//#include <ROOT/REveElement.hxx>
//#include <ROOT/REveScene.hxx>
//#include <ROOT/REveManager.hxx>
//#include <ROOT/REveTrack.hxx>
//#include <ROOT/REveTrackPropagator.hxx>

#include "TEveManager.h"
#include "TGeoManager.h"
#include "TEveGeoNode.h"
#include "TEvePointSet.h"
#include "TEveBoxSet.h"
#include "TEveLine.h"
#include "TEveScene.h"
#include "TEveEventManager.h"

#include "TGeoManager.h"
#include "TGeoMaterial.h"
#include "TGeoMedium.h"
#include "TGeoVolume.h"
#include "TGeoTrack.h"
#include "TParticle.h"
#include "TRandom.h"
#include "TTimer.h"
#include "TPad.h"
#include "TROOT.h"
#include "RtypesCore.h"

//==============================================================================
// Constants.
//------------------------------------------------------------------------------
const Double_t kX_max  = 300;       // Top Volume Box dimensions
const Double_t kY_max  = 300;
const Double_t kZ_max  = 300;

const Double_t kR_min = 240;        // child Tube dimensions
const Double_t kR_max = 250;
const Double_t kZ_d   = 300;

const TLorentzVector vrtxo    = TLorentzVector(0.,  0.,     0.,    0.);   // collision point
const TEveVectorD    origin   = TEveVectorD(0., 0., 0.);
//------------------------------------------------------------------------------

void pbr_create_geo()
{
// define a new geometry object "EZB_sim_geo"
    if (gGeoManager) {
       delete gGeoManager;
    }                      
// new call below initializes gGeoManager global pointer
    new TGeoManager("EZB_sim_geo", "simple detector geometry-cube enclosure+cylinder");

//-- materials definitions
     TGeoMaterial *matVacuum = new TGeoMaterial("Vacuum", 0,0,0);
     TGeoMaterial *matAl = new TGeoMaterial("Al", 26.98,13,2.7);
//-- media definitions
     TGeoMedium *Vacuum = new TGeoMedium("Vacuum",1, matVacuum);
     TGeoMedium *Al = new TGeoMedium("Root Material",2, matAl);
     matVacuum->SetTransparency(50);

// [0] this is the top volume cube
     TGeoVolume *top = gGeoManager->MakeBox("TOP",Vacuum,kX_max,kY_max,kZ_max);
     gGeoManager->SetTopVisible();
     gGeoManager->SetTopVolume(top);
     top->SetFillColor(3);

// [1] this is the cylinder
     TGeoVolume *vcylinder= gGeoManager->MakeTube("Cylinder",Al, kR_min, kR_max, kZ_d);  // Al <-> nullptr <- placeholder for TGeoMedium*
                 vcylinder->SetLineColor(kGreen);
     TGeoShape  *scylinder= vcylinder->GetShape();

     top->AddNode(vcylinder,1);

     gGeoManager->CloseGeometry();   

}

void qpbr_tracks()
{

     Double_t t_coll  = 1.;   // collision time (calc. below?)
     Double_t rfP0    = 1.0;  // set incoming beam particle momentum
     Double_t rfE0    = 10.0; // set incoming beam particle energy 

//_ geometry rendering
     pbr_create_geo();
     TEveManager::Create();   // this initializes gEve global pointer
     TEveGeoTopNode* top = new TEveGeoTopNode(gGeoManager, gGeoManager->GetTopNode()); // "/TOP_1/Cylinder_1"
     top->SetVisOption(0);
     top->SetVisLevel(6);
     gEve->AddGlobalElement(top);
//_ end geometry rendering

//_ track generation
     auto propag = new TEveTrackPropagator();
     propag->SetStepper(TEveTrackPropagator::kRungeKutta);
     //propag->SetRnrDecay(kFALSE);

     auto tracks  = new TEveElementList("Tracks");

     auto pmc = new TEvePathMarkD(TEvePathMarkD::kDecay, origin, t_coll); // collision vertex mark
                                                                          // at the origin
     // 2x primary particle beams
     Int_t Nptracks = 2;             
     auto p1 = new TParticle();
     auto p2 = new TParticle();
     // primary vertex
     p1->SetProductionVertex(0.,0., kZ_max   ,0.);
     p2->SetProductionVertex(0.,0.,-kZ_max   ,0.);
     p1->SetMomentum(0.,0.,-rfP0,rfE0);
     p2->SetMomentum(0.,0.,+rfP0,rfE0);

     auto track = new TEveTrack(p1,0,propag);
     track->AddPathMark(*pmc);
     track->MakeTrack();
     track->SetMainColor(kYellow);
     tracks->AddElement(track);

          track = new TEveTrack(p2,1,propag);
     track->AddPathMark(*pmc);
     track->MakeTrack();
     track->SetMainColor(kYellow);
     tracks->AddElement(track);

     // 4x secondary particle products (arbitrary Energy+Momentum)
     auto rnd = gRandom;
     Double_t rfE;

     Int_t Nstracks = 4;
     for (Int_t i =Nptracks; i<(Nstracks+Nptracks); i++) {

       auto p = new TParticle();
       rfE = rnd->Uniform(rfE0);
       p->SetProductionVertex(vrtxo);
       p->SetMomentum(3.*pow(-1,i),0.,(1.+i)*pow(-1,i),rfE);

       auto track = new TEveTrack(p,i,propag);
       track->MakeTrack();
       track->SetMainColor(kBlue);
       track->SetName(Form("track %d",i+1));
       track->SetLineColor((pow(-1,i) > 0 ? kBlue : kRed));

       track->SetRnrPoints(kTRUE);
       track->SetMarkerStyle(4);
       track->PrintPathMarks();

       tracks->AddElement(track);

     }

     gEve->GetEventScene()->AddElement(tracks);

//_ end track generation

     gEve->FullRedraw3D(kTRUE);

}