#ifndef POLY_UTILS_OPERATOR_H
#define POLY_UTILS_OPERATOR_H

#include "mfem.hpp"
#include "4DSTARTypes.h"
#include <memory>

#include "probe.h"

class PolytropeOperator : public mfem::Operator {
public:
    PolytropeOperator(
        std::unique_ptr<mfem::MixedBilinearForm> M,
        std::unique_ptr<mfem::MixedBilinearForm> Q,
        std::unique_ptr<mfem::BilinearForm> D,
        std::unique_ptr<mfem::NonlinearForm> f,
        const mfem::Array<int> &blockOffsets);
    ~PolytropeOperator() override = default;

    void Mult(const mfem::Vector &x, mfem::Vector &y) const override;


    mfem::Operator& GetGradient(const mfem::Vector &x) const override;

    void SetEssentialTrueDofs(const SSE::MFEMArrayPair& theta_ess_tdofs, const SSE::MFEMArrayPair& phi_ess_tdofs);
    void SetEssentialTrueDofs(const SSE::MFEMArrayPairSet& ess_tdof_pair_set);

    SSE::MFEMArrayPairSet GetEssentialTrueDofs() const;

    bool isFinalized() const { return m_isFinalized; }

    void finalize();

    const mfem::Array<int>& GetBlockOffsets() const { return m_blockOffsets; }

    const mfem::BlockOperator &GetJacobianOperator() const;

    mfem::BlockDiagonalPreconditioner &GetPreconditioner() const;


private:
    Probe::LogManager& m_logManager = Probe::LogManager::getInstance();
    quill::Logger* m_logger = m_logManager.getLogger("log");
    std::unique_ptr<mfem::MixedBilinearForm> m_M;
    std::unique_ptr<mfem::MixedBilinearForm> m_Q;
    std::unique_ptr<mfem::BilinearForm> m_D;
    std::unique_ptr<mfem::NonlinearForm> m_f;

    const mfem::Array<int> m_blockOffsets;

    SSE::MFEMArrayPair m_theta_ess_tdofs;
    SSE::MFEMArrayPair m_phi_ess_tdofs;

    std::unique_ptr<mfem::SparseMatrix> m_Mmat;
    std::unique_ptr<mfem::SparseMatrix> m_Qmat;
    std::unique_ptr<mfem::SparseMatrix> m_Dmat;

    std::unique_ptr<mfem::ScaledOperator> m_negM_op;
    std::unique_ptr<mfem::ScaledOperator> m_negQ_op;
    mutable std::unique_ptr<mfem::BlockOperator> m_jacobian;

    // TODO I think these need to be calculated in the GetGradient every time since they will always change
    mutable std::unique_ptr<mfem::SparseMatrix> m_invSchurCompliment;
    mutable std::unique_ptr<mfem::SparseMatrix> m_invNonlinearJacobian;

    /*
     * The schur preconditioner has the form
     *
     *  ⎡ḟ(θ)^-1  0 ⎤
     *  ⎣ 0     S^-1 ⎦
     *
     * Where S is the Schur compliment of the system
     *
     */

    mutable std::unique_ptr<mfem::BlockDiagonalPreconditioner> m_schurPreconditioner;

    bool m_isFinalized = false;

private:
    void updateInverseNonlinearJacobian(const mfem::Operator &grad) const;
    void updateInverseSchurCompliment() const;
};


#endif // POLY_UTILS_OPERATOR_H