1   /* Copyright 2002-2026 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  
18  package org.orekit.files.ccsds.ndm.odm.oem;
19  
20  import java.util.ArrayList;
21  import java.util.HashMap;
22  import java.util.List;
23  import java.util.Map;
24  
25  import org.orekit.data.DataContext;
26  import org.orekit.errors.OrekitException;
27  import org.orekit.errors.OrekitMessages;
28  import org.orekit.files.ccsds.definitions.TimeSystem;
29  import org.orekit.files.ccsds.ndm.NdmConstituent;
30  import org.orekit.files.ccsds.ndm.odm.OdmHeader;
31  import org.orekit.files.general.EphemerisFile;
32  import org.orekit.utils.IERSConventions;
33  import org.orekit.utils.TimeStampedPVCoordinates;
34  
35  /** This class stores all the information of the OEM File parsed by OEMParser.
36   * <p>
37   * It contains the header and a list of Ephemerides Blocks each containing
38   * metadata, a list of ephemerides data lines and optional covariance matrices
39   * (and their metadata).
40   * </p>
41   * @author sports
42   * @author Evan Ward
43   * @since 6.1
44   */
45  public class Oem extends NdmConstituent<OdmHeader, OemSegment>
46      implements EphemerisFile<TimeStampedPVCoordinates, OemSegment> {
47  
48      /** Root element for XML files. */
49      public static final String ROOT = "oem";
50  
51      /** Key for format version. */
52      public static final String FORMAT_VERSION_KEY = "CCSDS_OEM_VERS";
53  
54      /** Default name for unknown object. */
55      public static final String UNKNOWN_OBJECT = "UNKNOWN";
56  
57      /** Gravitational coefficient to use for building Cartesian/Keplerian orbits. */
58      private final double mu;
59  
60      /** Simple constructor.
61       * @param header file header
62       * @param segments file segments
63       * @param conventions IERS conventions
64       * @param dataContext used for creating frames, time scales, etc.
65       * @param mu gravitational coefficient
66       */
67      public Oem(final OdmHeader header, final List<OemSegment> segments,
68                 final IERSConventions conventions, final DataContext dataContext,
69                 final double mu) {
70          super(header, segments, conventions, dataContext);
71          this.mu = mu;
72      }
73  
74      /** {@inheritDoc}
75       * <p>
76       * The metadata entries checked for use as the key are the following ones,
77       * the first non-null being used. The map from OEM files always contains only
78       * one object.
79       * <ul>
80       *   <li>{@link org.orekit.files.ccsds.ndm.odm.OdmCommonMetadata#getObjectID()}  OBJECT_ID}
81       *   if non-null and not equal to {@link #UNKNOWN_OBJECT}</li>
82       *   <li>{@link org.orekit.files.ccsds.ndm.odm.OdmMetadata#getObjectName() OBJECT_NAME}</li>
83       *   <li>the default name {@link #UNKNOWN_OBJECT} for unknown objects</li>
84       * </ul>
85       */
86      @Override
87      public Map<String, OemSatelliteEphemeris> getSatellites() {
88          final Map<String, List<OemSegment>> byName = new HashMap<>();
89          for (final OemSegment segment : getSegments()) {
90              final String name;
91              if (segment.getMetadata().getObjectID() != null &&
92                  !UNKNOWN_OBJECT.equals(segment.getMetadata().getObjectID())) {
93                  name = segment.getMetadata().getObjectID();
94              } else if (segment.getMetadata().getObjectName() != null) {
95                  name = segment.getMetadata().getObjectName();
96              } else {
97                  name = UNKNOWN_OBJECT;
98              }
99              byName.putIfAbsent(name, new ArrayList<>());
100             byName.get(name).add(segment);
101         }
102         final Map<String, OemSatelliteEphemeris> ret = new HashMap<>();
103         for (final Map.Entry<String, List<OemSegment>> entry : byName.entrySet()) {
104             ret.put(entry.getKey(), new OemSatelliteEphemeris(entry.getKey(), mu, entry.getValue()));
105         }
106         return ret;
107     }
108 
109     /** Check that, according to the CCSDS standard, every OEMBlock has the same time system.
110      */
111     public void checkTimeSystems() {
112         TimeSystem referenceTimeSystem = null;
113         for (final OemSegment segment : getSegments()) {
114             final TimeSystem timeSystem = segment.getMetadata().getTimeSystem();
115             if (referenceTimeSystem == null) {
116                 referenceTimeSystem = timeSystem;
117             } else if (!referenceTimeSystem.equals(timeSystem)) {
118                 throw new OrekitException(OrekitMessages.CCSDS_INCONSISTENT_TIME_SYSTEMS,
119                                           referenceTimeSystem.name(), timeSystem.name());
120             }
121         }
122     }
123 
124 }