// $Id$
//
//  Copyright (C) 2009 Greg Landrum
//   @@ All Rights Reserved @@
//  This file is part of the RDKit.
//  The contents are covered by the terms of the BSD license
//  which is included in the file license.txt, found at the root
//  of the RDKit source tree.
//

#include <RDGeneral/Invariant.h>
#include <GraphMol/RDKitBase.h>
#include <GraphMol/MolPickler.h>
#include <GraphMol/SmilesParse/SmilesParse.h>
#include <GraphMol/SmilesParse/SmilesWrite.h>
#include <RDGeneral/RDLog.h>
#include <vector>
#include <algorithm>
#include <boost/mpi.hpp>
#include <iostream>
#include <cstdlib>
#include <string>

namespace mpi = boost::mpi;

void broadcastMols(mpi::communicator &world,
                   std::vector<RDKit::ROMOL_SPTR> &mols) {
  std::vector<std::string> data;
  if (world.rank() == 0) {
    data.reserve(mols.size());
    for (const auto &ptr : mols) {
      std::string pickle;
      RDKit::MolPickler::pickleMol(*ptr, pickle);
      data.push_back(pickle);
    }
  }
  broadcast(world, data, 0);
  if (world.rank() != 0) {
    mols.reserve(data.size());
    for (const std::string &pickle : data) {
      RDKit::ROMol *mol = new RDKit::ROMol;
      RDKit::MolPickler::molFromPickle(pickle, mol);
      mols.push_back(RDKit::ROMOL_SPTR(mol));
    }
  }
}

int main(int argc, char *argv[]) {
  mpi::environment env(argc, argv);
  mpi::communicator world;

  // construct the data:
  std::vector<RDKit::ROMOL_SPTR> data;
  if (world.rank() == 0) {
    for (unsigned int i = 0; i < 100; ++i) {
      std::string txt(i + 1, 'C');
      RDKit::ROMol *m = RDKit::SmilesToMol(txt);
      data.push_back(RDKit::ROMOL_SPTR(m));
    }
  }

  // broadcast it:
  broadcastMols(world, data);

  // process it:
  std::vector<unsigned int> res;
  std::vector<std::vector<unsigned int>> allRes;
  // start by finding our chunk:
  unsigned int nProcs = world.size();
  unsigned int chunkSize = data.size() / nProcs;
  unsigned int extraBits = data.size() % nProcs;

  // handle extra bits on the root node:
  if (world.rank() == 0) {
    for (unsigned int i = 0; i < extraBits; ++i) {
      res.push_back(data[i]->getNumAtoms());
    }
  }

  unsigned int pos = extraBits + world.rank() * chunkSize;
  for (unsigned int i = 0; i < chunkSize; ++i) {
    res.push_back(data[pos++]->getNumAtoms());
  }

  if (world.rank() == 0) {
    gather(world, res, allRes, 0);
  } else {
    gather(world, res, 0);
  }

  // reporting:
  if (world.rank() == 0) {
    for (unsigned int i = 0; i < static_cast<unsigned int>(world.size()); ++i) {
      std::cout << "results from process " << i << ": ";
      std::copy(allRes[i].begin(), allRes[i].end(),
                std::ostream_iterator<int, char>(std::cout, " "));
      std::cout << std::endl;
    }
  }
  return 0;
}
