// PosGen_FillShellRopes.cc
// Contact person: Juan-Pablo Yanez <j.p.yanez@ualberta.ca>
// See PosGen_FillShellRopes.hh for more details
//———————————————————————//
#include <CLHEP/Units/PhysicalConstants.h>
using namespace CLHEP;

#include <RAT/PosGen_FillShellRopes.hh>
#include <RAT/Log.hh>
#include <RAT/StringUtil.hh>
#include <RAT/string_utilities.hpp>
#include <RAT/GLG4VertexGen.hh>

#include <G4TransportationManager.hh>
#include <G4Navigator.hh>
#include <G4PhysicalVolumeStore.hh>
#include <Randomize.hh>

#include <TMath.h>

#include <sstream>

namespace RAT
{
  PosGen_FillShellRopes::PosGen_FillShellRopes(const char *arg_dbname)
    : GLG4PosGen(arg_dbname), pos(0.,0.,0.), max_iterations(10000000) { }


  // PosGen_FillShellRopes::SetState parses a string of generator parameters
  // to set the appropriate local variables.
  void PosGen_FillShellRopes::SetState(G4String newValues)
  {
    std::vector<std::string> params = split(newValues, " ");

    // it is a GLG4 convention that SetState with a null string argument
    // should print usage information
    if (newValues.length() == 0)
    {
      G4cout << "Current state of this GLG4PosGen_PointPaintFill:\n"
             << " \"" << GetState() << "\"\n" << G4endl;
      G4cout << "Usage: x_mm y_mm z_mm r_in r_out volname" << G4endl;
      return;
    }

    // Setting the values
    periodicity   = (360./10.)*pi/180.; // 36deg in rad
    mincosphi     = 0.6;
    maxcostheta   = 0.72;

    double x, y, z;
    G4ThreeVector vpos;

    x = to_double(params[0]);
    y = to_double(params[1]);
    z = to_double(params[2]);
    ri = to_double(params[3]);
    ro = to_double(params[4]);
    volname = params[5]; // hold_up or hold_down

    pos = G4ThreeVector(x, y, z);

    if(ri > ro) {
      info << "PosGen_FillShellRopes::SetState: Inner radius is greater than outer radius, flipping them.\n";
      double radius_temp = ro;
      ro = ri;
      ri = radius_temp;
    }

  }

  // PosGen_FillShellRopes::GetState returns a G4String containing the values
  // of all generator parameters, formatted like the input string
  G4String PosGen_FillShellRopes::GetState() const
  {
    std::string rv = dformat("%d %d %d %d %d %s", pos.x(), pos.y(), pos.z(), ri, ro,volname.c_str());
    return G4String(rv);
  }

  // PosGen_FillShellRopes::GeneratePosition sets argResult to a point uniformly
  // sampled from a spherical shell centered at the given origin (pos) and
  // within the specified physical volume (volname).
  void PosGen_FillShellRopes::GeneratePosition(G4ThreeVector &argResult)
  {
    G4Navigator* gNavigator = G4TransportationManager::GetTransportationManager()->GetNavigatorForTracking();
    G4ThreeVector rpos;
    G4bool holdup_system;

    int iterations = 0;
    while(1) {
      // a point is found by sampling uniformly in r^3, cos(theta), and phi
      double r = pow(G4UniformRand() * (pow(ro, 3.0) - pow(ri, 3.0)) + pow(ri, 3.0), 1.0/3);
      double phi = pi * G4UniformRand();
      double theta = acos(2.0 * G4UniformRand() - 1);
      if(G4UniformRand() > 0.5)
        theta = -theta;

      double x = r * sin(theta) * cos(phi);
      double y = r * sin(theta) * sin(phi);
      double z = r * cos(theta);

      double phi2 = atan2(y,x);
      double costheta = z/r;

      rpos = G4ThreeVector(x, y, z);
      rpos += pos;

      iterations++;
      Log::Assert(iterations<max_iterations, "PosGen_FillShellRopes::GeneratePosition: Failed to find a point within volumes in " + to_string(max_iterations) + " tries.");

      // Bool that finds if event seems to be in the HOLD UP system
      holdup_system = (cos(2*TMath::Pi()*phi2/periodicity) > mincosphi) && (costheta<maxcostheta);
      // If hold up requested, and value is False reject position
      if (volname == "hold_up"){
        if (!holdup_system){
          continue;
        }
      }else{ // If hold down requested and holdup is true, reject
        if (holdup_system){
          continue;
        }
      }

      // Only check the volume afterwards
      std::string thisvol = gNavigator->LocateGlobalPointAndSetup(rpos,0,true)->GetName();
      //G4cout<<"Volume generated "<<thisvol<<"\n";
      if (thisvol == "snorope"){
        break;
      }
    }

    debug << "PosGen_FillShellRopes::GeneratePosition: Point in volume found in " << iterations << " tries.\n";

    argResult = rpos;
  }

} // namespace RAT