// EPOS IO class

#include "GeneratorInterface/ReggeGribovPartonMCInterface/interface/IO_EPOS.h"
#include "HepMC/GenEvent.h"
#include <cstdio>  // needed for formatted output using sprintf

using namespace HepMC;

namespace EPOS {

  unsigned int EPOS_Wrapper::s_sizeof_int = 4;
  unsigned int EPOS_Wrapper::s_sizeof_real = sizeof(double);
  unsigned int EPOS_Wrapper::s_max_number_entries = 99900;

  IO_EPOS::IO_EPOS()
      : m_trust_mothers_before_daughters(true),
        m_trust_both_mothers_and_daughters(false),
        m_print_inconsistency_errors(true),
        m_trust_beam_particles(true),
        m_skip_nucl_frag(false) {}

  IO_EPOS::~IO_EPOS() {}

  void IO_EPOS::print(std::ostream& ostr) const {
    ostr << "IO_EPOS: reads an event from the FORTRAN EPOS g "
         << "common block. \n"
         << " trust_mothers_before_daughters = " << m_trust_mothers_before_daughters
         << " trust_both_mothers_and_daughters = " << m_trust_both_mothers_and_daughters
         << ", print_inconsistency_errors = " << m_print_inconsistency_errors << std::endl;
  }

  bool IO_EPOS::fill_next_event(HepMC::GenEvent* evt) {
    //
    // 1. test that evt pointer is not null and set event number
    if (!evt) {
      std::cerr << "IO_EPOS::fill_next_event error - passed null event." << std::endl;
      return false;
    }
    evt->set_event_number(EPOS_Wrapper::event_number());
    //
    // 2. create a particle instance for each EPOS entry and fill a map
    //    create a vector which maps from the EPOS particle index to the
    //    GenParticle address
    //    (+1 in size accounts for hepevt_particle[0] which is unfilled)
    std::vector<HepMC::GenParticle*> hepevt_particle(EPOS_Wrapper::number_entries() + 1);
    hepevt_particle[0] = nullptr;
    for (int i1 = 1; i1 <= EPOS_Wrapper::number_entries(); ++i1) {
      hepevt_particle[i1] = build_particle(i1);
    }

    HepMC::GenVertex* primaryVertex = new HepMC::GenVertex(HepMC::FourVector(0, 0, 0, 0), 0);
    evt->add_vertex(primaryVertex);
    if (!evt->signal_process_vertex())
      evt->set_signal_process_vertex(primaryVertex);

    std::set<HepMC::GenVertex*> new_vertices;
    //
    // Here we assume that the first two particles in the list
    // are the incoming beam particles.
    if (trust_beam_particles()) {
      evt->set_beam_particles(hepevt_particle[1], hepevt_particle[2]);
    }
    //
    // 3.+4. loop over EPOS particles AGAIN, this time creating vertices
    //MODIFICATION FROM HEPMC!! skipping nuclear fragments in event if option is set
    for (int i = 1; i <= EPOS_Wrapper::number_entries(); ++i) {
      if (m_skip_nucl_frag && abs(hepevt_particle[i]->pdg_id()) >= 1000000000)
        continue;
      // We go through and build EITHER the production or decay
      // vertex for each entry in hepevt, depending on the switch
      // m_trust_mothers_before_daughters (new 2001-02-28)
      // Note: since the EPOS pointers are bi-directional, it is
      //
      // 3. Build the production_vertex (if necessary)
      if (m_trust_mothers_before_daughters || m_trust_both_mothers_and_daughters) {
        build_production_vertex(i, hepevt_particle, evt);
      }
      //
      // 4. Build the end_vertex (if necessary)
      //    Identical steps as for production vertex
      if (!m_trust_mothers_before_daughters || m_trust_both_mothers_and_daughters) {
        build_end_vertex(i, hepevt_particle, evt);
      }
    }
    // 5.             01.02.2000
    // handle the case of particles in EPOS which come from nowhere -
    //  i.e. particles without mothers or daughters.
    //  These particles need to be attached to a vertex, or else they
    //  will never become part of the event. check for this situation
    //MODIFICATION FROM HEPMC!! skipping nuclear fragments in event if option is set
    for (int i3 = 1; i3 <= EPOS_Wrapper::number_entries(); ++i3) {
      if (m_skip_nucl_frag && abs(hepevt_particle[i3]->pdg_id()) >= 1000000000)
        continue;
      if (!hepevt_particle[i3]->end_vertex() && !hepevt_particle[i3]->production_vertex()) {
        HepMC::GenVertex* prod_vtx = new GenVertex();
        prod_vtx->add_particle_out(hepevt_particle[i3]);
        evt->add_vertex(prod_vtx);
      }
    }
    return true;
  }

  void IO_EPOS::write_event(const GenEvent* evt) {
    //
    if (!evt)
      return;
    //
    // map all particles onto a unique index
    std::vector<HepMC::GenParticle*> index_to_particle(EPOS_Wrapper::max_number_entries() + 1);
    index_to_particle[0] = nullptr;
    std::map<HepMC::GenParticle*, int> particle_to_index;
    int particle_counter = 0;
    for (HepMC::GenEvent::vertex_const_iterator v = evt->vertices_begin(); v != evt->vertices_end(); ++v) {
      // all "mothers" or particles_in are kept adjacent in the list
      // so that the mother indices in hepevt can be filled properly
      for (HepMC::GenVertex::particles_in_const_iterator p1 = (*v)->particles_in_const_begin();
           p1 != (*v)->particles_in_const_end();
           ++p1) {
        ++particle_counter;
        if (particle_counter > EPOS_Wrapper::max_number_entries())
          break;
        index_to_particle[particle_counter] = *p1;
        particle_to_index[*p1] = particle_counter;
      }
      // daughters are entered only if they aren't a mother of
      // another vtx
      for (HepMC::GenVertex::particles_out_const_iterator p2 = (*v)->particles_out_const_begin();
           p2 != (*v)->particles_out_const_end();
           ++p2) {
        if (!(*p2)->end_vertex()) {
          ++particle_counter;
          if (particle_counter > EPOS_Wrapper::max_number_entries()) {
            break;
          }
          index_to_particle[particle_counter] = *p2;
          particle_to_index[*p2] = particle_counter;
        }
      }
    }
    if (particle_counter > EPOS_Wrapper::max_number_entries()) {
      particle_counter = EPOS_Wrapper::max_number_entries();
    }
    //
    // fill the EPOS event record
    EPOS_Wrapper::set_event_number(evt->event_number());
    EPOS_Wrapper::set_number_entries(particle_counter);
    for (int i = 1; i <= particle_counter; ++i) {
      EPOS_Wrapper::set_status(i, index_to_particle[i]->status());
      EPOS_Wrapper::set_id(i, index_to_particle[i]->pdg_id());
      FourVector m = index_to_particle[i]->momentum();
      EPOS_Wrapper::set_momentum(i, m.px(), m.py(), m.pz(), m.e());
      EPOS_Wrapper::set_mass(i, index_to_particle[i]->generatedMass());
      // there should ALWAYS be particles in any vertex, but some generators
      // are making non-kosher HepMC events
      if (index_to_particle[i]->production_vertex() && index_to_particle[i]->production_vertex()->particles_in_size()) {
        FourVector p = index_to_particle[i]->production_vertex()->position();
        EPOS_Wrapper::set_position(i, p.x(), p.y(), p.z(), p.t());
        int num_mothers = index_to_particle[i]->production_vertex()->particles_in_size();
        int first_mother =
            find_in_map(particle_to_index, *(index_to_particle[i]->production_vertex()->particles_in_const_begin()));
        int last_mother = first_mother + num_mothers - 1;
        if (first_mother == 0)
          last_mother = 0;
        EPOS_Wrapper::set_parents(i, first_mother, last_mother);
      } else {
        EPOS_Wrapper::set_position(i, 0, 0, 0, 0);
        EPOS_Wrapper::set_parents(i, 0, 0);
      }
      EPOS_Wrapper::set_children(i, 0, 0);
    }
  }

  void IO_EPOS::build_production_vertex(int i, std::vector<HepMC::GenParticle*>& hepevt_particle, GenEvent* evt) {
    HepMC::GenParticle* p = hepevt_particle[i];
    // a. search to see if a production vertex already exists
    int mother = EPOS_Wrapper::first_parent(i);
    HepMC::GenVertex* prod_vtx = p->production_vertex();
    while (!prod_vtx && mother > 0) {
      prod_vtx = hepevt_particle[mother]->end_vertex();
      if (prod_vtx)
        prod_vtx->add_particle_out(p);
      // increment mother for next iteration
      if (++mother > EPOS_Wrapper::last_parent(i))
        mother = 0;
    }
    // b. if no suitable production vertex exists - and the particle
    // has atleast one mother or position information to store -
    // make one
    HepMC::FourVector prod_pos(EPOS_Wrapper::x(i), EPOS_Wrapper::y(i), EPOS_Wrapper::z(i), EPOS_Wrapper::t(i));
    if (!prod_vtx && (EPOS_Wrapper::number_parents(i) > 0 || prod_pos != FourVector(0, 0, 0, 0))) {
      prod_vtx = new HepMC::GenVertex();
      prod_vtx->add_particle_out(p);
      evt->add_vertex(prod_vtx);
    }
    // c. if prod_vtx doesn't already have position specified, fill it
    if (prod_vtx && prod_vtx->position() == FourVector(0, 0, 0, 0)) {
      prod_vtx->set_position(prod_pos);
    }
    // d. loop over mothers to make sure their end_vertices are
    //     consistent
    mother = EPOS_Wrapper::first_parent(i);
    while (prod_vtx && mother > 0) {
      if (!hepevt_particle[mother]->end_vertex()) {
        // if end vertex of the mother isn't specified, do it now
        prod_vtx->add_particle_in(hepevt_particle[mother]);
      } else if (hepevt_particle[mother]->end_vertex() != prod_vtx) {
        // problem scenario --- the mother already has a decay
        // vertex which differs from the daughter's produciton
        // vertex. This means there is internal
        // inconsistency in the EPOS event record. Print an
        // error
        // Note: we could provide a fix by joining the two
        //       vertices with a dummy particle if the problem
        //       arrises often with any particular generator.
        if (m_print_inconsistency_errors)
          std::cerr << "HepMC::IO_EPOS: inconsistent mother/daugher "
                    << "information in EPOS event " << EPOS_Wrapper::event_number() << ". \n I recommend you try "
                    << "inspecting the event first with "
                    << "\n\tEPOS_Wrapper::check_hepevt_consistency()"
                    << "\n This warning can be turned off with the "
                    << "IO_EPOS::print_inconsistency_errors switch." << std::endl;
      }
      if (++mother > EPOS_Wrapper::last_parent(i))
        mother = 0;
    }
  }

  void IO_EPOS::build_end_vertex(int i, std::vector<HepMC::GenParticle*>& hepevt_particle, GenEvent* evt) {
    //    Identical steps as for build_production_vertex
    HepMC::GenParticle* p = hepevt_particle[i];
    // a.
    int daughter = EPOS_Wrapper::first_child(i);
    HepMC::GenVertex* end_vtx = p->end_vertex();
    while (!end_vtx && daughter > 0) {
      end_vtx = hepevt_particle[daughter]->production_vertex();
      if (end_vtx)
        end_vtx->add_particle_in(p);
      if (++daughter > EPOS_Wrapper::last_child(i))
        daughter = 0;
    }
    // b. (different from 3c. because EPOS particle can not know its
    //        decay position )
    if (!end_vtx && EPOS_Wrapper::number_children(i) > 0) {
      end_vtx = new GenVertex();
      end_vtx->add_particle_in(p);
      evt->add_vertex(end_vtx);
    }
    // c+d. loop over daughters to make sure their production vertices
    //    point back to the current vertex.
    //    We get the vertex position from the daughter as well.
    daughter = EPOS_Wrapper::first_child(i);
    while (end_vtx && daughter > 0) {
      if (!hepevt_particle[daughter]->production_vertex()) {
        // if end vertex of the mother isn't specified, do it now
        end_vtx->add_particle_out(hepevt_particle[daughter]);
        //
        // 2001-03-29 M.Dobbs, fill vertex the position.
        if (end_vtx->position() == FourVector(0, 0, 0, 0)) {
          // again mm to cm conversion
          FourVector prod_pos(EPOS_Wrapper::x(daughter),
                              EPOS_Wrapper::y(daughter),
                              EPOS_Wrapper::z(daughter),
                              EPOS_Wrapper::t(daughter));
          if (prod_pos != FourVector(0, 0, 0, 0)) {
            end_vtx->set_position(prod_pos);
          }
        }
      } else if (hepevt_particle[daughter]->production_vertex() != end_vtx) {
        // problem scenario --- the daughter already has a prod
        // vertex which differs from the mother's end
        // vertex. This means there is internal
        // inconsistency in the EPOS event record. Print an
        // error
        if (m_print_inconsistency_errors)
          std::cerr << "HepMC::IO_EPOS: inconsistent mother/daugher "
                    << "information in EPOS event " << EPOS_Wrapper::event_number() << ". \n I recommend you try "
                    << "inspecting the event first with "
                    << "\n\tEPOS_Wrapper::check_hepevt_consistency()"
                    << "\n This warning can be turned off with the "
                    << "IO_EPOS::print_inconsistency_errors switch." << std::endl;
      }
      if (++daughter > EPOS_Wrapper::last_child(i))
        daughter = 0;
    }
    if (!p->end_vertex() && !p->production_vertex()) {
      // Added 2001-11-04, to try and handle Isajet problems.
      build_production_vertex(i, hepevt_particle, evt);
    }
  }

  HepMC::GenParticle* IO_EPOS::build_particle(int index) {
    //
    HepMC::GenParticle* p = new GenParticle(
        FourVector(EPOS_Wrapper::px(index), EPOS_Wrapper::py(index), EPOS_Wrapper::pz(index), EPOS_Wrapper::e(index)),
        EPOS_Wrapper::id(index),
        EPOS_Wrapper::status(index));
    p->setGeneratedMass(EPOS_Wrapper::m(index));
    p->suggest_barcode(index);
    return p;
  }

  int IO_EPOS::find_in_map(const std::map<HepMC::GenParticle*, int>& m, HepMC::GenParticle* p) const {
    std::map<HepMC::GenParticle*, int>::const_iterator iter = m.find(p);
    if (iter == m.end())
      return 0;
    return iter->second;
  }

}  // namespace EPOS