/**
   * Extract a list of data variables (and their canonical names if possible) from the dataset.
   *
   * @param threddsDataset open this dataset
   * @return ThreddsMetadata.Variables, or null if unable.
   * @throws IOException on read error
   */
  public static ThreddsMetadata.Variables extractVariables(InvDatasetImpl threddsDataset)
      throws IOException {
    ThreddsDataFactory.Result result = null;

    try {
      result = new ThreddsDataFactory().openFeatureDataset(threddsDataset, null);
      if (result.fatalError) {
        System.out.println(" openDatatype errs=" + result.errLog);
        return null;
      }

      if (result.featureType == FeatureType.GRID) {
        // System.out.println(" extractVariables GRID=" + result.location);
        GridDataset gridDataset = (GridDataset) result.featureDataset;
        return extractVariables(threddsDataset, gridDataset);

      } else if ((result.featureType == FeatureType.STATION)
          || (result.featureType == FeatureType.POINT)) {
        PointObsDataset pobsDataset = (PointObsDataset) result.featureDataset;
        ThreddsMetadata.Variables vars = new ThreddsMetadata.Variables("CF-1.0");
        for (VariableSimpleIF vs : pobsDataset.getDataVariables()) {
          ThreddsMetadata.Variable v = new ThreddsMetadata.Variable();
          vars.addVariable(v);

          v.setName(vs.getName());
          v.setDescription(vs.getDescription());
          v.setUnits(vs.getUnitsString());

          ucar.nc2.Attribute att = vs.findAttributeIgnoreCase("standard_name");
          v.setVocabularyName((att != null) ? att.getStringValue() : "N/A");
        }
        vars.sort();
        return vars;
      }

    } finally {
      try {
        if ((result != null) && (result.featureDataset != null)) result.featureDataset.close();
      } catch (IOException ioe) {
        logger.error("Closing dataset " + result.featureDataset, ioe);
      }
    }

    return null;
  }
  /**
   * Extract the lat/lon/alt bounding boxes from the dataset.
   *
   * @param threddsDataset open this dataset
   * @return ThreddsMetadata.GeospatialCoverage, or null if unable.
   * @throws IOException on read error
   */
  public static ThreddsMetadata.GeospatialCoverage extractGeospatial(InvDatasetImpl threddsDataset)
      throws IOException {
    ThreddsDataFactory.Result result = null;

    try {
      result = new ThreddsDataFactory().openFeatureDataset(threddsDataset, null);
      if (result.fatalError) {
        System.out.println(" openDatatype errs=" + result.errLog);
        return null;
      }

      if (result.featureType == FeatureType.GRID) {
        System.out.println(" GRID=" + result.location);
        GridDataset gridDataset = (GridDataset) result.featureDataset;
        return extractGeospatial(gridDataset);

      } else if (result.featureType == FeatureType.POINT) {
        PointObsDataset pobsDataset = (PointObsDataset) result.featureDataset;
        LatLonRect llbb = pobsDataset.getBoundingBox();
        if (null != llbb) {
          ThreddsMetadata.GeospatialCoverage gc = new ThreddsMetadata.GeospatialCoverage();
          gc.setBoundingBox(llbb);
          return gc;
        }
      } else if (result.featureType == FeatureType.STATION) {
        StationObsDataset sobsDataset = (StationObsDataset) result.featureDataset;
        LatLonRect llbb = sobsDataset.getBoundingBox();
        if (null != llbb) {
          ThreddsMetadata.GeospatialCoverage gc = new ThreddsMetadata.GeospatialCoverage();
          gc.setBoundingBox(llbb);
          return gc;
        }
      }

    } finally {
      try {
        if ((result != null) && (result.featureDataset != null)) result.featureDataset.close();
      } catch (IOException ioe) {
        logger.error("Closing dataset " + result.featureDataset, ioe);
      }
    }

    return null;
  }
  /**
   * Open a ucar.nc2.dt.PointObsDataset, write out in CF point format.
   *
   * @param fileIn open through TypedDatasetFactory.open(FeatureType.POINT, ..)
   * @param fileOut write to this netcdf-3 file
   * @param inMemory if true, read file into memory for efficiency
   * @return true on success
   * @throws IOException on read/write error
   */
  public static boolean rewritePointObsDataset(String fileIn, String fileOut, boolean inMemory)
      throws IOException {
    System.out.println(
        "Rewrite2 .nc files from " + fileIn + " to " + fileOut + " inMemory= " + inMemory);

    long start = System.currentTimeMillis();

    // do it in memory for speed
    NetcdfFile ncfile = inMemory ? NetcdfFile.openInMemory(fileIn) : NetcdfFile.open(fileIn);
    NetcdfDataset ncd = new NetcdfDataset(ncfile);

    StringBuilder errlog = new StringBuilder();
    PointObsDataset pobsDataset =
        (PointObsDataset) TypedDatasetFactory.open(FeatureType.POINT, ncd, null, errlog);
    if (pobsDataset == null) return false;

    writePointObsDataset(pobsDataset, fileOut);
    pobsDataset.close();

    long took = System.currentTimeMillis() - start;
    System.out.println(" that took " + (took - start) + " msecs");
    return true;
  }
  /**
   * write data from a ucar.nc2.dt.PointObsDataset into CF point format.
   *
   * @param pobsDataset rewrite data from here
   * @param fileOut write to tehis netcdf-3 file
   * @throws IOException on read/write error
   */
  public static void writePointObsDataset(PointObsDataset pobsDataset, String fileOut)
      throws IOException {

    // see if we have an altitude
    String altUnits = null;
    DataIterator iterOne = pobsDataset.getDataIterator(-1);
    while (iterOne.hasNext()) {
      PointObsDatatype pobsData = (PointObsDatatype) iterOne.nextData();
      ucar.unidata.geoloc.EarthLocation loc = pobsData.getLocation();
      altUnits = Double.isNaN(loc.getAltitude()) ? null : "meters";
      break;
    }

    List<VariableSimpleIF> vars = pobsDataset.getDataVariables();
    List<PointObVar> nvars = new ArrayList<PointObVar>(vars.size());

    // put vars in order
    for (VariableSimpleIF v : vars) {
      if (v.getDataType().isNumeric()) nvars.add(new PointObVar(v));
    }
    int ndoubles = vars.size();
    double[] dvals = new double[ndoubles];

    for (VariableSimpleIF v : vars) {
      if (v.getDataType().isString()) nvars.add(new PointObVar(v));
    }
    String[] svals = new String[vars.size() - ndoubles];

    FileOutputStream fos = new FileOutputStream(fileOut);
    DataOutputStream out = new DataOutputStream(fos);
    CFPointObWriter writer =
        new CFPointObWriter(out, pobsDataset.getGlobalAttributes(), altUnits, nvars, -1);

    DataIterator iter = pobsDataset.getDataIterator(1000 * 1000);
    while (iter.hasNext()) {
      PointObsDatatype pobsData = (PointObsDatatype) iter.nextData();
      StructureData sdata = pobsData.getData();

      int dcount = 0;
      int scount = 0;
      for (PointObVar v : nvars) {
        if (v.getDataType().isNumeric()) {
          Array data = sdata.getArray(v.getName());
          data.resetLocalIterator();
          if (data.hasNext()) dvals[dcount++] = data.nextDouble();

        } else if (v.getDataType().isString()) {
          ArrayChar data = (ArrayChar) sdata.getArray(v.getName());
          svals[scount++] = data.getString();
        }
      }

      ucar.unidata.geoloc.EarthLocation loc = pobsData.getLocation();
      writer.addPoint(
          loc.getLatitude(),
          loc.getLongitude(),
          loc.getAltitude(),
          pobsData.getObservationTimeAsDate(),
          dvals,
          svals);
    }

    writer.finish();
  }