/*
  Copyright 2017 SINTEF Digital, Mathematics and Cybernetics.
  Copyright 2017 Statoil ASA.

  This file is part of the Open Porous Media project (OPM).

  OPM 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.

  OPM 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 OPM.  If not, see <http://www.gnu.org/licenses/>.
*/


#ifndef OPM_MULTISEGMENTWELL_PRIMARY_VARIABLES_HEADER_INCLUDED
#define OPM_MULTISEGMENTWELL_PRIMARY_VARIABLES_HEADER_INCLUDED

#include <opm/material/densead/Evaluation.hpp>

#include <opm/simulators/wells/MultisegmentWellEquations.hpp>
#include <opm/input/eclipse/Schedule/SummaryState.hpp>
#include <opm/input/eclipse/Units/Units.hpp>

#include <array>
#include <cstddef>
#include <vector>

namespace Opm
{

class DeferredLogger;
template<class Scalar> class MultisegmentWellGeneric;
template<class FluidSystem, class Indices> class WellInterfaceIndices;
template<class Scalar> class WellState;

template<class FluidSystem, class Indices>
class MultisegmentWellPrimaryVariables
{
public:
    // TODO: for now, not considering the polymer, solvent and so on to simplify the development process.

    // TODO: we need to have order for the primary variables and also the order for the well equations.
    // sometimes, they are similar, while sometimes, they can have very different forms.

    // Table showing the primary variable indices, depending on what phases are present:
    //
    //         WOG     OG     WG     WO    W/O/G (single phase)
    // WQTotal   0      0      0      0                       0
    // WFrac     1  -1000  -1000      1                   -1000
    // GFrac     2      1      1  -1000                   -1000
    // Spres     3      2      2      2                       1

    static constexpr bool has_wfrac_variable = Indices::waterEnabled && Indices::oilEnabled;
    static constexpr bool has_gfrac_variable = Indices::gasEnabled && Indices::numPhases > 1;

    static constexpr int WQTotal = 0;
    static constexpr int WFrac = has_wfrac_variable ? 1 : -1000;
    static constexpr int GFrac = has_gfrac_variable ? has_wfrac_variable + 1 : -1000;
    static constexpr int SPres = has_wfrac_variable + has_gfrac_variable + 1;

    //  the number of well equations  TODO: it should have a more general strategy for it
    static constexpr int numWellEq = Indices::numPhases + 1;

    using Scalar = typename FluidSystem::Scalar;
    using EvalWell = DenseAd::Evaluation<Scalar, /*size=*/Indices::numEq + numWellEq>;

    using Equations = MultisegmentWellEquations<Scalar,numWellEq,Indices::numEq>;
    using BVectorWell = typename Equations::BVectorWell;

    explicit MultisegmentWellPrimaryVariables(const WellInterfaceIndices<FluidSystem,Indices>& well)
        : well_(well)
    {}

    //! \brief Resize values and evaluations.
    void resize(const int numSegments);

    //! \brief Copy values from well state.
    void update(const WellState<Scalar>& well_state,
                const bool stop_or_zero_rate_target);

    //! \brief Update values from newton update vector.
    void updateNewton(const BVectorWell& dwells,
                      const Scalar relaxation_factor,
                      const Scalar DFLimit,
                      const bool stop_or_zero_rate_target,
                      const Scalar max_pressure_change);

    //! \brief Copy values to well state.
    void copyToWellState(const MultisegmentWellGeneric<Scalar>& mswell,
                         const Scalar rho,
                         WellState<Scalar>& well_state,
                         const SummaryState& summary_state,
                         DeferredLogger& deferred_logger) const;

    //! \brief Returns scaled volume fraction for a component in a segment.
    //! \details F_p / g_p, the basic usage of this value is because Q_p = G_t * F_p / G_p
    EvalWell volumeFractionScaled(const int seg,
                                  const int compIdx) const;

    //! \brief Returns surface volume fraction for a component in a segment.
    //! \details basically Q_p / \sigma_p Q_p
    EvalWell surfaceVolumeFraction(const int seg,
                                   const int compIdx) const;

    //! \brief Returns upwinding rate for a component in a segment.
    EvalWell getSegmentRateUpwinding(const int seg,
                                     const int seg_upwind,
                                     const int comp_idx) const;

    //! \brief Get bottomhole pressure.
    EvalWell getBhp() const;

    //! \brief Get pressure for a segment.
    EvalWell getSegmentPressure(const int seg) const;

    //! \brief Get rate for a component in a segment.
    EvalWell getSegmentRate(const int seg,
                            const int comp_idx) const;

    //! \brief Returns scaled rate for a component.
    EvalWell getQs(const int comp_idx) const;

    //! \brief Get WQTotal.
    EvalWell getWQTotal() const;

    //! \brief Returns a const ref to an array of evaluations.
    const std::array<EvalWell, numWellEq>& eval(const int idx) const
    { return evaluation_[idx]; }

    //! \brief Returns a value array.
    const std::array<Scalar, numWellEq>& value(const int idx) const
    { return value_[idx]; }

    //! \brief Set a value array. Note that this does not also set the corresponding evaluation.
    void setValue(const int idx, const std::array<Scalar, numWellEq>& val)
    { value_[idx] = val; }

    //! output the segments with pressure close to lower pressure limit for debugging purpose
    void outputLowLimitPressureSegments(DeferredLogger& deferred_logger) const;

private:
    //! \brief Initialize evaluations from values.
    void setEvaluationsFromValues();

    //! \brief Handle non-reasonable fractions due to numerical overshoot.
    void processFractions(const int seg);

    //! \brief Returns volume fraction for component in a segment.
    EvalWell volumeFraction(const int seg,
                            const int compIdx) const;

    //! \brief The values for the primary variables
    //! \details Based on different solution strategies, the wells can have different primary variables
    std::vector<std::array<Scalar, numWellEq>> value_;

    //! \brief The Evaluation for the well primary variables.
    //! \details Contains derivatives and are used in AD calculation
    std::vector<std::array<EvalWell, numWellEq>> evaluation_;

    const WellInterfaceIndices<FluidSystem,Indices>& well_; //!< Reference to well interface

    static constexpr double bhp_lower_limit = 1. * unit::barsa - 1. * unit::Pascal;
    static constexpr double seg_pres_lower_limit = 0.;
};

}

#endif // OPM_MULTISEGMENTWELL_PRIMARY_VARIABLES_HEADER_INCLUDED
