/* Copyright 2022-2025 Romain Serra
    * 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.control.indirect.adjoint.cost;
  
  import org.hipparchus.CalculusFieldElement;
  import org.hipparchus.Field;
  import org.orekit.propagation.events.EventDetectionSettings;
  import org.orekit.propagation.events.FieldEventDetectionSettings;
  import org.orekit.propagation.events.FieldEventDetector;
  
  import java.util.stream.Stream;
  
  /**
   * Class for unbounded energy cost with Cartesian coordinates.
   * Here, the control vector is chosen as the thrust force, expressed in the propagation frame.
   * This leads to the optimal thrust being in the same direction as the adjoint velocity.
   *
   * @param <T> field type
   * @author Romain Serra
   * @see FieldUnboundedCartesianEnergyNeglectingMass
   * @see UnboundedCartesianEnergy
   * @since 13.0
   */
  public class FieldUnboundedCartesianEnergy<T extends CalculusFieldElement<T>> extends FieldCartesianEnergyConsideringMass<T> {
  
      /**
       * Constructor.
       * @param name name
       * @param massFlowRateFactor mass flow rate factor
       * @param eventDetectionSettings detection settings for singularity detections
       */
      public FieldUnboundedCartesianEnergy(final String name, final T massFlowRateFactor,
                                           final FieldEventDetectionSettings<T> eventDetectionSettings) {
          super(name, massFlowRateFactor, eventDetectionSettings);
      }
  
      /**
       * Constructor.
       * @param name name
       * @param massFlowRateFactor mass flow rate factor
       */
      public FieldUnboundedCartesianEnergy(final String name, final T massFlowRateFactor) {
          this(name, massFlowRateFactor, new FieldEventDetectionSettings<>(massFlowRateFactor.getField(),
                  EventDetectionSettings.getDefaultEventDetectionSettings()));
      }
  
      /** {@inheritDoc} */
      @Override
      protected T getFieldThrustForceNorm(final T[] adjointVariables, final T mass) {
          final T adjointVelocityNorm = getFieldAdjointVelocityNorm(adjointVariables);
          T factor = adjointVelocityNorm.divide(mass);
          if (getAdjointDimension() > 6) {
              factor = factor.subtract(adjointVariables[6].multiply(getMassFlowRateFactor()));
          }
          if (factor.getReal() < 0.) {
              return adjointVelocityNorm.getField().getZero();
          } else {
              return factor;
          }
      }
  
      /** {@inheritDoc} */
      @Override
      public Stream<FieldEventDetector<T>> getFieldEventDetectors(final Field<T> field) {
          return Stream.of(new FieldSingularityDetector(getEventDetectionSettings(), field.getZero()));
      }
  
      /** {@inheritDoc} */
      @Override
      public UnboundedCartesianEnergy toCartesianCost() {
          return new UnboundedCartesianEnergy(getAdjointName(), getMassFlowRateFactor().getReal(),
                  getEventDetectionSettings().toEventDetectionSettings());
      }
  }