/* Copyright 2002-2021 CS GROUP
    * Licensed to CS GROUP (CS) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * CS 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.ilrs;
  
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.Reader;
  import java.util.Optional;
  import java.util.regex.Pattern;
  import java.util.stream.Stream;
  
  import org.hipparchus.exception.LocalizedCoreFormats;
  import org.hipparchus.geometry.euclidean.threed.Vector3D;
  import org.orekit.annotation.DefaultDataContext;
  import org.orekit.data.DataContext;
  import org.orekit.data.DataSource;
  import org.orekit.errors.OrekitException;
  import org.orekit.errors.OrekitMessages;
  import org.orekit.files.general.EphemerisFileParser;
  import org.orekit.frames.Frame;
  import org.orekit.frames.Frames;
  import org.orekit.time.AbsoluteDate;
  import org.orekit.time.DateComponents;
  import org.orekit.time.TimeScale;
  import org.orekit.utils.CartesianDerivativesFilter;
  import org.orekit.utils.Constants;
  import org.orekit.utils.IERSConventions;
  
  /**
   * A parser for the CPF orbit file format.
   * <p>
   * It supports both 1.0 and 2.0 versions
   * <p>
   * <b>Note:</b> Only required header keys are read. Furthermore, only position data are read.
   * Other keys are simply ignored
   * Contributions are welcome to support more fields in the format.
   * </p>
   * @see <a href="https://ilrs.gsfc.nasa.gov/docs/2006/cpf_1.01.pdf">1.0 file format</a>
   * @see <a href="https://ilrs.gsfc.nasa.gov/docs/2018/cpf_2.00h-1.pdf">2.0 file format</a>
   * @author Bryan Cazabonne
   * @since 10.3
   */
  public class CPFParser implements EphemerisFileParser<CPF> {
  
      /** File format. */
      private static final String FILE_FORMAT = "CPF";
  
      /** Miscroseconds to seconds converter. */
      private static final double MS_TO_S = 1.0e-6;
  
      /** Pattern for delimiting regular expressions. */
      private static final Pattern SEPARATOR = Pattern.compile("\\s+");
  
      /** Default number of sample for interpolating data (See: reference documents. */
      private static final int DEFAULT_INTERPOLATION_SAMPLE = 10;
  
      /** Standard gravitational parameter in m^3 / s^2. */
      private final double mu;
  
      /** Time scale used to define epochs in CPF file. */
      private final TimeScale timeScale;
  
      /** Set of frames. */
      private final Frames frames;
  
      /** Interpolation sample for data interpolating. */
      private final int interpolationSample;
  
      /** IERS convention for frames. */
      private final IERSConventions iersConvention;
  
      /**
       * Default constructor.
       * <p>
       * This constructor uses the {@link DataContext#getDefault() default data context}.
       */
      @DefaultDataContext
      public CPFParser() {
          this(Constants.EIGEN5C_EARTH_MU, DEFAULT_INTERPOLATION_SAMPLE,
               IERSConventions.IERS_2010, DataContext.getDefault().getTimeScales().getUTC(),
               DataContext.getDefault().getFrames());
      }
  
      /**
       * Constructor.
      * @param mu standard gravitational parameter to use for
      *           creating {@link org.orekit.orbits.Orbit Orbits} from
      *           the ephemeris data.
      * @param interpolationSamples number of samples to use when interpolating
      * @param iersConventions IERS convention for frames definition
      * @param utc time scale used to define epochs in CPF files (UTC)
      * @param frames set of frames for satellite coordinates
      */
     public CPFParser(final double mu,
                      final int interpolationSamples,
                      final IERSConventions iersConventions,
                      final TimeScale utc,
                      final Frames frames) {
         this.mu                  = mu;
         this.interpolationSample = interpolationSamples;
         this.iersConvention      = iersConventions;
         this.timeScale           = utc;
         this.frames              = frames;
     }
 
     /** {@inheritDoc} */
     @Override
     public CPF parse(final DataSource source) {
 
         try (Reader reader = source.getOpener().openReaderOnce();
              BufferedReader br = (reader == null) ? null : new BufferedReader(reader)) {
 
             if (br == null) {
                 throw new OrekitException(OrekitMessages.UNABLE_TO_FIND_FILE, source.getName());
             }
 
             // initialize internal data structures
             final ParseInfo pi = new ParseInfo();
 
             int lineNumber = 0;
             Stream<LineParser> parsers = Stream.of(LineParser.H1);
             for (String line = br.readLine(); line != null; line = br.readLine()) {
                 ++lineNumber;
                 final String l = line;
                 final Optional<LineParser> selected = parsers.filter(p -> p.canHandle(l)).findFirst();
                 if (selected.isPresent()) {
                     try {
                         selected.get().parse(line, pi);
                     } catch (StringIndexOutOfBoundsException | NumberFormatException e) {
                         throw new OrekitException(e,
                                                   OrekitMessages.UNABLE_TO_PARSE_LINE_IN_FILE,
                                                   lineNumber, source.getName(), line);
                     }
                     parsers = selected.get().allowedNext();
                 }
                 if (pi.done) {
                     pi.file.setFilter(pi.hasVelocityEntries ?
                                                              CartesianDerivativesFilter.USE_PV :
                                                                  CartesianDerivativesFilter.USE_P);
                     // Return file
                     return pi.file;
                 }
             }
 
             // We never reached the EOF marker
             throw new OrekitException(OrekitMessages.CPF_UNEXPECTED_END_OF_FILE, lineNumber);
 
         } catch (IOException ioe) {
             throw new OrekitException(ioe, LocalizedCoreFormats.SIMPLE_MESSAGE, ioe.getLocalizedMessage());
         }
 
     }
 
     /** Transient data used for parsing a CPF file. The data is kept in a
      * separate data structure to make the parser thread-safe.
      * <p><b>Note</b>: The class intentionally does not provide accessor
      * methods, as it is only used internally for parsing a CPF file.</p>
      */
     private class ParseInfo {
 
         /** The corresponding CPF file. */
         private CPF file;
 
         /** IERS convention. */
         private IERSConventions convention;
 
         /** Set of frames. */
         private Frames frames;
 
         /** Frame for the ephemeris data. */
         private Frame frame;
 
         /** Time scale. */
         private TimeScale timeScale;
 
         /** Indicates if the SP3 file has velocity entries. */
         private boolean hasVelocityEntries;
 
         /** End Of File reached indicator. */
         private boolean done;
 
         /**
          * Constructor.
          */
         protected ParseInfo() {
 
             // Initialise file
             file = new CPF();
 
             // Time scale
             this.timeScale = CPFParser.this.timeScale;
 
             // Initialise fields
             file.setMu(mu);
             file.setInterpolationSample(interpolationSample);
             file.setTimeScale(timeScale);
 
             // Default values
             this.done               = false;
             this.hasVelocityEntries = false;
 
             // Default value for reference frame
             this.convention = CPFParser.this.iersConvention;
             this.frames     = CPFParser.this.frames;
             frame           = frames.getITRF(convention, false);
 
         }
 
     }
 
     /** Parsers for specific lines. */
     private enum LineParser {
 
         /** Header first line. */
         H1("H1") {
 
             /** {@inheritDoc} */
             @Override
             public void parse(final String line, final ParseInfo pi) {
 
                 // Data contained in the line
                 final String[] values = SEPARATOR.split(line);
 
                 // Index for reading data.
                 // Allow taking into consideration difference between 1.0 and 2.0 formats
                 int index = 1;
 
                 // Format
                 final String format = values[index++];
 
                 // Throw an exception if format is not equal to "CPF"
                 if (!FILE_FORMAT.equals(format)) {
                     throw new OrekitException(OrekitMessages.UNEXPECTED_FORMAT_FOR_ILRS_FILE, FILE_FORMAT, format);
                 }
 
                 // Fill first elements
                 pi.file.getHeader().setFormat(format);
                 pi.file.getHeader().setVersion(Integer.parseInt(values[index++]));
                 pi.file.getHeader().setSource(values[index++]);
 
                 // Epoch of ephemeris production
                 final int year  = Integer.parseInt(values[index++]);
                 final int month = Integer.parseInt(values[index++]);
                 final int day   = Integer.parseInt(values[index++]);
                 pi.file.getHeader().setProductionEpoch(new DateComponents(year, month, day));
 
                 // Hour of ephemeris production
                 pi.file.getHeader().setProductionHour(Integer.parseInt(values[index++]));
 
                 // Ephemeris sequence number
                 pi.file.getHeader().setSequenceNumber(Integer.parseInt(values[index++]));
 
                 // Difference between version 1.0 and 2.0: sub-daily ephemeris sequence number
                 if (pi.file.getHeader().getVersion() == 2) {
                     pi.file.getHeader().setSubDailySequenceNumber(Integer.parseInt(values[index++]));
                 }
 
                 // Target Name
                 pi.file.getHeader().setName(values[index]);
 
             }
 
             /** {@inheritDoc} */
             @Override
             public Stream<LineParser> allowedNext() {
                 return Stream.of(H2, ZERO);
             }
 
         },
 
         /** Header second line. */
         H2("H2") {
 
             /** {@inheritDoc} */
             @Override
             public void parse(final String line, final ParseInfo pi) {
 
                 // Data contained in the line
                 final String[] values = SEPARATOR.split(line);
 
                 // Identifiers
                 pi.file.getHeader().setIlrsSatelliteId(values[1]);
                 pi.file.getHeader().setSic(values[2]);
                 pi.file.getHeader().setNoradId(values[3]);
 
                 // Start epoch
                 final int    yearS   = Integer.parseInt(values[4]);
                 final int    monthS  = Integer.parseInt(values[5]);
                 final int    dayS    = Integer.parseInt(values[6]);
                 final int    hourS   = Integer.parseInt(values[7]);
                 final int    minuteS = Integer.parseInt(values[8]);
                 final double secondS = Integer.parseInt(values[9]);
 
                 pi.file.getHeader().setStartEpoch(new AbsoluteDate(yearS, monthS, dayS,
                                                                    hourS, minuteS, secondS,
                                                                    pi.file.getTimeScale()));
 
                 // End epoch
                 final int    yearE   = Integer.parseInt(values[10]);
                 final int    monthE  = Integer.parseInt(values[11]);
                 final int    dayE    = Integer.parseInt(values[12]);
                 final int    hourE   = Integer.parseInt(values[13]);
                 final int    minuteE = Integer.parseInt(values[14]);
                 final double secondE = Integer.parseInt(values[15]);
 
                 pi.file.getHeader().setEndEpoch(new AbsoluteDate(yearE, monthE, dayE,
                                                                  hourE, minuteE, secondE,
                                                                  pi.file.getTimeScale()));
 
                 // Time between table entries
                 pi.file.getHeader().setStep(Integer.parseInt(values[16]));
 
                 // Compatibility with TIVs
                 pi.file.getHeader().setIsCompatibleWithTIVs(Integer.parseInt(values[17]) == 1);
 
                 // Target class
                 pi.file.getHeader().setTargetClass(Integer.parseInt(values[18]));
 
                 // Reference frame
                 final int frameId = Integer.parseInt(values[19]);
                 switch (frameId) {
                     case 0:
                         pi.frame = pi.frames.getITRF(pi.convention, false);
                         break;
                     case 1:
                         pi.frame = pi.frames.getTOD(true);
                         break;
                     case 2:
                         pi.frame = pi.frames.getMOD(pi.convention);
                         break;
                     default:
                         pi.frame = pi.frames.getITRF(pi.convention, false);
                         break;
                 }
                 pi.file.getHeader().setRefFrame(pi.frame);
                 pi.file.getHeader().setRefFrameId(frameId);
 
                 // Last fields
                 pi.file.getHeader().setRotationalAngleType(Integer.parseInt(values[20]));
                 pi.file.getHeader().setIsCenterOfMassCorrectionApplied(Integer.parseInt(values[21]) == 1);
                 if (pi.file.getHeader().getVersion() == 2) {
                     pi.file.getHeader().setTargetLocation(Integer.parseInt(values[22]));
                 }
 
             }
 
             /** {@inheritDoc} */
             @Override
             public Stream<LineParser> allowedNext() {
                 return Stream.of(H3, H4, H5, H9, ZERO);
             }
 
         },
 
         /** Header third line. */
         H3("H3") {
 
             /** {@inheritDoc} */
             @Override
             public void parse(final String line, final ParseInfo pi) {
                 // Not implemented yet
             }
 
             /** {@inheritDoc} */
             @Override
             public Stream<LineParser> allowedNext() {
                 return Stream.of(H4, H5, H9, ZERO);
             }
 
         },
 
         /** Header fourth line. */
         H4("H4") {
 
             /** {@inheritDoc} */
             @Override
             public void parse(final String line, final ParseInfo pi) {
 
                 // Data contained in the line
                 final String[] values = SEPARATOR.split(line);
 
                 // Pulse Repetition Frequency (PRF)
                 pi.file.getHeader().setPrf(Double.parseDouble(values[1]));
 
                 // Transponder information
                 pi.file.getHeader().setTranspTransmitDelay(Double.parseDouble(values[2]) * MS_TO_S);
                 pi.file.getHeader().setTranspUtcOffset(Double.parseDouble(values[3]) * MS_TO_S);
                 pi.file.getHeader().setTranspOscDrift(Double.parseDouble(values[4]));
                 if (pi.file.getHeader().getVersion() == 2) {
                     pi.file.getHeader().setTranspClkRef(Double.parseDouble(values[5]));
                 }
 
             }
 
             /** {@inheritDoc} */
             @Override
             public Stream<LineParser> allowedNext() {
                 return Stream.of(H5, H9, ZERO);
             }
 
         },
 
         /** Header fifth line. */
         H5("H5") {
 
             /** {@inheritDoc} */
             @Override
             public void parse(final String line, final ParseInfo pi) {
 
                 // Approximate center of mass to reflector offset in meters
                 final double offset = Double.parseDouble(SEPARATOR.split(line)[1]);
                 pi.file.getHeader().setCenterOfMassOffset(offset);
 
             }
 
             /** {@inheritDoc} */
             @Override
             public Stream<LineParser> allowedNext() {
                 return Stream.of(H9, ZERO);
             }
 
         },
 
         /** Header last line. */
         H9("H9") {
 
             /** {@inheritDoc} */
             @Override
             public void parse(final String line, final ParseInfo pi) {
                 // End of header. Nothing to do
             }
 
             /** {@inheritDoc} */
             @Override
             public Stream<LineParser> allowedNext() {
                 return Stream.of(TEN, ZERO);
             }
 
         },
 
         /** Position values. */
         TEN("10") {
 
             /** {@inheritDoc} */
             @Override
             public void parse(final String line, final ParseInfo pi) {
 
                 // Data contained in the line
                 final String[] values = SEPARATOR.split(line);
 
                 // Epoch
                 final int mjd           = Integer.parseInt(values[2]);
                 final double secInDay   = Double.parseDouble(values[3]);
                 final AbsoluteDate date = AbsoluteDate.createMJDDate(mjd, secInDay, pi.timeScale);
 
                 // Leap second flag
                 final int leap = Integer.parseInt(values[4]);
 
                 // Coordinates
                 final double x = Double.parseDouble(values[5]);
                 final double y = Double.parseDouble(values[6]);
                 final double z = Double.parseDouble(values[7]);
                 final Vector3D position = new Vector3D(x, y, z);
 
                 // CPF coordinate
                 final CPF.CPFCoordinate coordinate = new CPF.CPFCoordinate(date, position, leap);
                 pi.file.addSatelliteCoordinate(pi.file.getHeader().getIlrsSatelliteId(), coordinate);
 
             }
 
             /** {@inheritDoc} */
             @Override
             public Stream<LineParser> allowedNext() {
                 return Stream.of(TEN, TWENTY, THIRTY, FORTY, FIFTY, SIXTY, SEVENTY, ZERO, EOF);
             }
 
         },
 
         /** Velocity values. */
         TWENTY("20") {
 
             /** {@inheritDoc} */
             @Override
             public void parse(final String line, final ParseInfo pi) {
                 // Not implemented yet
             }
 
             /** {@inheritDoc} */
             @Override
             public Stream<LineParser> allowedNext() {
                 return Stream.of(TEN, TWENTY, THIRTY, FORTY, FIFTY, SIXTY, SEVENTY, ZERO, EOF);
             }
 
         },
 
         /** Corrections. */
         THIRTY("30") {
 
             /** {@inheritDoc} */
             @Override
             public void parse(final String line, final ParseInfo pi) {
                 // Not implemented yet
             }
 
             /** {@inheritDoc} */
             @Override
             public Stream<LineParser> allowedNext() {
                 return Stream.of(TEN, TWENTY, THIRTY, FORTY, FIFTY, SIXTY, SEVENTY, ZERO, EOF);
             }
 
         },
 
         /** Transponder specific. */
         FORTY("40") {
 
             /** {@inheritDoc} */
             @Override
             public void parse(final String line, final ParseInfo pi) {
                 // Not implemented yet
             }
 
             /** {@inheritDoc} */
             @Override
             public Stream<LineParser> allowedNext() {
                 return Stream.of(TEN, TWENTY, THIRTY, FORTY, FIFTY, SIXTY, SEVENTY, ZERO, EOF);
             }
 
         },
 
         /** Offset from center of main body. */
         FIFTY("50") {
 
             /** {@inheritDoc} */
             @Override
             public void parse(final String line, final ParseInfo pi) {
                 // Not implemented yet
             }
 
             /** {@inheritDoc} */
             @Override
             public Stream<LineParser> allowedNext() {
                 return Stream.of(TEN, TWENTY, THIRTY, FORTY, FIFTY, SIXTY, SEVENTY, ZERO, EOF);
             }
 
         },
 
         /** Rotation angle of offset. */
         SIXTY("60") {
 
             /** {@inheritDoc} */
             @Override
             public void parse(final String line, final ParseInfo pi) {
                 // Not implemented yet
             }
 
             /** {@inheritDoc} */
             @Override
             public Stream<LineParser> allowedNext() {
                 return Stream.of(TEN, TWENTY, THIRTY, FORTY, FIFTY, SIXTY, SEVENTY, ZERO, EOF);
             }
 
         },
 
         /** Earth orientation. */
         SEVENTY("70") {
 
             /** {@inheritDoc} */
             @Override
             public void parse(final String line, final ParseInfo pi) {
                 // Not implemented yet
             }
 
             /** {@inheritDoc} */
             @Override
             public Stream<LineParser> allowedNext() {
                 return Stream.of(TEN, TWENTY, THIRTY, FORTY, FIFTY, SIXTY, SEVENTY, ZERO, EOF);
             }
 
         },
 
         /** Comments. */
         ZERO("00") {
 
             /** {@inheritDoc} */
             @Override
             public void parse(final String line, final ParseInfo pi) {
 
                 // Comment
                 final String comment = line.split(getIdentifier())[1].trim();
                 pi.file.getComments().add(comment);
 
             }
 
             /** {@inheritDoc} */
             @Override
             public Stream<LineParser> allowedNext() {
                 return Stream.of(H1, H2, H3, H4, H5, H9,
                                  TEN, TWENTY, THIRTY, FORTY, FIFTY, SIXTY, SEVENTY, ZERO, EOF);
             }
 
         },
 
         /** Last record in ephemeris. */
         EOF("99") {
 
             @Override
             public void parse(final String line, final ParseInfo pi) {
                 pi.done = true;
             }
 
             /** {@inheritDoc} */
             @Override
             public Stream<LineParser> allowedNext() {
                 return Stream.of(EOF);
             }
 
         };
 
         /** Pattern for identifying line. */
         private final Pattern pattern;
 
         /** Identifier. */
         private final String identifier;
 
         /** Simple constructor.
          * @param identifier regular expression for identifying line (i.e. first element)
          */
         LineParser(final String identifier) {
             this.identifier = identifier;
             pattern = Pattern.compile(identifier);
         }
 
         /**
          * Get the regular expression for identifying line.
          * @return the regular expression for identifying line
          */
         public String getIdentifier() {
             return identifier;
         }
 
         /** Parse a line.
          * @param line line to parse
          * @param pi holder for transient data
          */
         public abstract void parse(String line, ParseInfo pi);
 
         /** Get the allowed parsers for next line.
          * @return allowed parsers for next line
          */
         public abstract Stream<LineParser> allowedNext();
 
         /** Check if parser can handle line.
          * @param line line to parse
          * @return true if parser can handle the specified line
          */
         public boolean canHandle(final String line) {
             return pattern.matcher(SEPARATOR.split(line)[0]).matches();
         }
 
     }
 
 }