From bc2e5fa38af3ebed0c21ad41cb6b47b1aa996caf Mon Sep 17 00:00:00 2001
From: Valentin Volkl <valentin.volkl@cern.ch>
Date: Wed, 20 Oct 2021 15:54:26 +0200
Subject: [PATCH] [pythia8] add --pythiaExtraSettings property

---
 k4Gen/CMakeLists.txt                     | 11 ++++++++++-
 k4Gen/options/pythia.py                  |  1 +
 k4Gen/src/components/PythiaInterface.cpp |  8 ++++++--
 k4Gen/src/components/PythiaInterface.h   |  3 +++
 4 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/k4Gen/CMakeLists.txt b/k4Gen/CMakeLists.txt
index 5560031..8ea62fe 100644
--- a/k4Gen/CMakeLists.txt
+++ b/k4Gen/CMakeLists.txt
@@ -10,7 +10,7 @@ find_package(EvtGen)
 file(GLOB k4gen_plugin_sources src/components/*.cpp)
 gaudi_add_module(k4Gen
                  SOURCES ${k4gen_plugin_sources}
-                 LINK Gaudi::GaudiKernel ${HEPMC_LIBRARIES} Gaudi::GaudiAlgLib k4FWCore::k4FWCore k4FWCore::k4FWCorePlugins ${HEPPDT_LIBRARIES} ${EVTGEN_LIBRARIES} EDM4HEP::edm4hep EDM4HEP::edm4hepDict)
+                 LINK Gaudi::GaudiKernel ${HEPMC_LIBRARIES} Gaudi::GaudiAlgLib k4FWCore::k4FWCore ${HEPPDT_LIBRARIES} ${EVTGEN_LIBRARIES} EDM4HEP::edm4hep EDM4HEP::edm4hepDict)
 
 target_include_directories(k4Gen PUBLIC ${PYTHIA8_INCLUDE_DIRS}
   $<BUILD_INTERFACE:${CMAKE_CURRENT_LIST_DIR}/include>
@@ -56,6 +56,15 @@ add_test(NAME Pythia8Default
               )
 set_test_env(Pythia8Default)
 
+add_test(NAME Pythia8ExtraSettings
+               WORKING_DIRECTORY ${CMAKE_CURRENT_LIST_DIR}
+               COMMAND  k4run ${CMAKE_CURRENT_LIST_DIR}/options/pythia.py  --pythiaExtraSettings "Beams:idA = 13" "Beams:idB = -13"
+              )
+set_tests_properties(Pythia8ExtraSettings PROPERTIES
+  PASS_REGULAR_EXPRESSION "We collide mu- with mu"
+  )
+set_test_env(Pythia8ExtraSettings)
+
 #--- Install the example options to the directory where the spack installation
 #--- points the $K4GEN environment variable
 install(DIRECTORY ${CMAKE_CURRENT_LIST_DIR}/options
diff --git a/k4Gen/options/pythia.py b/k4Gen/options/pythia.py
index fba3c0e..57fa2ed 100644
--- a/k4Gen/options/pythia.py
+++ b/k4Gen/options/pythia.py
@@ -39,6 +39,7 @@
 pythia8gentool.pythiacard = pythiafile
 pythia8gentool.doEvtGenDecays = False
 pythia8gentool.printPythiaStatistics = True
+pythia8gentool.pythiaExtraSettings = [""]
 
 from Configurables import GenAlg
 pythia8gen = GenAlg("Pythia8")
diff --git a/k4Gen/src/components/PythiaInterface.cpp b/k4Gen/src/components/PythiaInterface.cpp
index 115f8f1..f1c9743 100644
--- a/k4Gen/src/components/PythiaInterface.cpp
+++ b/k4Gen/src/components/PythiaInterface.cpp
@@ -35,7 +35,7 @@ StatusCode PythiaInterface::initialize() {
 
   StatusCode sc = GaudiTool::initialize();
   if (!sc.isSuccess()) return sc;
-  if (m_pythiacard.empty()) {
+  if (m_pythiacard.empty() && m_pythia_extrasettings.size() < 2) {
     return Error("Define Pythia8 configuration file (*.cmd)!");
   }
 
@@ -62,7 +62,11 @@ StatusCode PythiaInterface::initialize() {
 
   // Read Pythia configuration files
   m_pythiaSignal->readFile(m_pythiacard.value().c_str());
-  // do not bother with pileup configuration if no pileup
+
+  // Apply any extra pythia8 settings
+  for (auto pythiacommand: m_pythia_extrasettings) {
+    m_pythiaSignal->settings.readString(pythiacommand);
+  }
 
   // Initialize variables from configuration file
   m_nAbort = m_pythiaSignal->settings.mode("Main:timesAllowErrors");  // how many aborts before run stops
diff --git a/k4Gen/src/components/PythiaInterface.h b/k4Gen/src/components/PythiaInterface.h
index 276d2ba..801d31d 100644
--- a/k4Gen/src/components/PythiaInterface.h
+++ b/k4Gen/src/components/PythiaInterface.h
@@ -53,6 +53,9 @@ class PythiaInterface : public GaudiTool, virtual public IHepMCProviderTool {
   /// Name of Pythia configuration file with Pythia simulation settings & input LHE file (if required)
   Gaudi::Property<std::string> m_pythiacard{this, "pythiacard", "Pythia_minbias_pp_100TeV.cmd"
                                                            "Name of the Pythia cmd file"};
+
+  Gaudi::Property<std::vector<std::string>> m_pythia_extrasettings{this, "pythiaExtraSettings", {""},
+                                                           "Additional strings with Pythia settings, applied after the card."};
   /// Pythia8 engine for jet clustering
   std::unique_ptr<Pythia8::SlowJet> m_slowJet{nullptr};
   // Tool to smear vertices