/* Contributed in the public domain.
    * Licensed to CS GROUP (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.files.ccsds.definitions;
  
  import org.orekit.bodies.CelestialBody;
  import org.orekit.bodies.CelestialBodyFactory;
  import org.orekit.errors.OrekitException;
  import org.orekit.errors.OrekitMessages;
  import org.orekit.frames.Frame;
  import org.orekit.time.AbsoluteDate;
  
  /**
   * Orekit's default implementation of {@link CcsdsFrameMapper}.
   *
   * @author Evan M. Ward
   * @since 14.0
   */
  public class OrekitCcsdsFrameMapper implements CcsdsFrameMapper {
  
      /** Message indicating no reference frame. */
      private static final String NO_REFERENCE_FRAME = "No reference frame";
  
      @Override
      public Frame buildCcsdsFrame(final FrameFacade orientation,
                                   final AbsoluteDate frameEpoch) {
          if (orientation == null) {
              throw new OrekitException(OrekitMessages.CCSDS_INVALID_FRAME, NO_REFERENCE_FRAME);
          }
          final Frame frame = orientation.asFrame();
          if (frame == null) {
              throw new OrekitException(OrekitMessages.CCSDS_INVALID_FRAME, orientation.getName());
          }
          return frame;
      }
  
      @Override
      public Frame buildCcsdsFrame(final BodyFacade center,
                                   final FrameFacade orientation,
                                   final AbsoluteDate frameEpoch) {
          if (center == null) {
              throw new OrekitException(OrekitMessages.NO_DATA_LOADED_FOR_CELESTIAL_BODY, "No Orbit center name");
          }
          final CelestialBody body = center.getBody();
          if (body == null) {
              throw new OrekitException(OrekitMessages.NO_DATA_LOADED_FOR_CELESTIAL_BODY, center.getName());
          }
          if (orientation == null) {
              throw new OrekitException(OrekitMessages.CCSDS_INVALID_FRAME, NO_REFERENCE_FRAME);
          }
          final Frame frame = orientation.asFrame();
          if (frame == null) {
              throw new OrekitException(OrekitMessages.CCSDS_INVALID_FRAME, orientation.getName());
          }
          // Just return frame if we don't need to shift the center based on CENTER_NAME
          // MCI and ICRF are the only non-Earth centered frames specified in Annex A.
          final CelestialBodyFrame celestialBodyFrame =
                  orientation.asCelestialBodyFrame();
          final boolean isMci = celestialBodyFrame == CelestialBodyFrame.MCI;
          final boolean isIcrf = celestialBodyFrame == CelestialBodyFrame.ICRF;
          final String centerName = body.getName();
          final boolean isCenterEarth = CelestialBodyFactory.EARTH.equals(centerName);
          final boolean isCenterMars = CelestialBodyFactory.MARS.equals(centerName);
          if (isIcrf) {
              // special case so Earth-centered ICRF is GCRF, #1914
              return body.getIcrfAlignedFrame();
          }
          if (!isMci && isCenterEarth || isMci && isCenterMars) {
              // ICRF and MCI are the only two frames in CelestialBodyFrame
              // that are not Earth-centered. If that changes then this code would
              // also need to be updated, perhaps by adding a getCenter() method
              // to CelestialBodyFrame or Frame.
              return frame;
          }
          // else, translate frame to specified center.
          return new ModifiedFrame(frame, celestialBodyFrame,
                  body, center.getName());
      }
  
      @Override
      public int hashCode() {
          return this.getClass().hashCode();
      }
  
      @Override
      public boolean equals(final Object obj) {
         return this == obj || this.getClass() == OrekitCcsdsFrameMapper.class &&
                 obj.getClass() == OrekitCcsdsFrameMapper.class;
     }
 
 }