//C++
#include <type_traits>
#include <vector>
#include <map>
#include <exception>
#include <string>
#include <sstream>
#include <functional>
#include <chrono>
#include <thread>
//root
#include <TROOT.h>
#include <ROOT/TDataFrame.hxx>
#include <TObject.h>
#include <TFile.h>
#include <TString.h>
#include <TTree.h>
#include <TLeaf.h>
#include <TBranch.h>
#include <TFriendElement.h>
#include <TObjArray.h>
#include <TObjString.h>
#include <TEntryList.h>
#include <TEnv.h>
#include <TStopwatch.h>
//BOOST
#include <boost/property_tree/ptree.hpp>
#include <boost/property_tree/info_parser.hpp>
#include <boost/algorithm/string.hpp>
#include <boost/optional.hpp>

template <typename STR = std::string>//template because we want to use r- and l-value std::strings
std::vector<std::string> parse_filenames(STR&& input_file_names, const std::string& workdir = "."){
  std::vector<std::string> input_files;
  //if the input string starts with '@', we have to parse a whole input file
  if(boost::algorithm::starts_with(input_file_names,"@")){
    std::string line;
    std::ifstream myfile;
    myfile.open(input_file_names.substr(1).data());//substr returns the string without the '@'
    if(!myfile)
      myfile.open((workdir + "/" + input_file_names.substr(1)).data());
    while(std::getline (myfile,line))
      input_files.push_back(line);//TODO: could be that there is a trailing character that needs to be removed
    myfile.close();
  }
  else //the input string doesn't start with '@', boost does the work for us :)
    boost::algorithm::split(input_files, input_file_names, boost::algorithm::is_any_of(";"));

  if(input_files.empty()) throw std::runtime_error("Is \"input_file_names\" empty?");
  return input_files;
}

template <typename STR1 = std::string, typename STR2 = std::string>//template because we want to use r- and l-value std::strings
std::unique_ptr<TChain> get_chain(STR1&& treename, STR2&& input_file_names, const std::string& workdir = ".", const std::string& chain_title = "Chain"){
  auto input_files = parse_filenames(input_file_names,workdir);
  std::unique_ptr<TChain> ch{new TChain(treename.data(),chain_title.data())};
  for(auto& infn : input_files)
    ch->Add(infn.data());
  if(!ch->GetFile()){
    std::cout << "Cannot find input files. Trying to prepend workdir." << std::endl;
    for(auto& infn : input_files)
      ch->Add((workdir+"/"+infn).data());
    if(!ch->GetFile()) throw std::runtime_error("TChain is empty. Check inputs!");
  }
  return std::move(ch);
}

int tree_trimmerTDF(const std::string& ifn, const std::string& itn, const std::string& ofn , const std::string& cfn, const std::string& wd = "."){

  TStopwatch clock;
  clock.Start();

  //get input as TChain
  auto chain = get_chain(itn,ifn,wd);
  chain->SetCacheSize();

  //get config-file
  boost::property_tree::ptree configtree;
  boost::property_tree::read_info(cfn,configtree,configtree);

  auto trim_vars = configtree.get_child_optional("variables");

  auto tmp_msg = "Trimming input tree(s) with cut " + configtree.get<std::string>("basiccuts","");
  if(trim_vars)
    printf("%s and writing out %lu variables\n",tmp_msg.data(),configtree.get_child("variables").size());
  else
    printf("%s and writing out full tree\n",tmp_msg.data());

  std::vector<std::string> branches_in = {};
  std::vector<std::string> default_branches_out = {};
  std::vector<std::pair<std::string,std::string>> transformations;
  if(trim_vars)
    for(const auto& var : *trim_vars){
      branches_in.push_back(var.first);
      if(var.first.find("[0]") != std::string::npos){
        default_branches_out.push_back(boost::algorithm::replace_all_copy(var.first, "[0]", "Z"));
        transformations.emplace_back(default_branches_out.back(),var.first);
      }
      else if(auto nn = var.second.get_optional<std::string>("new_name")){
        default_branches_out.push_back(*nn);
        if(auto tfm = var.second.get_optional<std::string>("transformation"))
          transformations.emplace_back(default_branches_out.back(),*tfm);
        else
          transformations.emplace_back(default_branches_out.back(),var.first);
      }
      else if(!var.second.get("to_output",1))
        printf("Using %s only as input branch\n",var.first.data());
      else
        default_branches_out.push_back(var.first);
    }

  //first, we need to know how many events there are and how many threads we use:
  ROOT::EnableImplicitMT();
  ROOT::Experimental::TDataFrame d(*chain.get(),branches_in);
  std::vector<ROOT::Experimental::TDF::TInterface<ROOT::Detail::TDF::TLoopManager>::TInterfaceJittedDefine> df{d};
  if(!transformations.empty())
    for(const auto& tf : transformations){
      printf("transforming %s to a new branch: %s\n",tf.second.data(),tf.first.data());
      df.push_back(df.back().Define(tf.first,tf.second));
    }
  //ROOT::Experimental::TDF::TSnapshotOptions tsno(configtree.get("outfopt","recreate"));
  //.Filter(configtree.get<std::string>("basiccuts",""))
  df.back().Snapshot(configtree.get("outtreename",itn),wd + "/" + ofn,default_branches_out);//,tsno

  clock.Stop();
  clock.Print();

  return 0;
}