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#ifndef ROCALUTION_PRECONDITIONER_BLOCKPRECOND_HPP_
#define ROCALUTION_PRECONDITIONER_BLOCKPRECOND_HPP_

#include "../../base/local_vector.hpp"
#include "../solver.hpp"
#include "export.hpp"
#include "preconditioner.hpp"

#include <vector>

namespace rocalution
{

    /** \ingroup precond_module
  * \class BlockPreconditioner
  * \brief Block-Preconditioner
  * \details
  * When handling vector fields, typically one can try to use different preconditioners
  * and/or solvers for the different blocks. For such problems, the library provides a
  * block-type preconditioner. This preconditioner builds the following block-type matrix
  * \f[
  *   P = \begin{pmatrix}
  *         A_{d} & 0     & . & 0     \\
  *         B_{1} & B_{d} & . & 0     \\
  *         .     & .     & . & .     \\
  *         Z_{1} & Z_{2} & . & Z_{d}
  *       \end{pmatrix}
  * \f]
  * The solution of \f$P\f$ can be performed in two ways. It can be solved by
  * block-lower-triangular sweeps with inversion of the blocks \f$A_{d} \ldots Z_{d}\f$
  * and with a multiplication of the corresponding blocks. This is set by SetLSolver()
  * (which is the default solution scheme). Alternatively, it can be used only with an
  * inverse of the diagonal \f$A_{d} \ldots Z_{d}\f$ (Block-Jacobi type) by using
  * SetDiagonalSolver().
  *
  * \tparam OperatorType - can be LocalMatrix
  * \tparam VectorType - can be LocalVector
  * \tparam ValueType - can be float, double, std::complex<float> or std::complex<double>
  */
    template <class OperatorType, class VectorType, typename ValueType>
    class BlockPreconditioner : public Preconditioner<OperatorType, VectorType, ValueType>
    {
    public:
        ROCALUTION_EXPORT
        BlockPreconditioner();
        ROCALUTION_EXPORT
        virtual ~BlockPreconditioner();

        ROCALUTION_EXPORT
        virtual void Print(void) const;
        ROCALUTION_EXPORT
        virtual void Clear(void);

        /** \brief Set number, size and diagonal solver */
        ROCALUTION_EXPORT
        void Set(int n, const int* size, Solver<OperatorType, VectorType, ValueType>** D_solver);

        /** \brief Set diagonal solver mode */
        ROCALUTION_EXPORT
        void SetDiagonalSolver(void);
        /** \brief Set lower triangular sweep mode */
        ROCALUTION_EXPORT
        void SetLSolver(void);

        /** \brief Set external last block matrix */
        ROCALUTION_EXPORT
        void SetExternalLastMatrix(const OperatorType& mat);

        /** \brief Set permutation vector */
        ROCALUTION_EXPORT
        virtual void SetPermutation(const LocalVector<int>& perm);

        ROCALUTION_EXPORT
        virtual void Build(void);

        ROCALUTION_EXPORT
        virtual void Solve(const VectorType& rhs, VectorType* x);

    protected:
        /** \brief The operator decomposition */
        OperatorType*** A_block_;
        /** \brief The operator of the last block */
        OperatorType* A_last_;

        /** \brief The precond matrix in CSR or not */
        bool op_mat_format_;
        /** \brief The precond matrix format */
        unsigned int precond_mat_format_;

        /** \brief Solution vector of each block */
        VectorType** x_block_;
        /** \brief Temporary vector objects */
        VectorType** tmp_block_;
        /** \brief Solution vector */
        VectorType x_;

        /** \brief Number of blocks */
        int num_blocks_;
        /** \brief Block sizes */
        int* block_sizes_;

        /** \brief Diagonal solvers */
        Solver<OperatorType, VectorType, ValueType>** D_solver_;

        /** \brief Flag if diagonal solves enabled */
        bool diag_solve_;

        virtual void MoveToHostLocalData_(void);
        virtual void MoveToAcceleratorLocalData_(void);
    };

} // namespace rocalution

#endif // ROCALUTION_PRECONDITIONER_BLOCKPRECOND_HPP_