#include <algorithm>
#include <array>
#include <catch2/catch_test_macros.hpp>
#include <cstddef>
#include <cstdint>
#include <mfem.hpp>

import mean_field;
import test_helpers;

namespace {
    mfem::Vector project_scalar(
        mfem::ParFiniteElementSpace &finiteElementSpace,
        mfem::Coefficient &coefficient
    ) {
        mfem::ParGridFunction field(&finiteElementSpace);

        field.ProjectCoefficient(coefficient);

        mfem::Vector trueVector;
        field.GetTrueDofs(trueVector);
        return trueVector;
    }

    mfem::Vector make_base_density(const mean_field::fem::FEM &f) {
        mfem::FunctionCoefficient coefficient([](const mfem::Vector &position) {
            return 0.42 + 0.025 * position(0) - 0.012 * position(1) +
                   0.007 * position(2);
        });

        return project_scalar(*f.densityFes, coefficient);
    }

    mfem::Vector make_base_enthalpy(const mean_field::fem::FEM &f) {
        mfem::FunctionCoefficient coefficient([](const mfem::Vector &position) {
            return 0.92 + 0.018 * position(0) - 0.011 * position(1) +
                   0.006 * position(2);
        });

        return project_scalar(*f.enthalpyFes, coefficient);
    }

    mfem::Vector make_enthalpy_variation(const mean_field::fem::FEM &f) {
        mfem::FunctionCoefficient coefficient([](const mfem::Vector &position) {
            return 0.065 + 0.014 * position(0) + 0.009 * position(2);
        });

        return project_scalar(*f.enthalpyFes, coefficient);
    }

    mfem::Vector make_combined_variation(
        const mfem::Vector &densityVariation,
        const mfem::Vector &enthalpyVariation
    ) {
        mfem::Vector combinedVariation(
            densityVariation.Size() + enthalpyVariation.Size()
        );

        for (int densityDof = 0; densityDof < densityVariation.Size();
             ++densityDof) {
            combinedVariation(densityDof) = densityVariation(densityDof);
        }

        for (int enthalpyDof = 0; enthalpyDof < enthalpyVariation.Size();
             ++enthalpyDof) {
            combinedVariation(densityVariation.Size() + enthalpyDof) =
                enthalpyVariation(enthalpyDof);
        }

        return combinedVariation;
    }
    struct ClosureCondition {
        const char *name;

        double polytropicIndex;
        double polytropicConstant;

        double enthalpyOffset;
        double enthalpyGradient;

        double densityFactor;
        double densityOffset;
        double densityGradient;

        double deformationScale;
        double directionPhase;
    };

    inline constexpr std::array<ClosureCondition, 3> conditions{
        {{.name               = "Linear barotrope on identity geometry",
          .polytropicIndex    = 1.0,
          .polytropicConstant = 0.8,
          .enthalpyOffset     = 0.65,
          .enthalpyGradient   = 0.06,
          .densityFactor      = 0.80,
          .densityOffset      = 0.015,
          .densityGradient    = 0.004,
          .deformationScale   = 0.0,
          .directionPhase     = 0.31},
         {.name               = "Fractional barotrope on moderate deformation",
          .polytropicIndex    = 1.5,
          .polytropicConstant = 1.2,
          .enthalpyOffset     = 0.90,
          .enthalpyGradient   = 0.09,
          .densityFactor      = 1.15,
          .densityOffset      = -0.003,
          .densityGradient    = 0.003,
          .deformationScale   = 0.45,
          .directionPhase     = 0.53},
         {.name               = "Target n=3 barotrope on strong deformation",
          .polytropicIndex    = 3.0,
          .polytropicConstant = 1.5,
          .enthalpyOffset     = 1.20,
          .enthalpyGradient   = 0.12,
          .densityFactor      = 1.40,
          .densityOffset      = 0.006,
          .densityGradient    = 0.002,
          .deformationScale   = 1.0,
          .directionPhase     = 0.79}}
    };

    double evaluate_enthalpy(
        const mfem::Vector &position,
        const ClosureCondition &condition
    ) {
        return condition.enthalpyOffset +
               condition.enthalpyGradient *
                   (0.50 * position(0) - 0.30 * position(1) +
                    0.20 * position(2));
    }

    mfem::Vector project_scalar_field(
        mfem::ParFiniteElementSpace &finiteElementSpace,
        mfem::Coefficient &coefficient
    ) {
        mfem::ParGridFunction field(&finiteElementSpace);

        field.ProjectCoefficient(coefficient);

        mfem::Vector trueVector;
        field.GetTrueDofs(trueVector);

        return trueVector;
    }

    mfem::Vector make_enthalpy(
        const mean_field::fem::FEM &f,
        const ClosureCondition &condition
    ) {
        mfem::FunctionCoefficient coefficient(
            [condition](const mfem::Vector &position) {
                return evaluate_enthalpy(position, condition);
            }
        );

        return project_scalar_field(*f.enthalpyFes, coefficient);
    }

    mfem::Vector make_density(
        const mean_field::fem::FEM &f,
        const mean_field::physics::PolytropicBarotrope &barotrope,
        const ClosureCondition &condition
    ) {
        mfem::FunctionCoefficient coefficient(
            [&barotrope, condition](const mfem::Vector &position) {
                const double enthalpy = evaluate_enthalpy(position, condition);

                return condition.densityFactor *
                           barotrope.density_from_enthalpy(enthalpy) +
                       condition.densityOffset +
                       condition.densityGradient *
                           (0.40 * position(0) + 0.25 * position(1) -
                            0.15 * position(2));
            }
        );

        return project_scalar_field(*f.densityFes, coefficient);
    }

    mfem::Vector make_constant_field(
        mfem::ParFiniteElementSpace &finiteElementSpace,
        const double value
    ) {
        mfem::ConstantCoefficient coefficient(value);

        return project_scalar_field(finiteElementSpace, coefficient);
    }

} // namespace

TEST_CASE(
    "Prepared Barotropic Closure Matches Stateless Kernels",
    tags::hydro &tags::prepared &tags::unit
) {
    auto args = test_utils::setup_args();

    mean_field::fem::FEM f =
        mean_field::fem::setup_fem(args.mesh_file, args, 0);

    const mean_field::physics::PolytropicBarotrope barotrope(3.0, 1.5);

    mean_field::operators::PreparedBarotropicClosureOperator preparedOperator(
        f, *f.domainMapperStateless, barotrope
    );

    REQUIRE_FALSE(preparedOperator.IsPrepared());
    REQUIRE(preparedOperator.Height() == f.densityFes->GetTrueVSize());
    REQUIRE(
        preparedOperator.Width() ==
        f.densityFes->GetTrueVSize() + f.enthalpyFes->GetTrueVSize()
    );
    REQUIRE(preparedOperator.GetDensitySize() == f.densityFes->GetTrueVSize());
    REQUIRE(
        preparedOperator.GetEnthalpySize() == f.enthalpyFes->GetTrueVSize()
    );

    const mfem::Vector baseDensity  = make_base_density(f);

    const mfem::Vector baseEnthalpy = make_base_enthalpy(f);

    const mfem::Vector displacement =
        gravity_prepared_test_utils::make_displacement(f, 1.0);

    const mfem::Vector densityVariation =
        gravity_prepared_test_utils::make_deterministic_vector(
            f.densityFes->GetTrueVSize(), 0.43
        );

    const mfem::Vector displacementVariation =
        gravity_prepared_test_utils::make_displacement(f, 0.63);

    const mfem::Vector enthalpyVariation = make_enthalpy_variation(f);

    mfem::Vector zeroDensity(f.densityFes->GetTrueVSize());
    zeroDensity = 0.0;

    mfem::Vector zeroEnthalpy(f.enthalpyFes->GetTrueVSize());
    zeroEnthalpy = 0.0;

    preparedOperator.Prepare(baseDensity, baseEnthalpy, displacement);

    mfem::Vector preparedResidual;
    mfem::Vector preparedDensityAction;
    mfem::Vector preparedEnthalpyAction;
    mfem::Vector preparedSplitAction;
    mfem::Vector preparedCombinedAction;

    preparedOperator.BuildResidual(preparedResidual);

    preparedOperator.Mult(
        densityVariation, zeroEnthalpy, displacementVariation,
        preparedDensityAction
    );

    preparedOperator.Mult(
        zeroDensity, enthalpyVariation, displacementVariation,
        preparedEnthalpyAction
    );

    preparedOperator.Mult(
        densityVariation, enthalpyVariation, displacementVariation,
        preparedSplitAction
    );

    const mfem::Vector combinedVariation =
        make_combined_variation(densityVariation, enthalpyVariation);

    preparedOperator.Mult(combinedVariation, preparedCombinedAction);

    mfem::Vector referenceResidual;
    mfem::Vector referenceDensityAction;
    mfem::Vector referenceEnthalpyAction;
    mfem::Vector referenceDisplacementAction;

    mean_field::operators::kernels::apply_barotropic_closure(
        f, *f.domainMapperStateless, barotrope, baseDensity, baseEnthalpy,
        displacement, referenceResidual
    );

    mean_field::operators::kernels::apply_barotropic_closure_density_action(
        f, *f.domainMapperStateless, barotrope, densityVariation, displacement,
        referenceDensityAction
    );

    mean_field::operators::kernels::apply_barotropic_closure_enthalpy_action(
        f, *f.domainMapperStateless, barotrope, baseEnthalpy, enthalpyVariation,
        displacement, referenceEnthalpyAction
    );

    mean_field::operators::kernels::
        apply_barotropic_closure_displacement_action(
            f, *f.domainMapperStateless, barotrope, baseDensity, baseEnthalpy,
            displacement, displacementVariation, referenceDisplacementAction
        );

    mfem::Vector referenceCombinedAction(referenceDensityAction);
    referenceCombinedAction += referenceEnthalpyAction;
    referenceCombinedAction += referenceDisplacementAction;

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

    const double residualError  = gravity_prepared_test_utils::relative_error(
        preparedResidual, referenceResidual, communicator
    );

    const double densityError = gravity_prepared_test_utils::relative_error(
        preparedDensityAction, referenceDensityAction, communicator
    );

    const double enthalpyError = gravity_prepared_test_utils::relative_error(
        preparedEnthalpyAction, referenceEnthalpyAction, communicator
    );

    const double splitError = gravity_prepared_test_utils::relative_error(
        preparedSplitAction, referenceCombinedAction, communicator
    );

    const double combinedError = gravity_prepared_test_utils::relative_error(
        preparedCombinedAction, referenceCombinedAction, communicator
    );

    INFO("Prepared residual error = " << residualError);
    INFO("Prepared density-action error = " << densityError);
    INFO("Prepared enthalpy-action error = " << enthalpyError);
    INFO("Prepared split-action error = " << splitError);
    INFO("Prepared combined-action error = " << combinedError);

    CHECK(preparedOperator.IsPrepared());
    CHECK(preparedOperator.GetPreparationCount() == 1);
    CHECK(residualError < 2.0e-12);
    CHECK(densityError < 2.0e-12);
    CHECK(enthalpyError < 2.0e-12);
    CHECK(splitError < 2.0e-12);
    CHECK(combinedError < 2.0e-12);
}

TEST_CASE(
    "Prepared Barotropic Closure Jacobian Matches Centered Difference",
    tags::hydro &tags::jacobian &tags::prepared &tags::unit
) {
    auto args = test_utils::setup_args();

    mean_field::fem::FEM f =
        mean_field::fem::setup_fem(args.mesh_file, args, 0);

    const mean_field::physics::PolytropicBarotrope barotrope(3.0, 1.5);

    mfem::Vector baseDensity  = make_base_density(f);

    mfem::Vector baseEnthalpy = make_base_enthalpy(f);

    const mfem::Vector displacement =
        gravity_prepared_test_utils::make_displacement(f, 1.0);

    const mfem::Vector densityVariation =
        gravity_prepared_test_utils::make_deterministic_vector(
            f.densityFes->GetTrueVSize(), 0.71
        );

    const mfem::Vector displacementVariation =
        gravity_prepared_test_utils::make_displacement(f, 0.63);

    const mfem::Vector enthalpyVariation = make_enthalpy_variation(f);

    mean_field::operators::PreparedBarotropicClosureOperator preparedOperator(
        f, *f.domainMapperStateless, barotrope
    );

    preparedOperator.Prepare(baseDensity, baseEnthalpy, displacement);

    mfem::Vector analyticAction;

    preparedOperator.Mult(
        densityVariation, enthalpyVariation, displacementVariation,
        analyticAction
    );

    constexpr double differenceStep = 1.0e-6;

    const mfem::Vector plusDensity =
        gravity_prepared_test_utils::linear_combination(
            baseDensity, 1.0, densityVariation, differenceStep
        );

    const mfem::Vector minusDensity =
        gravity_prepared_test_utils::linear_combination(
            baseDensity, 1.0, densityVariation, -differenceStep
        );

    const mfem::Vector plusEnthalpy =
        gravity_prepared_test_utils::linear_combination(
            baseEnthalpy, 1.0, enthalpyVariation, differenceStep
        );

    const mfem::Vector minusEnthalpy =
        gravity_prepared_test_utils::linear_combination(
            baseEnthalpy, 1.0, enthalpyVariation, -differenceStep
        );

    mfem::Vector plusResidual;
    mfem::Vector minusResidual;

    mean_field::operators::kernels::apply_barotropic_closure(
        f, *f.domainMapperStateless, barotrope, plusDensity, plusEnthalpy,
        displacement, plusResidual
    );

    mean_field::operators::kernels::apply_barotropic_closure(
        f, *f.domainMapperStateless, barotrope, minusDensity, minusEnthalpy,
        displacement, minusResidual
    );

    mfem::Vector finiteDifference(plusResidual);
    finiteDifference -= minusResidual;
    finiteDifference *= 1.0 / (2.0 * differenceStep);

    const double relativeError = gravity_prepared_test_utils::relative_error(
        analyticAction, finiteDifference, f.mesh->GetComm()
    );

    INFO("Prepared EOS centered-difference error = " << relativeError);

    CHECK(relativeError < 2.0e-8);
}

TEST_CASE(
    "Prepared Barotropic Closure Reuses Frozen Data",
    tags::hydro &tags::prepared &tags::unit
) {
    auto args = test_utils::setup_args();

    mean_field::fem::FEM f =
        mean_field::fem::setup_fem(args.mesh_file, args, 0);

    const mean_field::physics::PolytropicBarotrope barotrope(3.0, 1.5);

    mean_field::operators::PreparedBarotropicClosureOperator preparedOperator(
        f, *f.domainMapperStateless, barotrope
    );

    CHECK_FALSE(preparedOperator.IsPrepared());
    CHECK(preparedOperator.GetPreparationCount() == 0);

    mfem::Vector baseDensity  = make_base_density(f);

    mfem::Vector baseEnthalpy = make_base_enthalpy(f);

    mfem::Vector displacement =
        gravity_prepared_test_utils::make_displacement(f, 1.0);

    const mfem::Vector displacementVariation =
        gravity_prepared_test_utils::make_displacement(f, 0.63);

    const mfem::Vector densityVariation =
        gravity_prepared_test_utils::make_deterministic_vector(
            f.densityFes->GetTrueVSize(), 0.31
        );

    const mfem::Vector enthalpyVariation = make_enthalpy_variation(f);

    preparedOperator.Prepare(baseDensity, baseEnthalpy, displacement);

    REQUIRE(preparedOperator.IsPrepared());
    REQUIRE(preparedOperator.GetPreparationCount() == 1);

    mfem::Vector firstResidual;
    mfem::Vector firstAction;

    preparedOperator.BuildResidual(firstResidual);

    preparedOperator.Mult(
        densityVariation, enthalpyVariation, displacementVariation, firstAction
    );

    baseDensity  = 7.0;
    baseEnthalpy = 3.0;
    displacement *= -4.0;

    const std::uint64_t preparationCount =
        preparedOperator.GetPreparationCount();

    mfem::Vector repeatedResidual;
    mfem::Vector repeatedAction;

    preparedOperator.BuildResidual(repeatedResidual);

    preparedOperator.Mult(
        densityVariation, enthalpyVariation, displacementVariation,
        repeatedAction
    );

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

    const double residualReuseError =
        gravity_prepared_test_utils::relative_error(
            repeatedResidual, firstResidual, communicator
        );

    const double actionReuseError = gravity_prepared_test_utils::relative_error(
        repeatedAction, firstAction, communicator
    );

    INFO("Frozen residual reuse error = " << residualReuseError);
    INFO("Frozen action reuse error = " << actionReuseError);

    CHECK(residualReuseError < 2.0e-14);
    CHECK(actionReuseError < 2.0e-14);
    CHECK(preparedOperator.GetPreparationCount() == preparationCount);
}

TEST_CASE(
    "Prepared Barotropic Closure Reprepares For New Geometry",
    tags::hydro &tags::mapping &tags::prepared &tags::unit
) {
    auto args = test_utils::setup_args();

    mean_field::fem::FEM f =
        mean_field::fem::setup_fem(args.mesh_file, args, 0);

    const mean_field::physics::PolytropicBarotrope barotrope(3.0, 1.5);

    const mfem::Vector baseDensity  = make_base_density(f);

    const mfem::Vector baseEnthalpy = make_base_enthalpy(f);

    const mfem::Vector densityVariation =
        gravity_prepared_test_utils::make_deterministic_vector(
            f.densityFes->GetTrueVSize(), 0.59
        );

    mfem::Vector zeroEnthalpy(f.enthalpyFes->GetTrueVSize());
    zeroEnthalpy = 0.0;

    mean_field::operators::PreparedBarotropicClosureOperator preparedOperator(
        f, *f.domainMapperStateless, barotrope
    );

    mfem::Vector identityAction;
    mfem::Vector deformedAction;

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

        const mfem::Vector displacementVariation =
            gravity_prepared_test_utils::make_displacement(f, 0.63);

        preparedOperator.Prepare(baseDensity, baseEnthalpy, displacement);

        mfem::Vector preparedResidual;
        mfem::Vector preparedAction;
        mfem::Vector referenceResidual;
        mfem::Vector referenceAction;

        preparedOperator.BuildResidual(preparedResidual);

        preparedOperator.Mult(
            densityVariation, zeroEnthalpy, displacementVariation,
            preparedAction
        );

        mean_field::operators::kernels::apply_barotropic_closure(
            f, *f.domainMapperStateless, barotrope, baseDensity, baseEnthalpy,
            displacement, referenceResidual
        );

        mean_field::operators::kernels::apply_barotropic_closure_density_action(
            f, *f.domainMapperStateless, barotrope, densityVariation,
            displacement, referenceAction
        );

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

        const double residualError =
            gravity_prepared_test_utils::relative_error(
                preparedResidual, referenceResidual, communicator
            );

        const double actionError = gravity_prepared_test_utils::relative_error(
            preparedAction, referenceAction, communicator
        );

        INFO("Deformation scale = " << deformationScale);
        INFO("Reprepared residual error = " << residualError);
        INFO("Reprepared action error = " << actionError);

        CHECK(residualError < 2.0e-12);
        CHECK(actionError < 2.0e-12);

        if (deformationScale == 0.0) {
            identityAction = preparedAction;
        } else {
            deformedAction = preparedAction;
        }
    }

    const double geometryChange = gravity_prepared_test_utils::relative_error(
        deformedAction, identityAction, f.mesh->GetComm()
    );

    INFO("Prepared closure geometry change = " << geometryChange);

    CHECK(preparedOperator.GetPreparationCount() == 2);
    CHECK(geometryChange > 1.0e-5);
}

TEST_CASE(
    "Complete Barotropic Closure Matches Blocks And Centered Differences "
    "Across Conditions",
    tags::barotrope &tags::closure &tags::hydro &tags::integration
        &tags::jacobian &tags::mapping &tags::physics &tags::prepared
) {
    auto args = test_utils::setup_args();

    mean_field::fem::FEM f =
        mean_field::fem::setup_fem(args.mesh_file, args, 0);

    REQUIRE(f.domainMapperStateless != nullptr);

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

    constexpr double differenceStep = 1.0e-5;

    for (std::size_t conditionIndex = 0; conditionIndex <

                                         conditions.size();
         ++conditionIndex) {
        const auto &condition =

            conditions[conditionIndex];

        DYNAMIC_SECTION(condition.name) {
            const mean_field::physics::PolytropicBarotrope barotrope(
                condition.polytropicIndex, condition.polytropicConstant
            );

            const mfem::Vector baseDensity =

                make_density(f, barotrope, condition);

            const mfem::Vector baseEnthalpy =

                make_enthalpy(f, condition);

            const mfem::Vector baseDisplacement =
                gravity_prepared_test_utils::make_displacement(
                    f, condition.deformationScale
                );

            mfem::Vector densityVariation =
                gravity_prepared_test_utils::make_deterministic_vector(
                    f.densityFes->GetTrueVSize(), condition.directionPhase
                );

            mfem::Vector enthalpyVariation =
                gravity_prepared_test_utils::make_deterministic_vector(
                    f.enthalpyFes->GetTrueVSize(),
                    condition.directionPhase + 0.27
                );

            mfem::Vector displacementVariation =
                gravity_prepared_test_utils::make_displacement(
                    f, condition.directionPhase
                );

            mfem::Vector densityAction;
            mfem::Vector enthalpyAction;
            mfem::Vector displacementAction;

            mean_field::operators::kernels::
                apply_barotropic_closure_density_action(
                    f, *f.domainMapperStateless, barotrope, densityVariation,
                    baseDisplacement, densityAction
                );

            mean_field::operators::kernels::
                apply_barotropic_closure_enthalpy_action(
                    f, *f.domainMapperStateless, barotrope, baseEnthalpy,
                    enthalpyVariation, baseDisplacement, enthalpyAction
                );

            mean_field::operators::kernels::
                apply_barotropic_closure_displacement_action(
                    f, *f.domainMapperStateless, barotrope, baseDensity,
                    baseEnthalpy, baseDisplacement, displacementVariation,
                    displacementAction
                );

            double densityActionNorm = gravity_prepared_test_utils::global_norm(
                densityAction, communicator
            );

            double enthalpyActionNorm =
                gravity_prepared_test_utils::global_norm(
                    enthalpyAction, communicator
                );

            double displacementActionNorm =
                gravity_prepared_test_utils::global_norm(
                    displacementAction, communicator
                );

            REQUIRE(densityActionNorm > 1.0e-12);
            REQUIRE(enthalpyActionNorm > 1.0e-12);
            REQUIRE(displacementActionNorm > 1.0e-12);

            const double targetActionNorm = std::min(
                {densityActionNorm, enthalpyActionNorm, displacementActionNorm}
            );

            const double densityScale  = targetActionNorm / densityActionNorm;

            const double enthalpyScale = targetActionNorm / enthalpyActionNorm;

            const double displacementScale =
                targetActionNorm / displacementActionNorm;

            densityVariation *= densityScale;
            densityAction *= densityScale;

            enthalpyVariation *= enthalpyScale;
            enthalpyAction *= enthalpyScale;

            displacementVariation *= displacementScale;
            displacementAction *= displacementScale;

            densityActionNorm = gravity_prepared_test_utils::global_norm(
                densityAction, communicator
            );

            enthalpyActionNorm = gravity_prepared_test_utils::global_norm(
                enthalpyAction, communicator
            );

            displacementActionNorm = gravity_prepared_test_utils::global_norm(
                displacementAction, communicator
            );

            mean_field::operators::context::barotropic::
                BarotropicClosureLinearizationContext context(
                    f, *f.domainMapperStateless, barotrope
                );

            const std::uint64_t revisionBase =
                100 + static_cast<std::uint64_t>(10 * conditionIndex);

            const mean_field::operators::context::barotropic::
                BarotropicClosureRevisions revisions{
                    .density      = revisionBase + 1,
                    .enthalpy     = revisionBase + 2,
                    .displacement = revisionBase + 3
                };

            context.Prepare(
                baseDensity, baseEnthalpy, baseDisplacement, revisions
            );

            mfem::Vector preparedResidual;
            mfem::Vector referenceResidual;

            context.BuildResidual(preparedResidual);

            mean_field::operators::kernels::apply_barotropic_closure(
                f, *f.domainMapperStateless, barotrope, baseDensity,
                baseEnthalpy, baseDisplacement, referenceResidual
            );

            const double residualEvaluationError =
                gravity_prepared_test_utils::relative_error(
                    preparedResidual, referenceResidual, communicator
                );

            mfem::Vector preparedAction;

            context.GetOperator().Mult(
                densityVariation, enthalpyVariation, displacementVariation,
                preparedAction
            );

            mfem::Vector blockSum(densityAction);

            blockSum += enthalpyAction;
            blockSum += displacementAction;

            const double blockAssemblyError =
                gravity_prepared_test_utils::relative_error(
                    preparedAction, blockSum, communicator
                );

            mfem::Vector plusDensity(baseDensity);

            mfem::Vector minusDensity(baseDensity);

            mfem::Vector plusEnthalpy(baseEnthalpy);

            mfem::Vector minusEnthalpy(baseEnthalpy);

            mfem::Vector plusDisplacement(baseDisplacement);

            mfem::Vector minusDisplacement(baseDisplacement);

            plusDensity.Add(differenceStep, densityVariation);

            minusDensity.Add(-differenceStep, densityVariation);

            plusEnthalpy.Add(differenceStep, enthalpyVariation);

            minusEnthalpy.Add(-differenceStep, enthalpyVariation);

            plusDisplacement.Add(differenceStep, displacementVariation);

            minusDisplacement.Add(-differenceStep, displacementVariation);

            mfem::Vector plusResidual;
            mfem::Vector minusResidual;

            mean_field::operators::kernels::apply_barotropic_closure(
                f, *f.domainMapperStateless, barotrope, plusDensity,
                plusEnthalpy, plusDisplacement, plusResidual
            );

            mean_field::operators::kernels::apply_barotropic_closure(
                f, *f.domainMapperStateless, barotrope, minusDensity,
                minusEnthalpy, minusDisplacement, minusResidual
            );

            mfem::Vector finiteDifference(plusResidual);

            finiteDifference -= minusResidual;

            finiteDifference *= 1.0 / (2.0 * differenceStep);

            mfem::Vector finiteDifferenceError(preparedAction);

            finiteDifferenceError -= finiteDifference;

            const double finiteDifferenceErrorNorm =
                gravity_prepared_test_utils::global_norm(
                    finiteDifferenceError, communicator
                );

            const double blockNormSum =
                densityActionNorm + enthalpyActionNorm + displacementActionNorm;

            const double blockScaledDifferenceError =
                finiteDifferenceErrorNorm / blockNormSum;

            const double completeRelativeError =
                gravity_prepared_test_utils::relative_error(
                    preparedAction, finiteDifference, communicator
                );

            INFO("Condition = " << condition.name);

            INFO("Polytropic index = " << condition.polytropicIndex);

            INFO("Deformation scale = " << condition.deformationScale);

            INFO("Prepared residual error = " << residualEvaluationError);

            INFO("Complete block-assembly error = " << blockAssemblyError);

            INFO("Density-action norm = " << densityActionNorm);

            INFO("Enthalpy-action norm = " << enthalpyActionNorm);

            INFO("Displacement-action norm = " << displacementActionNorm);

            INFO(
                "Complete centered-difference relative error = "
                << completeRelativeError
            );

            INFO(
                "Block-scaled centered-difference error = "
                << blockScaledDifferenceError
            );

            CHECK(context.GetPreparationCount() == 1);
            CHECK(residualEvaluationError < 5.0e-12);
            CHECK(blockAssemblyError < 5.0e-12);
            CHECK(blockScaledDifferenceError < 2.0e-7);
        }
    }
}

TEST_CASE(
    "Exact Constant Barotropic Closure Remains Zero Under Deformation",
    tags::barotrope &tags::closure &tags::hydro &tags::integration
        &tags::jacobian &tags::mapping &tags::physics
) {
    auto args = test_utils::setup_args();

    mean_field::fem::FEM f =
        mean_field::fem::setup_fem(args.mesh_file, args, 0);

    REQUIRE(f.domainMapperStateless != nullptr);

    const mean_field::physics::PolytropicBarotrope barotrope(3.0, 1.5);

    constexpr double enthalpyValue = 1.20;

    const double equilibriumDensityValue =
        barotrope.density_from_enthalpy(enthalpyValue);

    const mfem::Vector enthalpy =
        make_constant_field(*f.enthalpyFes, enthalpyValue);

    const mfem::Vector equilibriumDensity =
        make_constant_field(*f.densityFes, equilibriumDensityValue);

    const mfem::Vector referenceDensity =
        make_constant_field(*f.densityFes, equilibriumDensityValue + 1.0);

    const mfem::Vector displacementVariation =
        gravity_prepared_test_utils::make_displacement(f, 0.67);

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

    for (const double deformationScale : {0.0, 0.5, 1.0}) {
        DYNAMIC_SECTION("Deformation scale = " << deformationScale) {
            const mfem::Vector displacement =
                gravity_prepared_test_utils::make_displacement(
                    f, deformationScale
                );

            mfem::Vector exactResidual;
            mfem::Vector referenceResidual;

            mean_field::operators::kernels::apply_barotropic_closure(
                f, *f.domainMapperStateless, barotrope, equilibriumDensity,
                enthalpy, displacement, exactResidual
            );

            mean_field::operators::kernels::apply_barotropic_closure(
                f, *f.domainMapperStateless, barotrope, referenceDensity,
                enthalpy, displacement, referenceResidual
            );

            mfem::Vector exactGeometryAction;
            mfem::Vector referenceGeometryAction;

            mean_field::operators::kernels::
                apply_barotropic_closure_displacement_action(
                    f, *f.domainMapperStateless, barotrope, equilibriumDensity,
                    enthalpy, displacement, displacementVariation,
                    exactGeometryAction
                );

            mean_field::operators::kernels::
                apply_barotropic_closure_displacement_action(
                    f, *f.domainMapperStateless, barotrope, referenceDensity,
                    enthalpy, displacement, displacementVariation,
                    referenceGeometryAction
                );

            const double exactResidualNorm =
                gravity_prepared_test_utils::global_norm(
                    exactResidual, communicator
                );

            const double referenceResidualNorm =
                gravity_prepared_test_utils::global_norm(
                    referenceResidual, communicator
                );

            const double exactGeometryNorm =
                gravity_prepared_test_utils::global_norm(
                    exactGeometryAction, communicator
                );

            const double referenceGeometryNorm =
                gravity_prepared_test_utils::global_norm(
                    referenceGeometryAction, communicator
                );

            INFO("Deformation scale = " << deformationScale);

            INFO("Exact-closure residual norm = " << exactResidualNorm);

            INFO("Reference residual norm = " << referenceResidualNorm);

            INFO("Exact-closure geometry-action norm = " << exactGeometryNorm);

            INFO("Reference geometry-action norm = " << referenceGeometryNorm);

            REQUIRE(referenceResidualNorm > 1.0e-12);
            REQUIRE(referenceGeometryNorm > 1.0e-14);

            CHECK(exactResidualNorm <= 5.0e-12 * referenceResidualNorm);

            CHECK(exactGeometryNorm <= 5.0e-12 * referenceGeometryNorm);
        }
    }
}