/* This file is part of the Palabos library.
 *
 * The Palabos softare is developed since 2011 by FlowKit-Numeca Group Sarl
 * (Switzerland) and the University of Geneva (Switzerland), which jointly
 * own the IP rights for most of the code base. Since October 2019, the
 * Palabos project is maintained by the University of Geneva and accepts
 * source code contributions from the community.
 * 
 * Contact:
 * Jonas Latt
 * Computer Science Department
 * University of Geneva
 * 7 Route de Drize
 * 1227 Carouge, Switzerland
 * jonas.latt@unige.ch
 *
 * The most recent release of Palabos can be downloaded at 
 * <https://palabos.unige.ch/>
 *
 * The library Palabos is free software: you can redistribute it and/or
 * modify it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * The library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

/** \file
 * Helper functions for the implementation of multi-phase models. This file is all
 * about efficiency. The generic template code is specialized for commonly
 * used Lattices, so that a maximum performance can be taken out of each
 * case.
 */
#ifndef MULTI_PHASE_TEMPLATES_3D_H
#define MULTI_PHASE_TEMPLATES_3D_H

#include "core/globalDefs.h"
#include "core/cell.h"
#include "multiPhysics/shanChenLattices3D.h"

namespace plb {

/// Helper functions with full-lattice access
template<typename T, template<typename U> class Descriptor>
struct multiPhaseTemplates3D {

static void shanChenInteraction( BlockLattice3D<T,Descriptor>& lattice,
                                 Array<T,Descriptor<T>::d>& rhoContribution,
                                 plint iX, plint iY, plint iZ )
{
    enum {
        densityOffset  = Descriptor<T>::ExternalField::densityBeginsAt
    };
                     
    rhoContribution.resetToZero();
    for (plint iPop = 0; iPop < Descriptor<T>::q; ++iPop) {
        plint nextX = iX + Descriptor<T>::c[iPop][0];
        plint nextY = iY + Descriptor<T>::c[iPop][1];
        plint nextZ = iZ + Descriptor<T>::c[iPop][2];
        Cell<T,Descriptor> const& cell = lattice.get(nextX,nextY,nextZ);
        T rho = *cell.getExternal(densityOffset);
        for (int iD = 0; iD < Descriptor<T>::d; ++iD) {
           rhoContribution[iD] += Descriptor<T>::t[iPop] * rho * Descriptor<T>::c[iPop][iD];
        }
    }
}

static void shanChenInteraction( BlockLattice3D<T,Descriptor>& lattice,
                                 ScalarField3D<T>& rhoBar,
                                 Array<T,Descriptor<T>::d>& rhoContribution,
                                 plint iX, plint iY, plint iZ )
{
    Dot3D ofs = computeRelativeDisplacement(lattice, rhoBar);
    rhoContribution.resetToZero();
    for (plint iPop = 0; iPop < Descriptor<T>::q; ++iPop) {
        plint nextX = iX + Descriptor<T>::c[iPop][0];
        plint nextY = iY + Descriptor<T>::c[iPop][1];
        plint nextZ = iZ + Descriptor<T>::c[iPop][2];
        T rho = Descriptor<T>::fullRho(rhoBar.get(nextX+ofs.x, nextY+ofs.y, nextZ+ofs.z));
        for (int iD = 0; iD < Descriptor<T>::d; ++iD) {
           rhoContribution[iD] += Descriptor<T>::t[iPop] * rho * Descriptor<T>::c[iPop][iD];
        }
    }
}

};

template<typename T>
struct multiPhaseTemplates3D<T, descriptors::ForcedShanChenD3Q19Descriptor> {
    typedef descriptors::ForcedShanChenD3Q19Descriptor<T> D;

static void shanChenInteraction (
        BlockLattice3D<T,descriptors::ForcedShanChenD3Q19Descriptor>& lattice,
        Array<T,D::d>& rhoContribution,
        plint iX, plint iY, plint iZ )
{

    enum {
        densityOffset  = D::ExternalField::densityBeginsAt
    };

    T rho;
    rho = *lattice.get(iX-1,iY  ,iZ  ).getExternal(densityOffset);
    rhoContribution[0] = -D::t[1] * rho;
    rho = *lattice.get(iX  ,iY-1,iZ  ).getExternal(densityOffset);
    rhoContribution[1] = -D::t[2] * rho;
    rho = *lattice.get(iX  ,iY  ,iZ-1).getExternal(densityOffset);
    rhoContribution[2] = -D::t[3] * rho;
    rho = *lattice.get(iX-1,iY-1,iZ  ).getExternal(densityOffset);
    rhoContribution[0] -= D::t[4] * rho;
    rhoContribution[1] -= D::t[4] * rho;
    rho = *lattice.get(iX-1,iY+1,iZ  ).getExternal(densityOffset);
    rhoContribution[0] -= D::t[5] * rho;
    rhoContribution[1] += D::t[5] * rho;
    rho = *lattice.get(iX-1,iY  ,iZ-1).getExternal(densityOffset);
    rhoContribution[0] -= D::t[6] * rho;
    rhoContribution[2] -= D::t[6] * rho;
    rho = *lattice.get(iX-1,iY  ,iZ+1).getExternal(densityOffset);
    rhoContribution[0] -= D::t[7] * rho;
    rhoContribution[2] += D::t[7] * rho;
    rho = *lattice.get(iX  ,iY-1,iZ-1).getExternal(densityOffset);
    rhoContribution[1] -= D::t[8] * rho;
    rhoContribution[2] -= D::t[8] * rho;
    rho = *lattice.get(iX  ,iY-1,iZ+1).getExternal(densityOffset);
    rhoContribution[1] -= D::t[9] * rho;
    rhoContribution[2] += D::t[9] * rho;

    rho = *lattice.get(iX+1,iY  ,iZ  ).getExternal(densityOffset);
    rhoContribution[0] += D::t[10] * rho;
    rho = *lattice.get(iX  ,iY+1,iZ  ).getExternal(densityOffset);
    rhoContribution[1] += D::t[11] * rho;
    rho = *lattice.get(iX  ,iY  ,iZ+1).getExternal(densityOffset);
    rhoContribution[2] += D::t[12] * rho;
    rho = *lattice.get(iX+1,iY+1,iZ  ).getExternal(densityOffset);
    rhoContribution[0] += D::t[13] * rho;
    rhoContribution[1] += D::t[13] * rho;
    rho = *lattice.get(iX+1,iY-1,iZ  ).getExternal(densityOffset);
    rhoContribution[0] += D::t[14] * rho;
    rhoContribution[1] -= D::t[14] * rho;
    rho = *lattice.get(iX+1,iY  ,iZ+1).getExternal(densityOffset);
    rhoContribution[0] += D::t[15] * rho;
    rhoContribution[2] += D::t[15] * rho;
    rho = *lattice.get(iX+1,iY  ,iZ-1).getExternal(densityOffset);
    rhoContribution[0] += D::t[16] * rho;
    rhoContribution[2] -= D::t[16] * rho;
    rho = *lattice.get(iX  ,iY+1,iZ+1).getExternal(densityOffset);
    rhoContribution[1] += D::t[17] * rho;
    rhoContribution[2] += D::t[17] * rho;
    rho = *lattice.get(iX  ,iY+1,iZ-1).getExternal(densityOffset);
    rhoContribution[1] += D::t[18] * rho;
    rhoContribution[2] -= D::t[18] * rho;
}

};

}  // namespace plb

#endif  // MULTI_PHASE_TEMPLATES_3D_H
