// -*- mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
// vi: set et ts=4 sw=4 sts=4:
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/*!
 * \file
 * \ingroup PorousmediumImmiscible
 * \brief Element-wise calculation of the residual for problems
 *        using the n-phase immiscible fully implicit models.
 */
#ifndef DUMUX_MY_LOCAL_RESIDUAL_HH
#define DUMUX_MY_LOCAL_RESIDUAL_HH

#include <dumux/common/properties.hh>

namespace Dumux
{
/*!
 * \ingroup PorousmediumImmiscible
 * \brief Element-wise calculation of the residual for problems
 *        using the n-phase immiscible fully implicit models.
 */
template<class TypeTag>
class MyLocalResidual : public GET_PROP_TYPE(TypeTag, BaseLocalResidual)
{
    using ParentType = typename GET_PROP_TYPE(TypeTag, BaseLocalResidual);
    using Scalar = typename GET_PROP_TYPE(TypeTag, Scalar);
    using Problem = typename GET_PROP_TYPE(TypeTag, Problem);
    using NumEqVector = typename GET_PROP_TYPE(TypeTag, NumEqVector);
    using VolumeVariables = typename GET_PROP_TYPE(TypeTag, VolumeVariables);
    using ElementVolumeVariables = typename GET_PROP_TYPE(TypeTag, GridVolumeVariables)::LocalView;
    using FluxVariables = typename GET_PROP_TYPE(TypeTag, FluxVariables);
    using ElementFluxVariablesCache = typename GET_PROP_TYPE(TypeTag, GridFluxVariablesCache)::LocalView;
    using FVElementGeometry = typename GET_PROP_TYPE(TypeTag, FVGridGeometry)::LocalView;
    using SubControlVolume = typename FVElementGeometry::SubControlVolume;
    using SubControlVolumeFace = typename FVElementGeometry::SubControlVolumeFace;
    using GridView = typename GET_PROP_TYPE(TypeTag, GridView);
    using Element = typename GridView::template Codim<0>::Entity;
    using EnergyLocalResidual = typename GET_PROP_TYPE(TypeTag, EnergyLocalResidual);

    using ModelTraits = typename GET_PROP_TYPE(TypeTag, ModelTraits);
    static constexpr int numPhases = ModelTraits::numPhases();
    static constexpr int conti0EqIdx = ModelTraits::Indices::conti0EqIdx; //!< first index for the mass balance

public:
    using ParentType::ParentType;

    /*!
     * \brief Evaluate the rate of change of all conservation
     *        quantites (e.g. phase mass) within a sub-control
     *        volume of a finite volume element for the immiscible models.
     * \param problem The problem
     * \param scv The sub control volume
     * \param volVars The current or previous volVars
     * \note This function should not include the source and sink terms.
     * \note The volVars can be different to allow computing
     *       the implicit euler time derivative here
     */
    // TODO: eliminate density from the storage term
    NumEqVector computeStorage(const Problem& problem,
                               const SubControlVolume& scv,
                               const VolumeVariables& volVars) const
    {
        // partial time derivative of the phase mass
        NumEqVector storage;
        for (int phaseIdx = 0; phaseIdx < numPhases; ++phaseIdx)
        {
            auto eqIdx = conti0EqIdx + phaseIdx;
            storage[eqIdx] = volVars.porosity()
                             * volVars.density(phaseIdx)
                             * volVars.saturation(phaseIdx);

            //! The energy storage in the fluid phase with index phaseIdx
            EnergyLocalResidual::fluidPhaseStorage(storage, scv, volVars, phaseIdx);
        }

        //! The energy storage in the solid matrix
        EnergyLocalResidual::solidPhaseStorage(storage, scv, volVars);

        return storage;
    }


    /*!
     * \brief Evaluate the mass flux over a face of a sub control volume
     *
     * \param problem The problem
     * \param element The element
     * \param fvGeometry The finite volume geometry context
     * \param elemVolVars The volume variables for all flux stencil elements
     * \param scvf The sub control volume face to compute the flux on
     * \param elemFluxVarsCache The cache related to flux compuation
     */
    // TODO: eliminate the density from the flux term
    NumEqVector computeFlux(const Problem& problem,
                            const Element& element,
                            const FVElementGeometry& fvGeometry,
                            const ElementVolumeVariables& elemVolVars,
                            const SubControlVolumeFace& scvf,
                            const ElementFluxVariablesCache& elemFluxVarsCache) const
    {
        FluxVariables fluxVars;
        fluxVars.init(problem, element, fvGeometry, elemVolVars, scvf, elemFluxVarsCache);

        NumEqVector flux;
        for (int phaseIdx = 0; phaseIdx < numPhases; ++phaseIdx)
        {
            // the physical quantities for which we perform upwinding
            auto upwindTerm = [phaseIdx](const auto& volVars)
                              { return volVars.density(phaseIdx)*volVars.mobility(phaseIdx); };

            auto eqIdx = conti0EqIdx + phaseIdx;
            flux[eqIdx] = fluxVars.advectiveFlux(phaseIdx, upwindTerm);

            //! Add advective phase energy fluxes. For isothermal model the contribution is zero.
            EnergyLocalResidual::heatConvectionFlux(flux, fluxVars, phaseIdx);
        }

        //! Add diffusive energy fluxes. For isothermal model the contribution is zero.
        EnergyLocalResidual::heatConductionFlux(flux, fluxVars);

        return flux;
    }
};

} // end namespace Dumux

#endif