package org.lcsim.recon.util;
   
   import java.util.ArrayList;
   import java.util.List;
   
   import org.lcsim.event.EventHeader;
   import org.lcsim.event.Track;
   import org.lcsim.event.TrackerHit;
   import org.lcsim.util.Driver;
  
  /**
   * Driver to filter and remove all tracker hits from a given track collection that
   * did not contribute to any track. In addition, allows to clear the RawTrackerHit
   * lists to allow writing out events without those collections.
   * 
   * @author <a href="mailto:christian.grefe@cern.ch">Christian Grefe</a>
   * 
   */
  public class RemoveUnusedTrackerHits extends Driver {
  
  	protected String trackHitCollection;
  	protected String trackCollection;
  	protected boolean clearRawTrackerHits;
  	
  	public RemoveUnusedTrackerHits() {
  		trackHitCollection = "HelicalTrackHits";
  		trackCollection = "Tracks";
  		clearRawTrackerHits = true;
  	}
  	
  	public void setTrackCollection(String trackCollection) {
  		this.trackCollection = trackCollection;
  	}
  	
  	public void setTrackHitCollection(String trackHitCollection) {
  		this.trackHitCollection = trackHitCollection;
  	}
  	
  	public void setClearRawTrackerHits(boolean clearRawTrackerHits) {
  		this.clearRawTrackerHits = clearRawTrackerHits;
  	}
  	
  	@Override
  	protected void process(EventHeader event) {
  		List<TrackerHit> trackerHits = event.get(TrackerHit.class, trackHitCollection);
  		List<Track> tracks = event.get(Track.class, trackCollection);
  		List<TrackerHit> unusedTrackerHits = new ArrayList<TrackerHit>();
  		unusedTrackerHits.addAll(trackerHits);
  		
  		for (Track track : tracks) {
  			unusedTrackerHits.removeAll(track.getTrackerHits());
  		}
  		
  		trackerHits.removeAll(unusedTrackerHits);
  		
  		if (clearRawTrackerHits) {
  			for (TrackerHit hit : trackerHits) {
  				hit.getRawHits().clear();
  			}
  		}
  	}
  	
  }