#include <CLI11.hpp>

#include "geometrycentral/surface/manifold_surface_mesh.h"
#include "geometrycentral/surface/meshio.h"
#include "geometrycentral/surface/vertex_position_geometry.h"

#include "polyscope/polyscope.h"
#include "polyscope/surface_mesh.h"
#include "polyscope/point_cloud.h"

using namespace geometrycentral;
using namespace geometrycentral::surface;

// == Geometry-central data
std::unique_ptr<ManifoldSurfaceMesh> mesh;
std::unique_ptr<VertexPositionGeometry> geometry;

int counter=0;
float lambda = 0.5;

Vector3 vertAverage(std::vector<Vector3> vertexPositions) {
  assert(vertexPositions.size() > 0);

  Vector3 out = {0, 0, 0};
  for (auto i=0; i < vertexPositions.size(); i++) {
    out = out + vertexPositions.at(i);
  }
  return out/vertexPositions.size();
}

void oneStep()
{
  for(Vertex v : mesh->vertices()) {
    std::vector<Vector3> adjVert;
    adjVert.push_back(geometry->vertexPositions[v]);
    for (Vertex v_adj : v.adjacentVertices()) {
      adjVert.push_back(geometry->vertexPositions[v_adj]);
    }
    Vector3 avgPos = vertAverage(adjVert);
    avgPos -= geometry->vertexPositions[v];

    geometry->vertexPositions[v] += lambda*avgPos;
  }
}

bool go=false;

void myCallback()
{
  if (ImGui::Button("Go!"))
    go= !go;
  
  if (go)
  {
    oneStep();
    polyscope::getSurfaceMesh("Input obj")->updateVertexPositions(geometry->vertexPositions);
   // polyscope::screenshot();
  }
  counter++;
}



int main(int argc, char **argv) {
  CLI::App app{"laplacian"};
  std::string inputObj;
  app.add_option("-i,--input", inputObj, "Source Obj")->required()->check(CLI::ExistingFile);;
  app.add_option("-l,--lambda", lambda, "Lambda (speed of transformation).");
  CLI11_PARSE(app, argc, argv);
  assert (lambda <= 1 && lambda > 0);

  // Initialize polyscope
  polyscope::init();

  // Load mesh
  std::tie(mesh, geometry) = readManifoldSurfaceMesh(inputObj);

  // Register the mesh with polyscope
  polyscope::registerSurfaceMesh("Input obj",
                                 geometry->inputVertexPositions,
                                 mesh->getFaceVertexList(),
                                 polyscopePermutations(*mesh));
  
  
  geometry->requireVertexPositions();
 
  // Specify the callback
  polyscope::state::userCallback = myCallback;
  
  // Give control to the polyscope gui
  polyscope::show();
  return EXIT_SUCCESS;
}