/*
  Copyright 2019 SINTEF Digital, Mathematics and Cybernetics.

  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/>.
*/

#include <config.h>

#define BOOST_TEST_MODULE OPM_test_FlexibleSolver
#include <boost/test/unit_test.hpp>
#include <boost/version.hpp>

#include <dune/common/version.hh>

#if DUNE_VERSION_NEWER(DUNE_ISTL, 2, 6) && \
    BOOST_VERSION / 100 % 1000 > 48

#include <opm/simulators/linalg/FlexibleSolver.hpp>
#include <opm/simulators/linalg/getQuasiImpesWeights.hpp>

#include <dune/common/fmatrix.hh>
#include <dune/istl/bcrsmatrix.hh>
#include <dune/istl/matrixmarket.hh>

#include <boost/property_tree/json_parser.hpp>
#include <boost/property_tree/ptree.hpp>
#include <fstream>
#include <iostream>


template <int bz>
Dune::BlockVector<Dune::FieldVector<double, bz>>
testSolver(const boost::property_tree::ptree& prm, const std::string& matrix_filename, const std::string& rhs_filename)
{
    using Matrix = Dune::BCRSMatrix<Dune::FieldMatrix<double, bz, bz>>;
    using Vector = Dune::BlockVector<Dune::FieldVector<double, bz>>;
    Matrix matrix;
    {
        std::ifstream mfile(matrix_filename);
        if (!mfile) {
            throw std::runtime_error("Could not read matrix file");
        }
        readMatrixMarket(matrix, mfile);
    }
    Vector rhs;
    {
        std::ifstream rhsfile(rhs_filename);
        if (!rhsfile) {
            throw std::runtime_error("Could not read rhs file");
        }
        readMatrixMarket(rhs, rhsfile);
    }
    bool transpose = false;

    if(prm.get<std::string>("preconditioner.type") == "cprt"){
        transpose = true;
    }
    auto wc = [&matrix, &prm, transpose]()
              {
                  return Opm::Amg::getQuasiImpesWeights<Matrix,
                                                        Vector>(matrix,
                                                                prm.get<int>("preconditioner.pressure_var_index"),
                                                                transpose);
              };
    using SeqOperatorType = Dune::MatrixAdapter<Matrix, Vector, Vector>;
    SeqOperatorType op(matrix);
    Dune::FlexibleSolver<Matrix, Vector> solver(op, prm, wc);
    Vector x(rhs.size());
    Dune::InverseOperatorResult res;
    solver.apply(x, rhs, res);
    return x;
}

BOOST_AUTO_TEST_CASE(TestFlexibleSolver)
{
    namespace pt = boost::property_tree;
    pt::ptree prm;

    // Read parameters.
    {
        std::ifstream file("options_flexiblesolver.json");
        pt::read_json(file, prm);
        // pt::write_json(std::cout, prm);
    }

    // Test with 1x1 block solvers.
    {
        const int bz = 1;
        auto sol = testSolver<bz>(prm, "matr33.txt", "rhs3.txt");
        Dune::BlockVector<Dune::FieldVector<double, bz>> expected {-1.62493,
                                                                   -1.76435e-06,
                                                                   1.86991e-10,
                                                                   -458.542,
                                                                   2.28308e-06,
                                                                   -2.45341e-07,
                                                                   -1.48005,
                                                                   -5.02264e-07,
                                                                   -1.049e-05};
        BOOST_REQUIRE_EQUAL(sol.size(), expected.size());
        for (size_t i = 0; i < sol.size(); ++i) {
            for (int row = 0; row < bz; ++row) {
                BOOST_CHECK_CLOSE(sol[i][row], expected[i][row], 1e-3);
            }
        }
    }

    // Test with 3x3 block solvers.
    {
        const int bz = 3;
        auto sol = testSolver<bz>(prm, "matr33.txt", "rhs3.txt");
        Dune::BlockVector<Dune::FieldVector<double, bz>> expected {{-1.62493, -1.76435e-06, 1.86991e-10},
                                                                   {-458.542, 2.28308e-06, -2.45341e-07},
                                                                   {-1.48005, -5.02264e-07, -1.049e-05}};
        BOOST_REQUIRE_EQUAL(sol.size(), expected.size());
        for (size_t i = 0; i < sol.size(); ++i) {
            for (int row = 0; row < bz; ++row) {
                BOOST_CHECK_CLOSE(sol[i][row], expected[i][row], 1e-3);
            }
        }
    }
}

#else

// Do nothing if we do not have at least Dune 2.6.
BOOST_AUTO_TEST_CASE(DummyTest)
{
    BOOST_REQUIRE(true);
}

#endif