//! \file xsdata.h
//! A collection of classes for containing the Multi-Group Cross Section data

#ifndef OPENMC_XSDATA_H
#define OPENMC_XSDATA_H

#include <memory>
#include <vector>

#include "xtensor/xtensor.hpp"

#include "openmc/hdf5_interface.h"
#include "openmc/scattdata.h"


namespace openmc {

//==============================================================================
// XSDATA contains the temperature-independent cross section data for an MGXS
//==============================================================================

class XsData {

  private:
    //! \brief Reads scattering data from the HDF5 file
    void
    scatter_from_hdf5(hid_t xsdata_grp, size_t n_ang,
     int scatter_format, int final_scatter_format, int order_data);

    //! \brief Reads fission data from the HDF5 file
    void
    fission_from_hdf5(hid_t xsdata_grp, size_t n_ang, bool is_isotropic);

    //! \brief Reads fission data formatted as chi and nu-fission vectors from
    //  the HDF5 file when beta is provided.
    void
    fission_vector_beta_from_hdf5(hid_t xsdata_grp, size_t n_ang, bool is_isotropic);

    //! \brief Reads fission data formatted as chi and nu-fission vectors from
    //  the HDF5 file when beta is not provided.
    void
    fission_vector_no_beta_from_hdf5(hid_t xsdata_grp, size_t n_ang);

    //! \brief Reads fission data formatted as chi and nu-fission vectors from
    //  the HDF5 file when no delayed data is provided.
    void
    fission_vector_no_delayed_from_hdf5(hid_t xsdata_grp, size_t n_ang);

    //! \brief Reads fission data formatted as a nu-fission matrix from
    //  the HDF5 file when beta is provided.
    void
    fission_matrix_beta_from_hdf5(hid_t xsdata_grp, size_t n_ang, bool is_isotropic);

    //! \brief Reads fission data formatted as a nu-fission matrix from
    //  the HDF5 file when beta is not provided.
    void
    fission_matrix_no_beta_from_hdf5(hid_t xsdata_grp, size_t n_ang);

    //! \brief Reads fission data formatted as a nu-fission matrix from
    //  the HDF5 file when no delayed data is provided.
    void
    fission_matrix_no_delayed_from_hdf5(hid_t xsdata_grp, size_t n_ang);

  public:

    // The following quantities have the following dimensions:
    // [angle][incoming group]
    xt::xtensor<double, 2> total;
    xt::xtensor<double, 2> absorption;
    xt::xtensor<double, 2> nu_fission;
    xt::xtensor<double, 2> prompt_nu_fission;
    xt::xtensor<double, 2> kappa_fission;
    xt::xtensor<double, 2> fission;
    xt::xtensor<double, 2> inverse_velocity;

    // decay_rate has the following dimensions:
    // [angle][delayed group]
    xt::xtensor<double, 2> decay_rate;
    // delayed_nu_fission has the following dimensions:
    // [angle][delayed group][incoming group]
    xt::xtensor<double, 3> delayed_nu_fission;
    // chi_prompt has the following dimensions:
    // [angle][incoming group][outgoing group]
    xt::xtensor<double, 3> chi_prompt;
    // chi_delayed has the following dimensions:
    // [angle][incoming group][outgoing group][delayed group]
    xt::xtensor<double, 4> chi_delayed;
    // scatter has the following dimensions: [angle]
    std::vector<std::shared_ptr<ScattData>> scatter;

    XsData() = default;

    //! \brief Constructs the XsData object metadata.
    //!
    //! @param num_groups Number of energy groups.
    //! @param num_delayed_groups Number of delayed groups.
    //! @param fissionable Is this a fissionable data set or not.
    //! @param scatter_format The scattering representation of the file.
    //! @param n_pol Number of polar angles.
    //! @param n_azi Number of azimuthal angles.
    XsData(bool fissionable, int scatter_format, int n_pol, int n_azi);

    //! \brief Loads the XsData object from the HDF5 file
    //!
    //! @param xs_id HDF5 group id for the cross section data.
    //! @param fissionable Is this a fissionable data set or not.
    //! @param scatter_format The scattering representation of the file.
    //! @param final_scatter_format The scattering representation after reading;
    //!   this is different from scatter_format if converting a Legendre to
    //!   a tabular representation.
    //! @param order_data The dimensionality of the scattering data in the file.
    //! @param is_isotropic Is this an isotropic or angular with respect to
    //!   the incoming particle.
    //! @param n_pol Number of polar angles.
    //! @param n_azi Number of azimuthal angles.
    void
    from_hdf5(hid_t xsdata_grp, bool fissionable, int scatter_format,
         int final_scatter_format, int order_data, bool is_isotropic, int n_pol,
         int n_azi);

    //! \brief Combines the microscopic data to a macroscopic object.
    //!
    //! @param micros Microscopic objects to combine.
    //! @param scalars Scalars to multiply the microscopic data by.
    void
    combine(const std::vector<XsData*>& those_xs, const std::vector<double>& scalars);

    //! \brief Checks to see if this and that are able to be combined
    //!
    //! This comparison is used when building macroscopic cross sections
    //! from microscopic cross sections.
    //! @param that The other XsData to compare to this one.
    //! @return True if they can be combined.
    bool
    equiv(const XsData& that);
};


} //namespace openmc
#endif // OPENMC_XSDATA_H