module;
#include <mfem.hpp>
export module mean_field:integrators.viscosity;
import :mapping.domain_mapper;

export namespace mean_field::integrators {
    class ViscosityIntegrator : public mfem::BlockNonlinearFormIntegrator {
    public:
        ViscosityIntegrator(
            const mapping::DomainMapper &mapper,
            const mfem::GridFunction &displacement,
            const mfem::GridFunction &compactification_coordinate,
            double mu,
            int quad_boost
        );

        void SetMu(const double mu);

        void AssembleElementVector(
            const mfem::Array<const mfem::FiniteElement *> &el,
            mfem::ElementTransformation &Tr,
            const mfem::Array<const mfem::Vector *> &elfun,
            const mfem::Array<mfem::Vector *> &elvec
        ) override;

        void AssembleElementGrad(
            const mfem::Array<const mfem::FiniteElement *> &el,
            mfem::ElementTransformation &Tr,
            const mfem::Array<const mfem::Vector *> &elfun,
            const mfem::Array2D<mfem::DenseMatrix *> &elmats
        ) override;

    private:
        mapping::GridFunctionMappingEvaluator m_mapping;
        double m_mu;
        int m_quad_boost;
    };

} // namespace mean_field::integrators