/* Copyright 2002-2024 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.propagation.integration;
  
  import java.util.Arrays;
  import java.util.Collections;
  import java.util.List;
  
  import org.hipparchus.CalculusFieldElement;
  import org.hipparchus.ode.FieldDenseOutputModel;
  import org.hipparchus.ode.FieldODEStateAndDerivative;
  import org.orekit.errors.OrekitException;
  import org.orekit.errors.OrekitMessages;
  import org.orekit.frames.Frame;
  import org.orekit.orbits.FieldOrbit;
  import org.orekit.propagation.FieldAdditionalStateProvider;
  import org.orekit.propagation.FieldBoundedPropagator;
  import org.orekit.propagation.FieldSpacecraftState;
  import org.orekit.propagation.PropagationType;
  import org.orekit.propagation.analytical.FieldAbstractAnalyticalPropagator;
  import org.orekit.time.FieldAbsoluteDate;
  import org.orekit.utils.FieldArrayDictionary;
  import org.orekit.utils.ParameterDriver;
  
  /** This class stores sequentially generated orbital parameters for
   * later retrieval.
   *
   * <p>
   * Instances of this class are built automatically when the {@link
   * org.orekit.propagation.FieldPropagator#getEphemerisGenerator()
   * getEphemerisGenerator} method has been called. They are created when propagation is over.
   * Random access to any intermediate state of the orbit throughout the propagation range is
   * possible afterwards through this object.
   * </p>
   * <p>
   * A typical use case is for numerically integrated orbits, which can be used by
   * algorithms that need to wander around according to their own algorithm without
   * cumbersome tight links with the integrator.
   * </p>
   * <p>
   * As this class implements the {@link org.orekit.propagation.Propagator Propagator}
   * interface, it can itself be used in batch mode to build another instance of the
   * same type. This is however not recommended since it would be a waste of resources.
   * </p>
   * <p>
   * Note that this class stores all intermediate states along with interpolation
   * models, so it may be memory intensive.
   * </p>
   *
   * @see org.orekit.propagation.numerical.NumericalPropagator
   * @author Mathieu Rom&eacute;ro
   * @author Luc Maisonobe
   * @author V&eacute;ronique Pommier-Maurussane
   * @param <T> type of the field elements
   */
  public class FieldIntegratedEphemeris <T extends CalculusFieldElement<T>>
      extends FieldAbstractAnalyticalPropagator<T> implements FieldBoundedPropagator<T> {
  
      /** Event detection requires evaluating the state slightly before / past an event. */
      private static final double EXTRAPOLATION_TOLERANCE = 1.0;
  
      /** Mapper between raw double components and spacecraft state. */
      private final FieldStateMapper<T> mapper;
  
      /** Type of orbit to output (mean or osculating).
       * <p>
       * This is used only in the case of semianalitical propagators where there is a clear separation between
       * mean and short periodic elements. It is ignored by the Numerical propagator.
       * </p>
       */
      private PropagationType type;
  
      /** Start date of the integration (can be min or max). */
      private final FieldAbsoluteDate<T> startDate;
  
      /** First date of the range. */
      private final FieldAbsoluteDate<T> minDate;
  
      /** Last date of the range. */
      private final FieldAbsoluteDate<T> maxDate;
  
      /** Underlying raw mathematical model. */
      private FieldDenseOutputModel<T> model;
  
      /** Unmanaged additional states that must be simply copied. */
     private final FieldArrayDictionary<T> unmanaged;
 
     /** Names of additional equations.
      * @since 11.2
      */
     private final String[] equations;
 
     /** Dimensions of additional equations.
      * @since 11.2
      */
     private final int[] dimensions;
 
     /** Creates a new instance of IntegratedEphemeris.
      * @param startDate Start date of the integration (can be minDate or maxDate)
      * @param minDate first date of the range
      * @param maxDate last date of the range
      * @param mapper mapper between raw double components and spacecraft state
      * @param type type of orbit to output (mean or osculating)
      * @param model underlying raw mathematical model
      * @param unmanaged unmanaged additional states that must be simply copied
      * @param providers generators for pre-integrated states
      * @param equations names of additional equations
      * @param dimensions dimensions of additional equations
      * @since 11.2
      */
     public FieldIntegratedEphemeris(final FieldAbsoluteDate<T> startDate,
                                     final FieldAbsoluteDate<T> minDate, final FieldAbsoluteDate<T> maxDate,
                                     final FieldStateMapper<T> mapper, final PropagationType type,
                                     final FieldDenseOutputModel<T> model,
                                     final FieldArrayDictionary<T> unmanaged,
                                     final List<FieldAdditionalStateProvider<T>> providers,
                                     final String[] equations, final int[] dimensions) {
 
         super(startDate.getField(), mapper.getAttitudeProvider());
 
         this.startDate = startDate;
         this.minDate   = minDate;
         this.maxDate   = maxDate;
         this.mapper    = mapper;
         this.type      = type;
         this.model     = model;
         this.unmanaged = unmanaged;
 
         // set up the pre-integrated providers
         for (final FieldAdditionalStateProvider<T> provider : providers) {
             addAdditionalStateProvider(provider);
         }
 
         this.equations  = equations.clone();
         this.dimensions = dimensions.clone();
 
         // set up initial state
         super.resetInitialState(getInitialState());
 
     }
 
     /** Interpolate the model at some date.
      * @param date desired interpolation date
      * @return state interpolated at date
           * of supported range
      */
     private FieldODEStateAndDerivative<T> getInterpolatedState(final FieldAbsoluteDate<T> date) {
 
         // compare using double precision instead of FieldAbsoluteDate<T>.compareTo(...)
         // because time is expressed as a double when searching for events
         if (date.compareTo(minDate.shiftedBy(-EXTRAPOLATION_TOLERANCE)) < 0) {
             // date is outside of supported range
             throw new OrekitException(OrekitMessages.OUT_OF_RANGE_EPHEMERIDES_DATE_BEFORE,
                     date, minDate, maxDate, minDate.durationFrom(date).getReal());
         }
         if (date.compareTo(maxDate.shiftedBy(EXTRAPOLATION_TOLERANCE)) > 0) {
             // date is outside of supported range
             throw new OrekitException(OrekitMessages.OUT_OF_RANGE_EPHEMERIDES_DATE_AFTER,
                     date, minDate, maxDate, date.durationFrom(maxDate).getReal());
         }
 
         return model.getInterpolatedState(date.durationFrom(startDate));
 
     }
 
     /** {@inheritDoc} */
     @Override
     protected FieldSpacecraftState<T> basicPropagate(final FieldAbsoluteDate<T> date) {
         final FieldODEStateAndDerivative<T> os = getInterpolatedState(date);
         FieldSpacecraftState<T> state = mapper.mapArrayToState(mapper.mapDoubleToDate(os.getTime(), date),
                                                                os.getPrimaryState(), os.getPrimaryDerivative(),
                                                                type);
         for (FieldArrayDictionary<T>.Entry initial : unmanaged.getData()) {
             state = state.addAdditionalState(initial.getKey(), initial.getValue());
         }
         return state;
     }
 
     /** {@inheritDoc} */
     @Override
     protected FieldOrbit<T> propagateOrbit(final FieldAbsoluteDate<T> date, final T[] parameters) {
         return basicPropagate(date).getOrbit();
     }
 
     /** {@inheritDoc} */
     @Override
     protected T getMass(final FieldAbsoluteDate<T> date) {
         return basicPropagate(date).getMass();
     }
 
     /** Get the first date of the range.
      * @return the first date of the range
      */
     @Override
     public FieldAbsoluteDate<T> getMinDate() {
         return minDate;
     }
 
     /** Get the last date of the range.
      * @return the last date of the range
      */
     @Override
     public FieldAbsoluteDate<T> getMaxDate() {
         return maxDate;
     }
 
     @Override
     public Frame getFrame() {
         return this.mapper.getFrame();
     }
 
     /** {@inheritDoc} */
     @Override
     public void resetInitialState(final FieldSpacecraftState<T> state) {
         throw new OrekitException(OrekitMessages.NON_RESETABLE_STATE);
     }
 
     /** {@inheritDoc} */
     @Override
     protected void resetIntermediateState(final FieldSpacecraftState<T> state, final boolean forward) {
         throw new OrekitException(OrekitMessages.NON_RESETABLE_STATE);
     }
 
     /** {@inheritDoc} */
     @Override
     public FieldSpacecraftState<T> getInitialState() {
         return updateAdditionalStates(basicPropagate(getMinDate()));
     }
 
     /** {@inheritDoc} */
     @Override
     protected FieldSpacecraftState<T> updateAdditionalStates(final FieldSpacecraftState<T> original) {
 
         FieldSpacecraftState<T> updated = super.updateAdditionalStates(original);
 
         if (equations.length > 0) {
             final FieldODEStateAndDerivative<T> osd                = getInterpolatedState(updated.getDate());
             final T[]                           combinedState      = osd.getSecondaryState(1);
             final T[]                           combinedDerivative = osd.getSecondaryDerivative(1);
             int index = 0;
             for (int i = 0; i < equations.length; ++i) {
                 final T[] state      = Arrays.copyOfRange(combinedState,      index, index + dimensions[i]);
                 final T[] derivative = Arrays.copyOfRange(combinedDerivative, index, index + dimensions[i]);
                 updated = updated.
                           addAdditionalState(equations[i], state).
                           addAdditionalStateDerivative(equations[i], derivative);
                 index += dimensions[i];
             }
         }
 
         return updated;
 
     }
 
     /** {@inheritDoc} */
     @Override
     public List<ParameterDriver> getParametersDrivers() {
         // Integrated Ephemeris propagation model does not have parameter drivers.
         return Collections.emptyList();
     }
 
 }