//FJSTARTHEADER
// $Id$
//
// Copyright (c) 2005-2024, Matteo Cacciari, Gavin P. Salam and Gregory Soyez
//
//----------------------------------------------------------------------
// This file is part of FastJet.
//
//  FastJet 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 2 of the License, or
//  (at your option) any later version.
//
//  The algorithms that underlie FastJet have required considerable
//  development. They are described in the original FastJet paper,
//  hep-ph/0512210 and in the manual, arXiv:1111.6097. If you use
//  FastJet as part of work towards a scientific publication, please
//  quote the version you use and include a citation to the manual and
//  optionally also to hep-ph/0512210.
//
//  FastJet 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 FastJet. If not, see <http://www.gnu.org/licenses/>.
//----------------------------------------------------------------------
//FJENDHEADER

#include <iostream>
#include "fastjet/ClusterSequence.hh"
#include "fastjet/ClusterSequenceArea.hh"
#include "fastjet/Selector.hh"
#include "fastjet/SISConePlugin.hh"

// Many calls below rely on caching information (input particles,
// ClusterSequence, jets) in fastjet structures so that one can query
// for extra information (e,g, jet constituents) after clustering.
//
// By default, this caching is not thread-safe.
//
// Uncommenting the following line results in defining all the cached
// variables as thread_local, meaning that clustering (with caching)
// and requesting extra information in the same thread is possible.
//
//#define FASTJET_FORTRAN_THREAD_LOCAL_CACHING

#ifdef FASTJET_FORTRAN_THREAD_LOCAL_CACHING
#include <thread>
#endif

using namespace std;
using namespace fastjet;

FASTJET_BEGIN_NAMESPACE      // defined in fastjet/internal/base.hh

/// a namespace for the fortran-wrapper which contains commonly-used
/// structures and means to transfer fortran <-> C++
namespace fwrapper {
#ifdef FASTJET_FORTRAN_THREAD_LOCAL_CACHING
  // use a thread local version of the caching so that this interface
  // works in a (reasonably) thread-safe way.
  thread_local vector<PseudoJet> input_particles, jets;
  thread_local SharedPtr<JetDefinition::Plugin> plugin;
  thread_local JetDefinition jet_def;
  thread_local SharedPtr<ClusterSequence> cs;
#else // FASTJET_FORTRAN_THREAD_LOCAL_CACHING not defined
  vector<PseudoJet> input_particles, jets;
  SharedPtr<JetDefinition::Plugin> plugin;
  JetDefinition jet_def;
  SharedPtr<ClusterSequence> cs;
#endif // FASTJET_FORTRAN_THREAD_LOCAL_CACHING

  /// helper routine to transform the fortran input particles into PseudoJets
  void convert_input_particles(const double * p, const int & npart, vector<PseudoJet> &fj_particles) {
    fj_particles.resize(0);
    fj_particles.reserve(npart);
    for (int i=0; i<npart; i++) {
      valarray<double> mom(4); // mom[0..3]
      for (int j=0;j<=3; j++) {
         mom[j] = *(p++);
      }
      PseudoJet psjet(mom);
      fj_particles.push_back(psjet);    
    }
  }

  /// helper routine to transfer fortran input particles into cached input_particles
  void transfer_input_particles(const double * p, const int & npart) {
    convert_input_particles(p, npart, input_particles);
  }

  /// helper routine to help convert fj_jets -> f77jets[4*ijet+0..3]
  void convert_jets(const vector<PseudoJet> & fj_jets, double * f77jets, int & njets) {
    njets = fj_jets.size();
    for (int i=0; i<njets; i++) {
      for (int j=0;j<=3; j++) {
        *f77jets = fj_jets[i][j];
        f77jets++;
      } 
    }
  }
  
  /// helper routine to help transfer jets -> f77jets[4*ijet+0..3]
  void transfer_jets(double * f77jets, int & njets) {
    convert_jets(jets, f77jets, njets);
    // njets = jets.size();
    // for (int i=0; i<njets; i++) {
    //   for (int j=0;j<=3; j++) {
    //     *f77jets = jets[i][j];
    //     f77jets++;
    //   } 
    // }
  }

  /// this returns a newly-created pointer to a ClusterSequence based
  /// on the particles and clustering parameters that have been provided
  ClusterSequence* cluster_base(const vector<PseudoJet> & particles,
                                const JetDefinition & jet_def,
                                const double & ghost_maxrap = 0.0,  
                                const int & nrepeat = 0, const double & ghost_area = 0.0) {
    // perform the clustering
    if ( ghost_maxrap == 0.0 ) {
      // cluster without areas
      return new ClusterSequence(particles,jet_def);
    } else {
      // cluster with areas
      GhostedAreaSpec area_spec(ghost_maxrap,nrepeat,ghost_area);
      AreaDefinition area_def(active_area, area_spec);
      return new ClusterSequenceArea(particles,jet_def,area_def);
    }
  }
  
  /// helper routine packaging the transfers, the clustering
  /// and the extraction of the jets
  /// This fills the f77jets and njets but does not cache anything
  void cluster_nocache(const double * p, const int & npart, 
                       const JetDefinition & jet_def,
                       double * f77jets, int & njets,
                       const double & ghost_maxrap = 0.0,  
                       const int & nrepeat = 0, const double & ghost_area = 0.0) {

    // transfer p[4*ipart+0..3] -> particles[i]
    vector<PseudoJet> fj_particles;
    convert_input_particles(p, npart, fj_particles);

    // cluster
    ClusterSequence *cs_local = cluster_base(fj_particles, jet_def,
                                             ghost_maxrap, nrepeat, ghost_area);
    
    // extract jets
    vector<PseudoJet> fj_jets;
    if (jet_def.is_spherical()){
      fj_jets = sorted_by_E(cs_local->inclusive_jets());
    } else {
      fj_jets = sorted_by_pt(cs_local->inclusive_jets());
    }
    
    convert_jets(fj_jets, f77jets, njets);

    // release memory
    delete cs_local;
  }

  /// helper routine packaging the transfers, the clustering
  /// and the extraction of the jets
  ///
  /// This fills the f77jets and njets and caches the input particles,
  /// the ClusterSequence and the jets for future manipulations
  void transfer_cluster_transfer(const double * p, const int & npart, 
                                 const JetDefinition & jet_def,
				 double * f77jets, int & njets,
				 const double & ghost_maxrap = 0.0,  
				 const int & nrepeat = 0, const double & ghost_area = 0.0) {

    // transfer p[4*ipart+0..3] -> input_particles[i]  (cached)
    transfer_input_particles(p, npart);

    // cluster 
    ClusterSequence *cs_local = cluster_base(input_particles, jet_def,
                                             ghost_maxrap, nrepeat, ghost_area);

    // cache
    cs.reset(cs_local);
    
    // extract jets (into cache)
    if (jet_def.is_spherical()){
      jets = sorted_by_E(cs_local->inclusive_jets());
    } else {
      jets = sorted_by_pt(cs_local->inclusive_jets());
    }
    
    // transfer jets -> f77jets[4*ijet+0..3]
    transfer_jets(f77jets, njets); 
  }

  
}
FASTJET_END_NAMESPACE

using namespace fastjet::fwrapper;


extern "C" {   

//------------------------------------------------------------------------
// Clustering routines
//------------------------------------------------------------------------
  
/// f77 interface to SISCone (via fastjet), as defined in arXiv:0704.0292
/// [see below for the interface to kt, Cam/Aachen & kt]
///
/// This caches the clustering structures for later access to extra
/// information (constituents, ...)
//
// Corresponds to the following Fortran subroutine
// interface structure:
//
//   SUBROUTINE FASTJETSISCONE(P,NPART,R,F,F77JETS,NJETS)
//   DOUBLE PRECISION P(4,*), R, F, F77JETS(4,*)
//   INTEGER          NPART, NJETS
// 
// where on input
//
//   P        the input particle 4-momenta
//   NPART    the number of input momenta
//   R        the radius parameter
//   F        the overlap threshold
//
// and on output 
//
//   F77JETS  the output jet momenta (whose second dim should be >= NPART)
//            sorted in order of decreasing p_t.
//   NJETS    the number of output jets 
//
// NOTE: if you are interfacing fastjet to Pythia 6, Pythia stores its
// momenta as a matrix of the form P(4000,5), whereas this fortran
// interface to fastjet expects them as P(4,NPART), i.e. you must take
// the transpose of the Pythia array and drop the fifth component
// (particle mass).
//
void fastjetsiscone_(const double * p, const int & npart,                   
                     const double & R, const double & f,                   
                     double * f77jets, int & njets) {  
  // prepare jet def
  plugin.reset(new SISConePlugin(R,f));
  jet_def = plugin.get();
  
  // do everything
  transfer_cluster_transfer(p,npart,jet_def,f77jets,njets);
}

/// same SISCone as above without the caching (invalidating calls to
/// constituents, ... but making this call thread-safe)
///
/// Note that as of SISCone 3.0.5 SISCone itself is not guaranteed to
/// be thread-safe
void fastjetsisconenocache_(const double * p, const int & npart,                   
                            const double & R, const double & f,                   
                            double * f77jets, int & njets) {
  // prepare jet def
  JetDefinition::Plugin *plugin_local = new SISConePlugin(R,f);
  JetDefinition jet_def_local = plugin_local;

  // do everything
  cluster_nocache(p,npart,jet_def_local,f77jets,njets);
  
  // release memory
  delete plugin_local;
}
 

/// f77 interface to SISCone (via fastjet), as defined in arXiv:0704.0292
/// [see below for the interface to kt, Cam/Aachen & kt]
/// Also calculates the active area of the jets, as defined in  
/// arXiv.org:0802.1188
//
// Corresponds to the following Fortran subroutine
// interface structure:
//
//   SUBROUTINE FASTJETSISCONEWITHAREA(P,NPART,R,F,GHMAXRAP,NREP,GHAREA,F77JETS,NJETS)
//   DOUBLE PRECISION P(4,*), R, F, F77JETS(4,*), GHMAXRAP, GHAREA
//   INTEGER          NPART, NJETS, NREP
// 
// where on input
//
//   P        the input particle 4-momenta
//   NPART    the number of input momenta
//   R        the radius parameter
//   F        the overlap threshold
//   GHMAXRAP the maximum (abs) rapidity covered by ghosts (FastJet default 6.0) 
//   NREP     the number of repetitions used to evaluate the area (FastJet default 1) 
//   GHAREA   the area of a single ghost (FastJet default 0.01) 
//
// and on output 
//
//   F77JETS  the output jet momenta (whose second dim should be >= NPART)
//            sorted in order of decreasing p_t.
//   NJETS    the number of output jets 
//
// NOTE: if you are interfacing fastjet to Pythia 6, Pythia stores its
// momenta as a matrix of the form P(4000,5), whereas this fortran
// interface to fastjet expects them as P(4,NPART), i.e. you must take
// the transpose of the Pythia array and drop the fifth component
// (particle mass).
//
void fastjetsisconewitharea_(const double * p, const int & npart,                   
                     const double & R, const double & f,                   
                     const double & ghost_rapmax, const int & nrepeat, const double & ghost_area,
                     double * f77jets, int & njets) {
  // prepare jet def
  plugin.reset(new SISConePlugin(R,f));
  jet_def = plugin.get();
  
  // do everything
  transfer_cluster_transfer(p,npart,jet_def,f77jets,njets,ghost_rapmax,nrepeat,ghost_area);
}

/// same SISCone+area as above without the caching (invalidating calls
/// to constituents, ... but making this call thread-safe)
///
/// Note that as of SISCone 3.0.5 SISCone itself is not guaranteed to
/// be thread-safe
void fastjetsisconewithareanocache_(const double * p, const int & npart,                   
                                    const double & R, const double & f,                   
                                    const double & ghost_rapmax, const int & nrepeat, const double & ghost_area,
                                    double * f77jets, int & njets) {
  // prepare jet def
  JetDefinition::Plugin *plugin_local = new SISConePlugin(R,f);
  JetDefinition jet_def_local = plugin_local;

  // do everything
  cluster_nocache(p,npart,jet_def_local,f77jets,njets,ghost_rapmax,nrepeat,ghost_area);

  // release memory
  delete plugin_local;
}


/// f77 interface to the pp generalised-kt (sequential recombination)
/// algorithms, as defined in arXiv.org:0802.1189, which includes
/// kt, Cambridge/Aachen and anti-kt as special cases.
//
// Corresponds to the following Fortran subroutine
// interface structure:
//
//   SUBROUTINE FASTJETPPGENKT(P,NPART,R,PALG,F77JETS,NJETS)
//   DOUBLE PRECISION P(4,*), R, PALG, F, F77JETS(4,*)
//   INTEGER          NPART, NJETS
// 
// where on input
//
//   P        the input particle 4-momenta
//   NPART    the number of input momenta
//   R        the radius parameter
//   PALG     the power for the generalised kt alg 
//            (1.0=kt, 0.0=C/A,  -1.0 = anti-kt)
//
// and on output 
//
//   F77JETS  the output jet momenta (whose second dim should be >= NPART)
//            sorted in order of decreasing p_t.
//   NJETS    the number of output jets 
//
// For the values of PALG that correspond to "standard" cases (1.0=kt,
// 0.0=C/A, -1.0 = anti-kt) this routine actually calls the direct
// implementation of those algorithms, whereas for other values of
// PALG it calls the generalised kt implementation.
//
// NOTE: if you are interfacing fastjet to Pythia 6, Pythia stores its
// momenta as a matrix of the form P(4000,5), whereas this fortran
// interface to fastjet expects them as P(4,NPART), i.e. you must take
// the transpose of the Pythia array and drop the fifth component
// (particle mass).
//
void fastjetppgenkt_(const double * p, const int & npart,                   
                     const double & R, const double & palg,
                     double * f77jets, int & njets) {
    
  // prepare jet def
  if (palg == 1.0) {
    jet_def = JetDefinition(kt_algorithm, R);
  }  else if (palg == 0.0) {
    jet_def = JetDefinition(cambridge_algorithm, R);
  }  else if (palg == -1.0) {
    jet_def = JetDefinition(antikt_algorithm, R);
  } else {
    jet_def = JetDefinition(genkt_algorithm, R, palg);
  }
  
  // do everything
  transfer_cluster_transfer(p,npart,jet_def,f77jets,njets);
}
  
/// same pp generalised-kt as above without the caching (invalidating
/// calls to constituents, ... but making this call thread-safe)
void fastjetppgenktnocache_(const double * p, const int & npart,                   
                            const double & R, const double & palg,
                            double * f77jets, int & njets) {
  
  // prepare jet def
  JetDefinition jet_def_local;
  if (palg == 1.0) {
    jet_def_local = JetDefinition(kt_algorithm, R);
  }  else if (palg == 0.0) {
    jet_def_local = JetDefinition(cambridge_algorithm, R);
  }  else if (palg == -1.0) {
    jet_def_local = JetDefinition(antikt_algorithm, R);
  } else {
    jet_def_local = JetDefinition(genkt_algorithm, R, palg);
  }
  
  // do everything
  cluster_nocache(p,npart,jet_def_local,f77jets,njets);
}



/// a routine that provides similar f77 functionality to fastjetppgenkt_, 
/// but for the e+e- algorithms instead of the pp ones; note this 
/// only gives the "inclusive" algorithms. The algorithms are as
/// defined in the FastJet manual.
void fastjeteegenkt_(const double * p, const int & npart,                   
                     const double & R, const double & palg,
                     double * f77jets, int & njets) {
    
  // prepare jet def
  jet_def = JetDefinition(ee_genkt_algorithm, R, palg);
  
  // do everything
  transfer_cluster_transfer(p,npart,jet_def,f77jets,njets);
}

/// same ee generalised-kt as above without the caching (invalidating
/// calls to constituents, ... but making this call thread-safe)
void fastjeteegenktnocache_(const double * p, const int & npart,                   
                            const double & R, const double & palg,
                            double * f77jets, int & njets) {
    
  // prepare jet def
  JetDefinition jet_def_local = JetDefinition(ee_genkt_algorithm, R, palg);
  
  // do everything
  cluster_nocache(p,npart,jet_def_local,f77jets,njets);
}

  
/// f77 interface to the pp generalised-kt (sequential recombination)
/// algorithms, as defined in arXiv.org:0802.1189, which includes
/// kt, Cambridge/Aachen and anti-kt as special cases.
/// Also calculates the active area of the jets, as defined in  
/// arXiv.org:0802.1188
//
// Corresponds to the following Fortran subroutine
// interface structure:
//
//   SUBROUTINE FASTJETPPGENKTWITHAREA(P,NPART,R,PALG,GHMAXRAP,NREP,GHAREA,F77JETS,NJETS)
//   DOUBLE PRECISION P(4,*), R, PALG, GHMAXRAP, GHAREA,  F77JETS(4,*)
//   INTEGER          NPART, NREP, NJETS
// 
// where on input
//
//   P        the input particle 4-momenta
//   NPART    the number of input momenta
//   R        the radius parameter
//   PALG     the power for the generalised kt alg 
//            (1.0=kt, 0.0=C/A,  -1.0 = anti-kt)
//   GHMAXRAP the maximum (abs) rapidity covered by ghosts (FastJet default 6.0) 
//   NREP     the number of repetitions used to evaluate the area (FastJet default 1) 
//   GHAREA   the area of a single ghost (FastJet default 0.01) 
//
// and on output 
//
//   F77JETS  the output jet momenta (whose second dim should be >= NPART)
//            sorted in order of decreasing p_t.
//   NJETS    the number of output jets 
//
// For the values of PALG that correspond to "standard" cases (1.0=kt,
// 0.0=C/A, -1.0 = anti-kt) this routine actually calls the direct
// implementation of those algorithms, whereas for other values of
// PALG it calls the generalised kt implementation.
//
// NOTE: if you are interfacing fastjet to Pythia 6, Pythia stores its
// momenta as a matrix of the form P(4000,5), whereas this fortran
// interface to fastjet expects them as P(4,NPART), i.e. you must take
// the transpose of the Pythia array and drop the fifth component
// (particle mass).
//
void fastjetppgenktwitharea_(const double * p, const int & npart,                   
                             const double & R, const double & palg,
                             const double & ghost_rapmax, const int & nrepeat, const double & ghost_area,
                             double * f77jets, int & njets) {
    
    // prepare jet def
    if (palg == 1.0) {
      jet_def = JetDefinition(kt_algorithm, R);
    }  else if (palg == 0.0) {
      jet_def = JetDefinition(cambridge_algorithm, R);
    }  else if (palg == -1.0) {
      jet_def = JetDefinition(antikt_algorithm, R);
    } else {
      jet_def = JetDefinition(genkt_algorithm, R, palg);
    }
        
    // do everything
    transfer_cluster_transfer(p,npart,jet_def,f77jets,njets,ghost_rapmax,nrepeat,ghost_area);
}


/// same pp generalised-kt+area as above without the caching
/// (invalidating calls to constituents, ... but making this call
/// thread-safe)
void fastjetppgenktwithareanocache_(const double * p, const int & npart,                   
                                    const double & R, const double & palg,
                                    const double & ghost_rapmax, const int & nrepeat, const double & ghost_area,
                                    double * f77jets, int & njets) {
    
  // prepare jet def
  JetDefinition jet_def_local;
  if (palg == 1.0) {
    jet_def_local = JetDefinition(kt_algorithm, R);
  }  else if (palg == 0.0) {
    jet_def_local = JetDefinition(cambridge_algorithm, R);
  }  else if (palg == -1.0) {
    jet_def_local = JetDefinition(antikt_algorithm, R);
  } else {
    jet_def_local = JetDefinition(genkt_algorithm, R, palg);
  }
  
  // do everything
  cluster_nocache(p,npart,jet_def_local,f77jets,njets,ghost_rapmax,nrepeat,ghost_area);
}


//------------------------------------------------------------------------
// routines which access the cached particles/CluterSequence/jets
//
// Note that this is not available in the "nocache" versions of the
// above clustering routines These routines may not work properly in a
// threaded environment unless the
// FASTJET_FORTRAN_THREAD_LOCAL_CACHING flag is defined
//------------------------------------------------------------------------
  
/// f77 interface to provide access to the constituents of a jet found
/// in the jet clustering with one of the above routines.
///
/// Given the index ijet of a jet (in the range 1...njets) obtained in
/// the last call to jet clustering, fill the array
/// constituent_indices, with nconstituents entries, with the indices
/// of the constituents that belong to that jet (which will be in the
/// range 1...npart)
//
// Corresponds to the following Fortran subroutine
// interface structure:
//
//   SUBROUTINE FASTJETCONSTITUENTS(IJET,CONSTITUENT_INDICES,NCONSTITUENTS)
//   INTEGER    IJET
//   INTEGER    CONSTITUENT_INDICES(*)
//   INTEGER    nconstituents
//
void fastjetconstituents_(const int & ijet, 
   	                  int * constituent_indices, int & nconstituents) {
  assert(cs.get() != 0);
  assert(ijet > 0 && ijet <= jets.size());

  vector<PseudoJet> constituents = cs->constituents(jets[ijet-1]);

  nconstituents = constituents.size();
  for (unsigned i = 0; i < nconstituents; i++) {
    constituent_indices[i] = constituents[i].cluster_hist_index()+1;
  }
}


/// f77 interface to provide access to the area of a jet found
/// in the jet clustering with one of the above "...witharea" routines.
///
/// Given the index ijet of a jet (in the range 1...njets) obtained in
/// the last call to jet clustering, return its area. If the jets have
/// not been obtained with a "...witharea" soutine it returns 0.
//
// Corresponds to the following Fortran subroutine
// interface structure:
//
//   FUNCTION FASTJETAREA(IJET)
//   DOUBLE PRECISION FASTJETAREA
//   INTEGER    IJET
//
double fastjetarea_(const int & ijet) {
  assert(ijet > 0 && ijet <= jets.size());
  const ClusterSequenceAreaBase * csab =
                    dynamic_cast<const ClusterSequenceAreaBase *>(cs.get());
  if (csab != 0) {
    // we have areas and can use csab to access all the area-related info
    return csab->area(jets[ijet-1]);
  } else {
    return 0.;
//  Error("No area information associated to this jet."); 
  }
}


/// return the dmin corresponding to the recombination that went from
/// n+1 to n jets (sometimes known as d_{n n+1}).
//
// Corresponds to the following Fortran interface
// 
//   FUNCTION FASTJETDMERGE(N)
//   DOUBLE PRECISION FASTJETDMERGE
//   INTEGER N
//   
double fastjetdmerge_(const int & n) {
  assert(cs.get() != 0);
  return cs->exclusive_dmerge(n);
}


/// return the maximum of the dmin encountered during all recombinations 
/// up to the one that led to an n-jet final state; identical to
/// exclusive_dmerge, except in cases where the dmin do not increase
/// monotonically.
//
// Corresponds to the following Fortran interface
// 
//   FUNCTION FASTJETDMERGEMAX(N)
//   DOUBLE PRECISION FASTJETDMERGEMAX
//   INTEGER N
//   
double fastjetdmergemax_(const int & n) {
  assert(cs.get() != 0);
  return cs->exclusive_dmerge_max(n);
}


/// return the background transverse momentum density per unit scalar
/// area rho, its fluctuation sigma, and the mean area of the jets used for the
/// background estimation in a given event,
/// as evaluated in the range [rapmin,rapmax] in rapidity and [phimin,phimax] in azimuth
//
// Corresponds to the following Fortran interface
// 
//   SUBROUTINE FASTJETGLOBALRHOANDSIGMA(RAPMIN,RAPMAX,PHIMIN,PHIMAX,RHO,SIGMA,MEANAREA)
//   DOUBLE PRECISION RAPMIN,RAPMAX,PHIMIN,PHIMAX
//   DOUBLE PRECISION RHO,SIGMA,MEANAREA
//   
void fastjetglobalrhoandsigma_(const double & rapmin, const double & rapmax,
                               const double & phimin, const double & phimax,
			       double & rho, double & sigma, double & meanarea) {
  const ClusterSequenceAreaBase * csab =
                    dynamic_cast<const ClusterSequenceAreaBase *>(cs.get());
  if (csab != 0) {
      // we have areas and can use csab to access all the area-related info
    Selector range =  SelectorRapRange(rapmin,rapmax) && SelectorPhiRange(phimin,phimax);
      bool use_area_4vector = false;
      csab->get_median_rho_and_sigma(range,use_area_4vector,rho,sigma,meanarea);
  } else {
      Error("Clustering with area is necessary in order to be able to evaluate rho."); 
  }
}




}
