/* Copyright 2019-2020 David Grote
 *
 * This file is part of WarpX.
 *
 * License: BSD-3-Clause-LBNL
 */
#ifndef WARPX_SPECTRAL_SOLVER_RZ_H_
#define WARPX_SPECTRAL_SOLVER_RZ_H_

#include "SpectralSolverRZ_fwd.H"

#include "SpectralAlgorithms/SpectralBaseAlgorithmRZ.H"
#include "SpectralFieldDataRZ.H"

/* \brief Top-level class for the electromagnetic spectral solver
 *
 * Stores the field in spectral space, and has member functions
 * to Fourier-transform the fields between real space and spectral space
 * and to update fields in spectral space over one time step.
 */
class SpectralSolverRZ
{
    public:
        // Inline definition of the member functions of `SpectralSolverRZ`,
        // except the constructor (see `SpectralSolverRZ.cpp`)
        // The body of these functions is short, since the work is done in the
        // underlying classes `SpectralFieldData` and `PsatdAlgorithm`

        // Constructor
        SpectralSolverRZ (const int lev,
                          amrex::BoxArray const & realspace_ba,
                          amrex::DistributionMapping const & dm,
                          int const n_rz_azimuthal_modes,
                          int const norder_z, bool const nodal,
                          const amrex::Array<amrex::Real,3>& v_galilean,
                          amrex::RealVect const dx, amrex::Real const dt,
                          bool const update_with_rho);

        /* \brief Transform the component `i_comp` of MultiFab `field_mf`
         *  to spectral space, and store the corresponding result internally
         *  (in the spectral field specified by `field_index`) */
        void ForwardTransform (const int lev, amrex::MultiFab const & field_mf, int const field_index,
                               int const i_comp=0);

        /* \brief Transform the two MultiFabs `field_mf1` and `field_mf2`
         *  to spectral space, and store the corresponding results internally
         *  (in the spectral field specified by `field_index1` and `field_index2`) */
        void ForwardTransform (const int lev, amrex::MultiFab const & field_mf1, int const field_index1,
                               amrex::MultiFab const & field_mf2, int const field_index2);

        /* \brief Transform spectral field specified by `field_index` back to
         * real space, and store it in the component `i_comp` of `field_mf` */
        void BackwardTransform (const int lev, amrex::MultiFab& field_mf, int const field_index,
                                int const i_comp=0);

        /* \brief Transform spectral fields specified by `field_index1` and `field_index2`
         * back to real space, and store it in `field_mf1` and `field_mf2`*/
        void BackwardTransform (const int lev, amrex::MultiFab& field_mf1, int const field_index1,
                                amrex::MultiFab& field_mf2, int const field_index2);

        /* \brief Update the fields in spectral space, over one timestep */
        void pushSpectralFields ();

        /* \brief Initialize K space filtering arrays */
        void InitFilter (amrex::IntVect const & filter_npass_each_dir,
                         bool const compensation)
        {
            field_data.InitFilter(filter_npass_each_dir, compensation, k_space);
        }

        /* \brief Apply K space filtering for a scalar */
        void ApplyFilter (int const field_index)
        {
            field_data.ApplyFilter(field_index);
        }

        /* \brief Apply K space filtering for a vector */
        void ApplyFilter (int const field_index1, int const field_index2, int const field_index3)
        {
            field_data.ApplyFilter(field_index1, field_index2, field_index3);
        }

        /**
          * \brief Public interface to call the member function ComputeSpectralDivE
          * of the base class SpectralBaseAlgorithmRZ from objects of class SpectralSolverRZ
          */
        void ComputeSpectralDivE (const int lev, const std::array<std::unique_ptr<amrex::MultiFab>,3>& Efield,
                                  amrex::MultiFab& divE);

        /**
         * \brief Public interface to call the virtual function \c CurrentCorrection,
         * defined in the base class SpectralBaseAlgorithmRZ and possibly overridden
         * by its derived classes (e.g. PsatdAlgorithmRZ), from
         * objects of class SpectralSolverRZ through the private unique pointer \c algorithm
         *
         * \param[in,out] current two-dimensional array of unique pointers to MultiFab
         *                        storing the three components of the current density
         * \param[in]     rho     unique pointer to MultiFab storing the charge density
         */
        void CurrentCorrection (const int lev, std::array<std::unique_ptr<amrex::MultiFab>,3>& current,
                                const std::unique_ptr<amrex::MultiFab>& rho);

        /**
         * \brief Public interface to call the virtual function \c VayDeposition,
         * declared in the base class SpectralBaseAlgorithmRZ and defined in its
         * derived classes, from objects of class SpectralSolverRZ through the private
         * unique pointer \c algorithm.
         *
         * \param[in,out] current Array of unique pointers to \c MultiFab storing
         * the three components of the current density
         */
        void VayDeposition (const int lev, std::array<std::unique_ptr<amrex::MultiFab>,3>& current);

    private:

        SpectralKSpaceRZ k_space; // Save the instance to initialize filtering
        SpectralFieldDataRZ field_data; // Store field in spectral space
                                        // and perform the Fourier transforms
        std::unique_ptr<SpectralBaseAlgorithmRZ> algorithm;
        // Defines field update equation in spectral space,
        // and the associated coefficients.
        // SpectralBaseAlgorithmRZ is a base class ; this pointer is meant
        // to point an instance of a *sub-class* defining a specific algorithm

};

#endif // WARPX_SPECTRAL_SOLVER_RZ_H_