/*
 * Copyright 1998-2014 University Corporation for Atmospheric Research/Unidata
 *
 *   Portions of this software were developed by the Unidata Program at the
 *   University Corporation for Atmospheric Research.
 *
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 *   any fee or cost, to use, copy, modify, alter, enhance and distribute
 *   this software, and any derivative works thereof, and its supporting
 *   documentation for any purpose whatsoever, provided that this entire
 *   notice appears in all copies of the software, derivative works and
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 *   IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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 */
package ucar.nc2.ft.point;

import ucar.nc2.ft.*;
import ucar.nc2.constants.FeatureType;
import ucar.nc2.units.DateUnit;
import ucar.unidata.geoloc.LatLonRect;
import ucar.unidata.geoloc.Station;

import java.util.List;
import java.io.IOException;

/**
 * Abstract superclass for StationProfileFeatureCollection
 * Subclasses must implement getNestedPointFeatureCollection
 * @author caron
 * @since Mar 20, 2008
 */
public abstract class StationProfileCollectionImpl extends MultipleNestedPointCollectionImpl implements StationProfileFeatureCollection {
  private volatile StationHelper stationHelper;
  protected NestedPointFeatureCollectionIterator localIterator;

  public StationProfileCollectionImpl(String name, DateUnit timeUnit, String altUnits) {
    super( name, timeUnit, altUnits, FeatureType.STATION_PROFILE);
  }

  // Double-check idiom for lazy initialization of instance fields. See Effective Java 2nd Ed, p. 283.
  protected StationHelper getStationHelper() {
    if (stationHelper == null) {
      synchronized (this) {
        if (stationHelper == null) {
          try {
            stationHelper = createStationHelper();
          } catch (IOException e) {
            // The methods that will call getStationHelper() aren't declared to throw IOException, so we must
            // wrap it in an unchecked exception.
            throw new RuntimeException(e);
          }
        }
      }
    }

    assert stationHelper != null : "We screwed this up.";
    return stationHelper;
  }

  // Allow StationHelper to be lazily initialized.
  protected abstract StationHelper createStationHelper() throws IOException;

  @Override
  public List<StationFeature> getStationFeatures() throws IOException {
    return getStationHelper().getStationFeatures();
  }

  public List<Station> getStations() {
    return getStationHelper().getStations();
  }

  public List<Station> getStations(List<String> stnNames) {
    return getStationHelper().getStations(stnNames);
  }

  public List<Station> getStations(LatLonRect boundingBox) throws IOException {
    return getStationHelper().getStations(boundingBox);
  }

  public Station getStation(String name) {
    return getStationHelper().getStation(name);
  }

  public LatLonRect getBoundingBox() {
    return getStationHelper().getBoundingBox();
  }

  public StationProfileCollectionImpl subset(List<Station> stations) throws IOException {
    if (stations == null) return this;
    return new StationProfileFeatureCollectionSubset(this, stations);
  }

  public StationProfileCollectionImpl subset(ucar.unidata.geoloc.LatLonRect boundingBox) throws IOException {
    return subset( getStations(boundingBox));
  }

  public StationProfileFeature getStationProfileFeature(Station s) throws IOException {
    return (StationProfileFeature) s;  // LOOK subclass must override if not true
  }

  public PointFeatureCollectionIterator getPointFeatureCollectionIterator(int bufferSize) throws IOException {
    throw new UnsupportedOperationException("StationProfileFeatureCollection does not implement getPointFeatureCollectionIterator()");
  }

  public boolean hasNext() throws IOException {
    if (localIterator == null) resetIteration();
    return localIterator.hasNext();
  }

  public StationProfileFeature next() throws IOException {
    return (StationProfileFeature) localIterator.next();
  }

  public void resetIteration() throws IOException {
    localIterator = getNestedPointFeatureCollectionIterator(-1);
  }

  public int compareTo(Station so) {
    return name.compareTo( so.getName());
  }

  // LOOK subset by filtering on the stations, but it would be easier if we could get the StationFeature from the Station
  private static class StationProfileFeatureCollectionSubset extends StationProfileCollectionImpl {
    private final StationProfileCollectionImpl from;
    private final List<Station> stations;

    StationProfileFeatureCollectionSubset(StationProfileCollectionImpl from, List<Station> stations) throws IOException {
      super( from.getName(), from.getTimeUnit(), from.getAltUnits());
      this.from = from;
      this.stations = stations;
    }

    protected StationHelper createStationHelper() throws IOException {
      return from.getStationHelper().subset(stations);
    }

    // use this only if it is multiply nested
    public NestedPointFeatureCollectionIterator getNestedPointFeatureCollectionIterator(int bufferSize) throws IOException {
      return new NestedPointCollectionIteratorFiltered( from.getNestedPointFeatureCollectionIterator(bufferSize), new Filter());
    }

    private class Filter implements NestedPointFeatureCollectionIterator.Filter {
      public boolean filter(NestedPointFeatureCollection pointFeatureCollection) {
        StationProfileFeature stationFeature = (StationProfileFeature) pointFeatureCollection;
        return getStationHelper().getStation(stationFeature.getName()) != null;
      }
    }
  }
}