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/*!
 * \file
 * \brief The main file for the two-phase porousmediumflow problem of exercise-basic
 */
#include <config.h>

#include <ctime>
#include <iostream>

#include <dune/common/parallel/mpihelper.hh>
#include <dune/common/timer.hh>
#include <dune/grid/io/file/dgfparser/dgfexception.hh>
#include <dune/grid/io/file/vtk.hh>

#include <dumux/common/properties.hh>
#include <dumux/common/parameters.hh>
#include <dumux/common/dumuxmessage.hh>
#include <dumux/common/defaultusagemessage.hh>

#include <dumux/linear/amgbackend.hh>
#include <dumux/linear/linearsolvertraits.hh>
#include <dumux/nonlinear/newtonsolver.hh>

#include <dumux/assembly/fvassembler.hh>
#include <dumux/assembly/diffmethod.hh>

#include <dumux/discretization/method.hh>

#include <dumux/io/vtkoutputmodule.hh>
#include <dumux/io/grid/gridmanager.hh>

// The properties file, where the compile time options are defined
#include "properties2p.hh"

////////////////////////
// the main function
////////////////////////
int main(int argc, char** argv)
{
    using namespace Dumux;

    // define the type tag for this problem
    using TypeTag = Properties::TTag::Injection2pCC;

    // initialize MPI, finalize is done automatically on exit
    const auto& mpiHelper = Dune::MPIHelper::instance(argc, argv);

    // print dumux start message
    if (mpiHelper.rank() == 0)
        DumuxMessage::print(/*firstCall=*/true);

    // parse command line arguments and input file
    Parameters::init(argc, argv);

    // try to create a grid (from the given grid file or the input file)
    GridManager<GetPropType<TypeTag, Properties::Grid>> gridManager;
    gridManager.init();

    ////////////////////////////////////////////////////////////
    // run instationary non-linear problem on this grid
    ////////////////////////////////////////////////////////////

    // we compute on the leaf grid view
    const auto& leafGridView = gridManager.grid().leafGridView();

    // create the finite volume grid geometry
    using FVGridGeometry = GetPropType<TypeTag, Properties::GridGeometry>;
    auto fvGridGeometry = std::make_shared<FVGridGeometry>(leafGridView);
    fvGridGeometry->update();

    // the problem (initial and boundary conditions)
    using Problem = GetPropType<TypeTag, Properties::Problem>;
    auto problem = std::make_shared<Problem>(fvGridGeometry);

    // the solution vector
    using SolutionVector = GetPropType<TypeTag, Properties::SolutionVector>;
    SolutionVector x;
    problem->applyInitialSolution(x);
    auto xOld = x;

    // the grid variables
    using GridVariables = GetPropType<TypeTag, Properties::GridVariables>;
    auto gridVariables = std::make_shared<GridVariables>(problem, fvGridGeometry);
    gridVariables->init(x);

    // get some time loop parameters
    using Scalar = GetPropType<TypeTag, Properties::Scalar>;
    const auto tEnd = getParam<Scalar>("TimeLoop.TEnd");
    const auto maxDt = getParam<Scalar>("TimeLoop.MaxTimeStepSize");
    auto dt = getParam<Scalar>("TimeLoop.DtInitial");

    // intialize the vtk output module
    using IOFields = GetPropType<TypeTag, Properties::IOFields>;

    // use non-conforming output for the test with interface solver
    const auto ncOutput = getParam<bool>("Problem.UseNonConformingOutput", false);
    VtkOutputModule<GridVariables, SolutionVector> vtkWriter(*gridVariables, x, problem->name(), "",
                                                             ncOutput ? Dune::VTK::nonconforming : Dune::VTK::conforming);
    using VelocityOutput = GetPropType<TypeTag, Properties::VelocityOutput>;
    vtkWriter.addVelocityOutput(std::make_shared<VelocityOutput>(*gridVariables));
    IOFields::initOutputModule(vtkWriter); //!< Add model specific output fields
    vtkWriter.write(0.0);

    // instantiate time loop
    auto timeLoop = std::make_shared<TimeLoop<Scalar>>(0.0, dt, tEnd);
    timeLoop->setMaxTimeStepSize(maxDt);

    // the assembler with time loop for instationary problem
    using Assembler = FVAssembler<TypeTag, DiffMethod::numeric>;
    auto assembler = std::make_shared<Assembler>(problem, fvGridGeometry, gridVariables, timeLoop, xOld);

    // the linear solver
    using LinearSolver = AMGBiCGSTABBackend<LinearSolverTraits<FVGridGeometry>>;
    auto linearSolver = std::make_shared<LinearSolver>(leafGridView, fvGridGeometry->dofMapper());

    // the non-linear solver
    using NewtonSolver = Dumux::NewtonSolver<Assembler, LinearSolver>;
    NewtonSolver nonLinearSolver(assembler, linearSolver);

    // time loop
    timeLoop->start();
    while (!timeLoop->finished())
    {
        // set previous solution for storage evaluations
        assembler->setPreviousSolution(xOld);

        //set time in problem (is used in time-dependent Neumann boundary condition)
        problem->setTime(timeLoop->time()+timeLoop->timeStepSize());

        // solve the non-linear system with time step control
        nonLinearSolver.solve(x, *timeLoop);

        // make the new solution the old solution
        xOld = x;
        gridVariables->advanceTimeStep();

        // advance to the time loop to the next step
        timeLoop->advanceTimeStep();

        // report statistics of this time step
        timeLoop->reportTimeStep();

        // set new dt as suggested by the newton solver
        timeLoop->setTimeStepSize(nonLinearSolver.suggestTimeStepSize(timeLoop->timeStepSize()));

        // output to vtk
        vtkWriter.write(timeLoop->time());
    }

    timeLoop->finalize(leafGridView.comm());

    ////////////////////////////////////////////////////////////
    // finalize, print dumux message to say goodbye
    ////////////////////////////////////////////////////////////

    // print dumux end message
    if (mpiHelper.rank() == 0)
    {
        Parameters::print();
        DumuxMessage::print(/*firstCall=*/false);
    }

    return 0;
} // end main