/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You 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.apache.commons.geometry.io.euclidean.threed.obj;
  
  import java.io.Reader;
  import java.util.ArrayList;
  import java.util.List;
  
  import org.apache.commons.geometry.euclidean.threed.Vector3D;
  import org.apache.commons.geometry.io.euclidean.threed.FacetDefinition;
  import org.apache.commons.geometry.io.euclidean.threed.FacetDefinitionReader;
  import org.apache.commons.geometry.io.euclidean.threed.SimpleFacetDefinition;
  
  /** Class for reading {@link FacetDefinition facets} from OBJ content.
   */
  public class ObjFacetDefinitionReader extends AbstractObjPolygonReader
      implements FacetDefinitionReader {
  
      /** List of vertices encountered in the input. */
      private final List<Vector3D> vertices = new ArrayList<>();
  
      /** List of normals encountered in the input. */
      private final List<Vector3D> normals = new ArrayList<>();
  
      /** Construct a new instance that reads OBJ content from the given reader.
       * @param reader reader to read from
       */
      public ObjFacetDefinitionReader(final Reader reader) {
          super(reader);
      }
  
      /** {@inheritDoc} */
      @Override
      public FacetDefinition readFacet() {
          final PolygonObjParser.Face face = readFace();
          if (face != null) {
              final List<Vector3D> faceVertices = face.getVertices(vertices::get);
              final Vector3D definedNormal = face.getDefinedCompositeNormal(normals::get);
  
              return new SimpleFacetDefinition(faceVertices, definedNormal);
          }
  
          return null;
      }
  
      /** {@inheritDoc} */
      @Override
      protected void handleVertex(final Vector3D vertex) {
          vertices.add(vertex);
      }
  
      /** {@inheritDoc} */
      @Override
      protected void handleNormal(final Vector3D normal) {
          normals.add(normal);
      }
  }