#include <catch2/catch_test_macros.hpp>
#include <catch2/matchers/catch_matchers_floating_point.hpp>
#include <mfem.hpp>

import mean_field;
import test_helpers;

using namespace mean_field;
using Catch::Matchers::WithinAbs;
namespace prepared_test = gravity_prepared_test_utils;

TEST_CASE(
    "Prepared Mapped Hdiv Mass Matches Stateless Kernel",
    tags::integration &tags::mfem_operators &tags::prepared
) {
    auto args  = test_utils::setup_args();
    fem::FEM f = fem::setup_fem(args.mesh_file, args, 0);

    operators::PreparedMappedHDivMassOperator prepared_operator(f, *f.domainMapperStateless);

    const mfem::Vector gravity_gradient =
        prepared_test::make_deterministic_vector(f.gravityFluxFes->GetTrueVSize(), 0.21);
    const MPI_Comm communicator = f.gravityFluxFes->GetComm();

    mfem::Vector identity_action;
    mfem::Vector deformed_action;

    for (const double deformation_scale : {0.0, 1.0}) {
        const mfem::Vector displacement = prepared_test::make_displacement(f, deformation_scale);

        prepared_operator.Prepare(displacement);

        mfem::Vector prepared_action;
        mfem::Vector reference_action;

        prepared_operator.Mult(gravity_gradient, prepared_action);
        operators::kernels::apply_mapped_hdiv_mass(
            f, *f.domainMapperStateless, gravity_gradient, displacement, reference_action
        );

        const double relative_error = prepared_test::relative_error(prepared_action, reference_action, communicator);

        INFO("Deformation scale = " << deformation_scale);
        INFO("Prepared action norm = " << prepared_test::global_norm(prepared_action, communicator));
        INFO("Reference action norm = " << prepared_test::global_norm(reference_action, communicator));
        INFO("Relative prepared-operator error = " << relative_error);

        REQUIRE(prepared_operator.IsPrepared());
        CHECK_THAT(relative_error, WithinAbs(0.0, 2.0e-11));

        if (deformation_scale == 0.0) {
            identity_action = prepared_action;
        } else {
            deformed_action = prepared_action;
        }
    }

    const double geometry_change = prepared_test::relative_error(deformed_action, identity_action, communicator);

    INFO("Relative action change under deformation = " << geometry_change);

    CHECK(prepared_operator.GetPreparationCount() == 2);
    CHECK(geometry_change > 1.0e-5);
}

TEST_CASE(
    "Prepared Mapped Hdiv Mass Preserves Operator Identities",
    tags::integration &tags::gravity &tags::prepared
) {
    auto args  = test_utils::setup_args();
    fem::FEM f = fem::setup_fem(args.mesh_file, args, 0);

    operators::PreparedMappedHDivMassOperator prepared_operator(f, *f.domainMapperStateless);
    const mfem::Vector displacement = prepared_test::make_displacement(f, 1.0);
    prepared_operator.Prepare(displacement);

    const mfem::Vector first       = prepared_test::make_deterministic_vector(f.gravityFluxFes->GetTrueVSize(), 0.17);
    const mfem::Vector second      = prepared_test::make_deterministic_vector(f.gravityFluxFes->GetTrueVSize(), 0.83);
    const mfem::Vector combination = prepared_test::linear_combination(first, 1.7, second, -0.4);

    mfem::Vector first_action;
    mfem::Vector second_action;
    mfem::Vector combination_action;
    mfem::Vector zero_action;

    prepared_operator.Mult(first, first_action);
    prepared_operator.Mult(second, second_action);
    prepared_operator.Mult(combination, combination_action);

    mfem::Vector expected_combination = prepared_test::linear_combination(first_action, 1.7, second_action, -0.4);

    mfem::Vector zero(first.Size());
    zero = 0.0;
    prepared_operator.Mult(zero, zero_action);

    const MPI_Comm communicator       = f.gravityFluxFes->GetComm();

    const double first_second_product = prepared_test::global_dot(first, second_action, communicator);
    const double second_first_product = prepared_test::global_dot(second, first_action, communicator);
    const double symmetry_error = prepared_test::relative_scalar_error(first_second_product, second_first_product);
    const double linearity_error =
        prepared_test::relative_error(combination_action, expected_combination, communicator);
    const double first_energy             = prepared_test::global_dot(first, first_action, communicator);
    const double second_energy            = prepared_test::global_dot(second, second_action, communicator);
    const std::uint64_t preparation_count = prepared_operator.GetPreparationCount();

    mfem::Vector repeated_action;
    prepared_operator.Mult(first, repeated_action);

    INFO("u^T M v = " << first_second_product);
    INFO("v^T M u = " << second_first_product);
    INFO("Relative symmetry error = " << symmetry_error);
    INFO("Relative linearity error = " << linearity_error);
    INFO("u^T M u = " << first_energy);
    INFO("v^T M v = " << second_energy);

    CHECK_THAT(symmetry_error, WithinAbs(0.0, 2.0e-12));
    CHECK_THAT(linearity_error, WithinAbs(0.0, 2.0e-12));
    CHECK_THAT(prepared_test::global_norm(zero_action, communicator), WithinAbs(0.0, 1.0e-14));
    CHECK(first_energy > 0.0);
    CHECK(second_energy > 0.0);
    CHECK(prepared_test::relative_error(repeated_action, first_action, communicator) < 2.0e-14);
    CHECK(prepared_operator.GetPreparationCount() == preparation_count);
}