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

The Medical Imaging Interaction Toolkit (MITK)

Copyright (c) German Cancer Research Center (DKFZ)
All rights reserved.

Use of this source code is governed by a 3-clause BSD license that can be
found in the LICENSE file.

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

#include <vtkMitkLevelWindowFilter.h>
#include <vtkObjectFactory.h>
#include <vtkColorTransferFunction.h>
#include <vtkImageData.h>
#include <vtkImageIterator.h>
#include <vtkInformation.h>
#include <vtkInformationVector.h>
#include <vtkLookupTable.h>
#include <vtkPiecewiseFunction.h>

#include <vtkStreamingDemandDrivenPipeline.h>

// used for acos etc.
#include <cmath>

// used for PI
#include <itkMath.h>

#include <mitkLog.h>

static const double PI = itk::Math::pi;

vtkStandardNewMacro(vtkMitkLevelWindowFilter);

vtkMitkLevelWindowFilter::vtkMitkLevelWindowFilter()
  : m_LookupTable(nullptr), m_OpacityFunction(nullptr), m_MinOpacity(0.0), m_MaxOpacity(255.0)
{
  // MITK_INFO << "mitk level/window filter uses " << GetNumberOfThreads() << " thread(s)";
}

vtkMitkLevelWindowFilter::~vtkMitkLevelWindowFilter()
{
}

vtkMTimeType vtkMitkLevelWindowFilter::GetMTime()
{
  vtkMTimeType mTime = this->vtkObject::GetMTime();
  vtkMTimeType time;

  if (this->m_LookupTable != nullptr)
  {
    time = this->m_LookupTable->GetMTime();
    mTime = (time > mTime ? time : mTime);
  }

  return mTime;
}

void vtkMitkLevelWindowFilter::SetLookupTable(vtkScalarsToColors *lookupTable)
{
  if (m_LookupTable != lookupTable)
  {
    m_LookupTable = lookupTable;
    this->Modified();
  }
}

vtkScalarsToColors *vtkMitkLevelWindowFilter::GetLookupTable()
{
  return m_LookupTable;
}

void vtkMitkLevelWindowFilter::SetOpacityPiecewiseFunction(vtkPiecewiseFunction *opacityFunction)
{
  if (m_OpacityFunction != opacityFunction)
  {
    m_OpacityFunction = opacityFunction;
    this->Modified();
  }
}

// This code was copied from the iil. The template works only for float and double.
// Internal method which should never be used anywhere else and should not be in th header.
// Convert color pixels from (R,G,B) to (H,S,I).
// Reference: "Digital Image Processing, 2nd. edition", R. Gonzalez and R. Woods. Prentice Hall, 2002.
template <class T>
void RGBtoHSI(T *RGB, T *HSI)
{
  T R = RGB[0], G = RGB[1], B = RGB[2], nR = (R < 0 ? 0 : (R > 255 ? 255 : R)) / 255,
    nG = (G < 0 ? 0 : (G > 255 ? 255 : G)) / 255, nB = (B < 0 ? 0 : (B > 255 ? 255 : B)) / 255,
    m = nR < nG ? (nR < nB ? nR : nB) : (nG < nB ? nG : nB),
    theta = (T)(std::acos(0.5f * ((nR - nG) + (nR - nB)) / std::sqrt(std::pow(nR - nG, 2) + (nR - nB) * (nG - nB))) *
                180 / PI),
    sum = nR + nG + nB;
  T H = 0, S = 0, I = 0;
  if (theta > 0)
    H = (nB <= nG) ? theta : 360 - theta;
  if (sum > 0)
    S = 1 - 3 / sum * m;
  I = sum / 3;
  HSI[0] = (T)H;
  HSI[1] = (T)S;
  HSI[2] = (T)I;
}

// This code was copied from the iil. The template works only for float and double.
// Internal method which should never be used anywhere else and should not be in th header.
// Convert color pixels from (H,S,I) to (R,G,B).
template <class T>
void HSItoRGB(T *HSI, T *RGB)
{
  T H = (T)HSI[0], S = (T)HSI[1], I = (T)HSI[2], a = I * (1 - S), R = 0, G = 0, B = 0;
  if (H < 120)
  {
    B = a;
    R = (T)(I * (1 + S * std::cos(H * PI / 180) / std::cos((60 - H) * PI / 180)));
    G = 3 * I - (R + B);
  }
  else if (H < 240)
  {
    H -= 120;
    R = a;
    G = (T)(I * (1 + S * std::cos(H * PI / 180) / std::cos((60 - H) * PI / 180)));
    B = 3 * I - (R + G);
  }
  else
  {
    H -= 240;
    G = a;
    B = (T)(I * (1 + S * std::cos(H * PI / 180) / std::cos((60 - H) * PI / 180)));
    R = 3 * I - (G + B);
  }
  R *= 255;
  G *= 255;
  B *= 255;
  RGB[0] = (T)(R < 0 ? 0 : (R > 255 ? 255 : R));
  RGB[1] = (T)(G < 0 ? 0 : (G > 255 ? 255 : G));
  RGB[2] = (T)(B < 0 ? 0 : (B > 255 ? 255 : B));
}

// Internal method which should never be used anywhere else and should not be in th header.
//----------------------------------------------------------------------------
// This templated function executes the filter for any type of data.
template <class T>
void vtkApplyLookupTableOnRGBA(vtkMitkLevelWindowFilter *self,
                               vtkImageData *inData,
                               vtkImageData *outData,
                               int outExt[6],
                               double *clippingBounds,
                               T *)
{
  vtkImageIterator<T> inputIt(inData, outExt);
  // Output is always declared as VTK_UNSIGNED_CHAR with 4 components in RequestInformation,
  // so the output iterator must always use unsigned char regardless of the input type.
  vtkImageIterator<unsigned char> outputIt(outData, outExt);
  vtkLookupTable *lookupTable;
  const int maxC = inData->GetNumberOfScalarComponents();

  double tableRange[2];

  lookupTable = dynamic_cast<vtkLookupTable *>(self->GetLookupTable());

  lookupTable->GetTableRange(tableRange);

  // parameters for RGB level window
  const double scale = (tableRange[1] - tableRange[0] > 0 ? 255.0 / (tableRange[1] - tableRange[0]) : 0.0);
  const double bias = tableRange[0] * scale;

  // parameters for opaque level window
  const double scaleOpac =
    (self->GetMaxOpacity() - self->GetMinOpacity() > 0 ? 255.0 / (self->GetMaxOpacity() - self->GetMinOpacity()) : 0.0);
  const double biasOpac = self->GetMinOpacity() * scaleOpac;

  int y = outExt[2];

  // Loop through output pixels
  while (!outputIt.IsAtEnd())
  {
    T *inputSI = inputIt.BeginSpan();
    unsigned char *outputSI = outputIt.BeginSpan();
    unsigned char *outputSIEnd = outputIt.EndSpan();

    if (y >= clippingBounds[2] && y < clippingBounds[3])
    {
      int x = outExt[0];

      while (outputSI != outputSIEnd)
      {
        if (x >= clippingBounds[0] && x < clippingBounds[1])
        {
          double rgb[3], alpha, hsi[3];

          // level/window mechanism for intensity in HSI space
          rgb[0] = static_cast<double>(*inputSI);
          inputSI++;
          rgb[1] = static_cast<double>(*inputSI);
          inputSI++;
          rgb[2] = static_cast<double>(*inputSI);
          inputSI++;

          RGBtoHSI<double>(rgb, hsi);
          hsi[2] = hsi[2] * 255.0 * scale - bias;
          hsi[2] = (hsi[2] > 255.0 ? 255 : (hsi[2] < 0.0 ? 0 : hsi[2]));
          hsi[2] /= 255.0;
          HSItoRGB<double>(hsi, rgb);

          *outputSI = static_cast<unsigned char>(rgb[0]);
          outputSI++;
          *outputSI = static_cast<unsigned char>(rgb[1]);
          outputSI++;
          *outputSI = static_cast<unsigned char>(rgb[2]);
          outputSI++;

          unsigned char finalAlpha = 255;

          // RGBA case
          if (maxC >= 4)
          {
            // level/window mechanism for opacity
            alpha = static_cast<double>(*inputSI);
            inputSI++;
            alpha = alpha * scaleOpac - biasOpac;
            if (alpha > 255.0)
            {
              alpha = 255.0;
            }
            else if (alpha < 0.0)
            {
              alpha = 0.0;
            }
            finalAlpha = static_cast<unsigned char>(alpha);

            for (int c = 4; c < maxC; c++)
              inputSI++;
          }

          *outputSI = finalAlpha;
          outputSI++;
        }
        else
        {
          inputSI += maxC;
          *outputSI = 0;
          outputSI++;
          *outputSI = 0;
          outputSI++;
          *outputSI = 0;
          outputSI++;
          *outputSI = 0;
          outputSI++;
        }

        x++;
      }
    }
    else
    {
      while (outputSI != outputSIEnd)
      {
        *outputSI = 0;
        outputSI++;
        *outputSI = 0;
        outputSI++;
        *outputSI = 0;
        outputSI++;
        *outputSI = 0;
        outputSI++;
      }
    }
    inputIt.NextSpan();
    outputIt.NextSpan();
    y++;
  }
}

// Internal method which should never be used anywhere else and should not be in th header.
//----------------------------------------------------------------------------
// This templated function executes the filter for any type of data.
template <class T>
void vtkApplyLookupTableOnScalarsFast(
  vtkMitkLevelWindowFilter *self, vtkImageData *inData, vtkImageData *outData, int outExt[6], T *)
{
  vtkImageIterator<T> inputIt(inData, outExt);
  vtkImageIterator<unsigned char> outputIt(outData, outExt);

  double tableRange[2];

  // access vtkLookupTable
  auto *lookupTable = dynamic_cast<vtkLookupTable *>(self->GetLookupTable());
  lookupTable->GetTableRange(tableRange);

  // access elements of the vtkLookupTable
  auto *realLookupTable = lookupTable->GetPointer(0);
  size_t maxIndex = lookupTable->GetNumberOfColors() - 1;

  const float scale = (tableRange[1] - tableRange[0] > 0 ? (maxIndex + 1) / (tableRange[1] - tableRange[0]) : 0.0);
  // ensuring that starting point is zero
  float bias = -tableRange[0] * scale;
  // due to later conversion to int for rounding
  bias += 0.5f;

  // Loop through output pixels
  while (!outputIt.IsAtEnd())
  {
    unsigned char *outputSI = outputIt.BeginSpan();
    unsigned char *outputSIEnd = outputIt.EndSpan();

    T *inputSI = inputIt.BeginSpan();

    while (outputSI != outputSIEnd)
    {
      // map to an index
      auto idx = std::min(static_cast<size_t>(std::max(0, static_cast<int>(*inputSI * scale + bias))), maxIndex) * 4;

      memcpy(outputSI, &realLookupTable[idx], 4);

      inputSI++;
      outputSI += 4;
    }

    inputIt.NextSpan();
    outputIt.NextSpan();
  }
}

// Internal method which should never be used anywhere else and should not be in th header.
//----------------------------------------------------------------------------
// This templated function executes the filter for any type of data.
template <class T>
void vtkApplyLookupTableOnScalars(vtkMitkLevelWindowFilter *self,
                                  vtkImageData *inData,
                                  vtkImageData *outData,
                                  int outExt[6],
                                  double *clippingBounds,
                                  T *)
{
  vtkImageIterator<T> inputIt(inData, outExt);
  vtkImageIterator<unsigned char> outputIt(outData, outExt);
  vtkScalarsToColors *lookupTable = self->GetLookupTable();

  int y = outExt[2];

  // Loop through output pixels
  while (!outputIt.IsAtEnd())
  {
    unsigned char *outputSI = outputIt.BeginSpan();
    const unsigned char * const outputSIEnd = outputIt.EndSpan();

    // do we iterate over the inner vertical clipping bounds
    if (y >= clippingBounds[2] && y < clippingBounds[3])
    {
      T *inputSI = inputIt.BeginSpan();

      int x = outExt[0];

      while (outputSI != outputSIEnd)
      {
        // is this pixel within horizontal clipping bounds
        if (x >= clippingBounds[0] && x < clippingBounds[1])
        {
          // fetching original value
          auto grayValue = static_cast<double>(*inputSI);
          // applying lookuptable
          memcpy(outputSI, lookupTable->MapValue(grayValue), 4);
        }
        else
        {
          // outer horizontal clipping bounds - write a transparent RGBA pixel as a single int
          memset(outputSI, 0, 4);
        }

        inputSI++;
        outputSI += 4;
        x++;
      }
    }
    else
    {
      // outer vertical clipping bounds - write a transparent RGBA line as ints
      while (outputSI != outputSIEnd)
      {
        *reinterpret_cast<int *>(outputSI) = 0;
        outputSI += 4;
      }
    }

    inputIt.NextSpan();
    outputIt.NextSpan();
    y++;
  }
}

// Internal method which should never be used anywhere else and should not be in th header.
//----------------------------------------------------------------------------
// This templated function executes the filter for any type of data.
template <class T>
void vtkApplyLookupTableOnScalarsCTF(vtkMitkLevelWindowFilter *self,
                                     vtkImageData *inData,
                                     vtkImageData *outData,
                                     int outExt[6],
                                     double *clippingBounds,
                                     T *)
{
  vtkImageIterator<T> inputIt(inData, outExt);
  vtkImageIterator<unsigned char> outputIt(outData, outExt);
  auto *lookupTable = dynamic_cast<vtkColorTransferFunction *>(self->GetLookupTable());
  vtkPiecewiseFunction *opacityFunction = self->GetOpacityPiecewiseFunction();

  int y = outExt[2];

  // Loop through output pixels
  while (!outputIt.IsAtEnd())
  {
    unsigned char *outputSI = outputIt.BeginSpan();
    unsigned char *outputSIEnd = outputIt.EndSpan();

    // do we iterate over the inner vertical clipping bounds
    if (y >= clippingBounds[2] && y < clippingBounds[3])
    {
      T *inputSI = inputIt.BeginSpan();

      int x = outExt[0];

      while (outputSI != outputSIEnd)
      {
        // is this pixel within horizontal clipping bounds
        if (x >= clippingBounds[0] && x < clippingBounds[1])
        {
          // fetching original value
          auto grayValue = static_cast<double>(*inputSI);

          // applying directly colortransferfunction
          // because vtkColorTransferFunction::MapValue is not threadsafe
          double rgba[4];
          lookupTable->GetColor(grayValue, rgba); // RGB mapping
          rgba[3] = 1.0;
          if (opacityFunction)
            rgba[3] = opacityFunction->GetValue(grayValue); // Alpha mapping

          for (int i = 0; i < 4; ++i)
          {
            outputSI[i] = static_cast<unsigned char>(255.0 * rgba[i] + 0.5);
          }
        }
        else
        {
          // outer horizontal clipping bounds - write a transparent RGBA pixel as a single int
          *reinterpret_cast<int *>(outputSI) = 0;
        }

        inputSI++;
        outputSI += 4;
        x++;
      }
    }
    else
    {
      // outer vertical clipping bounds - write a transparent RGBA line as ints
      while (outputSI != outputSIEnd)
      {
        *reinterpret_cast<int *>(outputSI) = 0;
        outputSI += 4;
      }
    }

    inputIt.NextSpan();
    outputIt.NextSpan();
    y++;
  }
}

int vtkMitkLevelWindowFilter::RequestInformation(vtkInformation *request,
                                                 vtkInformationVector **inputVector,
                                                 vtkInformationVector *outputVector)
{
  vtkInformation *outInfo = outputVector->GetInformationObject(0);

  // do nothing except copy scalar type info
  this->CopyInputArrayAttributesToOutput(request, inputVector, outputVector);

  vtkDataObject::SetPointDataActiveScalarInfo(outInfo, VTK_UNSIGNED_CHAR, 4);

  return 1;
}

// Method to run the filter in different threads.
void vtkMitkLevelWindowFilter::ThreadedExecute(vtkImageData *inData, vtkImageData *outData, int extent[6], int /*id*/)
{
  if (inData->GetNumberOfScalarComponents() > 2)
  {
    switch (inData->GetScalarType())
    {
      vtkTemplateMacro(
        vtkApplyLookupTableOnRGBA(this, inData, outData, extent, m_ClippingBounds, static_cast<VTK_TT *>(nullptr)));
      default:
        vtkErrorMacro(<< "Execute: Unknown ScalarType");
        return;
    }
  }
  else
  {
    bool dontClip = extent[2] >= m_ClippingBounds[2] && extent[3] <= m_ClippingBounds[3] &&
                    extent[0] >= m_ClippingBounds[0] && extent[1] <= m_ClippingBounds[1];

    if (this->GetLookupTable())
      this->GetLookupTable()->Build();

    auto *vlt = dynamic_cast<vtkLookupTable *>(this->GetLookupTable());
    auto *ctf = dynamic_cast<vtkColorTransferFunction *>(this->GetLookupTable());

    bool linearLookupTable = vlt && vlt->GetScale() == VTK_SCALE_LINEAR;

    bool useFast = dontClip && linearLookupTable;

    if (ctf)
    {
      switch (inData->GetScalarType())
      {
        vtkTemplateMacro(vtkApplyLookupTableOnScalarsCTF(
          this, inData, outData, extent, m_ClippingBounds, static_cast<VTK_TT *>(nullptr)));
        default:
          vtkErrorMacro(<< "Execute: Unknown ScalarType");
          return;
      }
    }
    else if (useFast)
    {
      switch (inData->GetScalarType())
      {
        vtkTemplateMacro(
          vtkApplyLookupTableOnScalarsFast(this, inData, outData, extent, static_cast<VTK_TT *>(nullptr)));
        default:
          vtkErrorMacro(<< "Execute: Unknown ScalarType");
          return;
      }
    }
    else
    {
      switch (inData->GetScalarType())
      {
        vtkTemplateMacro(vtkApplyLookupTableOnScalars(
          this, inData, outData, extent, m_ClippingBounds, static_cast<VTK_TT *>(nullptr)));
        default:
          vtkErrorMacro(<< "Execute: Unknown ScalarType");
          return;
      }
    }
  }
}

// void vtkMitkLevelWindowFilter::ExecuteInformation(
//    vtkImageData *vtkNotUsed(inData), vtkImageData *vtkNotUsed(outData))
//{
//}

void vtkMitkLevelWindowFilter::SetMinOpacity(double minOpacity)
{
  m_MinOpacity = minOpacity;
}

inline double vtkMitkLevelWindowFilter::GetMinOpacity() const
{
  return m_MinOpacity;
}

void vtkMitkLevelWindowFilter::SetMaxOpacity(double maxOpacity)
{
  m_MaxOpacity = maxOpacity;
}

inline double vtkMitkLevelWindowFilter::GetMaxOpacity() const
{
  return m_MaxOpacity;
}

void vtkMitkLevelWindowFilter::SetClippingBounds(double *bounds) // TODO does double[4] work??
{
  for (unsigned int i = 0; i < 4; ++i)
    m_ClippingBounds[i] = bounds[i];
}
