#ifndef FESA_ELEMENTS_THERMAL_SHELL_GEOMETRY_H_
#define FESA_ELEMENTS_THERMAL_SHELL_GEOMETRY_H_

#include <array>

#include "fesa/core/status.h"
#include "fesa/math/vector3.h"
#include "thermal_interval.h"

namespace fesa {
struct ModelDefinition;
namespace thermal_internal {

/// @brief Holds translated, power-of-two scaled tangents and their enclosures.
struct Geometry {
  Vector3 b;
  Vector3 c;
  Vector3 d;
  IntervalVector bi;
  IntervalVector ci;
  IntervalVector di;
  int length_exponent = 0;
  double scaled_jacobian_lower = 0;
};

/// @brief Holds actual-point product metric, gradients and orthonormal columns.
struct SurfacePoint {
  std::array<double, 4> shape{};
  std::array<Interval, 4> shape_interval{};
  std::array<Vector3, 4> gradient{};
  std::array<IntervalVector, 4> gradient_interval{};
  std::array<Vector3, 3> axes{};
  double jacobian = 0;
  Interval jacobian_interval;
};

/// @brief Certifies whole-patch rank/injectivity from fixed candidate
/// directions.
Result<Geometry> BuildGeometry(const std::array<Vector3, 4>& coordinates,
                               const SourceEntityId& source,
                               const SourceLocation& location);
/// @brief Checks finite metric inverse and gradients at one used surface point.
Result<SurfacePoint> EvaluateSurface(const Geometry& geometry, double xi,
                                     double eta, Interval xi_interval,
                                     Interval eta_interval,
                                     const SourceEntityId& source,
                                     const SourceLocation& location);
/// @brief Builds a geometry failure retaining original source element identity.
Status GeometryFailure(const SourceEntityId& source,
                       const SourceLocation& location, const char* code,
                       const char* message);
}  // namespace thermal_internal

/// @brief Validates DS4 whole-patch geometry and source-only manifold topology.
/// @pre Node indices and section assignments have been checked by Domain.
Status ValidateThermalShellMesh(const ModelDefinition& definition);

}  // namespace fesa
#endif  // FESA_ELEMENTS_THERMAL_SHELL_GEOMETRY_H_