/*
 *  Delphes: a framework for fast simulation of a generic collider experiment
 *  Copyright (C) 2012-2014  Universite catholique de Louvain (UCL), Belgium
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/** \class DenseTrackFilter
 *
 *  Applies reconstruction inefficiency on tracks in dense environment
 *
 *  \author M. Selvaggi - CERN
 *
 */

#include "modules/DenseTrackFilter.h"

#include "classes/DelphesClasses.h"
#include "classes/DelphesFactory.h"
#include "classes/DelphesFormula.h"

#include "ExRootAnalysis/ExRootClassifier.h"
#include "ExRootAnalysis/ExRootFilter.h"
#include "ExRootAnalysis/ExRootResult.h"

#include "TDatabasePDG.h"
#include "TFormula.h"
#include "TLorentzVector.h"
#include "TMath.h"
#include "TObjArray.h"
#include "TRandom3.h"
#include "TString.h"

#include <algorithm>
#include <iostream>
#include <sstream>
#include <stdexcept>

using namespace std;

//------------------------------------------------------------------------------

DenseTrackFilter::DenseTrackFilter() :
  fItTrackInputArray(0)
{
}

//------------------------------------------------------------------------------

DenseTrackFilter::~DenseTrackFilter()
{
}

//------------------------------------------------------------------------------

void DenseTrackFilter::Init()
{
  ExRootConfParam param, paramEtaBins, paramPhiBins, paramFractions;
  Long_t i, j, k, size, sizeEtaBins, sizePhiBins;
  TBinMap::iterator itEtaBin;
  set<Double_t>::iterator itPhiBin;
  vector<Double_t> *phiBins;

  // read eta and phi bins
  param = GetParam("EtaPhiBins");
  size = param.GetSize();
  fBinMap.clear();
  fEtaBins.clear();
  fPhiBins.clear();
  for(i = 0; i < size / 2; ++i)
  {
    paramEtaBins = param[i * 2];
    sizeEtaBins = paramEtaBins.GetSize();
    paramPhiBins = param[i * 2 + 1];
    sizePhiBins = paramPhiBins.GetSize();

    for(j = 0; j < sizeEtaBins; ++j)
    {
      for(k = 0; k < sizePhiBins; ++k)
      {
        fBinMap[paramEtaBins[j].GetDouble()].insert(paramPhiBins[k].GetDouble());
      }
    }
  }

  // for better performance we transform map of sets to parallel vectors:
  // vector< double > and vector< vector< double >* >
  for(itEtaBin = fBinMap.begin(); itEtaBin != fBinMap.end(); ++itEtaBin)
  {
    fEtaBins.push_back(itEtaBin->first);
    phiBins = new vector<double>(itEtaBin->second.size());
    fPhiBins.push_back(phiBins);
    phiBins->clear();
    for(itPhiBin = itEtaBin->second.begin(); itPhiBin != itEtaBin->second.end(); ++itPhiBin)
    {
      phiBins->push_back(*itPhiBin);
    }
  }

  // Eta x Phi smearing to be applied
  fEtaPhiRes = GetDouble("EtaPhiRes", 0.003);

  fTrackInputArray = ImportArray(GetString("TrackInputArray", "TrackMergerProp/tracks"));
  fItTrackInputArray = fTrackInputArray->MakeIterator();

  fTrackOutputArray = ExportArray(GetString("TrackOutputArray", "tracks"));
  fChargedHadronOutputArray = ExportArray(GetString("ChargedHadronOutputArray", "chargedHadrons"));
  fElectronOutputArray = ExportArray(GetString("ElectronOutputArray", "electrons"));
  fMuonOutputArray = ExportArray(GetString("MuonOutputArray", "muons"));
}

//------------------------------------------------------------------------------

void DenseTrackFilter::Finish()
{
  vector<vector<Double_t> *>::iterator itPhiBin;
  if(fItTrackInputArray) delete fItTrackInputArray;
  for(itPhiBin = fPhiBins.begin(); itPhiBin != fPhiBins.end(); ++itPhiBin)
  {
    delete *itPhiBin;
  }
}

//------------------------------------------------------------------------------

void DenseTrackFilter::Process()
{
  Candidate *track;
  TLorentzVector position, momentum;
  Short_t etaBin, phiBin, flags;
  Int_t number;
  Long64_t towerHit, towerEtaPhi, hitEtaPhi;
  Double_t ptmax;

  vector<Double_t>::iterator itEtaBin;
  vector<Double_t>::iterator itPhiBin;
  vector<Double_t> *phiBins;

  vector<Long64_t>::iterator itTowerHits;

  fTowerHits.clear();

  // loop over all tracks
  fItTrackInputArray->Reset();
  number = -1;
  while((track = static_cast<Candidate *>(fItTrackInputArray->Next())))
  {
    const TLorentzVector &trackPosition = track->Position;
    ++number;

    // find eta bin [1, fEtaBins.size - 1]
    itEtaBin = lower_bound(fEtaBins.begin(), fEtaBins.end(), trackPosition.Eta());
    if(itEtaBin == fEtaBins.begin() || itEtaBin == fEtaBins.end()) continue;
    etaBin = distance(fEtaBins.begin(), itEtaBin);

    // phi bins for given eta bin
    phiBins = fPhiBins[etaBin];

    // find phi bin [1, phiBins.size - 1]
    itPhiBin = lower_bound(phiBins->begin(), phiBins->end(), trackPosition.Phi());
    if(itPhiBin == phiBins->begin() || itPhiBin == phiBins->end()) continue;
    phiBin = distance(phiBins->begin(), itPhiBin);

    flags = 1;

    // make tower hit {16-bits for eta bin number, 16-bits for phi bin number, 8-bits for flags, 24-bits for track number}
    towerHit = (Long64_t(etaBin) << 48) | (Long64_t(phiBin) << 32) | (Long64_t(flags) << 24) | Long64_t(number);

    fTowerHits.push_back(towerHit);
  }

  // all hits are sorted first by eta bin number, then by phi bin number,
  // then by flags and then by particle or track number
  sort(fTowerHits.begin(), fTowerHits.end());

  // loop over all hits
  towerEtaPhi = 0;
  fBestTrack = 0;
  ptmax = 0.0;
  fTowerTrackHits = 0;

  for(itTowerHits = fTowerHits.begin(); itTowerHits != fTowerHits.end(); ++itTowerHits)
  {
    towerHit = (*itTowerHits);
    flags = (towerHit >> 24) & 0x00000000000000FFLL;
    number = (towerHit)&0x0000000000FFFFFFLL;
    hitEtaPhi = towerHit >> 32;

    if(towerEtaPhi != hitEtaPhi)
    {
      // switch to next tower
      towerEtaPhi = hitEtaPhi;

      // saving track with highest pT that hit the tower
      FillTrack();

      ptmax = 0.0;
      fTowerTrackHits = 0;
      fBestTrack = 0;
    }
    // check for track hits

    if(flags & 1)
    {
      ++fTowerTrackHits;
      track = static_cast<Candidate *>(fTrackInputArray->At(number));
      momentum = track->Momentum;

      if(momentum.Pt() > ptmax)
      {
        ptmax = momentum.Pt();
        fBestTrack = track;
      }
      continue;
    }
  }

  // here fill last tower
  FillTrack();
}

//------------------------------------------------------------------------------

void DenseTrackFilter::FillTrack()
{

  Candidate *candidate, *track;
  Double_t pt, eta, phi, m;
  Int_t numberOfCandidates;

  // saving track with highest pT that hit the tower
  if(fTowerTrackHits < 1) return;

  numberOfCandidates = fBestTrack->GetCandidates()->GetEntriesFast();
  if(numberOfCandidates < 1) return;

  track = static_cast<Candidate *>(fBestTrack->GetCandidates()->At(numberOfCandidates - 1));
  candidate = static_cast<Candidate *>(track->Clone());
  pt = candidate->Momentum.Pt();
  eta = candidate->Momentum.Eta();
  phi = candidate->Momentum.Phi();
  m = candidate->Momentum.M();

  eta = gRandom->Gaus(eta, fEtaPhiRes);
  phi = gRandom->Gaus(phi, fEtaPhiRes);
  candidate->Momentum.SetPtEtaPhiM(pt, eta, phi, m);
  candidate->AddCandidate(track);

  fTrackOutputArray->Add(candidate);
  switch(TMath::Abs(candidate->PID))
  {
  case 11:
    fElectronOutputArray->Add(candidate);
    break;
  case 13:
    fMuonOutputArray->Add(candidate);
    break;
  default:
    fChargedHadronOutputArray->Add(candidate);
  }
}