package org.lcsim.recon.tracking.vsegment.hit.base;
   
   import java.util.List;
   import java.util.ArrayList;
   
   import org.lcsim.event.MCParticle;
   
   import org.lcsim.recon.tracking.vsegment.geom.Sensor;
   import org.lcsim.recon.tracking.vsegment.hit.DigiTrackerHit;
  
  /**
   * Composite DigiTrackerHit.
   * Represents a sum of several digitized hits in a single channel. Typically used
   * for combining simulated events, or overlaying events and electronic noise.
   *
   * @author D.Onoprienko
   * @version $Id: DigiTrackerHitComposite.java,v 1.1 2008/12/06 21:53:44 onoprien Exp $
   */
  public class DigiTrackerHitComposite extends DigiTrackerHitAdapter {
  
  // -- Constructors :  ----------------------------------------------------------
    
    /** 
     * Default constructor. 
     * Signal, time, and cell ID will be set to zero.
     */
    public DigiTrackerHitComposite() {
      _signal = 0.;
      _time = 0.;
    }
    
    /** 
     * Fast constructor from data. 
     * No check is performed to see if all hits in the list have the same cell ID.
     * The list supplied as an argument will be owned by this composite hit.
     */
    public DigiTrackerHitComposite(double signal, double time, Sensor sensor, int channel, ArrayList<DigiTrackerHit> hitList) {
      _signal = signal;
      _time = time;
      _sensor = sensor;
      _channel = channel;
      _hitList = hitList;
    }
  
    /** 
     * Creates a composite hit from a list of hits. 
     * Signal is the sum of signals of constituent hits, time is signal-weighted average.
     * Throws <tt>IllegalArgumentException</tt> if not all of the hits in the list 
     * have the same channel ID. The list supplied as an argument will be copied.
     */
    public DigiTrackerHitComposite(List<DigiTrackerHit> hitList) {
      if (hitList.isEmpty()) throw new IllegalArgumentException("Empty list");
      _signal = 0.;
      _time = 0.;
      _channel = 0;
      _hitList = new ArrayList<DigiTrackerHit>(hitList.size());
      _hitList.addAll(hitList);
      for (DigiTrackerHit hit : hitList) {
        if (_sensor == null) {
          _sensor = hit.getSensor();
          _channel = hit.getChannel();
        } else {
          if ( ! ( _sensor == hit.getSensor() && _channel == hit.getChannel() ) ) {
            throw new IllegalArgumentException("Mismatched sensor or channel ID");
          }
        }
        _time += hit.getTime() * hit.getSignal();
        _signal += hit.getSignal();
      }
      _time /= _signal;
    }
  
    /** Copy constructor. */
    public DigiTrackerHitComposite(DigiTrackerHitComposite digiHit) {
      _signal = digiHit._signal;
      _time = digiHit._time;
      _sensor = digiHit._sensor;
      _channel = digiHit._channel;
      _hitList = new ArrayList<DigiTrackerHit>(digiHit._hitList);
      _hitList.trimToSize();
    }
    
  // -- Getters :  ---------------------------------------------------------------
  
    /**  
     * Returns <tt>true</tt> if the hit is a superposition of more than one elemental hit. 
     * Objects of this class always return <tt>true</tt>.
     */
    public boolean isComposite() {return true;}
  
    /** Returns <tt>null</tt> since the hit is composite. */
    public MCParticle getMCParticle() {return null;}
  
    /** Returns a list of underlying elemental hits. */
    public List<DigiTrackerHit> getElementalHits() {
      ArrayList<DigiTrackerHit> hList = new ArrayList<DigiTrackerHit>(_hitList.size());
      for (DigiTrackerHit hit : _hitList) {
        if (hit.isComposite()) {
          hList.addAll(hit.getElementalHits());
       } else {
         hList.add(hit);
       }
     }
     return hList;
   }
   
 // -- Modifiers :  -------------------------------------------------------------
   
   /** Add a hit to this composite hit. */
   public void addHit(DigiTrackerHit hit) {
     if (_hitList == null) {
       _signal = hit.getSignal();
       _time = hit.getTime();
       _sensor = hit.getSensor();
       _channel = hit.getChannel();
       _hitList = new ArrayList<DigiTrackerHit>(2);
     } else {
       if ( ! ( _sensor == hit.getSensor() && _channel == hit.getChannel() ) ) {
         System.out.println("throwing");
         throw new IllegalArgumentException("Mismatched cell ID");
       }
       double signal = hit.getSignal();
       _time = (_time * _signal + hit.getTime() * signal) / (_signal + signal);
       _signal += signal;
     }
     _hitList.add(hit);
   }
   
   /** Compact storage. */
   public void trimToSize() {
     _hitList.trimToSize();
   }
   
 // -- Private parts :  ---------------------------------------------------------
   
   protected ArrayList<DigiTrackerHit> _hitList;
 
 }