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//        MueLu: A package for multigrid based preconditioning
//                  Copyright 2012 Sandia Corporation
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// @HEADER
#ifndef MUELU_DIRECTSOLVER_DECL_HPP
#define MUELU_DIRECTSOLVER_DECL_HPP

#include <Teuchos_ParameterList.hpp>

#include <Xpetra_Matrix_fwd.hpp>

#include "MueLu_ConfigDefs.hpp"
#include "MueLu_DirectSolver_fwd.hpp"

#include "MueLu_SmootherPrototype.hpp"

#include "MueLu_FactoryBase_fwd.hpp"
#include "MueLu_Amesos2Smoother_fwd.hpp"
#include "MueLu_AmesosSmoother_fwd.hpp"

// Note: DirectSolver is a SmootherPrototype that cannot be turned into a smoother using Setup().
//       When this prototype is cloned using Copy(), the clone is an Amesos or an Amesos2 smoother.
//       The clone can be used as a smoother after calling Setup().

namespace MueLu {

  /*!
    @class DirectSolver
    @ingroup MueLuSmootherClasses 
    @brief Class that encapsulates direct solvers. Autoselection of AmesosSmoother or Amesos2Smoother according to the compile time configuration of Trilinos
  */

  template <class Scalar = SmootherPrototype<>::scalar_type,
            class LocalOrdinal = typename SmootherPrototype<Scalar>::local_ordinal_type,
            class GlobalOrdinal = typename SmootherPrototype<Scalar, LocalOrdinal>::global_ordinal_type,
            class Node = typename SmootherPrototype<Scalar, LocalOrdinal, GlobalOrdinal>::node_type>
  class DirectSolver : public SmootherPrototype<Scalar,LocalOrdinal,GlobalOrdinal,Node> {
#undef MUELU_DIRECTSOLVER_SHORT
#include "MueLu_UseShortNames.hpp"

  public:

    //! @name Constructors / destructors
    //@{

    //! @brief Constructor
    //! Note: only parameters shared by Amesos and Amesos2 should be used for type and paramList (example: type= "Klu", "Superlu", paramList = <empty>) .
    DirectSolver(const std::string& type = "", const Teuchos::ParameterList& paramList = Teuchos::ParameterList());

    //! Destructor
    virtual ~DirectSolver() { }

    //@}

    //! Input
    //@{

    void DeclareInput(Level& currentLevel) const;

    //@}

    //! @name Setup and Apply methods.
    //@{

    //! DirectSolver cannot be turned into a smoother using Setup(). Setup() always returns a RuntimeError exception.
    void Setup(Level& currentLevel);

    //! DirectSolver cannot be applied. Apply() always returns a RuntimeError exception.
    void Apply(MultiVector& X, const MultiVector& B, bool InitialGuessIsZero = false) const;

    //@}

    //! Custom SetFactory
    void SetFactory(const std::string& varName, const RCP<const FactoryBase>& factory);

    //! When this prototype is cloned using Copy(), the clone is an Amesos or an Amesos2 smoother.
    RCP<SmootherPrototype> Copy() const;

    //! @name Overridden from Teuchos::Describable
    //@{

    //! Return a simple one-line description of this object.
    std::string description() const;

    void print(Teuchos::FancyOStream& out, const VerbLevel verbLevel = Default) const;

    //@}

  private:

    //
    // Parameters
    //

    //! amesos1/2-specific key phrase that denote smoother type
    std::string type_;

    //
    // Underlying Smoother
    //

    //! Smoother
    RCP<SmootherPrototype> sEpetra_, sTpetra_;
    mutable
      RCP<SmootherPrototype> s_;

    // Records for the case if something goes wrong
    bool triedEpetra_, triedTpetra_;
    std::string errorEpetra_, errorTpetra_;

  }; // class DirectSolver

} // namespace MueLu

#define MUELU_DIRECTSOLVER_SHORT
#endif // MUELU_DIRECTSOLVER_DECL_HPP
