#ifndef OPENMC_GEOMETRY_H
#define OPENMC_GEOMETRY_H

#include <array>
#include <cmath>
#include <cstdint>
#include <vector>

#include "openmc/particle.h"


namespace openmc {

//==============================================================================
// Global variables
//==============================================================================

namespace model {

extern int root_universe;  //!< Index of root universe
extern int n_coord_levels; //!< Number of CSG coordinate levels

extern std::vector<int64_t> overlap_check_count;

} // namespace model

//==============================================================================
// Information about nearest boundary crossing
//==============================================================================

struct BoundaryInfo {
  double distance {INFINITY};   //!< distance to nearest boundary
  int surface_index {0}; //!< if boundary is surface, index in surfaces vector
  int coord_level;   //!< coordinate level after crossing boundary
  std::array<int, 3> lattice_translation {}; //!< which way lattice indices will change
};

//==============================================================================
//! Check two distances by coincidence tolerance
//==============================================================================

inline bool coincident(double d1, double d2) {
  return std::abs(d1 - d2) < FP_COINCIDENT;
}

//==============================================================================
//! Check for overlapping cells at a particle's position.
//==============================================================================

bool check_cell_overlap(Particle* p, bool error=true);

//==============================================================================
//! Locate a particle in the geometry tree and set its geometry data fields.
//!
//! \param p A particle to be located.  This function will populate the
//!   geometry-dependent data fields of the particle.
//! \param use_neighbor_lists If true, neighbor lists will be used to accelerate
//!   the geometry search, but this only works if the cell attribute of the
//!   particle's lowest coordinate level is valid and meaningful.
//! \return True if the particle's location could be found and ascribed to a
//!   valid geometry coordinate stack.
//==============================================================================

bool find_cell(Particle* p, bool use_neighbor_lists);

//==============================================================================
//! Move a particle into a new lattice tile.
//==============================================================================

void cross_lattice(Particle* p, const BoundaryInfo& boundary);

//==============================================================================
//! Find the next boundary a particle will intersect.
//==============================================================================

BoundaryInfo distance_to_boundary(Particle* p);

} // namespace openmc

#endif // OPENMC_GEOMETRY_H