#pragma once

#include "fesa/Math/Vector.hpp"
#include "fesa/Util/Diagnostics.hpp"

#include <array>
#include <cstddef>
#include <string>
#include <utility>
#include <vector>

namespace fesa {

using MITC4StrainVector = std::array<Real, 6>;
using MITC4MaterialMatrix = std::array<std::array<Real, 6>, 6>;

enum class MITC4StrainComponent {
  Eps11 = 0,
  Eps22 = 1,
  Eps33 = 2,
  Gamma23 = 3,
  Gamma13 = 4,
  Gamma12 = 5
};

inline std::size_t strainComponentIndex(MITC4StrainComponent component) {
  return static_cast<std::size_t>(component);
}

inline std::array<std::string, 6> mitc4StrainComponentLabels() {
  return {"eps11", "eps22", "eps33", "gamma23", "gamma13", "gamma12"};
}

struct MITC4MaterialMatrixEvaluation {
  MITC4MaterialMatrix matrix{};
  std::vector<Diagnostic> diagnostics;

  bool ok() const {
    return !hasError(diagnostics);
  }
};

inline Diagnostic mitc4MaterialDiagnostic(std::string code, std::string message) {
  return makeDiagnostic(Severity::Error, std::move(code), std::move(message), "mitc4", "<element>", 0);
}

inline MITC4MaterialMatrixEvaluation mitc4PlaneStressMaterialMatrix(Real elastic_modulus, Real poisson_ratio,
                                                                    Real shear_correction = 5.0 / 6.0,
                                                                    Real tolerance = 1.0e-12) {
  MITC4MaterialMatrixEvaluation result;
  if (!isFinite(elastic_modulus) || elastic_modulus <= tolerance) {
    result.diagnostics.push_back(
        mitc4MaterialDiagnostic("FESA-MITC4-MATERIAL", "MITC4 elastic modulus must be positive and finite"));
  }
  if (!isFinite(poisson_ratio) || poisson_ratio <= -1.0 || poisson_ratio >= 0.5) {
    result.diagnostics.push_back(
        mitc4MaterialDiagnostic("FESA-MITC4-POISSON", "MITC4 isotropic Poisson ratio must satisfy -1 < nu < 0.5"));
  }
  if (!isFinite(shear_correction) || shear_correction <= tolerance) {
    result.diagnostics.push_back(mitc4MaterialDiagnostic("FESA-MITC4-SHEAR-CORRECTION",
                                                         "MITC4 shear correction factor must be positive and finite"));
  }
  if (hasError(result.diagnostics)) {
    return result;
  }

  const Real scale = elastic_modulus / (1.0 - poisson_ratio * poisson_ratio);
  const Real shear_modulus = elastic_modulus / (2.0 * (1.0 + poisson_ratio));
  const std::size_t eps11 = strainComponentIndex(MITC4StrainComponent::Eps11);
  const std::size_t eps22 = strainComponentIndex(MITC4StrainComponent::Eps22);
  const std::size_t gamma23 = strainComponentIndex(MITC4StrainComponent::Gamma23);
  const std::size_t gamma13 = strainComponentIndex(MITC4StrainComponent::Gamma13);
  const std::size_t gamma12 = strainComponentIndex(MITC4StrainComponent::Gamma12);

  result.matrix[eps11][eps11] = scale;
  result.matrix[eps11][eps22] = poisson_ratio * scale;
  result.matrix[eps22][eps11] = poisson_ratio * scale;
  result.matrix[eps22][eps22] = scale;
  result.matrix[gamma23][gamma23] = shear_correction * shear_modulus;
  result.matrix[gamma13][gamma13] = shear_correction * shear_modulus;
  result.matrix[gamma12][gamma12] = shear_modulus;
  return result;
}

inline MITC4StrainVector multiplyMITC4MaterialMatrix(const MITC4MaterialMatrix& matrix,
                                                     const MITC4StrainVector& vector) {
  MITC4StrainVector result{};
  for (std::size_t row = 0; row < 6; ++row) {
    for (std::size_t col = 0; col < 6; ++col) {
      result[row] += matrix[row][col] * vector[col];
    }
  }
  return result;
}

inline Real dotMITC4Vector(const MITC4StrainVector& a, const MITC4StrainVector& b) {
  Real result = 0.0;
  for (std::size_t i = 0; i < 6; ++i) {
    result += a[i] * b[i];
  }
  return result;
}

inline MITC4MaterialMatrix mitc4TransformMaterialMatrix(const MITC4MaterialMatrix& local_material,
                                                        const MITC4MaterialMatrix& covariant_to_local) {
  MITC4MaterialMatrix result{};
  for (std::size_t i = 0; i < 6; ++i) {
    for (std::size_t j = 0; j < 6; ++j) {
      Real value = 0.0;
      for (std::size_t a = 0; a < 6; ++a) {
        for (std::size_t b = 0; b < 6; ++b) {
          value += covariant_to_local[a][i] * local_material[a][b] * covariant_to_local[b][j];
        }
      }
      result[i][j] = value;
    }
  }
  return result;
}

}  // namespace fesa