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

#include "MueLu_ConfigDefs.hpp"

#include <Xpetra_Import_fwd.hpp>
#include <Xpetra_ImportFactory_fwd.hpp>
#include <Xpetra_Map_fwd.hpp>
#include <Xpetra_MapFactory_fwd.hpp>
#include <Xpetra_Matrix_fwd.hpp>
#include <Xpetra_MultiVector_fwd.hpp>
#include <Xpetra_MultiVectorFactory_fwd.hpp>

#include "MueLu_SingleLevelFactoryBase.hpp"
#include "MueLu_BrickAggregationFactory_fwd.hpp"

#include "MueLu_Level_fwd.hpp"
#include "MueLu_Aggregates_fwd.hpp"
#include "MueLu_Exceptions.hpp"
#include "MueLu_Utilities_fwd.hpp"

/*!
  @class BrickAggregationFactory
  @brief Aggregation method for generating "brick" aggregates.
  
  This factory can generate:
    - In 2D, 2x2 and 3x3 aggregates
    - In 3D, 2x2x2 or 3x3x3 aggregates
*/

namespace MueLu {

  template <class Scalar = double,
            class LocalOrdinal = int,
            class GlobalOrdinal = LocalOrdinal,
            class Node = KokkosClassic::DefaultNode::DefaultNodeType>
  class BrickAggregationFactory : public SingleLevelFactoryBase {
#undef MUELU_BRICKAGGREGATIONFACTORY_SHORT
#include "MueLu_UseShortNames.hpp"
  private:
    typedef Teuchos::ScalarTraits<Scalar>                                  STS;

    // Comparator for doubles
    // Generally, the coordinates for coarser levels would come out of averaging of fine level coordinates
    // It is possible that the result of the averaging differs slightly between clusters, as we might have
    // 3x2 and 2x2 cluster which would result in averaging 6 and 4 y-coordinates respectively, leading to
    // slightly different results.
    // Therefore, we hardcode a constant so that close points are considered the same.
    class compare {
    public:
      bool operator()(const Scalar& x, const Scalar& y) const {
        if (STS::magnitude(x - y) < 1e-14)
          return false;
        return STS::real(x) < STS::real(y);
      }
    };
    typedef std::map<Scalar,GlobalOrdinal,compare> container;

  public:
    //! @name Constructors/Destructors.
    //@{

    //! Constructor.
    BrickAggregationFactory() : nDim_(-1), nx_(-1), ny_(-1), nz_(-1), bx_(-1), by_(-1), bz_(-1) { };

    //! Destructor.
    virtual ~BrickAggregationFactory() { }

    RCP<const ParameterList> GetValidParameterList() const;

    //@}

    // Options shared by all aggregation algorithms

    //! Input
    //@{

    void DeclareInput(Level &currentLevel) const;

    //@}

    //! @name Build methods.
    //@{

    /*! @brief Build aggregates. */
    void Build(Level &currentLevel) const;

    //@}

  private:
    void Setup(const RCP<const Teuchos::Comm<int> >& comm, const RCP<Xpetra::MultiVector<double,LO,GO,NO> >& coords, const RCP<const Map>& map) const;
    RCP<container> Construct1DMap(const RCP<const Teuchos::Comm<int> >& comm, const ArrayRCP<const double>& x) const;

    bool           isRoot  (LocalOrdinal LID) const;
    GlobalOrdinal getRoot  (LocalOrdinal LID) const;
    GlobalOrdinal getAggGID(LocalOrdinal LID) const;

    mutable
     int nDim_;
    mutable
     RCP<container> xMap_, yMap_, zMap_;
    mutable
     ArrayRCP<const double> x_, y_, z_;
    mutable
     int nx_, ny_, nz_;
    mutable
     int bx_, by_, bz_;
    mutable
     std::map<GlobalOrdinal,GlobalOrdinal> revMap_;
  }; // class BrickAggregationFactory

}

#define MUELU_BRICKAGGREGATIONFACTORY_SHORT
#endif /* MUELU_BRICKAGGREGATIONFACTORY_DECL_HPP_ */
