/* Copyright (C) 2020 GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt
   SPDX-License-Identifier: GPL-3.0-only
   Authors: Florian Uhlig [committer] */

// Configuration macro for Geant4 VirtualMC
void Config()
{
  ///    Create the run configuration
  /// In constructor user has to specify the geometry input
  /// and select geometry navigation via the following options:
  /// - geomVMCtoGeant4   - geometry defined via VMC, G4 native navigation
  /// - geomVMCtoRoot     - geometry defined via VMC, Root navigation
  /// - geomRoot          - geometry defined via Root, Root navigation
  /// - geomRootToGeant4  - geometry defined via Root, G4 native navigation
  /// - geomGeant4        - geometry defined via Geant4, G4 native navigation
  ///
  /// The second argument in the constructor selects physics list:
  /// - emStandard         - standard em physics (default)
  /// - emStandard+optical - standard em physics + optical physics
  /// - XYZ                - selected hadron physics list ( XYZ = LHEP, QGSP, ...)
  /// - XYZ+optical        - selected hadron physics list + optical physics
  ///
  /// The third argument activates the special processes in the TG4SpecialPhysicsList,
  /// which implement VMC features:
  /// - stepLimiter       - step limiter (default)
  /// - specialCuts       - VMC cuts
  /// - specialControls   - VMC controls for activation/inactivation selected processes
  /// - stackPopper       - stackPopper process
  /// When more than one options are selected, they should be separated with '+'
  /// character: eg. stepLimit+specialCuts.

  TG4RunConfiguration* runConfiguration =
    new TG4RunConfiguration("geomRoot", "QGSP_BERT_EMV+optical", "stepLimiter+specialCuts");

  /// Create the G4 VMC
  TGeant4* geant4 = new TGeant4("TGeant4", "The Geant4 Monte Carlo", runConfiguration);
  cout << "Geant4 has been created." << endl;

  /// create the Specific stack
  CbmStack* stack = new CbmStack(1000);
  stack->StoreSecondaries(kTRUE);
  //  stack->SetMinPoints(0);
  geant4->SetStack(stack);

  if (FairRunSim::Instance()->IsExtDecayer()) {
    TVirtualMCDecayer* decayer = TPythia6Decayer::Instance();
    geant4->SetExternalDecayer(decayer);
  }

  /// Customise Geant4 setting
  /// (verbose level, global range cut, ..)

  TString configm(gSystem->Getenv("CONFIG_DIR"));
  TString configm1 = configm + "/g4config.in";
  cout << " -I g4Config() using g4conf  macro: " << configm1 << endl;

  // set the common cuts
  TString cuts = configm + "/SetCuts.C";
  cout << "Physics cuts with script \n " << cuts.Data() << endl;
  Int_t cut = gROOT->LoadMacro(cuts.Data());
  if (cut == 0) gInterpreter->ProcessLine("SetCuts()");


  // --- Random seed and maximum number of steps
  size_t buf_size = 100;
  Text_t buffer[buf_size];
  // Get the infomation about the seed value defined by SetSeed from the base class.
  // Since ROOT 6.24 the derrived classes return a differnt value.
  Int_t randomSeed = gRandom->TRandom::GetSeed();
  LOG(info) << "Set Geant4 random seed to " << randomSeed;
  int result_length = snprintf(buffer, buf_size - 1, "/random/setSeeds %i  %i ", randomSeed, randomSeed);
  if (!(result_length > 0 && result_length < static_cast<int>(buf_size))) {
    LOG(fatal) << "Buffer overrun. Random seed for Geant4 would be improper.";
  }
  geant4->ProcessGeantCommand(buffer);

  geant4->SetMaxNStep(10000);  // default is 30000
  geant4->ProcessGeantMacro(configm1.Data());
}