// kstripper - read a hddm_s stream from a event generator
//             and strip out everything except the first k- particle,
//             store them one per event in output like a particle gun.
//
// author: richard.t.jones at uconn.edu
// version: may 1, 2020

#include <iostream>
#include <string>
#include <fstream>

#include <HDDM/hddm_s.hpp>

void usage()
{
   std::cout << "Usage: kstripper <input>.hddm ..." << std::endl;
   std::cout << "Output is written to <input>_stripped.hddm" << std::endl;
   exit(1);
}

int main(int argc, char* argv[])
{
   for (int iarg=1; iarg < argc; ++iarg) {
      std::string infile(argv[iarg]);
      int linfile = infile.size();
      if (linfile < 5 || infile.substr(linfile-5) != ".hddm")
         usage();
      std::string outfile(infile.substr(0,linfile-5) + "_stripped.hddm");
      std::ifstream ifs(infile);
      hddm_s::istream fin(ifs);
      std::cout << "reading from file " << infile << std::endl;
      std::ofstream ofs(outfile);
      hddm_s::ostream fout(ofs);
      hddm_s::HDDM rec;
      while (fin >> rec) {
         hddm_s::ReactionList reas = rec.getReactions();
         if (reas.size() > 0) {
            reas(0).deleteBeams();
            reas(0).deleteTargets();
            reas(0).deleteRandoms();
            hddm_s::VertexList vxs = reas(0).getVertices();
            hddm_s::ProductList prods = vxs(0).getProducts();
            int kminus = -1;
            for (int i=0; i < prods.size(); ++i) {
               if (prods(i).getType() == 11) {
                  kminus = i;
                  break;
               }
            }
            if (kminus+1 < prods.size())
               vxs(0).deleteProducts(-1, kminus+1);
            if (kminus > 0)
               vxs(0).deleteProducts(kminus, 0);
            if (kminus >= 0)
               fout << rec;
         }
      }
   }

   return 0;
}