// SPDX-FileCopyrightText: Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
// SPDX-License-Identifier: BSD-3-Clause
#include "vtkImageDivergence.h"

#include "vtkDataSetAttributes.h"
#include "vtkImageData.h"
#include "vtkInformation.h"
#include "vtkInformationVector.h"
#include "vtkObjectFactory.h"
#include "vtkStreamingDemandDrivenPipeline.h"

#include <cmath>

VTK_ABI_NAMESPACE_BEGIN
vtkStandardNewMacro(vtkImageDivergence);

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

vtkImageDivergence::vtkImageDivergence()
{
  this->SetNumberOfInputPorts(1);
  this->SetNumberOfOutputPorts(1);
}

//------------------------------------------------------------------------------
// This method tells the superclass that the first axis will collapse.
int vtkImageDivergence::RequestInformation(vtkInformation* vtkNotUsed(request),
  vtkInformationVector** vtkNotUsed(inputVector), vtkInformationVector* outputVector)
{
  vtkDataObject::SetPointDataActiveScalarInfo(outputVector->GetInformationObject(0), -1, 1);
  return 1;
}

//------------------------------------------------------------------------------
// Just clip the request.  The subclass may need to overwrite this method.
int vtkImageDivergence::RequestUpdateExtent(vtkInformation* vtkNotUsed(request),
  vtkInformationVector** inputVector, vtkInformationVector* outputVector)
{
  // get the info objects
  vtkInformation* outInfo = outputVector->GetInformationObject(0);
  vtkInformation* inInfo = inputVector[0]->GetInformationObject(0);

  int idx;
  int wholeExtent[6];

  vtkInformation* inScalarInfo = vtkDataObject::GetActiveFieldInformation(
    inInfo, vtkDataObject::FIELD_ASSOCIATION_POINTS, vtkDataSetAttributes::SCALARS);
  if (!inScalarInfo)
  {
    vtkErrorMacro("Missing scalar field on input information!");
    return 0;
  }

  int dimensionality = inScalarInfo->Get(vtkDataObject::FIELD_NUMBER_OF_COMPONENTS());

  if (dimensionality > 3)
  {
    vtkErrorMacro("Divergence has to have dimensionality <= 3");
    dimensionality = 3;
  }

  // handle XYZ
  inInfo->Get(vtkStreamingDemandDrivenPipeline::WHOLE_EXTENT(), wholeExtent);
  int inUExt[6];
  outInfo->Get(vtkStreamingDemandDrivenPipeline::UPDATE_EXTENT(), inUExt);

  // update and Clip
  for (idx = 0; idx < dimensionality; ++idx)
  {
    --inUExt[idx * 2];
    ++inUExt[idx * 2 + 1];
    inUExt[idx * 2] = std::max(inUExt[idx * 2], wholeExtent[idx * 2]);
    inUExt[idx * 2] = std::min(inUExt[idx * 2], wholeExtent[idx * 2 + 1]);
    inUExt[idx * 2 + 1] = std::max(inUExt[idx * 2 + 1], wholeExtent[idx * 2]);
    inUExt[idx * 2 + 1] = std::min(inUExt[idx * 2 + 1], wholeExtent[idx * 2 + 1]);
  }
  inInfo->Set(vtkStreamingDemandDrivenPipeline::UPDATE_EXTENT(), inUExt, 6);

  return 1;
}

//------------------------------------------------------------------------------
// This execute method handles boundaries.
// it handles boundaries. Pixels are just replicated to get values
// out of extent.
template <class T>
void vtkImageDivergenceExecute(vtkImageDivergence* self, vtkImageData* inData, T* inPtr,
  vtkImageData* outData, T* outPtr, VTK_FUTURE_CONST int outExt[6], int id)
{
  int idxC, idxX, idxY, idxZ;
  int maxC, maxX, maxY, maxZ;
  vtkIdType inIncX, inIncY, inIncZ;
  vtkIdType outIncX, outIncY, outIncZ;
  unsigned long count = 0;
  unsigned long target;
  vtkIdType inIncs[3];
  double r[3], d, sum;
  int useMin[3], useMax[3];

  // find the region to loop over
  maxC = inData->GetNumberOfScalarComponents();
  if (maxC > 3)
  {
    vtkGenericWarningMacro("Dimensionality must be less than or equal to 3");
    maxC = 3;
  }
  maxX = outExt[1] - outExt[0];
  maxY = outExt[3] - outExt[2];
  maxZ = outExt[5] - outExt[4];
  target = static_cast<unsigned long>((maxZ + 1) * (maxY + 1) / 50.0);
  target++;

  // Get increments to march through data
  inData->GetContinuousIncrements(outExt, inIncX, inIncY, inIncZ);
  outData->GetContinuousIncrements(outExt, outIncX, outIncY, outIncZ);

  // The spacing is important for computing the gradient.
  // central differences (2 * ratio).
  // Negative because below we have (min - max) for dx ...
  inData->GetSpacing(r);
  r[0] = -0.5 / r[0];
  r[1] = -0.5 / r[1];
  r[2] = -0.5 / r[2];

  // get some other info we need
  inData->GetIncrements(inIncs);
  const int* wholeExtent = inData->GetExtent();

  // Loop through output pixels
  for (idxZ = 0; idxZ <= maxZ; idxZ++)
  {
    useMin[2] = ((idxZ + outExt[4]) <= wholeExtent[4]) ? 0 : -inIncs[2];
    useMax[2] = ((idxZ + outExt[4]) >= wholeExtent[5]) ? 0 : inIncs[2];
    for (idxY = 0; !self->AbortExecute && idxY <= maxY; idxY++)
    {
      if (!id)
      {
        if (!(count % target))
        {
          self->UpdateProgress(count / (50.0 * target));
        }
        count++;
      }
      useMin[1] = ((idxY + outExt[2]) <= wholeExtent[2]) ? 0 : -inIncs[1];
      useMax[1] = ((idxY + outExt[2]) >= wholeExtent[3]) ? 0 : inIncs[1];
      for (idxX = 0; idxX <= maxX; idxX++)
      {
        useMin[0] = ((idxX + outExt[0]) <= wholeExtent[0]) ? 0 : -inIncs[0];
        useMax[0] = ((idxX + outExt[0]) >= wholeExtent[1]) ? 0 : inIncs[0];
        sum = 0.0;
        for (idxC = 0; idxC < maxC; idxC++)
        {
          // do X axis
          d = static_cast<double>(inPtr[useMin[idxC]]);
          d -= static_cast<double>(inPtr[useMax[idxC]]);
          sum += d * r[idxC];
          inPtr++;
        }
        *outPtr = static_cast<T>(sum);
        outPtr++;
      }
      outPtr += outIncY;
      inPtr += inIncY;
    }
    outPtr += outIncZ;
    inPtr += inIncZ;
  }
}

//------------------------------------------------------------------------------
// This method contains a switch statement that calls the correct
// templated function for the input data type.  The output data
// must match input type.  This method does handle boundary conditions.
void vtkImageDivergence::ThreadedExecute(
  vtkImageData* inData, vtkImageData* outData, VTK_FUTURE_CONST int outExt[6], int id)
{
  void* inPtr = inData->GetScalarPointerForExtent(outExt);
  void* outPtr = outData->GetScalarPointerForExtent(outExt);

  // this filter expects that input is the same type as output.
  if (inData->GetScalarType() != outData->GetScalarType())
  {
    vtkErrorMacro(<< "Execute: input ScalarType, " << inData->GetScalarType()
                  << ", must match out ScalarType " << outData->GetScalarType());
    return;
  }

  switch (inData->GetScalarType())
  {
    vtkTemplateMacro(vtkImageDivergenceExecute(this, inData, static_cast<VTK_TT*>(inPtr), outData,
      static_cast<VTK_TT*>(outPtr), outExt, id));
    default:
      vtkErrorMacro(<< "Execute: Unknown ScalarType");
      return;
  }
}
VTK_ABI_NAMESPACE_END
