/* Copyright 2002-2026 CS GROUP
    * 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.attitudes;
  
  import org.hipparchus.CalculusFieldElement;
  import org.orekit.frames.Frame;
  import org.orekit.time.AbstractFieldTimeInterpolator;
  import org.orekit.time.FieldTimeInterpolator;
  import org.orekit.time.FieldTimeStamped;
  import org.orekit.utils.TimeStampedFieldAngularCoordinates;
  
  import java.util.Collections;
  import java.util.List;
  import java.util.stream.Collectors;
  import java.util.stream.Stream;
  
  /**
   * Class for attitude interpolation.
   * <p>
   * The type of interpolation used is defined by given time stamped angular coordinates interpolator at construction.
   *
   * @param <KK> type of the field element
   *
   * @author Vincent Cucchietti
   * @see TimeStampedFieldAngularCoordinates
   * @see FieldTimeInterpolator
   */
  public class FieldAttitudeInterpolator<KK extends CalculusFieldElement<KK>>
          extends AbstractFieldTimeInterpolator<FieldAttitude<KK>, KK> {
  
      /** Reference frame from which attitude is defined. */
      private final Frame referenceFrame;
  
      /** Time stamped angular coordinates interpolator. */
      private final FieldTimeInterpolator<TimeStampedFieldAngularCoordinates<KK>, KK> interpolator;
  
      /**
       * Constructor.
       *
       * @param referenceFrame reference frame from which attitude is defined
       * @param interpolator time stamped angular coordinates interpolator
       */
      public FieldAttitudeInterpolator(final Frame referenceFrame,
                                       final FieldTimeInterpolator<TimeStampedFieldAngularCoordinates<KK>, KK> interpolator) {
          super(interpolator.getNbInterpolationPoints(), interpolator.getExtrapolationThreshold());
          this.referenceFrame = referenceFrame;
          this.interpolator   = interpolator;
      }
  
      /** Get reference frame from which attitude is defined.
       * @return reference frame from which attitude is defined
       */
      public Frame getReferenceFrame() {
          return referenceFrame;
      }
  
      /** Get time stamped angular coordinates interpolator.
       * @return time stamped angular coordinates interpolator
       */
      public FieldTimeInterpolator<TimeStampedFieldAngularCoordinates<KK>, KK> getAngularInterpolator() {
          return interpolator;
      }
  
      /** {@inheritDoc} */
      @Override
      protected FieldAttitude<KK> interpolate(final InterpolationData interpolationData) {
  
          // Convert sample to stream
          final Stream<FieldAttitude<KK>> sample = interpolationData.getNeighborList().stream();
  
          // Express all attitudes in the same reference frame
          final Stream<FieldAttitude<KK>> consistentSample =
                  sample.map(attitude -> attitude.withReferenceFrame(referenceFrame));
  
          // Map time stamped angular coordinates
          final List<TimeStampedFieldAngularCoordinates<KK>> angularSample =
                  consistentSample.map(FieldAttitude::getOrientation).collect(Collectors.toList());
  
          // Interpolate
          final TimeStampedFieldAngularCoordinates<KK> interpolated =
                  interpolator.interpolate(interpolationData.getInterpolationDate(), angularSample);
  
          return new FieldAttitude<>(referenceFrame, interpolated);
      }
  
     @Override
     public List<FieldTimeInterpolator<? extends FieldTimeStamped<KK>, KK>> getSubInterpolators() {
         return Collections.singletonList(interpolator);
     }
 }