/*=========================================================================

  Program:   Visualization Toolkit
  Module:    vtkParticleTracerBase.cxx

  Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
  All rights reserved.
  See Copyright.txt or http://www.kitware.com/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
     PURPOSE.  See the above copyright notice for more information.

=========================================================================*/
#include "vtkPParticleTracerBase.h"

#include "vtkCellData.h"
#include "vtkCommunicator.h"
#include "vtkCompositeDataSet.h"
#include "vtkDataArray.h"
#include "vtkDataSetAttributes.h"
#include "vtkInformation.h"
#include "vtkInformationVector.h"
#include "vtkMultiProcessController.h"
#include "vtkMultiProcessStream.h"
#include "vtkObjectFactory.h"
#include "vtkPointData.h"
#include "vtkPolyData.h"
#include "vtkSmartPointer.h"
#include "vtkStreamingDemandDrivenPipeline.h"
#include "vtkTemporalInterpolatedVelocityField.h"
#include <cassert>

#include <algorithm>

using namespace vtkParticleTracerBaseNamespace;

vtkPParticleTracerBase::vtkPParticleTracerBase()
{
  this->Controller = nullptr;
  this->SetController(vtkMultiProcessController::GetGlobalController());
}

//---------------------------------------------------------------------------
vtkPParticleTracerBase::~vtkPParticleTracerBase()
{
  this->SetController(nullptr);
  this->SetParticleWriter(nullptr);
}

//---------------------------------------------------------------------------
vtkPolyData* vtkPParticleTracerBase::Execute(vtkInformationVector** inputVector)
{
  vtkDebugMacro(<< "Clear MPI send list ");
  this->MPISendList.clear();
  this->Tail.clear();

  // clear out TailPointId
  ParticleListIterator  it_first = this->ParticleHistories.begin();
  ParticleListIterator  it_last  = this->ParticleHistories.end();
  for (ParticleListIterator it=it_first; it!=it_last;it++)
  {
    it->TailPointId = -1;
  }

  return vtkParticleTracerBase::Execute(inputVector);
}

//---------------------------------------------------------------------------
bool vtkPParticleTracerBase::SendParticleToAnotherProcess(
  ParticleInformation &info, ParticleInformation &previousInfo,
  vtkPointData* pd)
{
  if(info.PointId < 0 && info.TailPointId < 0)
  {
    vtkErrorMacro("Bad particle information.");
    assert(0);
    return true;
  }

  RemoteParticleInfo remoteInfo;

  remoteInfo.Current = info;

  remoteInfo.Previous = previousInfo;
  remoteInfo.PreviousPD = vtkSmartPointer<vtkPointData>::New();
  // the point data that we get values from.
  vtkPointData* fromPD = nullptr;
  vtkIdType fromTupleId = -1;
  // ProtoPD is ONLY used to properly copy allocate the new point data
  if(info.PointId >= 0)
  { // point data comes from the input pd and the tuple
    // location comes from the particles's PointId
    remoteInfo.PreviousPD->CopyAllocate(this->ProtoPD);
    fromPD = pd;
    fromTupleId = info.PointId;
  }
  else
  { // point data comes from this->Tail and the tuple
    // location comes from the particle's TailPointId
    remoteInfo.PreviousPD->CopyAllocate(this->ProtoPD);
    fromPD = this->Tail[info.TailPointId].PreviousPD;
    fromTupleId = 0;
  }

  //only copy those that correspond to the original data fields
  for(int i=0; i <this->ProtoPD->GetNumberOfArrays(); i++)
  {
    char* arrName = this->ProtoPD->GetArray(i)->GetName();
    vtkDataArray* arrFrom = fromPD->GetArray(arrName);
    vtkDataArray* arrTo = remoteInfo.PreviousPD->GetArray(i);
    assert(arrFrom->GetNumberOfComponents()==arrTo->GetNumberOfComponents());
    arrTo->InsertNextTuple(arrFrom->GetTuple(fromTupleId));
  }

  double eps = (this->GetCacheDataTime(1)-this->GetCacheDataTime(0))/100;
  if (info.CurrentPosition.x[3]<(this->GetCacheDataTime(0)-eps) ||
      info.CurrentPosition.x[3]>(this->GetCacheDataTime(1)+eps))
  {
    vtkErrorMacro(<< "Unexpected time value in MPISendList - expected ("
                  << this->GetCacheDataTime(0) << "-" << this->GetCacheDataTime(1) << ") got "
                  << info.CurrentPosition.x[3]);
  }

  if (this->MPISendList.capacity()<(this->MPISendList.size()+1))
  {
    this->MPISendList.reserve(static_cast<int>(this->MPISendList.size()*1.5));
  }
  this->MPISendList.push_back(remoteInfo);
  return true;
}

//---------------------------------------------------------------------------
void vtkPParticleTracerBase::AssignSeedsToProcessors(
  double t, vtkDataSet *source, int sourceID, int ptId,
  ParticleVector &localSeedPoints, int &localAssignedCount)
{
  if(!this->Controller)
  {
    return Superclass::AssignSeedsToProcessors(t, source, sourceID, ptId,
                                               localSeedPoints, localAssignedCount);
  }
  ParticleVector candidates;
  //
  // take points from the source object and create a particle list
  //
  vtkIdType numSeeds = source->GetNumberOfPoints();
  candidates.resize(numSeeds);
  //
  for (vtkIdType i=0; i<numSeeds; i++)
  {
    ParticleInformation &info = candidates[i];
    memcpy(info.CurrentPosition.x, source->GetPoint(i), sizeof(double)*3);
    info.CurrentPosition.x[3] = t;
    info.LocationState        = 0;
    info.CachedCellId[0]      =-1;
    info.CachedCellId[1]      =-1;
    info.CachedDataSetId[0]   = 0;
    info.CachedDataSetId[1]   = 0;
    info.SourceID             = sourceID;
    info.InjectedPointId      = i+ptId;
    info.InjectedStepId       = this->GetReinjectionCounter();
    info.TimeStepAge          = 0;
    info.UniqueParticleId     =-1;
    info.rotation             = 0.0;
    info.angularVel           = 0.0;
    info.time                 = 0.0;
    info.age                  = 0.0;
    info.speed                = 0.0;
    info.SimulationTime       = this->GetCurrentTimeValue();
    info.ErrorCode            = 0;
    info.PointId              = -1;
    info.TailPointId          = -1;
  }
  //
  // Check all Seeds on all processors for classification
  //
  std::vector<int> owningProcess(numSeeds, -1);
  int myRank = this->Controller->GetLocalProcessId();
  ParticleIterator it=candidates.begin();
  for (int i=0; it!=candidates.end(); ++it, ++i)
  {
    ParticleInformation &info = (*it);
    double *pos = info.CurrentPosition.x;
    // if outside bounds, reject instantly
    if (this->InsideBounds(pos))
    {
      // since this is first test, avoid bad cache tests
      this->GetInterpolator()->ClearCache();
      int searchResult = this->GetInterpolator()->TestPoint(pos);
      if(searchResult==ID_INSIDE_ALL || searchResult==ID_OUTSIDE_T0)
      {
        // this particle is in this process's domain for the latest time step
        owningProcess[i] = myRank;
      }
    }
  }
  std::vector<int> realOwningProcess(numSeeds);
  this->Controller->AllReduce(owningProcess.data(), realOwningProcess.data(), numSeeds,
                              vtkCommunicator::MAX_OP);

  for(size_t i=0;i<realOwningProcess.size();i++)
  {
    if(realOwningProcess[i] == myRank)
    {
      localSeedPoints.push_back(candidates[i]);
    }
  }

  // Assign unique identifiers taking into account uneven distribution
  // across processes and seeds which were rejected
  this->AssignUniqueIds(localSeedPoints);
}

//---------------------------------------------------------------------------
void vtkPParticleTracerBase::AssignUniqueIds(
  vtkParticleTracerBaseNamespace::ParticleVector &localSeedPoints)
{
  if(!this->Controller)
  {
    return Superclass::AssignUniqueIds(localSeedPoints);
  }

  vtkIdType particleCountOffset = 0;
  vtkIdType numParticles = static_cast<vtkIdType>(localSeedPoints.size());

  if (this->Controller->GetNumberOfProcesses()>1)
  {
    // everyone starts with the master index
    this->Controller->Broadcast(&this->UniqueIdCounter, 1, 0);
    // setup arrays used by the AllGather call.
    std::vector<vtkIdType> recvNumParticles(this->Controller->GetNumberOfProcesses(), 0);
    // Broadcast and receive count to/from all other processes.
    this->Controller->AllGather(&numParticles, recvNumParticles.data(), 1);
    // Each process is allocating a certain number.
    // start our indices from sum[0,this->Rank](numparticles)
    for (int i=0; i<this->Controller->GetLocalProcessId(); ++i)
    {
      particleCountOffset += recvNumParticles[i];
    }
    for (vtkIdType i=0; i<numParticles; i++)
    {
      localSeedPoints[i].UniqueParticleId =
        this->UniqueIdCounter + particleCountOffset + i;
    }
    for (int i=0; i<this->Controller->GetNumberOfProcesses(); ++i)
    {
      this->UniqueIdCounter += recvNumParticles[i];
    }
  }
  else
  {
    for (vtkIdType i=0; i<numParticles; i++)
    {
      localSeedPoints[i].UniqueParticleId =
        this->UniqueIdCounter + particleCountOffset + i;
    }
    this->UniqueIdCounter += numParticles;
  }
}

//---------------------------------------------------------------------------
bool vtkPParticleTracerBase::SendReceiveParticles(RemoteParticleVector &sParticles,
                                                  RemoteParticleVector &rParticles)
{
  int numParticles = static_cast<int>(sParticles.size());

  std::vector<int> allNumParticles(this->Controller->GetNumberOfProcesses(), 0);
  // Broadcast and receive size to/from all other processes.
  this->Controller->AllGather(&numParticles, allNumParticles.data(), 1);

  // write the message
  const int size1 = sizeof(ParticleInformation);
  const int nArrays = this->ProtoPD->GetNumberOfArrays();
  unsigned int typeSize = 2*size1;
  for(int i=0; i<this->ProtoPD->GetNumberOfArrays();i++)
  {
    typeSize+= this->ProtoPD->GetArray(i)->GetNumberOfComponents()*sizeof(double);
  }

  vtkIdType messageSize = numParticles*typeSize;
  std::vector<char> sendMessage(messageSize,0);
  for(int i=0; i<numParticles; i++)
  {
    memcpy(&sendMessage[i*typeSize],        &sParticles[i].Current, size1);
    memcpy(&sendMessage[i*typeSize]+size1 , &sParticles[i].Previous, size1);

    vtkPointData* pd = sParticles[i].PreviousPD;
    char* data = &sendMessage[i*typeSize] + 2*size1;
    for(int j=0; j<nArrays;j++)
    {
      vtkDataArray* arr = pd->GetArray(j);
      assert(arr->GetNumberOfTuples()==1);
      int numComponents = arr->GetNumberOfComponents();
      double* y = arr->GetTuple(0);
      int dataSize = sizeof(double)*numComponents;
      memcpy(data, y, dataSize);
      data+=dataSize;
    }
  }

  std::vector<vtkIdType> messageLength(this->Controller->GetNumberOfProcesses(), 0);
  std::vector<vtkIdType> messageOffset(this->Controller->GetNumberOfProcesses(), 0);
  int allMessageSize(0);
  int numAllParticles(0);
  for (int i=0; i<this->Controller->GetNumberOfProcesses(); ++i)
  {
    numAllParticles+= allNumParticles[i];
    messageLength[i] = allNumParticles[i]*typeSize;
    messageOffset[i] =allMessageSize;
    allMessageSize+= messageLength[i];
  }

  //receive the message

  std::vector<char> recvMessage(allMessageSize,0);
  this->Controller->AllGatherV(messageSize>0?  sendMessage.data() : nullptr,
                               allMessageSize>0? recvMessage.data() : nullptr,
                               messageSize, messageLength.data(),
                               messageOffset.data());


  int myRank = this->Controller->GetLocalProcessId();

  // owningProcess is used to make sure that particles that are sent aren't added
  // on multiple processes
  std::vector<vtkIdType> owningProcess(numAllParticles, -1);
  // we automatically ignore particles that we sent
  int ignoreBegin = messageOffset[myRank]/typeSize;
  int ignoreEnd = ignoreBegin+messageLength[myRank]/typeSize;
  for(int i=0; i<numAllParticles; i++)
  {
    if(i < ignoreBegin || i >= ignoreEnd)
    {
      ParticleInformation tmpParticle;
      memcpy(&tmpParticle, &recvMessage[i*typeSize], size1);
      // since this is first test, avoid bad cache tests
      this->GetInterpolator()->ClearCache();
      int searchResult =
        this->GetInterpolator()->TestPoint(tmpParticle.CurrentPosition.x);
      if(searchResult==ID_INSIDE_ALL || searchResult==ID_OUTSIDE_T0)
      {
        // this particle is in this process's domain for the latest time step
        owningProcess[i] = myRank;
      }
    }
  }
  std::vector<vtkIdType> realOwningProcess(numAllParticles);
  if (numAllParticles)
  {
    this->Controller->AllReduce(owningProcess.data(), realOwningProcess.data(),
                                numAllParticles, vtkCommunicator::MAX_OP);
  }

  // if any value in realOwningProcess array is not -1 then we know
  // that a particle was moved to another process and probably needs
  // to be integrated further
  bool particlesMoved = false; // assume no particles moved

  //read the message for the particles that we really want
  int counter = 0;
  for(std::vector<vtkIdType>::iterator it=realOwningProcess.begin();
      it!=realOwningProcess.end();++it)
  {
    if(*it != -1)
    {
      particlesMoved = true;
      if(*it == myRank)
      {
        counter++;
      }
    }
  }
  rParticles.resize(counter);
  counter = 0;
  // owningProcess is used to make sure that particles that are sent aren't added
  // on multiple processes

  for(int i=0; i<numAllParticles; i++)
  {
    if(realOwningProcess[i] == myRank)
    {
      memcpy(&rParticles[counter].Current,  &recvMessage[i*typeSize],     size1);
      memcpy(&rParticles[counter].Previous, &recvMessage[i*typeSize]+size1,size1);

      rParticles[counter].PreviousPD = vtkSmartPointer<vtkPointData>::New();
      rParticles[counter].PreviousPD->CopyAllocate(this->ProtoPD);
      vtkPointData* pd = rParticles[counter].PreviousPD;
      char* data = &recvMessage[i*typeSize] + 2*size1;
      for(int j=0; j<nArrays;j++)
      {
        vtkDataArray* arr = pd->GetArray(j);
        int numComponents = arr->GetNumberOfComponents();
        int dataSize = sizeof(double)*numComponents;
        std::vector<double> xi(numComponents);
        memcpy(xi.data(), data, dataSize);
        arr->InsertNextTuple(xi.data());
        data+=dataSize;
      }
      counter++;
    }
  }

  // don't want the ones that we sent away
  this->MPISendList.clear();

  return particlesMoved;
}

//---------------------------------------------------------------------------
int vtkPParticleTracerBase::RequestUpdateExtent(
  vtkInformation* request, vtkInformationVector** inputVector,
  vtkInformationVector* outputVector)
{
  int numSources = inputVector[1]->GetNumberOfInformationObjects();
  for (int i=0; i<numSources; i++)
  {
    vtkInformation *sourceInfo = inputVector[1]->GetInformationObject(i);
    if (sourceInfo)
    {
      sourceInfo->Set(vtkStreamingDemandDrivenPipeline::UPDATE_PIECE_NUMBER(), 0);
      sourceInfo->Set(vtkStreamingDemandDrivenPipeline::UPDATE_NUMBER_OF_PIECES(), 1);
    }
  }

  return Superclass::RequestUpdateExtent(request,inputVector,outputVector);
}

//---------------------------------------------------------------------------
void vtkPParticleTracerBase::PrintSelf(ostream& os, vtkIndent indent)
{
  this->Superclass::PrintSelf(os,indent);

  os << indent << "Controller: " << this->Controller << endl;
}

//---------------------------------------------------------------------------
bool vtkPParticleTracerBase::UpdateParticleListFromOtherProcesses()
{
  if(!this->Controller)
  {
    return false;
  }
  RemoteParticleVector received;

  bool particlesMoved = this->SendReceiveParticles(this->MPISendList, received);

  for(size_t i=0;i<received.size();i++)
  {
    RemoteParticleInfo& info(received[i]);
    info.Current.PointId = -1;
    info.Current.CachedDataSetId[0] = info.Current.CachedDataSetId[1] = -1;
    info.Current.CachedCellId[0] = info.Current.CachedCellId[1] = -1;
    info.Previous.CachedDataSetId[0] = info.Previous.CachedDataSetId[1] = -1;
    info.Previous.CachedCellId[0] = info.Previous.CachedCellId[1] = -1;
    info.Current.TailPointId = info.Previous.TailPointId = static_cast<vtkIdType>(this->Tail.size());
    this->Tail.push_back(info);
    this->ParticleHistories.push_back(info.Current);
  }

  return particlesMoved;
}

//---------------------------------------------------------------------------
bool vtkPParticleTracerBase::IsPointDataValid(vtkDataObject* input)
{
  if(this->Controller->GetNumberOfProcesses() == 1)
  {
    return this->Superclass::IsPointDataValid(input);
  }
  int retVal = 1;
  vtkMultiProcessStream stream;
  if(this->Controller->GetLocalProcessId() == 0)
  {
    std::vector<std::string> arrayNames;
    if(vtkCompositeDataSet* cdInput = vtkCompositeDataSet::SafeDownCast(input))
    {
      retVal = (int) this->Superclass::IsPointDataValid(cdInput, arrayNames);
    }
    else
    {
      this->GetPointDataArrayNames(vtkDataSet::SafeDownCast(input), arrayNames);
    }
    stream << retVal;
    // only need to send the array names to check if proc 0 has valid point data
    if(retVal == 1)
    {
      stream << (int)arrayNames.size();
      for(std::vector<std::string>::iterator it=arrayNames.begin();
          it!=arrayNames.end();++it)
      {
        stream << *it;
      }
    }
  }
  this->Controller->Broadcast(stream, 0);
  if(this->Controller->GetLocalProcessId() != 0)
  {
    stream >> retVal;
    if(retVal == 0)
    {
      return false;
    }
    int numArrays;
    stream >> numArrays;
    std::vector<std::string> arrayNames(numArrays);
    for(int i=0;i<numArrays;i++)
    {
      stream >> arrayNames[i];
    }
    std::vector<std::string> tempNames;
    if(vtkCompositeDataSet* cdInput = vtkCompositeDataSet::SafeDownCast(input))
    {
      retVal = (int) this->Superclass::IsPointDataValid(cdInput, tempNames);
      if(retVal)
      {
        retVal = (std::equal(tempNames.begin(), tempNames.end(), arrayNames.begin()) == true ?
                  1 : 0);
      }
    }
    else
    {
      this->GetPointDataArrayNames(vtkDataSet::SafeDownCast(input), tempNames);
      retVal = (std::equal(tempNames.begin(), tempNames.end(), arrayNames.begin()) == true ?
                1 : 0);
    }
  }
  else if(retVal == 0)
  {
    return false;
  }
  int tmp = retVal;
  this->Controller->AllReduce(&tmp, &retVal, 1, vtkCommunicator::MIN_OP);

  return (retVal != 0);
}

//---------------------------------------------------------------------------
vtkCxxSetObjectMacro(vtkPParticleTracerBase, Controller, vtkMultiProcessController);
//---------------------------------------------------------------------------
