1   /* Copyright 2022-2025 Luc Maisonobe
2    * Licensed to CS GROUP (CS) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * CS licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *   http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  
18  package org.orekit.propagation.events.intervals;
19  
20  import org.hipparchus.CalculusFieldElement;
21  import org.hipparchus.Field;
22  import org.hipparchus.util.FastMath;
23  import org.orekit.propagation.FieldSpacecraftState;
24  import org.orekit.propagation.SpacecraftState;
25  import org.orekit.propagation.events.EventDetector;
26  
27  /** This interface represents an event checking interval that depends on state.
28  *
29  * @see EventDetector
30  * @author Luc Maisonobe
31  * @since 12.0
32  *
33  */
34  @FunctionalInterface
35  public interface AdaptableInterval {
36  
37      /**
38       * Get the current value of maximal time interval between events handler checks.
39       *
40       * @param state     current state
41       * @param isForward direction of propagation
42       * @return current value of maximal time interval between events handler checks
43       */
44      double currentInterval(SpacecraftState state, boolean isForward);
45  
46      /**
47       * Method creating an interval taking the minimum value of all candidates.
48       * @param defaultMaxCheck default value if no intervals is given as input
49       * @param adaptableIntervals intervals
50       * @return adaptable interval ready to be added to an event detector
51       * @since 13.0
52       */
53      static AdaptableInterval of(final double defaultMaxCheck, final AdaptableInterval... adaptableIntervals) {
54          return (state, isForward) -> {
55              double maxCheck = defaultMaxCheck;
56              for (final AdaptableInterval interval : adaptableIntervals) {
57                  maxCheck = FastMath.min(maxCheck, interval.currentInterval(state, isForward));
58              }
59              return maxCheck;
60          };
61      }
62  
63      /**
64       * Method creating an interval taking the minimum value of all candidates.
65       * @param field field
66       * @param fieldAdaptableInterval field interval
67       * @param <T> field type
68       * @return adaptable interval ready to be added to an event detector
69       * @since 14.0
70       */
71      static <T extends CalculusFieldElement<T>> AdaptableInterval of(final Field<T> field,
72                                                                      final FieldAdaptableInterval<T> fieldAdaptableInterval) {
73          return (state, isForward) -> fieldAdaptableInterval.currentInterval(new FieldSpacecraftState<>(field, state), isForward);
74      }
75  }