/* Copyright 2002-2022 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.ocm;
  
  import java.io.IOException;
  import java.util.List;
  
  import org.hipparchus.linear.RealMatrix;
  import org.hipparchus.util.FastMath;
  import org.orekit.files.ccsds.definitions.TimeConverter;
  import org.orekit.files.ccsds.section.AbstractWriter;
  import org.orekit.files.ccsds.utils.FileFormat;
  import org.orekit.files.ccsds.utils.generation.Generator;
  import org.orekit.utils.AccurateFormatter;
  import org.orekit.utils.units.Unit;
  
  /** Writer for covariance history data.
   * @author Luc Maisonobe
   * @since 11.0
   */
  class CovarianceHistoryWriter extends AbstractWriter {
  
      /** Covariance history block. */
      private final CovarianceHistory history;
  
      /** Converter for dates. */
      private final TimeConverter timeConverter;
  
      /** Create a writer.
       * @param covarianceHistory covariance history to write
       * @param timeConverter converter for dates
       */
      CovarianceHistoryWriter(final CovarianceHistory covarianceHistory,
                              final TimeConverter timeConverter) {
          super(OcmDataSubStructureKey.covar.name(), OcmDataSubStructureKey.COV.name());
          this.history       = covarianceHistory;
          this.timeConverter = timeConverter;
      }
  
      /** {@inheritDoc} */
      @Override
      protected void writeContent(final Generator generator) throws IOException {
  
          // covariance history block
          final CovarianceHistoryMetadata metadata = history.getMetadata();
          generator.writeComments(metadata.getComments());
  
          // identifiers
          generator.writeEntry(CovarianceHistoryMetadataKey.COV_ID.name(),       metadata.getCovID(),      null, false);
          generator.writeEntry(CovarianceHistoryMetadataKey.COV_PREV_ID.name(),  metadata.getCovPrevID(),  null, false);
          generator.writeEntry(CovarianceHistoryMetadataKey.COV_NEXT_ID.name(),  metadata.getCovNextID(),  null, false);
          generator.writeEntry(CovarianceHistoryMetadataKey.COV_BASIS.name(),    metadata.getCovBasis(),   null, false);
          generator.writeEntry(CovarianceHistoryMetadataKey.COV_BASIS_ID.name(), metadata.getCovBasisID(), null, false);
  
          // references
          generator.writeEntry(CovarianceHistoryMetadataKey.COV_REF_FRAME.name(),   metadata.getCovReferenceFrame().getName(),  null, false);
          generator.writeEntry(CovarianceHistoryMetadataKey.COV_FRAME_EPOCH.name(), timeConverter, metadata.getCovFrameEpoch(),       false);
  
          // scaling
          generator.writeEntry(CovarianceHistoryMetadataKey.COV_SCALE_MIN.name(),  metadata.getCovScaleMin(), Unit.ONE,       false);
          generator.writeEntry(CovarianceHistoryMetadataKey.COV_SCALE_MAX.name(),  metadata.getCovScaleMax(), Unit.ONE,       false);
          generator.writeEntry(CovarianceHistoryMetadataKey.COV_CONFIDENCE.name(), metadata.getCovConfidence(), Unit.PERCENT, false);
  
          // elements
          generator.writeEntry(CovarianceHistoryMetadataKey.COV_TYPE.name(),     metadata.getCovType(),                                     false);
          generator.writeEntry(CovarianceHistoryMetadataKey.COV_ORDERING.name(), metadata.getCovOrdering(),                                 false);
          generator.writeEntry(CovarianceHistoryMetadataKey.COV_UNITS.name(),    generator.unitsListToString(metadata.getCovUnits()), null, false);
  
          // data
          final List<Unit> units = metadata.getCovType().getUnits();
          for (final Covariance covariance : history.getCovariances()) {
              final RealMatrix        matrix   = covariance.getMatrix();
              final Ordering          ordering = metadata.getCovOrdering();
              final CovarianceIndexer indexer  = new CovarianceIndexer(units.size());
              final StringBuilder     line     = new StringBuilder();
              line.append(generator.dateToString(timeConverter, covariance.getDate()));
              for (int k = 0; k < ordering.nbElements(units.size()); ++k) {
                  final int i = indexer.getRow();
                  final int j = indexer.getColumn();
                  final double cij;
                  if (indexer.isCrossCorrelation()) {
                      // we need to compute the cross-correlation
                      cij = matrix.getEntry(i, j) /
                                      FastMath.sqrt(matrix.getEntry(i, i) * matrix.getEntry(j, j));
                 } else {
                     // we need to get the covariance
                     cij = units.get(i).fromSI(units.get(j).fromSI(matrix.getEntry(i, j)));
                 }
                 line.append(' ');
                 line.append(AccurateFormatter.format(cij));
                 ordering.update(indexer);
             }
             if (generator.getFormat() == FileFormat.XML) {
                 generator.writeEntry(Ocm.COV_LINE, line.toString(), null, true);
             } else {
                 generator.writeRawData(line);
                 generator.newLine();
             }
 
         }
 
     }
 
 }