/* 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.propagation.events.handlers;
  
  import org.hipparchus.CalculusFieldElement;
  import org.hipparchus.Field;
  import org.hipparchus.ode.events.Action;
  import org.orekit.propagation.FieldSpacecraftState;
  import org.orekit.propagation.events.FieldEventDetector;
  import org.orekit.time.AbsoluteDate;
  import org.orekit.time.FieldAbsoluteDate;
  
  /**
   * Event handler wrapping another, arbitrary one whilst remembering date of last detection.
   * If never used, the cache is null.
   * If used but nothing detected, it returns past infinity in case of forward propagation and future infinity otherwise.
   * @author Romain Serra
   * @see RecallLastOccurrence
   * @since 12.1
   * @param <T> field type
   */
  public class FieldRecallLastOccurrence<T extends CalculusFieldElement<T>> implements FieldEventHandler<T> {
  
      /** Wrapped event handler. */
      private final FieldEventHandler<T> wrappedHandler;
  
      /** Last date at which the wrapped event occurred. */
      private FieldAbsoluteDate<T> lastOccurrence;
  
      /** Constructor.
       * @param wrappedHandler event handler to wrap
       */
      public FieldRecallLastOccurrence(final FieldEventHandler<T> wrappedHandler) {
          this.wrappedHandler = wrappedHandler;
      }
  
      /** Getter for last occurrence.
       * @return last date when underlying event was detected
       */
      public FieldAbsoluteDate<T> getLastOccurrence() {
          return lastOccurrence;
      }
  
      /** {@inheritDoc} */
      @Override
      public void init(final FieldSpacecraftState<T> initialState, final FieldAbsoluteDate<T> target,
                       final FieldEventDetector<T> detector) {
          final boolean isForward = target.isAfter(initialState.getDate());
          final Field<T> field = target.getField();
          final AbsoluteDate date = isForward ? AbsoluteDate.PAST_INFINITY : AbsoluteDate.FUTURE_INFINITY;
          lastOccurrence = new FieldAbsoluteDate<>(field, date);
          wrappedHandler.init(initialState, target, detector);
      }
  
      /** {@inheritDoc} */
      @Override
      public Action eventOccurred(final FieldSpacecraftState<T> s, final FieldEventDetector<T> detector,
                                  final boolean increasing) {
          lastOccurrence = s.getDate();
          return wrappedHandler.eventOccurred(s, detector, increasing);
      }
  
      /** {@inheritDoc} */
      @Override
      public FieldSpacecraftState<T> resetState(final FieldEventDetector<T> detector,
                                                final FieldSpacecraftState<T> oldState) {
          return wrappedHandler.resetState(detector, oldState);
      }
  
      /** {@inheritDoc} */
      @Override
      public void finish(final FieldSpacecraftState<T> finalState, final FieldEventDetector<T> detector) {
          wrappedHandler.finish(finalState, detector);
      }
  }