package org.lcsim.recon.tracking.vsegment.digitization;
   
   import java.util.*;
   
   import org.lcsim.event.EventHeader;
   import org.lcsim.recon.cat.util.NoSuchParameterException;
   import org.lcsim.util.Driver;
   
   import org.lcsim.recon.tracking.vsegment.geom.Sensor;
  import org.lcsim.recon.tracking.vsegment.hit.DigiTrackerHit;
  import org.lcsim.recon.tracking.vsegment.hit.base.DigiTrackerHitComposite;
  
  /**
   * Driver that merges several collections of {@link DigiTrackerHit} objects into one,
   * combining hits in the same channels.
   * <p>
   * Input collections (either <tt>HashMap&lt;Sensor, ArrayList&lt;DigiTrackerHit&gt;&gt;</tt> or
   * <tt>Collection&lt;DigiTrackerHit&gt;</tt>) are fetched from the event usung name supplied
   * through calls to <tt>set("ADD_INPUT_COLLECTION", name)</tt>, and output collection
   * (type <tt>HashMap&lt;Sensor, ArrayList&lt;DigiTrackerHit&gt;&gt;</tt>) is attached
   * to the event with the name set by a call to <tt>set("OUTPUT_MAP_NAME", name)</tt>.
   * <p>
   * Whenever input collections contain hits in the same channels, new <tt>DigiTrackerHit</tt>
   * objects of type {@link DigiTrackerHitComposite} are created and stored in the output
   * map. These new objects reference all the original hits as their constituents.
   * <p>
   * {@link #merge} methods can also be called directly by other classes.
   *
   * @author D. Onoprienko
   * @version $Id: MergeDriver.java,v 1.1 2008/12/06 21:53:43 onoprien Exp $
   */
  public class MergeDriver extends Driver {
    
  // -- Constructors :  ----------------------------------------------------------
    
    /** Default constructor. */
    public MergeDriver() {}
    
  // -- Setters :  ---------------------------------------------------------------
  
    /**
     * Set parameters. 
     * The following parameters can be set with this method:
     * <dl>
     * <dt>"ADD_INPUT_COLLECTION"</dt> <dd>Name of input collection of digitized hits
     *                 (type <tt>HashMap<Sensor, ArrayList<DigiTrackerHit>></tt>).<br>
     *                 No default.</dd>
     * <dt>"OUTPUT_MAP_NAME"</dt> <dd>Name of output collection of clusters
     *                 (type <tt>HashMap<Sensor, ArrayList<DigiTrackerHit>></tt>).<br>
     *                 No default.</dd></dl>
     * 
     * @param name   Name of parameter to be set. Case is ignored.
     * @param value  Value to be assigned to the parameter.
     * @throws NoSuchParameterException Thrown if the supplied parameter name is unknown.
     *         Subclasses may catch this exception after a call to <tt>super.set()</tt>
     *         and set their own parameters.
     */
    public void set(String name, Object value) {
      try {
        if (name.equalsIgnoreCase("ADD_INPUT_COLLECTION")) {
          _inMapNames.add((String)value);
        } else if (name.equalsIgnoreCase("OUTPUT_MAP_NAME")) {
          _outMapName = (String)value;
        } else {
          throw new NoSuchParameterException(name, this.getClass());
        }
      } catch (ClassCastException x) {
        throw new IllegalArgumentException("Value of incompatible type", x);
      }
   }
    
  // -- Event processing :  ------------------------------------------------------
    
    /** Called by framework to process event. */
    public void process(EventHeader event) {
      
      if (_inMapNames == null) throw new RuntimeException("No input collection names provided");
      if (_outMapName == null) throw new RuntimeException("No output collection name provided");
      
      ArrayList<HashMap<Sensor, ArrayList<DigiTrackerHit>>> inMaps = 
              new ArrayList<HashMap<Sensor, ArrayList<DigiTrackerHit>>>(_inMapNames.size());
      for (String name : _inMapNames) {
        inMaps.add((HashMap<Sensor, ArrayList<DigiTrackerHit>>) event.get(name));
      }
      
      HashMap<Sensor, ArrayList<DigiTrackerHit>> outMap = merge(inMaps);
      event.put(_outMapName, outMap);
    }
    
  // -- Merging :  ---------------------------------------------------------------
    
    /**
     * Returns the result of merging <tt>DigiTrackerHits</tt> from several maps.
     */
    public HashMap<Sensor, ArrayList<DigiTrackerHit>> merge(Collection<HashMap<Sensor, ArrayList<DigiTrackerHit>>> hitMaps) {
      HashMap<Sensor, ArrayList<DigiTrackerHit>> outMap = new HashMap<Sensor, ArrayList<DigiTrackerHit>>();
      for (HashMap<Sensor, ArrayList<DigiTrackerHit>> inMap : hitMaps) {
        for (Sensor sensor : inMap.keySet()) {
          ArrayList<DigiTrackerHit> inList = inMap.get(sensor);
         ArrayList<DigiTrackerHit> outList = outMap.get(sensor);
         if (outList == null) {
           outList = new ArrayList<DigiTrackerHit>(inList.size());
           outMap.put(sensor, outList);
         }
         outList.addAll(inList);
       }
     }
     for (Sensor sensor : outMap.keySet()) {
       outMap.put(sensor, merge(outMap.get(sensor)));
     }
     return outMap;
   }
   
   /**
    * Returns a list of hits produced by merging hits in the list supplied as an argument.
    * The output list is sorted by channel ID.
    */
   public ArrayList<DigiTrackerHit> merge(ArrayList<DigiTrackerHit> hitList) {
     Collections.sort(hitList);
     ArrayList<DigiTrackerHit> outList = new ArrayList<DigiTrackerHit>(hitList.size());
     int channel = -1;
     ArrayList<DigiTrackerHit> buffer = new ArrayList<DigiTrackerHit>();
     for (DigiTrackerHit hit : hitList) {
       int newChannel = hit.getChannel();
       if (buffer.isEmpty()) {
         buffer.add(hit);
         channel = newChannel;
       } else if (channel == newChannel) {
         buffer.add(hit);
       } else {
         if (buffer.size() == 1) {
           outList.add(buffer.get(0));
         } else {
           outList.add(new DigiTrackerHitComposite(buffer));
         }
         buffer.clear();
         buffer.add(hit);
         channel = newChannel;
       }
     }
     if (! buffer.isEmpty()) {
       if (buffer.size() == 1) {
         outList.add(buffer.get(0));
       } else {
         outList.add(new DigiTrackerHitComposite(buffer));
       }
     }
     outList.trimToSize();
     return outList;
   }
 
 // -- Private parts :  ---------------------------------------------------------
 
   ArrayList<String> _inMapNames;
   String _outMapName;
 }