/* Copyright 2002-2021 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.files.general;
  
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.List;
  import java.util.Map;
  import java.util.concurrent.ConcurrentHashMap;
  
  import org.orekit.attitudes.BoundedAttitudeProvider;
  import org.orekit.attitudes.FixedFrameBuilder;
  import org.orekit.attitudes.TabulatedProvider;
  import org.orekit.errors.OrekitIllegalArgumentException;
  import org.orekit.errors.OrekitMessages;
  import org.orekit.frames.Frame;
  import org.orekit.propagation.SpacecraftState;
  import org.orekit.time.AbsoluteDate;
  import org.orekit.utils.AngularDerivativesFilter;
  import org.orekit.utils.TimeStampedAngularCoordinates;
  
  /**
   * A class for encapsulating Orekit propagators within an {@link AttitudeEphemerisFile}
   * complaint object that makes for easy serialization to external ephemeris
   * formats like AEM.
   *
   * @author Raphaël Fermé
   * @since 10.3
   *
   */
  public class OrekitAttitudeEphemerisFile
      implements AttitudeEphemerisFile<TimeStampedAngularCoordinates,
                                       OrekitAttitudeEphemerisFile.OrekitAttitudeEphemerisSegment> {
  
      /** Hashmap of satellite ephemeris. **/
      private final Map<String, OrekitSatelliteAttitudeEphemeris> satellites;
  
      /**
       * Standard default constructor.
       */
      public OrekitAttitudeEphemerisFile() {
          this.satellites = new ConcurrentHashMap<>();
      }
  
      /** {@inheritDoc} */
      @Override
      public Map<String, OrekitSatelliteAttitudeEphemeris> getSatellites() {
          return Collections.unmodifiableMap(satellites);
      }
  
      /**
       * Adds a new satellite to this object.
       *
       * @param id
       *            ID to use for this satellite
       * @return the new satellite object
       */
      public OrekitSatelliteAttitudeEphemeris addSatellite(final String id) {
          final OrekitSatelliteAttitudeEphemeris newSat = new OrekitSatelliteAttitudeEphemeris(id);
          this.satellites.put(id, newSat);
          return newSat;
      }
  
      /**
       * Inner class of {@link OrekitAttitudeEphemerisFile} that defines the
       * {@link OrekitSatelliteAttitudeEphemeris} corresponding object for this ephemeris type.
       *
       */
      public static class OrekitSatelliteAttitudeEphemeris
          implements SatelliteAttitudeEphemeris<TimeStampedAngularCoordinates,
                                                OrekitAttitudeEphemerisFile.OrekitAttitudeEphemerisSegment> {
  
          /** Default interpolation sample size if it is not specified. **/
          public static final String DEFAULT_INTERPOLATION_METHOD = "LINEAR";
  
          /** Default interpolation sample size if it is not specified. **/
          public static final int DEFAULT_INTERPOLATION_SIZE = 2;
  
          /** ID of the space object encapsulated here. **/
          private final String id;
  
          /** Earliest date of this file. **/
          private AbsoluteDate startDate;
  
          /** Latest date of this file. **/
         private AbsoluteDate stopDate;
 
         /** List of segments in the file. **/
         private final List<OrekitAttitudeEphemerisSegment> segments;
 
         /**
          * Standard constructor for building the satellite Ephemeris object.
          *
          * @param id
          *            the ID of the space object for this data
          */
         public OrekitSatelliteAttitudeEphemeris(final String id) {
             this.id = id;
             this.segments = new ArrayList<>();
         }
 
         /** {@inheritDoc} */
         @Override
         public String getId() {
             return id;
         }
 
         /** {@inheritDoc} */
         @Override
         public List<OrekitAttitudeEphemerisSegment> getSegments() {
             return Collections.unmodifiableList(this.segments);
         }
 
         /** {@inheritDoc} */
         @Override
         public AbsoluteDate getStart() {
             return this.startDate;
         }
 
         /** {@inheritDoc} */
         @Override
         public AbsoluteDate getStop() {
             return this.stopDate;
         }
 
         /**
          * Injects pre-computed satellite states into this attitude ephemeris file
          * object, returning the generated {@link OrekitAttitudeEphemerisSegment} that
          * has been stored internally.
          *
          * @param states
          *          a list of {@link SpacecraftState} that will comprise this
          *          new unit
          * @param interpolationMethod
          *          the interpolation method that should be used when processed
          *          by another system
          * @param interpolationSamples
          *          the number of interpolation samples that should be used
          *          when processed by another system
          * @param availableDerivatives derivatives to use for interpolation
          * @return the generated {@link OrekitAttitudeEphemerisSegment}
          */
         public OrekitAttitudeEphemerisSegment addNewSegment(final List<SpacecraftState> states,
                                                             final String interpolationMethod,
                                                             final int interpolationSamples,
                                                             final AngularDerivativesFilter availableDerivatives) {
             final int minimumSampleSize = 2;
             if (states == null || states.size() == 0) {
                 throw new OrekitIllegalArgumentException(OrekitMessages.NULL_ARGUMENT, "states");
             }
 
             if (interpolationSamples < minimumSampleSize) {
                 throw new OrekitIllegalArgumentException(OrekitMessages.NOT_ENOUGH_DATA_FOR_INTERPOLATION,
                         interpolationSamples);
             }
 
             final AbsoluteDate start = states.get(0).getDate();
             final AbsoluteDate stop = states.get(states.size() - 1).getDate();
 
             if (this.startDate == null || start.compareTo(this.startDate) < 0) {
                 this.startDate = start;
             }
 
             if (this.stopDate == null || stop.compareTo(this.stopDate) > 0) {
                 this.stopDate = stop;
             }
 
             final List<TimeStampedAngularCoordinates> attitudeDataLines = new ArrayList<>();
             for (SpacecraftState state : states) {
                 attitudeDataLines.add(state.getAttitude().getOrientation());
             }
 
             final OrekitAttitudeEphemerisSegment newSeg =
                             new OrekitAttitudeEphemerisSegment(attitudeDataLines, interpolationMethod, interpolationSamples,
                                                                states.get(0).getFrame(), availableDerivatives);
             this.segments.add(newSeg);
             return newSeg;
         }
     }
 
     public static class OrekitAttitudeEphemerisSegment
         implements AttitudeEphemerisFile.AttitudeEphemerisSegment<TimeStampedAngularCoordinates> {
 
         /** List of attitude data lines. */
         private List<TimeStampedAngularCoordinates> attitudeDataLines;
 
         /** The interpolation method to be used. */
         private String interpolationMethod;
 
         /** The number of interpolation samples. */
         private int interpolationSamples;
 
         /** Enumerate for selecting which derivatives to use in {@link #attitudeDataLines} interpolation. */
         private AngularDerivativesFilter availableDerivatives;
 
         /** Reference frame from which attitude is defined. */
         private Frame referenceFrame;
 
         /**
          * Constructor for OrekitAttitudeEphemerisSegment.
          *
          * @param attitudeDataLines
          *          attitude data lines for this segment.
          * @param interpolationMethod
          *          the interpolation method to use.
          * @param interpolationSamples
          *          the number of samples to use during interpolation.
          * @param referenceFrame
          *          reference frame from which the attitude is defined
          * @param availableDerivatives derivatives to use for interpolation
          */
         public OrekitAttitudeEphemerisSegment(final List<TimeStampedAngularCoordinates> attitudeDataLines,
                                               final String interpolationMethod,
                                               final int interpolationSamples,
                                               final Frame referenceFrame,
                                               final AngularDerivativesFilter availableDerivatives) {
             this.attitudeDataLines    = attitudeDataLines;
             this.interpolationMethod  = interpolationMethod;
             this.interpolationSamples = interpolationSamples;
             this.referenceFrame       = referenceFrame;
             this.availableDerivatives = availableDerivatives;
         }
 
         /** {@inheritDoc} */
         @Override
         public List<TimeStampedAngularCoordinates> getAngularCoordinates() {
             return Collections.unmodifiableList(attitudeDataLines);
         }
 
         /** {@inheritDoc} */
         @Override
         public Frame getReferenceFrame() {
             return referenceFrame;
         }
 
         /** {@inheritDoc} */
         @Override
         public AbsoluteDate getStart() {
             return attitudeDataLines.get(0).getDate();
         }
 
         /** {@inheritDoc} */
         @Override
         public AbsoluteDate getStop() {
             return attitudeDataLines.get(attitudeDataLines.size() - 1).getDate();
         }
 
         /** {@inheritDoc} */
         @Override
         public String getInterpolationMethod() {
             return interpolationMethod;
         }
 
         /** {@inheritDoc} */
         @Override
         public int getInterpolationSamples() {
             return interpolationSamples;
         }
 
         /** {@inheritDoc} */
         @Override
         public AngularDerivativesFilter getAvailableDerivatives() {
             return availableDerivatives;
         }
 
         /** {@inheritDoc} */
         @Override
         public BoundedAttitudeProvider getAttitudeProvider() {
             return new TabulatedProvider(getAngularCoordinates(),
                                          getInterpolationSamples(), getAvailableDerivatives(),
                                          getStart(), getStop(),
                                          new FixedFrameBuilder(getReferenceFrame()));
         }
 
     }
 
 }