// $Id$
//
//    File: DTrackTimeBased_factory_Kalman.cc
// Created: Thu Sep  4 14:02:44 EDT 2008
// Creator: davidl (on Darwin harriet.jlab.org 8.11.1 i386)
//
// This is a copy of the DTrackTimeBased_factory.cc file except
// it is hardwired to use the "Kalman" tagged track fitting
// algorithm. This is so one can get tracks fit by the Kalman
// and ALT1 methods simultaneously in the same program for the
// same event.

#include <iostream>
#include <iomanip>
using namespace std;

#include "DTrackTimeBased_factory_Kalman.h"
#include <TRACKING/DTrackWireBased.h>
#include <TRACKING/DReferenceTrajectory.h>
#include <TRACKING/DTrackFitter.h>
#include <TRACKING/DTrackHitSelector.h>
using namespace jana;

//------------------
// init
//------------------
jerror_t DTrackTimeBased_factory_Kalman::init(void)
{
	fitter = NULL;

	DEBUG_LEVEL = 0;
	MOMENTUM_CUT_FOR_DEDX=0.5;

	gPARMS->SetDefaultParameter("TRKFIT:DEBUG_LEVEL",					DEBUG_LEVEL);
	gPARMS->SetDefaultParameter("TRKFIT:MOMENTUM_CUT_FOR_DEDX",MOMENTUM_CUT_FOR_DEDX);
	return NOERROR;
}

//------------------
// brun
//------------------
jerror_t DTrackTimeBased_factory_Kalman::brun(jana::JEventLoop *loop, int runnumber)
{
	// Get pointer to TrackFitter object that actually fits a track
	vector<const DTrackFitter *> fitters;
	loop->Get(fitters,"Kalman");
	if(fitters.size()<1){
		_DBG_<<"Unable to get a DTrackFitter object! NO Charged track fitting will be done!"<<endl;
		return RESOURCE_UNAVAILABLE;
	}
	
	// Drop the const qualifier from the DTrackFitter pointer (I'm surely going to hell for this!)
	fitter = const_cast<DTrackFitter*>(fitters[0]);

	// Warn user if something happened that caused us NOT to get a fitter object pointer
	if(!fitter){
		_DBG_<<"Unable to get a DTrackFitter object! NO Charged track fitting will be done!"<<endl;
		return RESOURCE_UNAVAILABLE;
	}

	string MASS_HYPOTHESES = "0.13957, 0.93827";
	gPARMS->SetDefaultParameter("TRKFIT:MASS_HYPOTHESES", MASS_HYPOTHESES);
	
	// Reserve the first mass hypothesis slot for the one decided on by the wire-base fit
	mass_hypotheses.push_back(0.0);
	
	// Parse MASS_HYPOTHESES string to make list of masses to try
	if(MASS_HYPOTHESES.length()>0){
		string &str = MASS_HYPOTHESES;
		unsigned int cutAt;
		while( (cutAt = str.find(",")) != (unsigned int)str.npos ){
			if(cutAt > 0)mass_hypotheses.push_back(atof(str.substr(0,cutAt).c_str()));
			str = str.substr(cutAt+1);
		}
		if(str.length() > 0)mass_hypotheses.push_back(atof(str.c_str()));
	}

	return NOERROR;
}

//------------------
// evnt
//------------------
jerror_t DTrackTimeBased_factory_Kalman::evnt(JEventLoop *loop, int eventnumber)
{
	if(!fitter)return NOERROR;
	
	// Get candidates and hits
	vector<const DTrackWireBased*> tracks;
	loop->Get(tracks,"Kalman");
	
	// Loop over candidates
	for(unsigned int i=0; i<tracks.size(); i++){
		const DTrackWireBased *track = tracks[i];

		// Make sure there are enough DReferenceTrajectory objects
		while(rtv.size()<=_data.size())rtv.push_back(new DReferenceTrajectory(fitter->GetDMagneticFieldMap()));
		DReferenceTrajectory *rt = rtv[_data.size()];

		// Copy in the mass from the wire-based fit as the first one to try
		mass_hypotheses[0] = track->mass();

		// Loop over potential particle masses until one is found that gives a chisq/Ndof<3.0
		// If none does, then use the one with the smallest chisq
		DTrackTimeBased *best_track = NULL;
		double best_fom = 0.0;
		for(unsigned int j=0; j<mass_hypotheses.size(); j++){

			// If best_track is set then check if the fom is large enough
			// that we can skip additional hypotheses
			//if(best_fom>1.0E-5)break;
		
			// Don't try the same mass twice!
			if(j!=0 && mass_hypotheses[j]==mass_hypotheses[0])continue;

			if(DEBUG_LEVEL>1){_DBG__;_DBG_<<"---- Starting time based fit with mass: "<<mass_hypotheses[j]<<endl;}

			// Do the fit
			fitter->SetFitType(DTrackFitter::kTimeBased);
			DTrackFitter::fit_status_t status = fitter->FindHitsAndFitTrack(*track, rt, loop, mass_hypotheses[j]);
			DTrackTimeBased *dtrack = NULL;
			switch(status){
				case DTrackFitter::kFitNotDone:
					_DBG_<<"Fitter returned kFitNotDone. This should never happen!!"<<endl;
				case DTrackFitter::kFitFailed:
					continue;
					break;
				case DTrackFitter::kFitSuccess:
				case DTrackFitter::kFitNoImprovement:
					dtrack = MakeDTrackTimeBased(track);
					break;
			}
			
			// Avoid division by zero below
			if(dtrack->Ndof < 1){
				if(DEBUG_LEVEL>1)_DBG_<<"-- new track with mass "<<mass_hypotheses[j]<<" has Ndof="<<dtrack->Ndof<<". Dropping ..."<<endl;
				delete dtrack;
				continue;
			}
			
			// If best_track hasn't been set, then this is the best track!
			if(!best_track){
				best_track = dtrack;
				best_fom = GetFOM(best_track);

				if(DEBUG_LEVEL>1)_DBG_<<"-- first successful fit this candidate with mass: "<<mass_hypotheses[j]<<" (chisq/Ndof="<<(best_track->chisq/best_track->Ndof)<<") fom="<<best_fom<<endl;

				// Break if the momentum is sufficiently high for dEdx to have no 
				// discriminating power between particle types. Also break if the charge 
				// is negative -- we assume that we don't need to worry about anti-protons

				if (best_track->charge()<0 || best_track->momentum().Mag()>MOMENTUM_CUT_FOR_DEDX) break;
				// Otherwise go on to the next guess.

				continue;
			}
			
			// If the fit wasn't sucessful, try next mass
			if(!dtrack){
				if(DEBUG_LEVEL>1)_DBG_<<"-- no DTrack made for track with mass "<<mass_hypotheses[j]<<endl;
				continue;
			}
			
			// OK, now we have to make a choice as to which track to keep. 
			// For low momentum tracks, dEdx in the chambers can be used to distinguish protons
			// from pions.
			// Form a figure of merit based on the expected dEdx for the current hypothesis.
			double fom = GetFOM(dtrack);
				
			// There can be only one! (Highlander)
			if(fom > best_fom){
				if(DEBUG_LEVEL>1)_DBG_<<"-- new best track with mass "<<mass_hypotheses[j]<<" (old chisq/Ndof="<<(best_track->chisq/best_track->Ndof)<<" , new chisq/Ndof="<<(dtrack->chisq/dtrack->Ndof)<<") (old fom="<<best_fom<<" , new fom="<<fom<<")"<<endl;
				delete best_track;
				best_track = dtrack;
				best_fom = fom;
			}else{
				if(DEBUG_LEVEL>1)_DBG_<<"-- keeping best track with mass "<<best_track->mass()<<" (old chisq/Ndof="<<(best_track->chisq/best_track->Ndof)<<" , new chisq/Ndof="<<(dtrack->chisq/dtrack->Ndof)<<") (old fom="<<best_fom<<" , new fom="<<fom<<")"<<endl;
				delete dtrack;
			}
		}

		// If a track fit was successfull, then keep it
		if(best_track)_data.push_back(best_track);
	}

	return NOERROR;
}

//------------------
// erun
//------------------
jerror_t DTrackTimeBased_factory_Kalman::erun(void)
{
	return NOERROR;
}

//------------------
// fini
//------------------
jerror_t DTrackTimeBased_factory_Kalman::fini(void)
{
	for(unsigned int i=0; i<rtv.size(); i++)delete rtv[i];
	rtv.clear();

	return NOERROR;
}

//------------------
// MakeDTrackTimeBased
//------------------
DTrackTimeBased* DTrackTimeBased_factory_Kalman::MakeDTrackTimeBased(const DTrackWireBased *track)
{
	// Allocate a DReferenceTrajectory object if needed.
	// These each have a large enough memory footprint that
	// it causes noticable performance problems if we allocated
	// and deallocated them every event. Therefore, we allocate
	// when needed, but recycle them on the next event.
	// They are deleted in the fini method.
	while(rtv.size()<=_data.size())rtv.push_back(new DReferenceTrajectory(fitter->GetDMagneticFieldMap()));
	DReferenceTrajectory *rt = rtv[_data.size()];

	DTrackTimeBased *timebased_track = new DTrackTimeBased;
	
	// Copy over DKinematicData part
	DKinematicData *track_kd = timebased_track;
	*track_kd = fitter->GetFitParameters();
	rt->SetMass(track_kd->mass());
	rt->Swim(timebased_track->position(), timebased_track->momentum(), timebased_track->charge());
	
	timebased_track->rt = rt;
	timebased_track->chisq = fitter->GetChisq();
	timebased_track->Ndof = fitter->GetNdof();
	timebased_track->trackid = track->id;

	// Add hits used as associated objects
	const vector<const DCDCTrackHit*> &cdchits = fitter->GetCDCFitHits();
	const vector<const DFDCPseudo*> &fdchits = fitter->GetFDCFitHits();
	for(unsigned int i=0; i<cdchits.size(); i++)
	  timebased_track->AddAssociatedObject(cdchits[i]);
	for(unsigned int i=0; i<fdchits.size(); i++)
	  timebased_track->AddAssociatedObject(fdchits[i]);
	
	// Add DTrack object as associate object
	timebased_track->AddAssociatedObject(track);
	
	return timebased_track;
}

//------------------
// GetFOM
//------------------
double DTrackTimeBased_factory_Kalman::GetFOM(DTrackTimeBased *dtrack)
{
  double dedx,mean_path_length,p_avg;
  unsigned int num_hits=0;
  if (fitter->GetdEdx(dtrack->rt,dedx,mean_path_length,p_avg,num_hits)
      ==NOERROR){
    dtrack->setdEdx(dedx);
    double dedx_sigma=fitter->GetdEdxSigma(num_hits,mean_path_length);
    double dedx_most_probable=fitter->GetdEdx(p_avg,dtrack->rt->GetMass(),mean_path_length);
    
    //figure of merit
    double prob=TMath::Prob(fitter->GetChisq(),fitter->GetNdof());
    return ( prob*dedx_sigma/fabs(dedx/dedx_most_probable-1.) );
  }
  
  // If we got here, GetdEdx failed for this track
  dtrack->setdEdx(0.);
  return 0.;
}