, Integer> getCounter() {
          return counter;
      }
  
      public void resolveCrossLodReferences(AbstractFeature feature, ReferenceResolver referenceResolver) {
          referenceResolver.resolveReferences(feature);
          resolveCrossLodReferences(feature);
      }
  
      public void resolveCrossLodReferences(AbstractFeature feature) {
          Map<AbstractGeometry, List<GeometryProperty<?>>> references = lodReferenceCollector.process(feature);
          if (!references.isEmpty()) {
              if (mode == Mode.RESOLVE) {
                  copyBuilder.withLocalAppearanceHelper(AppearanceHelper.of(feature));
                  for (Map.Entry<AbstractGeometry, List<GeometryProperty<?>>> entry : references.entrySet()) {
                      GeometryProperty<?> targetProperty = getTargetProperty(entry.getValue());
                      AbstractGeometry geometry = copyBuilder.copy(entry.getKey(), feature);
  
                      targetProperty.setInlineObjectIfValid(geometry);
                      targetProperty.setHref(null);
                      counter.merge(Mode.RESOLVE, 1, Integer::sum);
  
                      if (entry.getValue().size() > 1) {
                          entry.getValue().stream()
                                  .filter(property -> property != targetProperty)
                                  .forEach(property -> {
                                      property.setHref("#" + geometry.getId());
                                      counter.merge(Mode.RESOLVE, 1, Integer::sum);
                                  });
                      }
                  }
              } else {
                  references.values().stream()
                          .flatMap(Collection::stream)
                          .forEach(property -> {
                              Child parent = property.getParent();
                              if (parent instanceof GMLObject) {
                                  ((GMLObject) parent).unsetProperty(property);
                                  counter.merge(Mode.REMOVE_LOD4_REFERENCES, 1, Integer::sum);
                              }
                          });
              }
          }
  
          lodReferenceCollector.clear();
      }
  
      private GeometryProperty<?> getTargetProperty(List<GeometryProperty<?>> properties) {
          if (properties.size() > 1) {
              for (GeometryProperty<?> property : properties) {
                  if (property.getParent(AbstractSpaceBoundary.class) != null) {
                      return property;
                  }
              }
          }
  
          return properties.get(0);
      }
  
      private class CrossLodReferenceCollector extends ObjectWalker {
          private final Map<AbstractGeometry, List<GeometryProperty<?>>> references = new IdentityHashMap<>();
          private final Map<GeometryProperty<?>, Integer> propertiesByLod = new IdentityHashMap<>();
  
          public Map<AbstractGeometry, List<GeometryProperty<?>>> process(AbstractFeature feature) {
              GeometryInfo geometryInfo = feature.getGeometryInfo(true);
              for (int lod : geometryInfo.getLods()) {
                  geometryInfo.getGeometries(lod).forEach(property -> propertiesByLod.put(property, lod));
              }
  
              propertiesByLod.keySet().forEach(this::visit);
              return references;
          }
  
          public void clear() {
              references.clear();
              propertiesByLod.clear();
          }
  
          @Override
          public void visit(GeometryProperty<?> property) {
              if (property.isSetReferencedObject() && property.getHref() != null) {
                  Integer lod = getLod(property);
                  Integer otherLod = getLod(property.getObject().getParent(GeometryProperty.class));
                  if (lod != null && otherLod != null && !lod.equals(otherLod)) {
                      if (mode == Mode.RESOLVE || (mode == Mode.REMOVE_LOD4_REFERENCES && otherLod == 4)) {
                          references.computeIfAbsent(property.getObject(), v -> new ArrayList<>()).add(property);
                      }
                  }
              }
  
              super.visit(property);
          }
  
          private Integer getLod(GeometryProperty<?> property) {
              Integer lod = null;
              if (property != null) {
                  do {
                      lod = propertiesByLod.get(property);
                  } while (lod == null && (property = property.getParent(GeometryProperty.class)) != null);
              }
  
              return lod;
          }
      }
  }
  