/* Copyright 2002-2026 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.ccsds.ndm.odm.opm;
  
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Map;
  import java.util.function.Function;
  
  import org.orekit.data.DataContext;
  import org.orekit.files.ccsds.definitions.CcsdsFrameMapper;
  import org.orekit.files.ccsds.ndm.ParsedUnitsBehavior;
  import org.orekit.files.ccsds.ndm.odm.CartesianCovariance;
  import org.orekit.files.ccsds.ndm.odm.CartesianCovarianceKey;
  import org.orekit.files.ccsds.ndm.odm.OdmCommonMetadata;
  import org.orekit.files.ccsds.ndm.odm.CommonMetadataKey;
  import org.orekit.files.ccsds.ndm.odm.KeplerianElements;
  import org.orekit.files.ccsds.ndm.odm.KeplerianElementsKey;
  import org.orekit.files.ccsds.ndm.odm.OdmHeader;
  import org.orekit.files.ccsds.ndm.odm.OdmMetadataKey;
  import org.orekit.files.ccsds.ndm.odm.OdmParser;
  import org.orekit.files.ccsds.ndm.odm.SpacecraftParameters;
  import org.orekit.files.ccsds.ndm.odm.SpacecraftParametersKey;
  import org.orekit.files.ccsds.ndm.odm.StateVector;
  import org.orekit.files.ccsds.ndm.odm.StateVectorKey;
  import org.orekit.files.ccsds.ndm.odm.UserDefined;
  import org.orekit.files.ccsds.section.CommentsContainer;
  import org.orekit.files.ccsds.section.HeaderProcessingState;
  import org.orekit.files.ccsds.section.MetadataKey;
  import org.orekit.files.ccsds.section.Segment;
  import org.orekit.files.ccsds.section.XmlStructureProcessingState;
  import org.orekit.files.ccsds.utils.ContextBinding;
  import org.orekit.files.ccsds.utils.FileFormat;
  import org.orekit.files.ccsds.utils.lexical.ParseToken;
  import org.orekit.files.ccsds.utils.lexical.TokenType;
  import org.orekit.files.ccsds.utils.lexical.UserDefinedXmlTokenBuilder;
  import org.orekit.files.ccsds.utils.lexical.XmlTokenBuilder;
  import org.orekit.files.ccsds.utils.parsing.ErrorState;
  import org.orekit.files.ccsds.utils.parsing.ProcessingState;
  import org.orekit.frames.Frame;
  import org.orekit.time.AbsoluteDate;
  import org.orekit.utils.IERSConventions;
  
  /** A parser for the CCSDS OPM (Orbit Parameter Message).
   * <p>
   * Note than starting with Orekit 11.0, CCSDS message parsers are
   * mutable objects that gather the data being parsed, until the
   * message is complete and the {@link #parseMessage(org.orekit.data.DataSource)
   * parseMessage} method has returned. This implies that parsers
   * should <em>not</em> be used in a multi-thread context. The recommended
   * way to use parsers is to either dedicate one parser for each message
   * and drop it afterwards, or to use a single-thread loop.
   * </p>
   * @author sports
   * @author Luc Maisonobe
   * @since 6.1
   */
  public class OpmParser extends OdmParser<Opm, OpmParser> {
  
      /** Default mass to use if there are no spacecraft parameters block logical block in the file. */
      private final double defaultMass;
  
      /** File header. */
      private OdmHeader header;
  
      /** File segments. */
      private List<Segment<OdmCommonMetadata, OpmData>> segments;
  
      /** OPM metadata being read. */
      private OdmCommonMetadata metadata;
  
      /** Context binding valid for current metadata. */
      private ContextBinding context;
  
      /** State vector logical block being read. */
      private StateVector stateVectorBlock;
  
      /** Keplerian elements logical block being read. */
      private KeplerianElements keplerianElementsBlock;
  
      /** Spacecraft parameters logical block being read. */
      private SpacecraftParameters spacecraftParametersBlock;
  
      /** Covariance matrix logical block being read. */
      private CartesianCovariance covarianceBlock;
 
     /** Current maneuver. */
     private Maneuver currentManeuver;
 
     /** All maneuvers. */
     private List<Maneuver> maneuverBlocks;
 
     /** User defined parameters. */
     private UserDefined userDefinedBlock;
 
     /** Processor for global message structure. */
     private ProcessingState structureProcessor;
 
     /** Complete constructor.
      * <p>
      * Calling this constructor directly is not recommended. Users should rather use
      * {@link org.orekit.files.ccsds.ndm.ParserBuilder#buildOpmParser()
      * parserBuilder.buildOpmParser()}.
      * </p>
      * @param conventions IERS Conventions
      * @param simpleEOP if true, tidal effects are ignored when interpolating EOP
      * @param dataContext used to retrieve frames, time scales, etc.
      * @param missionReferenceDate reference date for Mission Elapsed Time or Mission Relative Time time systems
      * @param mu gravitational coefficient
      * @param defaultMass default mass to use if there are no spacecraft parameters block logical block in the file
      * @param parsedUnitsBehavior behavior to adopt for handling parsed units
      * @param filters filters to apply to parse tokens
      * @param frameMapper for creating an Orekit {@link Frame}.
      * @since 13.1.5
      */
     public OpmParser(final IERSConventions conventions, final boolean simpleEOP,
                      final DataContext dataContext,
                      final AbsoluteDate missionReferenceDate, final double mu,
                      final double defaultMass, final ParsedUnitsBehavior parsedUnitsBehavior,
                      final Function<ParseToken, List<ParseToken>>[] filters,
                      final CcsdsFrameMapper frameMapper) {
         super(Opm.ROOT, Opm.FORMAT_VERSION_KEY, conventions, simpleEOP, dataContext,
                 missionReferenceDate, mu, parsedUnitsBehavior, filters,
                 frameMapper);
         this.defaultMass = defaultMass;
     }
 
     /** {@inheritDoc} */
     @Override
     public Map<String, XmlTokenBuilder> getSpecialXmlElementsBuilders() {
 
         final Map<String, XmlTokenBuilder> builders = super.getSpecialXmlElementsBuilders();
 
         // special handling of user-defined parameters
         builders.put(UserDefined.USER_DEFINED_XML_TAG, new UserDefinedXmlTokenBuilder());
 
         return builders;
 
     }
 
     /** {@inheritDoc} */
     @Override
     public OdmHeader getHeader() {
         return header;
     }
 
     /** {@inheritDoc} */
     @Override
     public void reset(final FileFormat fileFormat) {
         header                    = new OdmHeader();
         segments                  = new ArrayList<>();
         metadata                  = null;
         context                   = null;
         stateVectorBlock          = null;
         keplerianElementsBlock    = null;
         spacecraftParametersBlock = null;
         covarianceBlock           = null;
         currentManeuver           = null;
         maneuverBlocks            = new ArrayList<>();
         userDefinedBlock          = null;
         if (fileFormat == FileFormat.XML) {
             structureProcessor = new XmlStructureProcessingState(Opm.ROOT, this);
             reset(fileFormat, structureProcessor);
         } else {
             structureProcessor = new ErrorState(); // should never be called
             reset(fileFormat, new HeaderProcessingState(this));
         }
     }
 
     /** {@inheritDoc} */
     @Override
     public boolean prepareHeader() {
         anticipateNext(new HeaderProcessingState(this));
         return true;
     }
 
     /** {@inheritDoc} */
     @Override
     public boolean inHeader() {
         anticipateNext(getFileFormat() == FileFormat.XML ? structureProcessor : this::processMetadataToken);
         return true;
     }
 
     /** {@inheritDoc} */
     @Override
     public boolean finalizeHeader() {
         header.validate(header.getFormatVersion());
         return true;
     }
 
     /** {@inheritDoc} */
     @Override
     public boolean prepareMetadata() {
         if (metadata != null) {
             return false;
         }
         metadata  = new OdmCommonMetadata(getFrameMapper());
         context   = new ContextBinding(this::getConventions, this::isSimpleEOP,
                                        this::getDataContext, this::getParsedUnitsBehavior,
                                        this::getMissionReferenceDate,
                                        metadata::getTimeSystem, () -> 0.0, () -> 1.0);
         anticipateNext(this::processMetadataToken);
         return true;
     }
 
     /** {@inheritDoc} */
     @Override
     public boolean inMetadata() {
         anticipateNext(getFileFormat() == FileFormat.XML ? structureProcessor : this::processStateVectorToken);
         return true;
     }
 
     /** {@inheritDoc} */
     @Override
     public boolean finalizeMetadata() {
         metadata.finalizeMetadata(context);
         metadata.validate(header.getFormatVersion());
         if (metadata.getCenter().getBody() != null) {
             setMuCreated(metadata.getCenter().getBody().getGM());
         }
         return true;
     }
 
     /** {@inheritDoc} */
     @Override
     public boolean prepareData() {
         anticipateNext(getFileFormat() == FileFormat.XML ? this::processXmlSubStructureToken : this::processStateVectorToken);
         return true;
     }
 
     /** {@inheritDoc} */
     @Override
     public boolean inData() {
         return true;
     }
 
     /** {@inheritDoc} */
     @Override
     public boolean finalizeData() {
         if (metadata != null) {
             if (userDefinedBlock != null && userDefinedBlock.getParameters().isEmpty()) {
                 userDefinedBlock = null;
             }
             if (keplerianElementsBlock != null) {
                 keplerianElementsBlock.setEpoch(stateVectorBlock.getEpoch());
                 if (Double.isNaN(keplerianElementsBlock.getMu())) {
                     keplerianElementsBlock.setMu(getSelectedMu());
                 } else {
                     setMuParsed(keplerianElementsBlock.getMu());
                 }
             }
             final double  mass = spacecraftParametersBlock == null ?
                                  defaultMass : spacecraftParametersBlock.getMass();
             final OpmData data = new OpmData(stateVectorBlock, keplerianElementsBlock,
                                              spacecraftParametersBlock, covarianceBlock,
                                              maneuverBlocks, userDefinedBlock,
                                              mass);
             data.validate(header.getFormatVersion());
             segments.add(new Segment<>(metadata, data));
         }
         metadata                  = null;
         context                   = null;
         stateVectorBlock          = null;
         keplerianElementsBlock    = null;
         spacecraftParametersBlock = null;
         covarianceBlock           = null;
         currentManeuver           = null;
         maneuverBlocks            = null;
         userDefinedBlock          = null;
         return true;
     }
 
     /** {@inheritDoc} */
     @Override
     public Opm build() {
         // OPM KVN file lack a DATA_STOP keyword, hence we can't call finalizeData()
         // automatically before the end of the file
         finalizeData();
         return new Opm(header, segments, getConventions(), getDataContext(), getSelectedMu());
     }
 
     /** Manage state vector section.
      * @param starting if true, parser is entering the section
      * otherwise it is leaving the section
      * @return always return true
      */
     boolean manageStateVectorSection(final boolean starting) {
         anticipateNext(starting ? this::processStateVectorToken : structureProcessor);
         return true;
     }
 
     /** Manage Keplerian elements section.
      * @param starting if true, parser is entering the section
      * otherwise it is leaving the section
      * @return always return true
      */
     boolean manageKeplerianElementsSection(final boolean starting) {
         anticipateNext(starting ? this::processKeplerianElementsToken : structureProcessor);
         return true;
     }
 
     /** Manage spacecraft parameters section.
      * @param starting if true, parser is entering the section
      * otherwise it is leaving the section
      * @return always return true
      */
     boolean manageSpacecraftParametersSection(final boolean starting) {
         anticipateNext(starting ? this::processSpacecraftParametersToken : structureProcessor);
         return true;
     }
 
     /** Manage covariance matrix section.
      * @param starting if true, parser is entering the section
      * otherwise it is leaving the section
      * @return always return true
      */
     boolean manageCovarianceSection(final boolean starting) {
         anticipateNext(starting ? this::processCovarianceToken : structureProcessor);
         return true;
     }
 
     /** Manage maneuvers section.
      * @param starting if true, parser is entering the section
      * otherwise it is leaving the section
      * @return always return true
      */
     boolean manageManeuversSection(final boolean starting) {
         anticipateNext(starting ? this::processManeuverToken : structureProcessor);
         return true;
     }
 
     /** Manage user-defined parameters section.
      * @param starting if true, parser is entering the section
      * otherwise it is leaving the section
      * @return always return true
      */
     boolean manageUserDefinedParametersSection(final boolean starting) {
         anticipateNext(starting ? this::processUserDefinedToken : structureProcessor);
         return true;
     }
 
     /** Process one metadata token.
      * @param token token to process
      * @return true if token was processed, false otherwise
      */
     private boolean processMetadataToken(final ParseToken token) {
         if (metadata == null) {
             // OPM KVN file lack a META_START keyword, hence we can't call prepareMetadata()
             // automatically before the first metadata token arrives
             prepareMetadata();
         }
         inMetadata();
         try {
             return token.getName() != null &&
                    MetadataKey.valueOf(token.getName()).process(token, context, metadata);
         } catch (IllegalArgumentException iaeM) {
             try {
                 return OdmMetadataKey.valueOf(token.getName()).process(token, context, metadata);
             } catch (IllegalArgumentException iaeD) {
                 try {
                     return CommonMetadataKey.valueOf(token.getName()).process(token, context, metadata);
                 } catch (IllegalArgumentException iaeC) {
                     // token has not been recognized
                     return false;
                 }
             }
         }
     }
 
     /** Process one XML data substructure token.
      * @param token token to process
      * @return true if token was processed, false otherwise
      */
     private boolean processXmlSubStructureToken(final ParseToken token) {
         try {
             return token.getName() != null &&
                    XmlSubStructureKey.valueOf(token.getName()).process(token, this);
         } catch (IllegalArgumentException iae) {
             // token has not been recognized
             return false;
         }
     }
 
     /** Process one state vector data token.
      * @param token token to process
      * @return true if token was processed, false otherwise
      */
     private boolean processStateVectorToken(final ParseToken token) {
         if (stateVectorBlock == null) {
             // OPM KVN file lack a META_STOP keyword, hence we can't call finalizeMetadata()
             // automatically before the first data token arrives
             finalizeMetadata();
             // OPM KVN file lack a DATA_START keyword, hence we can't call prepareData()
             // automatically before the first data token arrives
             prepareData();
             stateVectorBlock = new StateVector();
         }
         anticipateNext(getFileFormat() == FileFormat.XML ? this::processXmlSubStructureToken : this::processKeplerianElementsToken);
         try {
             return token.getName() != null &&
                    StateVectorKey.valueOf(token.getName()).process(token, context, stateVectorBlock);
         } catch (IllegalArgumentException iae) {
             // token has not been recognized
             return false;
         }
     }
 
     /** Process one Keplerian elements data token.
      * @param token token to process
      * @return true if token was processed, false otherwise
      */
     private boolean processKeplerianElementsToken(final ParseToken token) {
         if (keplerianElementsBlock == null) {
             keplerianElementsBlock = new KeplerianElements();
         }
         anticipateNext(getFileFormat() == FileFormat.XML ? this::processXmlSubStructureToken : this::processSpacecraftParametersToken);
         try {
             return token.getName() != null &&
                    KeplerianElementsKey.valueOf(token.getName()).process(token, context, keplerianElementsBlock);
         } catch (IllegalArgumentException iae) {
             // token has not been recognized
             return false;
         }
     }
 
     /** Process one spacecraft parameters data token.
      * @param token token to process
      * @return true if token was processed, false otherwise
      */
     private boolean processSpacecraftParametersToken(final ParseToken token) {
         if (spacecraftParametersBlock == null) {
             spacecraftParametersBlock = new SpacecraftParameters();
             if (moveCommentsIfEmpty(keplerianElementsBlock, spacecraftParametersBlock)) {
                 // get rid of the empty logical block
                 keplerianElementsBlock = null;
             }
         }
         anticipateNext(getFileFormat() == FileFormat.XML ? this::processXmlSubStructureToken : this::processCovarianceToken);
         try {
             return token.getName() != null &&
                    SpacecraftParametersKey.valueOf(token.getName()).process(token, context, spacecraftParametersBlock);
         } catch (IllegalArgumentException iae) {
             // token has not been recognized
             return false;
         }
     }
 
     /** Process one covariance matrix data token.
      * @param token token to process
      * @return true if token was processed, false otherwise
      */
     private boolean processCovarianceToken(final ParseToken token) {
         if (covarianceBlock == null) {
             // save the current metadata for later retrieval of reference frame
             final OdmCommonMetadata savedMetadata = metadata;
             covarianceBlock = new CartesianCovariance(
                     savedMetadata::getReferenceFrame,
                     savedMetadata.getFrameMapper());
             if (moveCommentsIfEmpty(spacecraftParametersBlock, covarianceBlock)) {
                 // get rid of the empty logical block
                 spacecraftParametersBlock = null;
             }
         }
         anticipateNext(getFileFormat() == FileFormat.XML ? this::processXmlSubStructureToken : this::processManeuverToken);
         try {
             return token.getName() != null &&
                    CartesianCovarianceKey.valueOf(token.getName()).process(token, context, covarianceBlock);
         } catch (IllegalArgumentException iae) {
             // token has not been recognized
             return false;
         }
     }
 
     /** Process one maneuver data token.
      * @param token token to process
      * @return true if token was processed, false otherwise
      */
     private boolean processManeuverToken(final ParseToken token) {
         if (currentManeuver == null) {
             currentManeuver = new Maneuver();
             if (covarianceBlock != null && moveCommentsIfEmpty(covarianceBlock, currentManeuver)) {
                 // get rid of the empty logical block
                 covarianceBlock = null;
             }
         }
         anticipateNext(getFileFormat() == FileFormat.XML ? this::processXmlSubStructureToken : this::processUserDefinedToken);
         try {
             if (token.getName() != null &&
                 ManeuverKey.valueOf(token.getName()).process(token, context, currentManeuver)) {
                 // the token was processed properly
                 if (currentManeuver.completed()) {
                     // current maneuver is completed
                     maneuverBlocks.add(currentManeuver);
                     currentManeuver = null;
                 }
                 return true;
             }
         } catch (IllegalArgumentException iae) {
             // ignored, delegate to next state below
         }
         // the token was not processed
         return false;
     }
 
     /** Process one maneuver data token.
      * @param token token to process
      * @return true if token was processed, false otherwise
      */
     private boolean processUserDefinedToken(final ParseToken token) {
         if (userDefinedBlock == null) {
             userDefinedBlock = new UserDefined();
             if (moveCommentsIfEmpty(currentManeuver, userDefinedBlock)) {
                 // get rid of the empty logical block
                 currentManeuver = null;
             }
         }
         anticipateNext(getFileFormat() == FileFormat.XML ? this::processXmlSubStructureToken : new ErrorState());
         if (token.getName().startsWith(UserDefined.USER_DEFINED_PREFIX)) {
             if (token.getType() == TokenType.ENTRY) {
                 userDefinedBlock.addEntry(token.getName().substring(UserDefined.USER_DEFINED_PREFIX.length()),
                                           token.getContentAsNormalizedString());
             }
             return true;
         } else {
             // the token was not processed
             return false;
         }
     }
 
     /** Move comments from one empty logical block to another logical block.
      * @param origin origin block
      * @param destination destination block
      * @return true if origin block was empty
      */
     private boolean moveCommentsIfEmpty(final CommentsContainer origin, final CommentsContainer destination) {
         if (origin != null && origin.acceptComments()) {
             // origin block is empty, move the existing comments
             for (final String comment : origin.getComments()) {
                 destination.addComment(comment);
             }
             return true;
         } else {
             return false;
         }
     }
 
 }