// Gmsh - Copyright (C) 1997-2025 C. Geuzaine, J.-F. Remacle
//
// See the LICENSE.txt file in the Gmsh root directory for license information.
// Please report all issues on https://gitlab.onelab.info/gmsh/gmsh/issues.

#include <cmath>
#include <algorithm>
#include "pyramidalBasis.h"
#include "pointsGenerators.h"

pyramidalBasis::pyramidalBasis(int tag) : nodalBasis(tag), bergot(nullptr)
{
  if(serendip && order > 2) {
    Msg::Warning("Serendipity pyramid for order %i not yet implemented", order);
    return;
  }

  bergot = new BergotBasis(order, serendip);

  int num_points = points.size1();

  bergotCoefficients.resize(num_points, num_points);
  double *fval = new double[num_points];

  // Invert the Vandermonde matrix
  fullMatrix<double> VDM(num_points, num_points);
  for(int j = 0; j < num_points; j++) {
    bergot->f(points(j, 0), points(j, 1), points(j, 2), fval);
    for(int i = 0; i < num_points; i++) VDM(i, j) = fval[i];
  }
  VDM.invert(bergotCoefficients);

  coefficients.resize(num_points, num_points);
  monomials.resize(num_points, 3);

  int idx = 0;
  for(int i = 0; i <= order; i++) {
    for(int j = 0; j <= order; j++) {
      if(bergot->validIJ(i, j)) {
        for(int k = 0; k <= order - std::max(i, j); k++, idx++) {
          monomials(idx, 0) = i;
          monomials(idx, 1) = j;
          monomials(idx, 2) = k;

          for(int l = 0; l < num_points; l++) {
            double oneMinW = std::max(1e-14, 1 - points(l, 2));
            VDM(idx, l) = std::pow(points(l, 0), i);
            VDM(idx, l) *= std::pow(points(l, 1), j);
            VDM(idx, l) *= std::pow(points(l, 2), k);
            VDM(idx, l) *= std::pow(oneMinW, std::max(i, j) - i - j);
          }
        }
      }
    }
  }
  VDM.invert(coefficients);

  delete[] fval;
}

pyramidalBasis::~pyramidalBasis()
{
  if(bergot) delete bergot;
}

int pyramidalBasis::getNumShapeFunctions() const { return points.size1(); }

void pyramidalBasis::f(double u, double v, double w, double *val) const
{
  if(!bergot) return;

  const int N = points.size1();

  double *fval = new double[N];
  bergot->f(u, v, w, fval);

  for(int i = 0; i < N; i++) {
    val[i] = 0.;
    for(int j = 0; j < N; j++) val[i] += bergotCoefficients(i, j) * fval[j];
  }

  delete[] fval;
}

void pyramidalBasis::f(const fullMatrix<double> &coord,
                       fullMatrix<double> &sf) const
{
  if(!bergot) return;

  const int N = points.size1(), NPts = coord.size1();

  sf.resize(NPts, N);
  double *fval = new double[N];

  for(int iPt = 0; iPt < NPts; iPt++) {
    bergot->f(coord(iPt, 0), coord(iPt, 1), coord(iPt, 2), fval);
    for(int i = 0; i < N; i++) {
      sf(iPt, i) = 0.;
      for(int j = 0; j < N; j++)
        sf(iPt, i) += bergotCoefficients(i, j) * fval[j];
    }
  }

  delete[] fval;
}

void pyramidalBasis::f(double u, double v, double w, int i, double *val) const
{
  if(!bergot) return;

  if(i < 0 || i >= bergotCoefficients.size1()) {
    Msg::Error("Node out of range for pyramidal basis");
    return;
  }

  const int N = points.size1();

  double *fval = new double[N];
  bergot->f(u, v, w, fval);

  *val = 0.;
  for(int j = 0; j < N; j++) *val += bergotCoefficients(i, j) * fval[j];

  delete[] fval;
}

void pyramidalBasis::df(double u, double v, double w, double grads[][3]) const
{
  if(!bergot) return;

  const int N = points.size1();

  double(*dfval)[3] = new double[N][3];
  bergot->df(u, v, w, dfval);

  for(int i = 0; i < N; i++) {
    grads[i][0] = 0.;
    grads[i][1] = 0.;
    grads[i][2] = 0.;
    for(int j = 0; j < N; j++) {
      grads[i][0] += bergotCoefficients(i, j) * dfval[j][0];
      grads[i][1] += bergotCoefficients(i, j) * dfval[j][1];
      grads[i][2] += bergotCoefficients(i, j) * dfval[j][2];
    }
  }

  delete[] dfval;
}

void pyramidalBasis::df(const fullMatrix<double> &coord,
                        fullMatrix<double> &dfm) const
{
  if(!bergot) return;

  const int N = points.size1(), NPts = coord.size1();

  double(*dfv)[3] = new double[N][3];
  dfm.resize(3 * NPts, N, false);

  for(int iPt = 0; iPt < NPts; iPt++) {
    df(coord(iPt, 0), coord(iPt, 1), coord(iPt, 2), dfv);
    for(int i = 0; i < N; i++) {
      dfm(3 * iPt + 0, i) = dfv[i][0];
      dfm(3 * iPt + 1, i) = dfv[i][1];
      dfm(3 * iPt + 2, i) = dfv[i][2];
    }
  }

  delete[] dfv;
}

void pyramidalBasis::df(double u, double v, double w, int i,
                        double grad[3]) const
{
  if(!bergot) return;

  if(i < 0 || i >= bergotCoefficients.size1()) {
    Msg::Error("Node out of range for pyramidal basis gradient");
    return;
  }

  const int N = points.size1();

  double(*dfval)[3] = new double[N][3];
  bergot->df(u, v, w, dfval);

  grad[0] = 0.;
  grad[1] = 0.;
  grad[2] = 0.;
  for(int j = 0; j < N; j++) {
    grad[0] += bergotCoefficients(i, j) * dfval[j][0];
    grad[1] += bergotCoefficients(i, j) * dfval[j][1];
    grad[2] += bergotCoefficients(i, j) * dfval[j][2];
  }

  delete[] dfval;
}
