1   /* Copyright 2002-2025 CS GROUP
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.files.ccsds.definitions;
18  
19  import org.orekit.time.AbsoluteDate;
20  import org.orekit.time.DateTimeComponents;
21  import org.orekit.time.SatelliteClockScale;
22  import org.orekit.time.TimeScale;
23  
24  /** Dates reader/writer.
25   *
26   * @author Luc Maisonobe
27   * @since 11.0
28   */
29  public class TimeConverter {
30  
31      /** Base time scale. */
32      private final TimeScale timeScale;
33  
34      /** Reference date for relative dates (may be null if no relative dates are used). */
35      private final AbsoluteDate referenceDate;
36  
37      /** Build a time system.
38       * @param timeScale base time scale
39       * @param referenceDate reference date for relative dates (may be null if no relative dates are used)
40       */
41      public TimeConverter(final TimeScale timeScale, final AbsoluteDate referenceDate) {
42          this.timeScale     = timeScale;
43          this.referenceDate = referenceDate;
44      }
45  
46      /** Parse a relative or absolute date.
47       * @param s string to parse
48       * @return parsed date
49       */
50      public AbsoluteDate parse(final String s) {
51  
52          if (referenceDate != null && s.indexOf('T') < 0) {
53  
54              // relative date
55              final double delta = Double.parseDouble(s);
56              if (timeScale instanceof SatelliteClockScale) {
57                  // satellite clock scale handles drifts internally
58                  return ((SatelliteClockScale) timeScale).dateAtCount(delta);
59              } else {
60                  // regular relative date from a known reference
61                  return referenceDate.shiftedBy(delta);
62              }
63  
64          } else {
65  
66              // absolute date
67              return new AbsoluteDate(s, timeScale);
68  
69          }
70  
71      }
72  
73      /** Generate calendar components.
74       * @param date date to convert
75       * @return date components
76       */
77      public DateTimeComponents components(final AbsoluteDate date) {
78          return date.getComponents(timeScale);
79      }
80  
81      /** Generate relative offset.
82       * @param date date to convert
83       * @return relative offset
84       */
85      public double offset(final AbsoluteDate date) {
86          return date.durationFrom(referenceDate);
87      }
88  
89      /** Get the base time scale.
90       * @return base time scale
91       */
92      public TimeScale getTimeScale() {
93          return timeScale;
94      }
95  
96      /** Get the reference date for relative dates (may be null if no relative dates are used).
97       * @return reference date for relative dates (may be null if no relative dates are used)
98       * @since 12.0
99       */
100     public AbsoluteDate getReferenceDate() {
101         return referenceDate;
102     }
103 
104 }