package org.lcsim.recon.tracking.digitization.sisim.config;
   
   import java.util.List;
   
   import org.lcsim.detector.DetectorElementStore;
   import org.lcsim.detector.IDetectorElement;
   import org.lcsim.detector.identifier.IExpandedIdentifier;
   import org.lcsim.detector.identifier.IIdentifier;
   import org.lcsim.detector.identifier.IIdentifierDictionary;
  import org.lcsim.detector.tracker.silicon.SiSensor;
  import org.lcsim.event.EventHeader;
  import org.lcsim.event.EventHeader.LCMetaData;
  import org.lcsim.event.RawTrackerHit;
  
  /**
   * Assigns {@link org.lcsim.detector.IDetectorElement}s to {@link org.lcsim.event.RawTrackerHit}s.
   * 
   * @author jeremym
   */
  public class RawTrackerHitSensorSetup extends CollectionHandler {
      
      public RawTrackerHitSensorSetup() {
      }
  
      public void setReadoutCollections(String[] collectionNames) {
          super.setCollections(collectionNames);
      }
  
  
      protected void process(EventHeader header) {
          super.process(header);
          List<List<RawTrackerHit>> collections = header.get(RawTrackerHit.class);
          for (List<RawTrackerHit> collection : collections) {
              LCMetaData meta = header.getMetaData(collection);
              if (canHandle(meta.getName())) {                
                  // Set the sensor links on the hits.
                  setSensors(meta, collection);
              }
          }
      }
      
      static public final void setSensors(LCMetaData meta, List<RawTrackerHit> hits) {
  
          // Get the ID dictionary and field information.
          IIdentifierDictionary dict = meta.getIDDecoder().getSubdetector().getDetectorElement().getIdentifierHelper().getIdentifierDictionary();
          int fieldIdx = dict.getFieldIndex("side");
          int sideIdx = dict.getFieldIndex("strip");
          
          for (RawTrackerHit hit : hits) {
                 
              // The "side" and "strip" fields needs to be stripped from the ID for sensor lookup.
              IExpandedIdentifier expId = dict.unpack(hit.getIdentifier());
              expId.setValue(fieldIdx, 0);
              expId.setValue(sideIdx, 0);
              IIdentifier strippedId = dict.pack(expId);
          
              // Find the sensor DetectorElement.
              List<IDetectorElement> des = DetectorElementStore.getInstance().find(strippedId);
              if (des == null || des.size() == 0) {
                  throw new RuntimeException("Failed to find any DetectorElements with stripped ID <0x" + Long.toHexString(strippedId.getValue()) + ">.");
              }
              else if (des.size() == 1) {
                  hit.setDetectorElement((SiSensor)des.get(0));
              }
              else {
                  // Use first sensor found, which should work unless there are sensors with duplicate IDs.
                  for (IDetectorElement de : des) {
                      if (de instanceof SiSensor) {
                          hit.setDetectorElement((SiSensor)de);
                          break;
                      }
                  }
              }   
              
              // No sensor was found.
              if (hit.getDetectorElement() == null) {
                  throw new RuntimeException("No sensor was found for hit with stripped ID <0x" + Long.toHexString(strippedId.getValue()) + ">.");
              }
          }
      }
      
  }