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// The manager class for MPI applications.

// Author: Ivana Hrivnacova, 25/06/2015  (ivana@ipno.in2p3.fr)

using std::to_string;

//_____________________________________________________________________________
template <typename HT>
inline
G4bool G4MPIToolsManager::Send(G4int nofActiveT,
                               const std::vector<HT*>& htVector,
                               const std::vector<G4HnInformation*>& hnVector)
{
  auto result = true;

  // send object to destination rank
  // G4cout << "Begin send for " << nofActiveT << G4endl;
  fHmpi->beg_send(nofActiveT);

  // pack objects
  for ( G4int i=0; i<G4int(htVector.size()); ++i ) {
    // skip sending if activation is enabled and HT is inactivated
    auto info = hnVector[i];
    if ( ( fState.GetIsActivation() && ( ! info->GetActivation() ) ) ) continue;
    // pack histogram for sending
    // G4cout << "Packed " << i << "th T" << G4endl;
    auto ht = htVector[i];
    result &= fHmpi->pack(*ht);
  }

  //G4cout << "Go to send all " << G4endl;
  if ( ! fHmpi->send(fHmpi->rank()) ) {
    G4Analysis::Warn(
      "Rank: " + to_string(fHmpi->rank()) + " : can't send histos.",
      fkClass, "Send");
    return false;
  }

  return result;
}

//_____________________________________________________________________________
template <typename HT>
inline
G4bool G4MPIToolsManager::Receive(G4int nofActiveT,
                                  const std::vector<HT*>& htVector,
                                  const std::vector<G4HnInformation*>& hnVector)
{
  G4int commSize;
  G4bool result = fHmpi->comm_size(commSize);
  if ( ! result ) {
    G4Analysis::Warn(
      "Failed to get MPI commander size.\nMerging will not be performed.",
      fkClass, "Receive");
    return false;
  }

  // get objects from source ranks
  for (G4int srank = 0; srank < commSize; ++srank) {

    // skip destination rank
    if ( srank == fHmpi->rank() ) continue;

    // get objects from this source rank
    // G4cout << "Go to wait_histos " << srank << G4endl;
    using class_pointer = std::pair<std::string,void*>;
    std::vector<class_pointer> hs;
    if ( ! fHmpi->wait_histos(srank, hs) ) {
      G4Analysis::Warn(
        "Wait_histos from " + to_string(srank) + " : failed.",
        fkClass, "Receive");
      return false;
    }

    // check that we got the right number of objects
    if ( G4int(hs.size()) != nofActiveT ) {
      G4Analysis::Warn(
        "srank: " + to_string(srank) + " : got " + to_string(hs.size()) +
        " objects, while " + to_string(nofActiveT) +" were expected.",
        fkClass, "Receive");
      return false;
    }

    // merge the objects to destination rank
    G4int counter = 0;
    for ( G4int i=0; i<G4int(htVector.size()); ++i ) {
      // skip sending if activation is enabled and HT is inactivated
      auto info = hnVector[i];
      if ( ( fState.GetIsActivation() && ( ! info->GetActivation() ) ) ) continue;
      // merge histograms
      auto ht = htVector[i];
      auto newHt = static_cast<HT*>(hs[counter++].second);
      ht->add(*newHt);
    }
  }
  return true;
}


//_____________________________________________________________________________
template <typename HT>
inline
G4bool G4MPIToolsManager::Merge(const std::vector<HT*>& htVector,
                                const std::vector<G4HnInformation*>& hnVector)
{
  if ( ! htVector.size() ) return true;

  // Get number of objects to be sent
  G4int nofActiveT = 0;
  if ( fState.GetIsActivation() ) {
    // only activated histograms will be treated
    for ( G4int i=0; i<G4int(htVector.size()); ++i ) {
      auto activation = hnVector[i]->GetActivation();
      if ( activation ) ++nofActiveT;
    }
  } else {
      nofActiveT = G4int(htVector.size());
  }

  if ( ! nofActiveT ) return true;

  G4int commRank;
  if ( ! fHmpi->comm_rank(commRank) ) {
    G4Analysis::Warn(
      "Failed to get MPI commander rank.\nMerging will not be performed.",
      fkClass, "Merge");
    return false;
  }

  auto result = true;

  if ( commRank != fHmpi->rank() ) {
    fState.Message(G4Analysis::kVL3, "mpi send", "Hn|Pn",
      "on rank "  + to_string(commRank) +
      " destination rank: " + to_string(fHmpi->rank()));

    result &= Send(nofActiveT, htVector, hnVector);

    fState.Message(G4Analysis::kVL1, "mpi send", "Hn|Pn",
      "on rank "  + to_string(commRank) +
      " destination rank: " + to_string(fHmpi->rank()));

  } else {
    fState.Message(G4Analysis::kVL3, "mpi wait_histos", "Hn|Pn",
      "on rank "  + to_string(commRank) +
      " destination rank: " + to_string(fHmpi->rank()));

    result &= Receive(nofActiveT, htVector, hnVector);

    fState.Message(G4Analysis::kVL1, "mpi wait_histos", "Hn|Pn",
      "on rank "  + to_string(commRank) +
      " destination rank: " + to_string(fHmpi->rank()));
  }
  return result;
}