#ifndef WARPX_SUM_GUARD_CELLS_H_
#define WARPX_SUM_GUARD_CELLS_H_

#include <AMReX_MultiFab.H>

/* \brief Sum the values of `mf`, where the different boxes overlap
 * (i.e. in the guard cells)
 *
 * This is typically called for the sources of the Maxwell equations (J/rho)
 * after deposition from the macroparticles.
 *
 *  - When WarpX is compiled with a finite-difference scheme: this only
 *    updates the *valid* cells of `mf`
 *  - When WarpX is compiled with a spectral scheme (WARPX_USE_PSATD): this
 *    updates both the *valid* cells and *guard* cells. (This is because a
 *    spectral solver requires the value of the sources over a large stencil.)
 */
void
WarpXSumGuardCells(amrex::MultiFab& mf, const amrex::Periodicity& period,
                   const int icomp=0, const int ncomp=1){
#ifdef WARPX_USE_PSATD
   // Update both valid cells and guard cells
   const amrex::IntVect n_updated_guards = mf.nGrowVect();
#else
   // Update only the valid cells
   const amrex::IntVect n_updated_guards = amrex::IntVect::TheZeroVector();
#endif
    mf.SumBoundary(icomp, ncomp, n_updated_guards, period);
}

/* \brief Sum the values of `src` where the different boxes overlap
 * (i.e. in the guard cells) and copy them into `dst`
 *
 * This is typically called for the sources of the Maxwell equations (J/rho)
 * after deposition from the macroparticles + filtering.
 *
 *  - When WarpX is compiled with a finite-difference scheme: this only
 *    updates the *valid* cells of `dst`
 *  - When WarpX is compiled with a spectral scheme (WARPX_USE_PSATD): this
 *    updates both the *valid* cells and *guard* cells. (This is because a
 *    spectral solver requires the value of the sources over a large stencil.)
 *
 * Note: `i_comp` is the component where the results will be stored in `dst`;
 *       The component from which we copy in `src` is always 0.
 */
void
WarpXSumGuardCells(amrex::MultiFab& dst, amrex::MultiFab& src,
                   const amrex::Periodicity& period,
                   const int icomp=0, const int ncomp=1){
#ifdef WARPX_USE_PSATD
    // Update both valid cells and guard cells
    const amrex::IntVect n_updated_guards = dst.nGrowVect();
#else
    // Update only the valid cells
    const amrex::IntVect n_updated_guards = amrex::IntVect::TheZeroVector();
#endif
    src.SumBoundary(icomp, ncomp, n_updated_guards, period);
    amrex::Copy( dst, src, 0, icomp, ncomp, n_updated_guards );
}

#endif // WARPX_SUM_GUARD_CELLS_H_