/* Copyright 2016 Applied Defense Solutions (ADS)
* Licensed to CS Systèmes d'Information (CS) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* ADS licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.orekit.files.ccsds;
import java.io.IOException;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import org.orekit.errors.OrekitException;
import org.orekit.errors.OrekitIllegalArgumentException;
import org.orekit.errors.OrekitMessages;
import org.orekit.files.ccsds.StreamingOemWriter.Segment;
import org.orekit.files.general.EphemerisFile;
import org.orekit.files.general.EphemerisFile.EphemerisSegment;
import org.orekit.files.general.EphemerisFileWriter;
import org.orekit.time.TimeScale;
import org.orekit.utils.TimeStampedPVCoordinates;
/**
* An OEM Writer class that can take in a general {@link EphemerisFile} object
* and export it as a valid OEM file.
*
* @author Hank Grabowski
* @author Evan Ward
* @since 9.0
* @see <a href="https://public.ccsds.org/Pubs/502x0b2c1.pdf">CCSDS 502.0-B-2 Orbit Data
* Messages</a>
* @see <a href="https://public.ccsds.org/Pubs/500x0g3.pdf">CCSDS 500.0-G-3 Navigation
* Data Definitions and Conventions</a>
* @see StreamingOemWriter
*/
public class OEMWriter implements EphemerisFileWriter {
/** Version number implemented. **/
public static final String CCSDS_OEM_VERS = "2.0";
/** Default interpolation method if the user specifies none. **/
public static final InterpolationMethod DEFAULT_INTERPOLATION_METHOD = InterpolationMethod.LAGRANGE;
/** Default originator field value if user specifies none. **/
public static final String DEFAULT_ORIGINATOR = "OREKIT";
/**
* The space object ID we want to export, or null if we will process
* whichever space object is in an {@link EphemerisFile} with only one space
* object in it.
*/
private final InterpolationMethod interpolationMethod;
/** Originator name, usually the organization and/or country. **/
private final String originator;
/**
* Space object ID, usually an official international designator such as
* "1998-067A".
**/
private final String spaceObjectId;
/** Space object name, usually a common name for an object like "ISS". **/
private final String spaceObjectName;
/**
* Standard default constructor that creates a writer with default
* configurations.
*/
public OEMWriter() {
this(DEFAULT_INTERPOLATION_METHOD, DEFAULT_ORIGINATOR, null, null);
}
/**
* Constructor used to create a new OEM writer configured with the necessary
* parameters to successfully fill in all required fields that aren't part
* of a standard @{link EphemerisFile} object.
*
* @param interpolationMethod
* The interpolation method to specify in the OEM file
* @param originator
* The originator field string
* @param spaceObjectId
* The spacecraft ID
* @param spaceObjectName
* The space object common name
*/
public OEMWriter(final InterpolationMethod interpolationMethod, final String originator, final String spaceObjectId,
final String spaceObjectName) {
this.interpolationMethod = interpolationMethod;
this.originator = originator;
this.spaceObjectId = spaceObjectId;
this.spaceObjectName = spaceObjectName;
}
/** {@inheritDoc} */
@Override
public void write(final Appendable writer, final EphemerisFile ephemerisFile)
throws OrekitException, IOException {
if (writer == null) {
throw new OrekitIllegalArgumentException(OrekitMessages.NULL_ARGUMENT, "writer");
}
if (ephemerisFile == null) {
return;
}
final String idToProcess;
if (spaceObjectId != null) {
if (ephemerisFile.getSatellites().containsKey(spaceObjectId)) {
idToProcess = spaceObjectId;
} else {
throw new OrekitIllegalArgumentException(OrekitMessages.VALUE_NOT_FOUND, spaceObjectId, "ephemerisFile");
}
} else if (ephemerisFile.getSatellites().keySet().size() == 1) {
idToProcess = ephemerisFile.getSatellites().keySet().iterator().next();
} else {
throw new OrekitIllegalArgumentException(OrekitMessages.EPHEMERIS_FILE_NO_MULTI_SUPPORT);
}
// Get satellite and ephemeris segments to output.
final EphemerisFile.SatelliteEphemeris satEphem = ephemerisFile.getSatellites().get(idToProcess);
final List<? extends EphemerisSegment> segments = satEphem.getSegments();
if (segments.isEmpty()) {
// no data -> no output
return;
}
final EphemerisSegment firstSegment = segments.get(0);
final String objectName = this.spaceObjectName == null ?
idToProcess : this.spaceObjectName;
// Only one time scale per OEM file, see Section 5.2.4.5
final TimeScale timeScale = firstSegment.getTimeScale();
// metadata that is constant for the whole OEM file
final Map<Keyword, String> metadata = new LinkedHashMap<>();
metadata.put(Keyword.TIME_SYSTEM, firstSegment.getTimeScaleString());
metadata.put(Keyword.ORIGINATOR, this.originator);
// Only one object in an OEM file, see Section 2.1
metadata.put(Keyword.OBJECT_ID, idToProcess);
metadata.put(Keyword.OBJECT_NAME, objectName);
metadata.put(Keyword.INTERPOLATION, this.interpolationMethod.toString());
final StreamingOemWriter oemWriter =
new StreamingOemWriter(writer, timeScale, metadata);
oemWriter.writeHeader();
for (final EphemerisSegment segment : segments) {
// segment specific metadata
metadata.clear();
metadata.put(Keyword.CENTER_NAME, segment.getFrameCenterString());
metadata.put(Keyword.REF_FRAME, segment.getFrameString());
metadata.put(Keyword.START_TIME, segment.getStart().toString(timeScale));
metadata.put(Keyword.STOP_TIME, segment.getStop().toString(timeScale));
metadata.put(Keyword.INTERPOLATION_DEGREE,
String.valueOf(segment.getInterpolationSamples() - 1));
final Segment segmentWriter = oemWriter.newSegment(null, metadata);
segmentWriter.writeMetadata();
for (final TimeStampedPVCoordinates coordinates : segment.getCoordinates()) {
segmentWriter.writeEphemerisLine(coordinates);
}
}
}
/** OEM interpolation method. See Table 5-3. */
public enum InterpolationMethod {
/** Hermite interpolation. */
HERMITE,
/** Lagrange interpolation. */
LAGRANGE,
/** Linear interpolation. */
LINEAR
}
}