/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     | Website:  https://openfoam.org
    \\  /    A nd           | Copyright (C) 2019-2020 OpenFOAM Foundation
     \\/     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 "addToRunTimeSelectionTable.H"
#include "fixedValueFvPatchField.H"
#include "fvcDdt.H"
#include "fvcDiv.H"
#include "fvmDdt.H"
#include "fvmDiv.H"
#include "fvmLaplacian.H"
#include "nonOrthogonalSolutionControl.H"
#include "phaseScalarTransport.H"
#include "surfaceFields.H"
#include "momentumTransportModel.H"
#include "wallFvPatch.H"
#include "zeroGradientFvPatchField.H"

#define PhiDimensionErrorInFunction(phi)                                       \
    FatalErrorInFunction                                                       \
        << "Incompatible dimensions for " << phi.name() << ": "                \
        << phi.dimensions() << nl                                              \
        << "Dimensions should be " << dimMass/dimTime << " or "                \
        << dimVolume/dimTime << exit(FatalError)

// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //

namespace Foam
{
namespace functionObjects
{
    defineTypeNameAndDebug(phaseScalarTransport, 0);

    addToRunTimeSelectionTable
    (
        functionObject,
        phaseScalarTransport,
        dictionary
    );
}
}


// * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //

Foam::volScalarField& Foam::functionObjects::phaseScalarTransport::Phi()
{
    if (!PhiPtr_.valid())
    {
        const surfaceScalarField& phi =
            mesh_.lookupObject<surfaceScalarField>(phiName_);
        const volScalarField& p =
            mesh_.lookupObject<volScalarField>(pName_);

        wordList PhiPatchFieldTypes(mesh_.boundaryMesh().size());
        forAll(p.boundaryField(), patchi)
        {
            PhiPatchFieldTypes[patchi] =
                p.boundaryField()[patchi].fixesValue()
              ? fixedValueFvPatchField<scalar>::typeName
              : zeroGradientFvPatchField<scalar>::typeName;
        }

        PhiPtr_.set
        (
            new volScalarField
            (
                IOobject
                (
                    "Phi" + s_.name(),
                    mesh_.time().timeName(),
                    mesh_,
                    IOobject::READ_IF_PRESENT,
                    IOobject::AUTO_WRITE
                ),
                mesh_,
                dimensionedScalar(phi.dimensions()/dimLength, Zero),
                PhiPatchFieldTypes
            )
        );

        mesh_.setFluxRequired(PhiPtr_->name());
    }

    return PhiPtr_();
}


Foam::tmp<Foam::surfaceScalarField>
Foam::functionObjects::phaseScalarTransport::alphaPhi()
{
    // If alphaPhi exists then return it
    if (mesh_.foundObject<surfaceScalarField>(alphaPhiName_))
    {
        return mesh_.lookupObject<surfaceScalarField>(alphaPhiName_);
    }

    // Otherwise generate it ...
    Info<< type() << ": " << surfaceScalarField::typeName << " "
        << alphaPhiName_ << " was not found, so generating it" << endl;

    const volScalarField& alpha =
        mesh_.lookupObject<volScalarField>(alphaName_);
    const surfaceScalarField& phi =
        mesh_.lookupObject<surfaceScalarField>(phiName_);

    // Make a crude guess of the phase flux using default interpolation
    tmp<surfaceScalarField> tAlphaPhi
    (
        new surfaceScalarField
        (
            alphaPhiName_,
            phi*fvc::interpolate(alpha)
        )
    );
    surfaceScalarField& alphaPhi = tAlphaPhi.ref();

    // Get the potential field
    volScalarField& Phi(this->Phi());

    // Construct the scheme names
    const word laplacianScheme = "laplacian(" + pName_ + ")";

    // Debug writing. Write the material derivative of alpha, before and after
    // the solution of the potential and the correction of alphaPhi. Before
    // correction the field should be non-zero, and after it should be
    // comparable to the solution tolerance.
    auto writeDDt = [&](const label i)
    {
        const volScalarField DDtAlpha
        (
            "DDt("
          + IOobject::groupName
            (
                IOobject::member(alpha.name()) + Foam::name(i),
                IOobject::group(alpha.name())
            )
          + ")",
            fvc::ddt(alpha) + fvc::div(alphaPhi)
        );
        Info<< type() << ": Writing " << DDtAlpha.name() << endl;
        DDtAlpha.write();
    };
    if (debug && mesh_.time().writeTime())
    {
        writeDDt(0);
    }

    // Lookup the non-orthogonal solution control
    nonOrthogonalSolutionControl& control =
        mesh_.lookupObjectRef<nonOrthogonalSolutionControl>
        (
            solutionControl::typeName
        );

    // Solve for the potential and correct alphaPhi with the resulting flux
    if (phi.dimensions() == dimVolume/dimTime)
    {
        while (control.correctNonOrthogonal())
        {
            fvScalarMatrix PhiEqn
            (
                fvm::laplacian(Phi, laplacianScheme)
              + fvc::ddt(alpha)
              + fvc::div(alphaPhi)
            );

            PhiEqn.solve(pName_);

            if (control.finalNonOrthogonalIter())
            {
                alphaPhi += PhiEqn.flux();
            }
        }
    }
    else if (phi.dimensions() == dimMass/dimTime)
    {
        const volScalarField& rho =
            mesh_.lookupObject<volScalarField>(rhoName_);

        while (control.correctNonOrthogonal())
        {
            fvScalarMatrix PhiEqn
            (
                fvm::laplacian(Phi, laplacianScheme)
              + fvc::ddt(rho, alpha)
              + fvc::div(alphaPhi)
            );

            PhiEqn.solve(pName_);

            if (control.finalNonOrthogonalIter())
            {
                alphaPhi += PhiEqn.flux();
            }
        }
    }
    else
    {
        PhiDimensionErrorInFunction(phi);
    }

    // Debug writing
    if (debug && mesh_.time().writeTime())
    {
        writeDDt(1);
    }

    return tAlphaPhi;
}


Foam::tmp<Foam::volScalarField>
Foam::functionObjects::phaseScalarTransport::D
(
    const surfaceScalarField& alphaPhi
) const
{
    if (constantD_)
    {
        return volScalarField::New
        (
            "D" + s_.name(),
            mesh_,
            dimensionedScalar(alphaPhi.dimensions()/dimLength, D_)
        );
    }

    const word& nameNoPhase = momentumTransportModel::typeName;
    const word namePhase = IOobject::groupName(nameNoPhase, phaseName_);

    const word& name =
        mesh_.foundObject<momentumTransportModel>(namePhase)
      ? namePhase
      : mesh_.foundObject<momentumTransportModel>(nameNoPhase)
      ? nameNoPhase
      : word::null;

    if (name == word::null)
    {
        return volScalarField::New
        (
            "D" + s_.name(),
            mesh_,
            dimensionedScalar(alphaPhi.dimensions()/dimLength, 0)
        );
    }

    const momentumTransportModel& turbulence =
        mesh_.lookupObject<momentumTransportModel>(name);

    if (alphaPhi.dimensions() == dimVolume/dimTime)
    {
        return alphaD_*turbulence.nu() + alphaDt_*turbulence.nut();
    }
    else if (alphaPhi.dimensions() == dimMass/dimTime)
    {
        return alphaD_*turbulence.mu() + alphaDt_*turbulence.mut();
    }
    else
    {
        PhiDimensionErrorInFunction(alphaPhi);
        return tmp<volScalarField>(nullptr);
    }
}


// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //

Foam::functionObjects::phaseScalarTransport::phaseScalarTransport
(
    const word& name,
    const Time& runTime,
    const dictionary& dict
)
:
    fvMeshFunctionObject(name, runTime, dict),
    fieldName_(dict.lookup("field")),
    phaseName_(IOobject::group(fieldName_)),
    nCorr_(0),
    residualAlpha_(rootSmall),
    fvOptions_(mesh_),
    s_
    (
        IOobject
        (
            fieldName_,
            mesh_.time().timeName(),
            mesh_,
            IOobject::MUST_READ,
            IOobject::AUTO_WRITE
        ),
        mesh_
    ),
    alphaSPtr_(nullptr),
    PhiPtr_(nullptr)
{
    if (phaseName_ == word::null)
    {
        FatalErrorInFunction
            << "Field \"" << fieldName_ << "\" does not have a phase extension "
            << "in its name. If it is associated with \"phaseA\" then it "
            << "should be named \"" << fieldName_ << ".phaseA\"."
            << exit(FatalError);
    }

    read(dict);
}


// * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //

Foam::functionObjects::phaseScalarTransport::~phaseScalarTransport()
{}


// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //

bool Foam::functionObjects::phaseScalarTransport::read(const dictionary& dict)
{
    fvMeshFunctionObject::read(dict);

    alphaName_ =
        dict.lookupOrDefault<word>
        (
            "alpha",
            IOobject::groupName("alpha", phaseName_)
        );
    alphaPhiName_ =
        dict.lookupOrDefault<word>
        (
            "alphaPhi",
            IOobject::groupName("alphaPhi", phaseName_)
        );
    phiName_ = dict.lookupOrDefault<word>("phi", "phi");
    rhoName_ =
        dict.lookupOrDefault<word>
        (
            "rho",
            IOobject::groupName("rho", phaseName_)
        );
    pName_ = dict.lookupOrDefault<word>("p", "p");
    schemesField_ = dict.lookupOrDefault<word>("schemesField", fieldName_);

    constantD_ = dict.readIfPresent("D", D_);
    alphaD_ = dict.lookupOrDefault<scalar>("alphaD", 1);
    alphaDt_ = dict.lookupOrDefault<scalar>("alphaDt", 1);

    dict.readIfPresent("nCorr", nCorr_);
    dict.readIfPresent("residualAlpha", residualAlpha_);
    writeAlphaField_ = dict.lookupOrDefault<bool>("writeAlphaField", true);

    if (dict.found("fvOptions"))
    {
        fvOptions_.reset(dict.subDict("fvOptions"));
    }

    return true;
}


bool Foam::functionObjects::phaseScalarTransport::execute()
{
    Info<< type() << ": Executing" << endl;

    const volScalarField& alpha =
        mesh_.lookupObject<volScalarField>(alphaName_);

    // Get the phase flux
    tmp<surfaceScalarField> tAlphaPhi(this->alphaPhi());
    const surfaceScalarField& alphaPhi = tAlphaPhi();

    // Get the diffusivity
    const volScalarField D(this->D(alphaPhi));

    // Construct the scheme names
    const word divScheme =
        "div("  + alphaPhi.name() + "," + schemesField_ + ")";
    const word laplacianScheme =
        "laplacian(" + D.name() + "," + schemesField_ + ")";

    // Get the relaxation coefficient
    const scalar relaxCoeff =
        mesh_.relaxEquation(schemesField_)
      ? mesh_.equationRelaxationFactor(schemesField_)
      : 0;

    // Solve
    if (alphaPhi.dimensions() == dimVolume/dimTime)
    {
        for (int i=0; i<=nCorr_; i++)
        {
            fvScalarMatrix fieldEqn
            (
                fvm::ddt(alpha, s_)
              + fvm::div(alphaPhi, s_, divScheme)
              - fvm::laplacian
                (
                    fvc::interpolate(alpha)*fvc::interpolate(D),
                    s_,
                    laplacianScheme
                )
             ==
                fvOptions_(alpha, s_)
              - fvm::ddt(residualAlpha_, s_)
              + fvc::ddt(residualAlpha_, s_)
            );

            fieldEqn.relax(relaxCoeff);
            fvOptions_.constrain(fieldEqn);
            fieldEqn.solve(schemesField_);
        }
    }
    else if (alphaPhi.dimensions() == dimMass/dimTime)
    {
        const volScalarField& rho =
            mesh_.lookupObject<volScalarField>(rhoName_);

        for (int i=0; i<=nCorr_; i++)
        {
            fvScalarMatrix fieldEqn
            (
                fvm::ddt(alpha, rho, s_)
              + fvm::div(alphaPhi, s_, divScheme)
              - fvm::laplacian
                (
                    fvc::interpolate(alpha)*fvc::interpolate(D),
                    s_,
                    laplacianScheme
                )
             ==
                fvOptions_(alpha, rho, s_)
              - fvm::ddt(residualAlpha_*rho, s_)
              + fvc::ddt(residualAlpha_*rho, s_)
            );

            fieldEqn.relax(relaxCoeff);
            fvOptions_.constrain(fieldEqn);
            fieldEqn.solve(schemesField_);
        }
    }
    else
    {
        PhiDimensionErrorInFunction(alphaPhi);
    }

    // Update
    if (writeAlphaField_)
    {
        if (!alphaSPtr_.valid())
        {
            alphaSPtr_.set
            (
                new volScalarField
                (
                    IOobject
                    (
                        "alpha"
                      + word(toupper(fieldName_[0]))
                      + fieldName_(1, fieldName_.size() - 1),
                        mesh_.time().timeName(),
                        mesh_,
                        IOobject::NO_READ,
                        IOobject::AUTO_WRITE
                    ),
                    mesh_,
                    dimensionedScalar(s_.dimensions(), Zero)
                )
            );
        }

        alphaSPtr_() = alpha*s_;
    }
    else
    {
        if (alphaSPtr_.valid())
        {
            alphaSPtr_().clear();
        }
    }

    Info<< endl;

    return true;
}


bool Foam::functionObjects::phaseScalarTransport::write()
{
    return true;
}


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