#include <iostream>
#include <iomanip>
#include <fstream.h>
#include <sstream>
#include <vector>
#include <string>
#include "TTree.h"
#include "TFile.h"

//class ifstream;

void txt2tree( char* infilename, char* outfilename ) {

  // Macro to read data from an ascii file and create a root file with a TTree
  //  gROOT->Reset();

  // open file
  ifstream infile;
  infile.open(infilename);

  // read first non-empty line
  std::string line;
  line.clear();
  while (line.size() == 0) {
    getline(infile,line,'\n');
  }

  // find variable names and remove whitespaces
  std::string::size_type pos = 0;
  std::vector<std::string> var_names;
  while ( pos < line.length() ) {
    pos=line.find(" ");
    if ( pos != 0 ) var_names.push_back( line.substr(0,pos) );
    line = line.substr(pos+1,line.length());
    //    std::cout << "line="<<line<<std::endl;
  }
  if (line.length() > 0) {
    var_names.push_back(line);
  }
  //  std::cout << "last line="<< line << std::endl;

  // declare vector to contain floating point variables and initialize to zero
  std::vector<float> variables;
  variables.resize(var_names.size(), 0);

  // create a TTree
  TTree *tree = new TTree("T",infilename);

  // create tree branches 
  for ( unsigned int i=0; i<var_names.size(); ++i ) {
    std::string format = var_names[i]+"/F";
    tree->Branch(var_names[i].c_str(),&(variables[i]),format.c_str());
  }

  // fill the tree from the values in ASCII file 
  unsigned int i=0;
  while ( !infile.eof() ) {
    infile >> variables[i];
    i++;
    // reset i and write variables to tree
    if ( i == var_names.size() ) {
      //      for ( unsigned int j=0; j<var_names.size(); ++j ) std::cout << var_names[j] << "=" << variables[j] << " ";
      //      std::cout << std::endl;
      tree->Fill();
      i=0;
    }
  }  

  // create a new ROOT file and write TTree into it
  TFile *outfile = new TFile(outfilename,"RECREATE");
  tree->Write();
  tree->Print();

  // close files
  infile.close();
  outfile->Close();

  return;
}

int main(int argc, char* argv[]) {

  if (argc == 2 && std::string(argv[1])=="-h") {
    std::cout << std::endl;
    std::cout << "TEXT2TREE -- RG,9 Oct.2009" << std::endl;
    std::cout << std::endl;
    std::cout << "txt2tree reads formatted data from an ASCII file and writes it as a ROOT TTree" << std::endl;
    std::cout << "Input file format: " << std::endl;
    std::cout << "First line: variable names separated by one or more spaces" << std::endl;
    std::cout << "Other lines: variable values in columns (as many as variable names)" << std::endl;
    std::cout << std::endl;
    std::cout << "usage: txt2tree [input file] [root file]" << std::endl;
    std::cout << std::endl;

  } else if (argc == 3) {
    std::cout << std::endl;
    std::cout << "txt2tree: reading ASCII file " << argv[1] << " and writing ROOT file " << argv[2] << std::endl;
    std::cout << std::endl;
    txt2tree( argv[1], argv[2] );

  } else {
    std::cout << "ERROR: two arguments required; do txt2tree -h" << std::endl;
    return 1;
  }

  return 0;
}