/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     |
    \\  /    A nd           | Copyright (C) 1991-2010 OpenCFD Ltd.
     \\/     M anipulation  |
-------------------------------------------------------------------------------
License
    This file is part of OpenFOAM.

    OpenFOAM is free software: you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    OpenFOAM 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 General Public License
    for more details.

    You should have received a copy of the GNU General Public License
    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.

\*---------------------------------------------------------------------------*/

#include "MULES.H"
#include "upwind.H"
#include "uncorrectedSnGrad.H"
#include "gaussConvectionScheme.H"
#include "gaussLaplacianScheme.H"
#include "uncorrectedSnGrad.H"
#include "surfaceInterpolate.H"
#include "fvcSurfaceIntegrate.H"
#include "slicedSurfaceFields.H"
#include "syncTools.H"

#include "fvm.H"

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

template<class RhoType, class SpType, class SuType>
void Foam::MULES::explicitSolve
(
    const RhoType& rho,
    volScalarField& psi,
    const surfaceScalarField& phi,
    surfaceScalarField& phiPsi,
    const SpType& Sp,
    const SuType& Su,
    const scalar psiMax,
    const scalar psiMin
)
{
    Info<< "MULES: Solving for " << psi.name() << endl;

    const fvMesh& mesh = psi.mesh();
    psi.correctBoundaryConditions();

    surfaceScalarField phiBD = upwind<scalar>(psi.mesh(), phi).flux(psi);

    surfaceScalarField& phiCorr = phiPsi;
    phiCorr -= phiBD;

    scalarField allLambda(mesh.nFaces(), 1.0);

    slicedSurfaceScalarField lambda
    (
        IOobject
        (
            "lambda",
            mesh.time().timeName(),
            mesh,
            IOobject::NO_READ,
            IOobject::NO_WRITE,
            false
        ),
        mesh,
        dimless,
        allLambda,
        false   // Use slices for the couples
    );

    limiter
    (
        allLambda,
        rho,
        psi,
        phiBD,
        phiCorr,
        Sp,
        Su,
        psiMax,
        psiMin,
        3
    );

    phiPsi = phiBD + lambda*phiCorr;

    scalarField& psiIf = psi;
    const scalarField& psi0 = psi.oldTime();
    const scalar deltaT = mesh.time().deltaTValue();

    psiIf = 0.0;
    fvc::surfaceIntegrate(psiIf, phiPsi);

    if (mesh.moving())
    {
        psiIf =
        (
            mesh.Vsc0()().field()*rho.oldTime().field()
           *psi0/(deltaT*mesh.Vsc()().field())
          + Su.field()
          - psiIf
        )/(rho.field()/deltaT - Sp.field());
    }
    else
    {
        psiIf =
        (
            rho.oldTime().field()*psi0/deltaT
          + Su.field()
          - psiIf
        )/(rho.field()/deltaT - Sp.field());
    }

    psi.correctBoundaryConditions();
}


template<class RhoType, class SpType, class SuType>
void Foam::MULES::implicitSolve
(
    const RhoType& rho,
    volScalarField& psi,
    const surfaceScalarField& phi,
    surfaceScalarField& phiPsi,
    const SpType& Sp,
    const SuType& Su,
    const scalar psiMax,
    const scalar psiMin
)
{
    const fvMesh& mesh = psi.mesh();

    const dictionary& MULEScontrols = mesh.solverDict(psi.name());

    label maxIter
    (
        readLabel(MULEScontrols.lookup("maxIter"))
    );

    label nLimiterIter
    (
        readLabel(MULEScontrols.lookup("nLimiterIter"))
    );

    scalar maxUnboundedness
    (
        readScalar(MULEScontrols.lookup("maxUnboundedness"))
    );

    scalar CoCoeff
    (
        readScalar(MULEScontrols.lookup("CoCoeff"))
    );

    scalarField allCoLambda(mesh.nFaces());

    {
        surfaceScalarField Cof =
            mesh.time().deltaT()*mesh.surfaceInterpolation::deltaCoeffs()
           *mag(phi)/mesh.magSf();

        slicedSurfaceScalarField CoLambda
        (
            IOobject
            (
                "CoLambda",
                mesh.time().timeName(),
                mesh,
                IOobject::NO_READ,
                IOobject::NO_WRITE,
                false
            ),
            mesh,
            dimless,
            allCoLambda,
            false   // Use slices for the couples
        );

        CoLambda == 1.0/max(CoCoeff*Cof, scalar(1));
    }

    scalarField allLambda(allCoLambda);
    //scalarField allLambda(mesh.nFaces(), 1.0);

    slicedSurfaceScalarField lambda
    (
        IOobject
        (
            "lambda",
            mesh.time().timeName(),
            mesh,
            IOobject::NO_READ,
            IOobject::NO_WRITE,
            false
        ),
        mesh,
        dimless,
        allLambda,
        false   // Use slices for the couples
    );

    linear<scalar> CDs(mesh);
    upwind<scalar> UDs(mesh, phi);
    //fv::uncorrectedSnGrad<scalar> snGrads(mesh);

    fvScalarMatrix psiConvectionDiffusion
    (
        fvm::ddt(rho, psi)
      + fv::gaussConvectionScheme<scalar>(mesh, phi, UDs).fvmDiv(phi, psi)
        //- fv::gaussLaplacianScheme<scalar, scalar>(mesh, CDs, snGrads)
        //.fvmLaplacian(Dpsif, psi)
      - fvm::Sp(Sp, psi)
      - Su
    );

    surfaceScalarField phiBD = psiConvectionDiffusion.flux();

    surfaceScalarField& phiCorr = phiPsi;
    phiCorr -= phiBD;

    for (label i=0; i<maxIter; i++)
    {
        if (i != 0 && i < 4)
        {
            allLambda = allCoLambda;
        }

        limiter
        (
            allLambda,
            rho,
            psi,
            phiBD,
            phiCorr,
            Sp,
            Su,
            psiMax,
            psiMin,
            nLimiterIter
        );

        solve
        (
            psiConvectionDiffusion + fvc::div(lambda*phiCorr),
            MULEScontrols
        );

        scalar maxPsiM1 = gMax(psi.internalField()) - 1.0;
        scalar minPsi = gMin(psi.internalField());

        scalar unboundedness = max(max(maxPsiM1, 0.0), -min(minPsi, 0.0));

        if (unboundedness < maxUnboundedness)
        {
            break;
        }
        else
        {
            Info<< "MULES: max(" << psi.name() << " - 1) = " << maxPsiM1
                << " min(" << psi.name() << ") = " << minPsi << endl;

            phiBD = psiConvectionDiffusion.flux();

            /*
            word gammaScheme("div(phi,gamma)");
            word gammarScheme("div(phirb,gamma)");

            const surfaceScalarField& phir =
                mesh.lookupObject<surfaceScalarField>("phir");

            phiCorr =
                fvc::flux
                (
                    phi,
                    psi,
                    gammaScheme
                )
              + fvc::flux
                (
                    -fvc::flux(-phir, scalar(1) - psi, gammarScheme),
                    psi,
                    gammarScheme
                )
                - phiBD;
            */
        }
    }

    phiPsi = psiConvectionDiffusion.flux() + lambda*phiCorr;
}


template<class RhoType, class SpType, class SuType>
void Foam::MULES::limiter
(
    scalarField& allLambda,
    const RhoType& rho,
    const volScalarField& psi,
    const surfaceScalarField& phiBD,
    const surfaceScalarField& phiCorr,
    const SpType& Sp,
    const SuType& Su,
    const scalar psiMax,
    const scalar psiMin,
    const label nLimiterIter
)
{
    const scalarField& psiIf = psi;
    const volScalarField::GeometricBoundaryField& psiBf = psi.boundaryField();

    const scalarField& psi0 = psi.oldTime();

    const fvMesh& mesh = psi.mesh();

    const unallocLabelList& owner = mesh.owner();
    const unallocLabelList& neighb = mesh.neighbour();
    tmp<volScalarField::DimensionedInternalField> tVsc = mesh.Vsc();
    const scalarField& V = tVsc();
    const scalar deltaT = mesh.time().deltaTValue();

    const scalarField& phiBDIf = phiBD;
    const surfaceScalarField::GeometricBoundaryField& phiBDBf =
        phiBD.boundaryField();

    const scalarField& phiCorrIf = phiCorr;
    const surfaceScalarField::GeometricBoundaryField& phiCorrBf =
        phiCorr.boundaryField();

    slicedSurfaceScalarField lambda
    (
        IOobject
        (
            "lambda",
            mesh.time().timeName(),
            mesh,
            IOobject::NO_READ,
            IOobject::NO_WRITE,
            false
        ),
        mesh,
        dimless,
        allLambda,
        false   // Use slices for the couples
    );

    scalarField& lambdaIf = lambda;
    surfaceScalarField::GeometricBoundaryField& lambdaBf =
        lambda.boundaryField();

    scalarField psiMaxn(psiIf.size(), psiMin);
    scalarField psiMinn(psiIf.size(), psiMax);

    scalarField sumPhiBD(psiIf.size(), 0.0);

    scalarField sumPhip(psiIf.size(), VSMALL);
    scalarField mSumPhim(psiIf.size(), VSMALL);

    forAll(phiCorrIf, facei)
    {
        label own = owner[facei];
        label nei = neighb[facei];

        psiMaxn[own] = max(psiMaxn[own], psiIf[nei]);
        psiMinn[own] = min(psiMinn[own], psiIf[nei]);

        psiMaxn[nei] = max(psiMaxn[nei], psiIf[own]);
        psiMinn[nei] = min(psiMinn[nei], psiIf[own]);

        sumPhiBD[own] += phiBDIf[facei];
        sumPhiBD[nei] -= phiBDIf[facei];

        scalar phiCorrf = phiCorrIf[facei];

        if (phiCorrf > 0.0)
        {
            sumPhip[own] += phiCorrf;
            mSumPhim[nei] += phiCorrf;
        }
        else
        {
            mSumPhim[own] -= phiCorrf;
            sumPhip[nei] -= phiCorrf;
        }
    }

    forAll(phiCorrBf, patchi)
    {
        const fvPatchScalarField& psiPf = psiBf[patchi];
        const scalarField& phiBDPf = phiBDBf[patchi];
        const scalarField& phiCorrPf = phiCorrBf[patchi];

        const labelList& pFaceCells = mesh.boundary()[patchi].faceCells();

        if (psiPf.coupled())
        {
            scalarField psiPNf = psiPf.patchNeighbourField();

            forAll(phiCorrPf, pFacei)
            {
                label pfCelli = pFaceCells[pFacei];

                psiMaxn[pfCelli] = max(psiMaxn[pfCelli], psiPNf[pFacei]);
                psiMinn[pfCelli] = min(psiMinn[pfCelli], psiPNf[pFacei]);
            }
        }
        else
        {
            forAll(phiCorrPf, pFacei)
            {
                label pfCelli = pFaceCells[pFacei];

                psiMaxn[pfCelli] = max(psiMaxn[pfCelli], psiPf[pFacei]);
                psiMinn[pfCelli] = min(psiMinn[pfCelli], psiPf[pFacei]);
            }
        }

        forAll(phiCorrPf, pFacei)
        {
            label pfCelli = pFaceCells[pFacei];

            sumPhiBD[pfCelli] += phiBDPf[pFacei];

            scalar phiCorrf = phiCorrPf[pFacei];

            if (phiCorrf > 0.0)
            {
                sumPhip[pfCelli] += phiCorrf;
            }
            else
            {
                mSumPhim[pfCelli] -= phiCorrf;
            }
        }
    }

    psiMaxn = min(psiMaxn, psiMax);
    psiMinn = max(psiMinn, psiMin);

    //scalar smooth = 0.5;
    //psiMaxn = min((1.0 - smooth)*psiIf + smooth*psiMaxn, psiMax);
    //psiMinn = max((1.0 - smooth)*psiIf + smooth*psiMinn, psiMin);

    if (mesh.moving())
    {
        tmp<volScalarField::DimensionedInternalField> V0 = mesh.Vsc0();

        psiMaxn =
            V*((rho.field()/deltaT - Sp.field())*psiMaxn - Su.field())
          - (V0().field()/deltaT)*rho.oldTime().field()*psi0
          + sumPhiBD;

        psiMinn =
            V*(Su.field() - (rho.field()/deltaT - Sp.field())*psiMinn)
          + (V0().field()/deltaT)*rho.oldTime().field()*psi0
          - sumPhiBD;
    }
    else
    {
        psiMaxn =
            V
           *(
               (rho.field()/deltaT - Sp.field())*psiMaxn
             - (rho.oldTime().field()/deltaT)*psi0
             - Su.field()
            )
          + sumPhiBD;

        psiMinn =
            V
           *(
               (rho.field()/deltaT)*psi0
             - (rho.oldTime().field()/deltaT - Sp.field())*psiMinn + Su.field()
            )
          - sumPhiBD;
    }

    scalarField sumlPhip(psiIf.size());
    scalarField mSumlPhim(psiIf.size());

    for (int j=0; j<nLimiterIter; j++)
    {
        sumlPhip = 0.0;
        mSumlPhim = 0.0;

        forAll(lambdaIf, facei)
        {
            label own = owner[facei];
            label nei = neighb[facei];

            scalar lambdaPhiCorrf = lambdaIf[facei]*phiCorrIf[facei];

            if (lambdaPhiCorrf > 0.0)
            {
                sumlPhip[own] += lambdaPhiCorrf;
                mSumlPhim[nei] += lambdaPhiCorrf;
            }
            else
            {
                mSumlPhim[own] -= lambdaPhiCorrf;
                sumlPhip[nei] -= lambdaPhiCorrf;
            }
        }

        forAll(lambdaBf, patchi)
        {
            scalarField& lambdaPf = lambdaBf[patchi];
            const scalarField& phiCorrfPf = phiCorrBf[patchi];

            const labelList& pFaceCells = mesh.boundary()[patchi].faceCells();

            forAll(lambdaPf, pFacei)
            {
                label pfCelli = pFaceCells[pFacei];

                scalar lambdaPhiCorrf = lambdaPf[pFacei]*phiCorrfPf[pFacei];

                if (lambdaPhiCorrf > 0.0)
                {
                    sumlPhip[pfCelli] += lambdaPhiCorrf;
                }
                else
                {
                    mSumlPhim[pfCelli] -= lambdaPhiCorrf;
                }
            }
        }

        forAll(sumlPhip, celli)
        {
            sumlPhip[celli] =
                max(min
                (
                    (sumlPhip[celli] + psiMaxn[celli])/mSumPhim[celli],
                    1.0), 0.0
                );

            mSumlPhim[celli] =
                max(min
                (
                    (mSumlPhim[celli] + psiMinn[celli])/sumPhip[celli],
                    1.0), 0.0
                );
        }

        const scalarField& lambdam = sumlPhip;
        const scalarField& lambdap = mSumlPhim;

        forAll(lambdaIf, facei)
        {
            if (phiCorrIf[facei] > 0.0)
            {
                lambdaIf[facei] = min
                (
                    lambdaIf[facei],
                    min(lambdap[owner[facei]], lambdam[neighb[facei]])
                );
            }
            else
            {
                lambdaIf[facei] = min
                (
                    lambdaIf[facei],
                    min(lambdam[owner[facei]], lambdap[neighb[facei]])
                );
            }
        }


        forAll(lambdaBf, patchi)
        {
            fvsPatchScalarField& lambdaPf = lambdaBf[patchi];
            const scalarField& phiCorrfPf = phiCorrBf[patchi];

            const labelList& pFaceCells = mesh.boundary()[patchi].faceCells();

            forAll(lambdaPf, pFacei)
            {
                label pfCelli = pFaceCells[pFacei];

                if (phiCorrfPf[pFacei] > 0.0)
                {
                    lambdaPf[pFacei] = min(lambdaPf[pFacei], lambdap[pfCelli]);
                }
                else
                {
                    lambdaPf[pFacei] = min(lambdaPf[pFacei], lambdam[pfCelli]);
                }
            }
        }

        syncTools::syncFaceList(mesh, allLambda, minEqOp<scalar>());
    }
}


// ************************************************************************* //