// 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 <algorithm>
#include "STensor3.h"
#include "fullMatrix.h"

SMetric3::SMetric3(const double l1, // l1 = h1^-2
                   const double l2, const double l3, const SVector3 &t1,
                   const SVector3 &t2, const SVector3 &t3)
{
  // M = e^t * diag * e
  // where the elements of diag are l_i = h_i^-2
  // and the rows of e are the UNIT and ORTHOGONAL directions

  fullMatrix<double> e(3, 3);
  e(0, 0) = t1(0);
  e(0, 1) = t1(1);
  e(0, 2) = t1(2);
  e(1, 0) = t2(0);
  e(1, 1) = t2(1);
  e(1, 2) = t2(2);
  e(2, 0) = t3(0);
  e(2, 1) = t3(1);
  e(2, 2) = t3(2);
  e.transposeInPlace();

  fullMatrix<double> tmp(3, 3);
  tmp(0, 0) = l1 * e(0, 0);
  tmp(0, 1) = l2 * e(0, 1);
  tmp(0, 2) = l3 * e(0, 2);
  tmp(1, 0) = l1 * e(1, 0);
  tmp(1, 1) = l2 * e(1, 1);
  tmp(1, 2) = l3 * e(1, 2);
  tmp(2, 0) = l1 * e(2, 0);
  tmp(2, 1) = l2 * e(2, 1);
  tmp(2, 2) = l3 * e(2, 2);

  e.transposeInPlace();

  _val[0] = tmp(0, 0) * e(0, 0) + tmp(0, 1) * e(1, 0) + tmp(0, 2) * e(2, 0);
  _val[1] = tmp(1, 0) * e(0, 0) + tmp(1, 1) * e(1, 0) + tmp(1, 2) * e(2, 0);
  _val[2] = tmp(1, 0) * e(0, 1) + tmp(1, 1) * e(1, 1) + tmp(1, 2) * e(2, 1);
  _val[3] = tmp(2, 0) * e(0, 0) + tmp(2, 1) * e(1, 0) + tmp(2, 2) * e(2, 0);
  _val[4] = tmp(2, 0) * e(0, 1) + tmp(2, 1) * e(1, 1) + tmp(2, 2) * e(2, 1);
  _val[5] = tmp(2, 0) * e(0, 2) + tmp(2, 1) * e(1, 2) + tmp(2, 2) * e(2, 2);
}

void SMetric3::getMat(fullMatrix<double> &mat) const
{
  for(int i = 0; i < 3; i++) {
    for(int j = 0; j < 3; j++) { mat(i, j) = _val[getIndex(i, j)]; }
  }
}

void SMetric3::setMat(const fullMatrix<double> &mat)
{
  for(int i = 0; i < 3; i++)
    for(int j = 0; j < 3; j++) _val[getIndex(i, j)] = mat(i, j);
}

SMetric3 SMetric3::invert() const
{
  fullMatrix<double> m(3, 3);
  getMat(m);
  m.invertInPlace();
  SMetric3 ithis;
  ithis.setMat(m);
  return ithis;
}

double SMetric3::determinant() const
{
  fullMatrix<double> m(3, 3);
  getMat(m);
  double det = m.determinant();
  return det;
}

SMetric3 &SMetric3::operator*=(const SMetric3 &other)
{
  fullMatrix<double> m1(3, 3), m2(3, 3), m3(3, 3);
  getMat(m1);
  other.getMat(m2);
  m1.mult(m2, m3);
  setMat(m3);
  return *this;
}

SMetric3 SMetric3::transform(fullMatrix<double> &V)
{
  fullMatrix<double> m(3, 3);
  getMat(m);
  fullMatrix<double> result(3, 3), temp(3, 3);
  V.transpose().mult(m, temp);
  temp.mult(V, result);
  SMetric3 a;
  a.setMat(result);
  return a;
}

void SMetric3::eig(fullMatrix<double> &V, fullVector<double> &S, bool s) const
{
  fullMatrix<double> me(3, 3), left(3, 3);
  fullVector<double> im(3);
  getMat(me);
  me.eig(S, im, left, V, s);
}

void SMetric3::print(const char *s) const
{
  printf(" metric %s : %12.5E %12.5E %12.5E %12.5E %12.5E %12.5E \n", s,
         (*this)(0, 0), (*this)(1, 1), (*this)(2, 2), (*this)(0, 1),
         (*this)(0, 2), (*this)(1, 2));
}

SMetric3 intersection(const SMetric3 &m1, const SMetric3 &m2)
{
  SMetric3 im1 = m1.invert();
  fullMatrix<double> V(3, 3);
  fullVector<double> S(3);
  im1 *= m2;
  im1.eig(V, S, true);
  SVector3 v0(V(0, 0), V(1, 0), V(2, 0));
  SVector3 v1(V(0, 1), V(1, 1), V(2, 1));
  SVector3 v2(V(0, 2), V(1, 2), V(2, 2));
  double l0 = std::max(dot(v0, m1, v0), dot(v0, m2, v0));
  double l1 = std::max(dot(v1, m1, v1), dot(v1, m2, v1));
  double l2 = std::max(dot(v2, m1, v2), dot(v2, m2, v2));

  // Correction from the PhD thesis of Frederic Alauzet p.16
  // If m2 = alpha*m1, then take the largest metric
  static const double eps = 1.e-2; // Tolerance to detect triple eigenvalue
                                   // (i.e. proportional metrics)
  const double max_eig = std::max(S(0), std::max(S(1), S(2)));
  const double min_eig = std::min(S(0), std::min(S(1), S(2)));
  const double range_eig = fabs((max_eig - min_eig) / max_eig);
  if(range_eig < eps) return (max_eig >= 1.) ? m2 : m1;

  SMetric3 iv(l0, l1, l2, v0, v1, v2);
  return iv;
}

SMetric3 intersection_alauzet(const SMetric3 &m1, const SMetric3 &m2)
{
  SMetric3 im1 = m1.invert();
  fullMatrix<double> V(3, 3);
  fullVector<double> S(3);
  im1 *= m2;
  im1.eig(V, S, true);
  SVector3 v0(V(0, 0), V(1, 0), V(2, 0));
  SVector3 v1(V(0, 1), V(1, 1), V(2, 1));
  SVector3 v2(V(0, 2), V(1, 2), V(2, 2));
  double l0 = std::max(dot(v0, m1, v0), dot(v0, m2, v0));
  double l1 = std::max(dot(v1, m1, v1), dot(v1, m2, v1));
  double l2 = std::max(dot(v2, m1, v2), dot(v2, m2, v2));
  SMetric3 iv(l0, l1, l2, v0, v1, v2);
  return iv;
}

// preserve orientation of m1 !!!
SMetric3 intersection_conserveM1(const SMetric3 &m1, const SMetric3 &m2)
{
  // we should do
  // return intersection (m1,m2);
  fullMatrix<double> V(3, 3);
  fullVector<double> S(3);
  m1.eig(V, S, false);
  SVector3 v0(V(0, 0), V(1, 0), V(2, 0));
  SVector3 v1(V(0, 1), V(1, 1), V(2, 1));
  SVector3 v2(V(0, 2), V(1, 2), V(2, 2));
  double l0 = std::max(dot(v0, m1, v0), dot(v0, m2, v0));
  double l1 = std::max(dot(v1, m1, v1), dot(v1, m2, v1));
  double l2 = std::max(dot(v2, m1, v2), dot(v2, m2, v2));
  SMetric3 iv(l0, l1, l2, v0, v1, v2);
  return iv;
}

namespace {

  double anisoRatio2D(double v0x, double v0y, double v0z, double v1x,
                      double v1y, double v1z, double v2x, double v2y,
                      double v2z, double s0, double s1, double s2)
  {
    static const double eps = 1.e-8;

    double ratio;
    if(v0x * v0x + v0y * v0y + (v0z - 1.) * (v0z - 1.) <
       eps) // If 1st eigenvect corresponds to z dir. ...
      ratio =
        std::min(fabs(s1 / s2),
                 fabs(s2 / s1)); // ... consider ratio of 2nd and 3rd eigenval.
    else if(v1x * v1x + v1y * v1y + (v1z - 1.) * (v1z - 1.) <
            eps) // If 2nd eigenvect corresponds to z dir. ...
      ratio =
        std::min(fabs(s0 / s2),
                 fabs(s2 / s0)); // ... consider ratio of 1st and 3rd eigenval.
    else if(v2x * v2x + v2y * v2y + (v2z - 1.) * (v2z - 1.) <
            eps) // If 3rd eigenvect corresponds to z dir. ...
      ratio =
        std::min(fabs(s0 / s1),
                 fabs(s1 / s0)); // ... consider ratio of 1st and 2nd eigenval.
    else {
      printf("Error in anisoRatio2D: z direction not found!\n");
      ratio = 0.;
    }

    return ratio;
  }

} // namespace

// preserve orientation of the most anisotropic metric !!!
SMetric3 intersection_conserve_mostaniso(const SMetric3 &m1, const SMetric3 &m2)
{
  fullMatrix<double> V1(3, 3);
  fullVector<double> S1(3);
  m1.eig(V1, S1, true);
  double ratio1 =
    fabs(S1(0) / S1(2)); // Minimum ratio because we take sorted eigenvalues
  fullMatrix<double> V2(3, 3);
  fullVector<double> S2(3);
  m2.eig(V2, S2, true);
  double ratio2 =
    fabs(S2(0) / S2(2)); // Minimum ratio because we take sorted eigenvalues

  if(ratio1 < ratio2)
    return intersection_conserveM1(m1, m2);
  else
    return intersection_conserveM1(m2, m1);
}

// preserve orientation of the most anisotropic metric in 2D!!!
SMetric3 intersection_conserve_mostaniso_2d(const SMetric3 &m1,
                                            const SMetric3 &m2)
{
  fullMatrix<double> V1(3, 3);
  fullVector<double> S1(3);
  m1.eig(V1, S1, false);
  double ratio1 =
    anisoRatio2D(V1(0, 0), V1(1, 0), V1(2, 0), V1(0, 1), V1(1, 1), V1(2, 1),
                 V1(0, 2), V1(1, 2), V1(2, 2), S1(0), S1(1), S1(2));

  fullMatrix<double> V2(3, 3);
  fullVector<double> S2(3);
  m2.eig(V2, S2, false);
  double ratio2 =
    anisoRatio2D(V2(0, 0), V2(1, 0), V2(2, 0), V2(0, 1), V2(1, 1), V2(2, 1),
                 V2(0, 2), V2(1, 2), V2(2, 2), S2(0), S2(1), S2(2));

  if(ratio1 < ratio2)
    return intersection_conserveM1(m1, m2);
  else
    return intersection_conserveM1(m2, m1);
}

// (1-t) * m1 + t * m2
SMetric3 interpolation(const SMetric3 &m1, const SMetric3 &m2, const double t)
{
  SMetric3 im1 = m1.invert();
  SMetric3 im2 = m2.invert();
  im1 *= (1. - t);
  im2 *= t;
  im1 += im2;
  return im1.invert();
}

SMetric3 interpolation(const SMetric3 &m1, const SMetric3 &m2,
                       const SMetric3 &m3, const double u, const double v)
{
  SMetric3 im1 = m1.invert();
  SMetric3 im2 = m2.invert();
  SMetric3 im3 = m3.invert();
  im1 *= (1. - u - v);
  im2 *= u;
  im3 *= v;
  im1 += im2;
  im1 += im3;
  return im1.invert();
}

SMetric3 interpolation(const SMetric3 &m1, const SMetric3 &m2,
                       const SMetric3 &m3, const SMetric3 &m4, const double u,
                       const double v, const double w)
{
  SMetric3 im1 = m1.invert();
  SMetric3 im2 = m2.invert();
  SMetric3 im3 = m3.invert();
  SMetric3 im4 = m4.invert();
  im1 *= (1. - u - v - w);
  im2 *= u;
  im3 *= v;
  im4 *= w;
  im1 += im2;
  im1 += im3;
  im1 += im4;
  return im1.invert();
}

void STensor3::getMat(fullMatrix<double> &mat) const
{
  for(int i = 0; i < 3; i++) {
    for(int j = 0; j < 3; j++) { mat(i, j) = _val[getIndex(i, j)]; }
  }
}

void STensor3::setMat(const fullMatrix<double> &mat)
{
  for(int i = 0; i < 3; i++)
    for(int j = 0; j < 3; j++) _val[getIndex(i, j)] = mat(i, j);
}

void STensor3::eig(fullMatrix<double> &V, fullVector<double> &S, bool s) const
{
  fullMatrix<double> me(3, 3), left(3, 3);
  fullVector<double> im(3);
  this->getMat(me);
  me.eig(S, im, left, V, s);
}

void STensor3::print(const char *s) const
{
  printf(
    " tensor %s : \n"
    " %12.5E %12.5E %12.5E \n %12.5E %12.5E %12.5E \n %12.5E %12.5E %12.5E \n",
    s, (*this)(0, 0), (*this)(0, 1), (*this)(0, 2), (*this)(1, 0),
    (*this)(1, 1), (*this)(1, 2), (*this)(2, 0), (*this)(2, 1), (*this)(2, 2));
}
