GribMetadataReader.java

package com.meteogroup.grib2geotiff.grib;

import java.awt.geom.Rectangle2D;

import org.joda.time.DateTime;
import org.joda.time.DateTimeZone;

import ucar.grib.grib2.Grib2GDSVariables;
import ucar.grib.grib2.Grib2GridDefinitionSection;
import ucar.grib.grib2.Grib2IdentificationSection;
import ucar.grib.grib2.Grib2IndicatorSection;
import ucar.grib.grib2.Grib2Pds;
import ucar.grib.grib2.Grib2ProductDefinitionSection;
import ucar.grib.grib2.Grib2Record;
import ucar.grib.grib2.Grib2Tables;
import ucar.grib.grib2.ParameterTable;

import com.meteogroup.grib2geotiff.RecordMetadata;

/**
 * Created by danielt on 25.09.15.
 */
public class GribMetadataReader {

  private static Grib2IndicatorSection is;
  private static Grib2IdentificationSection id;
  private static Grib2GDSVariables gdsv;
  private static Grib2Pds pdsv;
  private static Grib2ProductDefinitionSection pds;
  private static Grib2GridDefinitionSection gds;

  /**
   * @param record
   * @return
   */
  public static RecordMetadata getGfsRecordMetadata(Grib2Record record) {
    inferMetadataObjects(record);

    RecordMetadata metadata = new RecordMetadata();
    applyCommonMetadata(metadata);
    applyTimeMetadata(metadata);
    applyLevelMetadata(metadata);
    applyBboxMetadata(metadata);

    return metadata;
  }

  /**
   * @param record
   */
  private static void inferMetadataObjects(Grib2Record record) {
    is = record.getIs();
    id = record.getId();
    gds = record.getGDS();
    pds = record.getPDS();
    pdsv = pds.getPdsVars();
    gdsv = gds.getGdsVars();
  }

  /**
   * @param metadata
   */
  private static void applyBboxMetadata(RecordMetadata metadata) {
    metadata.setBbox(new Rectangle2D.Double(gdsv.getLo1(), gdsv.getLa1(), gdsv.getLo2(), gdsv.getLa2()));
  }

  /**
   * @param metadata
   */
  private static void applyLevelMetadata(RecordMetadata metadata) {
    String level1Type = pdsv.getLevelType1() + " " + Grib2Tables.codeTable4_5(pdsv.getLevelType1());
    if (pdsv.getLevelType1() != 255) {
      metadata.setLevelType1(Grib2Tables.codeTable4_5(pdsv.getLevelType1()));
      metadata.setLevelValue1(pdsv.getLevelValue1());
    }
    if (pdsv.getLevelType2() != 255) {
      metadata.setLevelType2(Grib2Tables.codeTable4_5(pdsv.getLevelType2()));
      metadata.setLevelValue2(pdsv.getLevelValue2());
    }
  }

  /**
   * @param metadata
   */
  private static void applyTimeMetadata(RecordMetadata metadata) {
    DateTime referenceTimeUtc = new DateTime(pdsv.getReferenceTime(), DateTimeZone.UTC);
    metadata.setReferenceTime(referenceTimeUtc.getMillis());
    DateTime forecastTimeUtc = new DateTime(referenceTimeUtc.plusHours(pdsv.getForecastTime()));
    metadata.setForecastTime(forecastTimeUtc.getMillis());
  }

  /**
   * @param metadata
   */
  private static void applyCommonMetadata(RecordMetadata metadata) {
    metadata.setId(pdsv.getParameterNumber());
    metadata.setCategory(ParameterTable.getCategoryName(is.getDiscipline(), pdsv.getParameterCategory()));
    metadata.setName(ParameterTable.getParameterName(is.getDiscipline(), pdsv.getParameterCategory(), pdsv.getParameterNumber()));
    metadata.setUnit(ParameterTable.getParameterUnit(is.getDiscipline(), pdsv.getParameterCategory(), pdsv.getParameterNumber()));
    metadata.setColumns(gdsv.getNx());
    metadata.setRows(gdsv.getNy());
  }

}