1   /* Copyright 2002-2024 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  package org.orekit.time;
18  
19  import org.hipparchus.CalculusFieldElement;
20  
21  /** Base class for time scales with constant offset with respect to to TAI.
22   * @author Luc Maisonobe
23   * @since 12.1
24   */
25  public class ConstantOffsetTimeScale implements TimeScale {
26  
27      /** Serializable UID. */
28      private static final long serialVersionUID = 20240720L;
29  
30      /** Name of the time scale. */
31      private final String name;
32  
33      /** Offset from TAI. */
34      private final TimeOffset offset;
35  
36      /** Negated offset from TAI.
37       * @since 13.0
38       */
39      private final TimeOffset negatedOffset;
40  
41      /** Simple constructor.
42       * @param name name of the time scale
43       * @param offset offset from TAI
44       */
45      public ConstantOffsetTimeScale(final String name, final TimeOffset offset) {
46          this.name          = name;
47          this.offset        = offset;
48          this.negatedOffset = offset.negate();
49      }
50  
51      /** {@inheritDoc} */
52      @Override
53      public TimeOffset offsetFromTAI(final AbsoluteDate date) {
54          return offset;
55      }
56  
57      /** {@inheritDoc} */
58      @Override
59      public <T extends CalculusFieldElement<T>> T offsetFromTAI(final FieldAbsoluteDate<T> date) {
60          return date.getField().getZero().newInstance(offset.toDouble());
61      }
62  
63      /** {@inheritDoc} */
64      @Override
65      public TimeOffset offsetToTAI(final DateComponents date, final TimeComponents time) {
66          return negatedOffset;
67      }
68  
69      /** {@inheritDoc} */
70      public String getName() {
71          return name;
72      }
73  
74      /** {@inheritDoc} */
75      public String toString() {
76          return getName();
77      }
78  
79  }