/* Copyright 2013-2019 CS Systèmes d'Information
    * Licensed to CS Systèmes d'Information (CS) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * CS 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.orekit.rugged.intersection;
  
  import org.hipparchus.geometry.euclidean.threed.Vector3D;
  import org.orekit.bodies.GeodeticPoint;
  import org.orekit.rugged.api.AlgorithmId;
  import org.orekit.rugged.errors.DumpManager;
  import org.orekit.rugged.utils.ExtendedEllipsoid;
  import org.orekit.rugged.utils.NormalizedGeodeticPoint;
  
  /** Intersection ignoring Digital Elevation Model.
   * <p>
   * This dummy implementation simply uses the ellipsoid itself.
   * </p>
   * @author Luc Maisonobe
   */
  public class ConstantElevationAlgorithm implements IntersectionAlgorithm {
  
      /** Constant elevation over ellipsoid. */
      private final double constantElevation;
  
      /** Simple constructor.
       * @param constantElevation constant elevation over ellipsoid
       */
      public ConstantElevationAlgorithm(final double constantElevation) {
          this.constantElevation = constantElevation;
      }
  
      /** {@inheritDoc} */
      @Override
      public NormalizedGeodeticPoint intersection(final ExtendedEllipsoid ellipsoid,
                                                  final Vector3D position, final Vector3D los) {
          DumpManager.dumpAlgorithm(AlgorithmId.CONSTANT_ELEVATION_OVER_ELLIPSOID, constantElevation);
          final Vector3D      p  = ellipsoid.pointAtAltitude(position, los, constantElevation);
          final GeodeticPoint gp = ellipsoid.transform(p, ellipsoid.getFrame(), null);
          return new NormalizedGeodeticPoint(gp.getLatitude(), gp.getLongitude(), gp.getAltitude(), 0.0);
      }
  
      /** {@inheritDoc} */
      @Override
      public NormalizedGeodeticPoint refineIntersection(final ExtendedEllipsoid ellipsoid,
                                                        final Vector3D position, final Vector3D los,
                                                        final NormalizedGeodeticPoint closeGuess) {
          DumpManager.dumpAlgorithm(AlgorithmId.CONSTANT_ELEVATION_OVER_ELLIPSOID, constantElevation);
          final Vector3D      p  = ellipsoid.pointAtAltitude(position, los, constantElevation);
          final GeodeticPoint gp = ellipsoid.transform(p, ellipsoid.getFrame(), null);
          return new NormalizedGeodeticPoint(gp.getLatitude(), gp.getLongitude(), gp.getAltitude(),
                  closeGuess.getLongitude());
      }
  
      /** {@inheritDoc}
       * <p>
       * As this algorithm uses a constant elevation,
       * this method always returns the same value.
       * </p>
       */
      @Override
      public double getElevation(final double latitude, final double longitude) {
          DumpManager.dumpAlgorithm(AlgorithmId.CONSTANT_ELEVATION_OVER_ELLIPSOID, constantElevation);
          return constantElevation;
      }
  
  }