/afs/cern.ch/work/a/aaltunda/public/www/CMSSW_6_2_5/src/RecoMuon/DetLayers/src/PhiBorderFinder.h

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#ifndef PhiBorderFinder_H
#define PhiBorderFinder_H

#include <Geometry/CommonDetUnit/interface/GeomDet.h>

#include <DataFormats/GeometrySurface/interface/BoundingBox.h>
#include <DataFormats/GeometrySurface/interface/GeometricSorting.h>

#include <DataFormats/GeometryVector/interface/Pi.h>
#include <Utilities/General/interface/precomputed_value_sort.h>
#include <TrackingTools/DetLayers/interface/simple_stat.h>
#include <FWCore/Utilities/interface/Exception.h>

// FIXME: remove this include
#include "FWCore/MessageLogger/interface/MessageLogger.h"

#include <vector>

class PhiBorderFinder {
public:
  
  typedef DetRod Det; //FIXME!!!
  typedef geomsort::ExtractPhi<Det,float> DetPhi;


  PhiBorderFinder(std::vector<const Det*> theDets) 
    : theNbins(theDets.size()), isPhiPeriodic_(false), isPhiOverlapping_(false) {
    precomputed_value_sort(theDets.begin(), theDets.end(), DetPhi());

    const std::string metname = "Muon|RecoMuon|RecoMuonDetLayers|PhiBorderFinder";

    double step = 2.*Geom::pi()/theNbins;

    LogTrace(metname) << "RecoMuonDetLayers::PhiBorderFinder "
                      << "step w: " << step << " # of bins: " << theNbins;
    
    std::vector<double> spread(theNbins);
    std::vector<std::pair<double,double> > phiEdge;
    phiEdge.reserve(theNbins);
    thePhiBorders.reserve(theNbins);
    thePhiBins.reserve(theNbins);
    for ( unsigned int i = 0; i < theNbins; i++ ) {
      thePhiBins.push_back(theDets[i]->position().phi());
      spread.push_back(theDets[i]->position().phi()
        - (theDets[0]->position().phi() + i*step));
      
      LogTrace(metname) << "bin: " << i << " phi bin: " << thePhiBins[i]
                        << " spread: " <<  spread[i];
      

      ConstReferenceCountingPointer<BoundPlane> plane = 
        dynamic_cast<const BoundPlane*>(&theDets[i]->surface());
      if (plane==0) {
        //FIXME
        throw cms::Exception("UnexpectedState") << ("PhiBorderFinder: det surface is not a BoundPlane");
      }
      
      std::vector<GlobalPoint> dc = 
        BoundingBox().corners(*plane);

      float phimin(999.), phimax(-999.);
      for (std::vector<GlobalPoint>::const_iterator pt=dc.begin();
           pt!=dc.end(); pt++) {
        float phi = (*pt).phi();
//      float z = pt->z();
        if (phi < phimin) phimin = phi;
        if (phi > phimax) phimax = phi;
      }
      if (phimin*phimax < 0. &&           //Handle pi border:
          phimax - phimin > Geom::pi()) { //Assume that the Det is on
                                          //the shortest side 
        std::swap(phimin,phimax);
      }
      phiEdge.push_back(std::pair<double,double>(phimin,phimax));
    }
    
    for (unsigned int i = 0; i < theNbins; i++) {
      
      // Put the two phi values in the [0,2pi] range
      double firstPhi  = positiveRange(phiEdge[i].first);
      double secondPhi = positiveRange(phiEdge[binIndex(i-1)].second);

      // Reformat them in the [-pi,pi] range
      Geom::Phi<double> firstEdge(firstPhi);
      Geom::Phi<double> secondEdge(secondPhi);

      // Calculate the mean and format the result in the [-pi,pi] range
      // Get their value in order to perform the mean in the correct way
      Geom::Phi<double> mean((firstEdge.value() + secondEdge.value())/2.);
      
      // Special case: at +-pi there is a discontinuity
      if ( phiEdge[i].first * phiEdge[binIndex(i-1)].second < 0 &&
           fabs(firstPhi-secondPhi) < Geom::pi() ) 
        mean = Geom::pi() - mean;
     
      thePhiBorders.push_back(mean);
    }
  
    for (unsigned int i = 0; i < theNbins; i++) {
      if (Geom::Phi<double>(phiEdge[i].first)
          - Geom::Phi<double>(phiEdge[binIndex(i-1)].second) < 0) {
        isPhiOverlapping_ = true;
        break;
      }
    }

    double rms = stat_RMS(spread); 
    if ( rms < 0.01*step) { 
      isPhiPeriodic_ = true;
    }

    //Check that everything is proper
    if (thePhiBorders.size() != theNbins || thePhiBins.size() != theNbins) 
      //FIXME
      throw cms::Exception("UnexpectedState") << "PhiBorderFinder: consistency error";
  }
  

  virtual ~PhiBorderFinder(){};

  inline unsigned int nBins() {return theNbins;}

  inline bool isPhiPeriodic() const { return isPhiPeriodic_; }
  
  inline bool isPhiOverlapping() const { return isPhiOverlapping_; }

  inline const std::vector<double>& phiBorders() const { return thePhiBorders; }

  inline const std::vector<double>& phiBins() const { return thePhiBins; }

  //  inline std::vector<double> etaBorders() {}
  //  inline std::vector<double> zBorders() {}

private:
  unsigned int theNbins;
  bool isPhiPeriodic_;
  bool isPhiOverlapping_;
  std::vector<double> thePhiBorders;
  std::vector<double> thePhiBins;

  inline double positiveRange (double phi) const
  {
    return (phi > 0) ? phi : phi + Geom::twoPi();
  }

  int binIndex( int i) const {
    int ind = i % (int)theNbins;
    return (ind < 0) ? ind+theNbins : ind;
  }


};
#endif