#include <QVTKOpenGLNativeWidget.h>
#include <vtkActor.h>
#include <vtkDataSetMapper.h>
#include <vtkDoubleArray.h>
#include <vtkGenericOpenGLRenderWindow.h>
#include <vtkPointData.h>
#include <vtkProperty.h>
#include <vtkRenderer.h>
#include <vtkSphereSource.h>

#include <QApplication>
#include <QDockWidget>
#include <QGridLayout>
#include <QLabel>
#include <QMainWindow>
#include <QPointer>
#include <QPushButton>
#include <QVBoxLayout>

#include <cmath>
#include <cstdlib>
#include <random>

namespace {
/**
 * Deform the sphere source using a random amplitude and modes and render it in
 * the window
 *
 * @param sphere the original sphere source
 * @param mapper the mapper for the scene
 * @param window the window to render to
 * @param randEng the random number generator engine
 */
void Randomize(vtkSphereSource* sphere, vtkDataSetMapper* mapper,
               vtkGenericOpenGLRenderWindow* window, std::mt19937& randEng);
} // namespace

int main(int argc, char* argv[])
{
  QSurfaceFormat::setDefaultFormat(QVTKOpenGLNativeWidget::defaultFormat());

  QApplication app(argc, argv);

  // Main window.
  QMainWindow mainWindow;
  mainWindow.resize(1200, 900);

  // Control area.
  QDockWidget controlDock;
  mainWindow.addDockWidget(Qt::LeftDockWidgetArea, &controlDock);

  QLabel controlDockTitle("Control Dock");
  controlDockTitle.setMargin(20);
  controlDock.setTitleBarWidget(&controlDockTitle);

  QPointer<QVBoxLayout> dockLayout = new QVBoxLayout();
  QWidget layoutContainer;
  layoutContainer.setLayout(dockLayout);
  controlDock.setWidget(&layoutContainer);

  QPushButton randomizeButton;
  randomizeButton.setText("Randomize");
  dockLayout->addWidget(&randomizeButton);

  // Render area.
  QPointer<QVTKOpenGLNativeWidget> vtkRenderWidget =
      new QVTKOpenGLNativeWidget();
  mainWindow.setCentralWidget(vtkRenderWidget);

  // VTK part.
  vtkNew<vtkGenericOpenGLRenderWindow> window;
  vtkRenderWidget->setRenderWindow(window.Get());

  vtkNew<vtkSphereSource> sphere;
  sphere->SetRadius(1.0);
  sphere->SetThetaResolution(100);
  sphere->SetPhiResolution(100);

  vtkNew<vtkDataSetMapper> mapper;
  mapper->SetInputConnection(sphere->GetOutputPort());

  vtkNew<vtkActor> actor;
  actor->SetMapper(mapper);
  actor->GetProperty()->SetEdgeVisibility(true);
  actor->GetProperty()->SetRepresentationToSurface();

  vtkNew<vtkRenderer> renderer;
  renderer->AddActor(actor);

  window->AddRenderer(renderer);

  // Setup initial status.
  std::mt19937 randEng(0);
  ::Randomize(sphere, mapper, window, randEng);

  // connect the buttons
  QObject::connect(&randomizeButton, &QPushButton::released,
                   [&]() { ::Randomize(sphere, mapper, window, randEng); });

  mainWindow.show();

  return app.exec();
}

namespace {
void Randomize(vtkSphereSource* sphere, vtkDataSetMapper* mapper,
               vtkGenericOpenGLRenderWindow* window, std::mt19937& randEng)
{
  // Generate randomness.
  double randAmp = 0.2 + ((randEng() % 1000) / 1000.0) * 0.2;
  double randThetaFreq = 1.0 + (randEng() % 9);
  double randPhiFreq = 1.0 + (randEng() % 9);

  // Extract and prepare data.
  sphere->Update();
  vtkSmartPointer<vtkPolyData> newSphere;
  newSphere.TakeReference(sphere->GetOutput()->NewInstance());
  newSphere->DeepCopy(sphere->GetOutput());
  vtkNew<vtkDoubleArray> height;
  height->SetName("Height");
  height->SetNumberOfComponents(1);
  height->SetNumberOfTuples(newSphere->GetNumberOfPoints());
  newSphere->GetPointData()->AddArray(height);

  // Deform the sphere.
  for (int iP = 0; iP < newSphere->GetNumberOfPoints(); iP++)
  {
    double pt[3] = {0.0};
    newSphere->GetPoint(iP, pt);
    double theta = std::atan2(pt[1], pt[0]);
    double phi =
        std::atan2(pt[2], std::sqrt(std::pow(pt[0], 2) + std::pow(pt[1], 2)));
    double thisAmp =
        randAmp * std::cos(randThetaFreq * theta) * std::sin(randPhiFreq * phi);
    height->SetValue(iP, thisAmp);
    pt[0] += thisAmp * std::cos(theta) * std::cos(phi);
    pt[1] += thisAmp * std::sin(theta) * std::cos(phi);
    pt[2] += thisAmp * std::sin(phi);
    newSphere->GetPoints()->SetPoint(iP, pt);
  }
  newSphere->GetPointData()->SetScalars(height);

  // Reconfigure the pipeline to take the new deformed sphere.
  mapper->SetInputDataObject(newSphere);
  mapper->SetScalarModeToUsePointData();
  mapper->ColorByArrayComponent("Height", 0);
  window->Render();
}
} // namespace