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.util.FastMath;
21  import org.orekit.propagation.SpacecraftState;
22  import org.orekit.propagation.events.EventDetector;
23  
24  /** This interface represents an event checking interval that depends on state.
25  *
26  * @see EventDetector
27  * @author Luc Maisonobe
28  * @since 12.0
29  *
30  */
31  @FunctionalInterface
32  public interface AdaptableInterval {
33  
34      /**
35       * Get the current value of maximal time interval between events handler checks.
36       *
37       * @param state     current state
38       * @param isForward direction of propagation
39       * @return current value of maximal time interval between events handler checks
40       */
41      double currentInterval(SpacecraftState state, boolean isForward);
42  
43      /**
44       * Method creating a constant interval provider.
45       * @param constantInterval value of constant interval
46       * @return adaptable interval ready to be added to an event detector
47       * @since 12.1
48       */
49      static AdaptableInterval of(final double constantInterval) {
50          return (state, isForward) -> constantInterval;
51      }
52  
53      /**
54       * Method creating an interval taking the minimum value of all candidates.
55       * @param defaultMaxCheck default value if no intervals is given as input
56       * @param adaptableIntervals intervals
57       * @return adaptable interval ready to be added to an event detector
58       * @since 13.0
59       */
60      static AdaptableInterval of(final double defaultMaxCheck, final AdaptableInterval... adaptableIntervals) {
61          return (state, isForward) -> {
62              double maxCheck = defaultMaxCheck;
63              for (final AdaptableInterval interval : adaptableIntervals) {
64                  maxCheck = FastMath.min(maxCheck, interval.currentInterval(state, isForward));
65              }
66              return maxCheck;
67          };
68      }
69  }