// SPDX-FileCopyrightText: Copyright (c) Kitware Inc.
// SPDX-FileCopyrightText: Copyright (c) Sandia Corporation
// SPDX-License-Identifier: BSD-3-Clause
#include "pqPresetToPixmap.h"

#include "pqActiveObjects.h"
#include "vtkFloatArray.h"
#include "vtkImageData.h"
#include "vtkMath.h"
#include "vtkNew.h"
#include "vtkPVDiscretizableColorTransferFunction.h"
#include "vtkPiecewiseFunction.h"
#include "vtkSMPropertyHelper.h"
#include "vtkSMSession.h"
#include "vtkSMSessionProxyManager.h"
#include "vtkSMTransferFunctionPresets.h"
#include "vtkSMTransferFunctionProxy.h"
#include "vtkSmartPointer.h"
#include "vtkUnsignedCharArray.h"

#include <QImage>
#include <QPainter>
#include <QPainterPath>
#include <QPen>
#include <QPixmap>
#include <QSize>

class pqPresetToPixmap::pqInternals
{
  vtkSmartPointer<vtkSMProxy> PVLookupTable;
  vtkSmartPointer<vtkSMProxy> PiecewiseFunction;

public:
  pqInternals()
  {
    vtkSMSessionProxyManager* pxm = pqActiveObjects::instance().proxyManager();
    this->PiecewiseFunction.TakeReference(
      pxm->NewProxy("piecewise_functions", "PiecewiseFunction"));
    this->PiecewiseFunction->SetLocation(vtkSMSession::CLIENT);
    this->PiecewiseFunction->UpdateVTKObjects();

    this->PVLookupTable.TakeReference(pxm->NewProxy("lookup_tables", "PVLookupTable"));
    this->PVLookupTable->SetLocation(vtkSMSession::CLIENT);
    vtkSMPropertyHelper(this->PVLookupTable, "ScalarOpacityFunction").Set(this->PiecewiseFunction);
  }

  vtkSMProxy* lookupTable() const
  {
    this->PVLookupTable->ResetPropertiesToXMLDefaults();
    this->PVLookupTable->UpdateVTKObjects();
    return this->PVLookupTable;
  }

  vtkSMProxy* piecewiseFunction() const
  {
    this->PiecewiseFunction->ResetPropertiesToXMLDefaults();
    this->PiecewiseFunction->UpdateVTKObjects();
    return this->PiecewiseFunction;
  }

  bool loadPreset(vtkSMProxy* proxy, const Json::Value& preset)
  {
    return vtkSMTransferFunctionProxy::ApplyPreset(proxy, preset);
  }
};

//-----------------------------------------------------------------------------
pqPresetToPixmap::pqPresetToPixmap(QObject* parentObject)
  : Superclass(parentObject)
  , Internals(new pqPresetToPixmap::pqInternals())
{
}

//-----------------------------------------------------------------------------
pqPresetToPixmap::~pqPresetToPixmap() = default;

//-----------------------------------------------------------------------------
QPixmap pqPresetToPixmap::render(const Json::Value& preset, const QSize& resolution) const
{
  if (resolution.width() <= 0 || resolution.height() <= 0)
  {
    return QPixmap();
  }

  pqInternals& internals = (*this->Internals);
  vtkSMProxy* lutProxy = internals.lookupTable();
  vtkSMTransferFunctionProxy::ApplyPreset(lutProxy, preset);
  vtkSMTransferFunctionProxy::RescaleTransferFunction(lutProxy, 1, 100, false);
  vtkScalarsToColors* stc = vtkScalarsToColors::SafeDownCast(lutProxy->GetClientSideObject());
  if (stc->GetIndexedLookup())
  {
    return this->renderIndexedColorTransferFunction(stc, resolution);
  }
  else
  {
    vtkPiecewiseFunction* pf = nullptr;
    auto presets = vtkSMTransferFunctionPresets::GetInstance();
    if (presets->GetPresetHasOpacities(preset))
    {
      vtkSMProxy* piecewiseFunctionProxy = internals.piecewiseFunction();
      vtkSMTransferFunctionProxy::ApplyPreset(piecewiseFunctionProxy, preset);
      vtkSMTransferFunctionProxy::RescaleTransferFunction(piecewiseFunctionProxy, 1, 100, false);
      pf = vtkPiecewiseFunction::SafeDownCast(piecewiseFunctionProxy->GetClientSideObject());
    }
    return this->renderColorTransferFunction(stc, pf, resolution);
  }
}

//-----------------------------------------------------------------------------
QPixmap pqPresetToPixmap::renderColorTransferFunction(
  vtkScalarsToColors* stc, vtkPiecewiseFunction* pf, const QSize& resolution) const
{
  int numSamples = std::min(256, std::max(2, resolution.width()));
  vtkNew<vtkFloatArray> data;
  data->SetNumberOfTuples(numSamples);
  const double* range = stc->GetRange();
  int isUsingLog = stc->UsingLogScale();
  double lrange[2];
  if (isUsingLog)
  {
    lrange[0] = log10(range[0]);
    lrange[1] = log10(range[1]);
  }
  for (vtkIdType cc = 0, max = numSamples; cc < max; ++cc)
  {
    double normVal = static_cast<double>(cc) / (max - 1);
    double val;
    if (isUsingLog)
    {
      double lval = lrange[0] + normVal * (lrange[1] - lrange[0]);
      val = pow(10.0, lval);
    }
    else
    {
      val = (range[1] - range[0]) * normVal + range[0];
    }
    data->SetValue(cc, val);
  }
  vtkSmartPointer<vtkUnsignedCharArray> colors;
  colors.TakeReference(vtkUnsignedCharArray::SafeDownCast(
    stc->MapScalars(data.GetPointer(), VTK_COLOR_MODE_MAP_SCALARS, 0)));
  QImage image(numSamples, 1, QImage::Format_RGB888);
  for (int cc = 0; cc < numSamples; ++cc)
  {
    unsigned char* ptr = colors->GetPointer(4 * cc);
    image.setPixel(cc, 0, qRgb(ptr[0], ptr[1], ptr[2]));
  }
  if (pf)
  {
    image = image.scaled(image.width(), resolution.height());
    QPixmap pixmap = QPixmap::fromImage(image);
    QPainterPath path;
    path.moveTo(0, 0);
    for (vtkIdType cc = 0, max = numSamples; cc < max; cc += 10)
    {
      float x = data->GetValue(cc);
      int y = static_cast<int>(resolution.height() * (1.0 - pf->GetValue(x)));
      path.lineTo(cc, y);
    }
    QPainter painter(&pixmap);
    painter.setPen(Qt::black);
    // painter.setRenderHint(QPainter::Antialiasing, true);
    QPen pen = painter.pen();
    pen.setWidth(2);
    painter.strokePath(path, pen);
    return pixmap;
  }
  else
  {
    image = image.scaled(resolution);
    return QPixmap::fromImage(image);
  }
}

//-----------------------------------------------------------------------------
// This is brought over directly from pqColorMapModel::generateCategoricalPreview().
//-----------------------------------------------------------------------------

// The smallest number of pixels along an edge that a color swatch should be.
#define PQ_MIN_SWATCH_DIM 6
// The amount of padding between swatches and the edge of the palette and/or a neighbor swatch
// [pixels].
#define PQ_SWATCH_PAD 2
// The number of pixels each swatch's insert border color should be drawn.
#define PQ_SWATCH_BORDER 1
QPixmap pqPresetToPixmap::renderIndexedColorTransferFunction(
  vtkScalarsToColors* stc, const QSize& size) const
{
  vtkPVDiscretizableColorTransferFunction* dct =
    vtkPVDiscretizableColorTransferFunction::SafeDownCast(stc);
  int numSwatches = static_cast<int>(dct->GetNumberOfIndexedColorsInFullSet());
  if (numSwatches < 1)
  {
    return QPixmap();
  }

  // This is needed since the vtkDiscretizableColorTransferFunction only
  // respects categorical colors for which annotations are present (currently)
  dct->ResetAnnotationsInFullSet();
  for (int cc = 0; cc < numSwatches; cc++)
  {
    dct->SetAnnotationInFullSet(vtkVariant(cc), "");
  }
  dct->Build();

  // Create a pixmap and painter.
  QPixmap palette(size);
  QPainter painter(&palette);

  int wmp = size.width() - PQ_SWATCH_PAD, hmp = size.height() - PQ_SWATCH_PAD;

  // I. Determine the maximum number of rows and columns of swatches
  // Maximum if we constrain height:
  int Nvmax = hmp / (PQ_MIN_SWATCH_DIM + PQ_SWATCH_PAD);
  // Maximum if we don't constrain height:
  int NvUnconstrained = static_cast<int>(ceil(sqrt(numSwatches)));

  // II. Determine the actual number of rows and columns
  int N = numSwatches, Nh = N, Nv = 1;
  while (((wmp / Nh < PQ_MIN_SWATCH_DIM + PQ_SWATCH_PAD) ||
           // aspect ratio < 2/3 (integer math) and we have headroom.
           ((hmp * Nh * 10) / (Nv * wmp) > 15 && Nv < Nvmax)) &&
    Nv < NvUnconstrained)
  {
    ++Nv;
    // Now determine the value for Nh that makes the swatch
    // aspect ratio as near to square as possible:
    double bestQ = vtkMath::Inf();
    int best = -1;
    int searchNh;
    for (searchNh = Nh; searchNh * Nv >= N; --searchNh)
    {
      double ar = Nv * wmp / static_cast<double>(hmp * searchNh);
      double q = (ar >= 1.0) ? ar : 1. / ar;
      if (q < bestQ)
      {
        bestQ = q;
        best = searchNh;
      }
    }
    Nh = best;
  }

  // III. Determine swatch size and number of swatches that can actually be displayed
  int ws = wmp / Nh - PQ_SWATCH_PAD;
  int hs = hmp / Nv - PQ_SWATCH_PAD;
  if (ws < 0)
    ws = PQ_MIN_SWATCH_DIM;
  if (hs < 0)
    hs = PQ_MIN_SWATCH_DIM;
  int Nd =
    Nh * Nv; // This may be more or less than N, but no more than this many swatches will be drawn.
  int ss = ws < hs ? ws : hs; // Force aspect ratio to 1 and then update Nh, Nv, Nd
  Nh = wmp / (ss + PQ_SWATCH_PAD);
  Nv = hmp / (ss + PQ_SWATCH_PAD);
  Nd = Nh * Nv;
  int elideLf = (Nd < N ? Nd / 2 : N - 1);
  int elideRt = (Nd < N ? N - Nd / 2 + 1 : N);
  Nd = Nd > N ? N : Nd;

  // IV. Clear to background.
  QPen blank(Qt::NoPen);
  painter.setBrush(QColor("white"));
  painter.setPen(blank);
  painter.drawRect(0, 0, size.width(), size.height());

  // IV. Draw swatches.
  QPen outline(Qt::SolidLine);
  outline.setWidth(PQ_SWATCH_BORDER);
  painter.setPen(outline);
  int row, col, swatch;
  for (row = 0, col = 0, swatch = 0; swatch <= elideLf; ++swatch)
  {
    double drgba[4];
    dct->GetIndexedColorInFullSet(swatch, drgba);
    painter.setBrush(QColor::fromRgbF(drgba[0], drgba[1], drgba[2]));
    painter.drawRect(PQ_SWATCH_PAD + col * (PQ_SWATCH_PAD + ss) + 0.5,
      PQ_SWATCH_PAD + row * (PQ_SWATCH_PAD + ss) + 0.5, ss, ss);

    if (++col == Nh)
    {
      col = 0;
      ++row;
    }
  }

  // Advance one entry over the elided swatch
  if (++col == Nh)
  {
    col = 0;
    ++row;
  }
  ++swatch;

  // Now pick up and draw the remaining swatches, if any
  int entry = elideRt;
  for (; swatch < Nd; ++swatch, ++entry)
  {
    double drgba[4];
    dct->GetIndexedColorInFullSet(swatch, drgba);
    painter.setBrush(QColor::fromRgbF(drgba[0], drgba[1], drgba[2]));
    painter.drawRect(PQ_SWATCH_PAD + col * (PQ_SWATCH_PAD + ss) + 0.5,
      PQ_SWATCH_PAD + row * (PQ_SWATCH_PAD + ss) + 0.5, ss, ss);

    if (++col == Nh)
    {
      col = 0;
      ++row;
    }
  }

  return palette;
}
