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//       Ifpack: Object-Oriented Algebraic Preconditioner Package
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#ifndef IFPACK_OVERLAPGRAPH_H
#define IFPACK_OVERLAPGRAPH_H

#include "Ifpack_ConfigDefs.h"
#include "Epetra_Object.h"
#include "Epetra_CrsGraph.h"
#include "Epetra_Import.h"
#include "Teuchos_RefCountPtr.hpp"

class Epetra_Comm;
class Epetra_BlockMap;
class Epetra_RowMatrix;

namespace Teuchos {
  class ParameterList;
}

//! Ifpack_OverlapGraph: Constructs a graph for use with Ifpack preconditioners.

class Ifpack_OverlapGraph: public Epetra_Object {

 public:
  //@{ \name Constructors/Destructor
  //! Constructor using Epetra_CrsGraph.
  /*! Creates an Ifpack_OverlapGraph object from the user graph. 
    \param In
           UserMatrixGraph_in - Graph from user matrix.
  */
  Ifpack_OverlapGraph(const Teuchos::RefCountPtr<const Epetra_CrsGraph>& UserMatrixGraph_in, int OverlapLevel_in);

  //! Constructor using Epetra_RowMatrix.
  /*! Creates an Ifpack_OverlapGraph object from the user graph implicitly defined by the
	 Epetra_RowMatrix interface. 
    \param In
            RowMatrix - An object that has implemented the Epetra_RowMatrix interface.
  */
  Ifpack_OverlapGraph(const Teuchos::RefCountPtr<const Epetra_RowMatrix>& UserMatrix_in, int OverlapLevel_in);
  
  //! Copy constructor.
  Ifpack_OverlapGraph(const Ifpack_OverlapGraph & Source);

  //! Ifpack_CrsIlut Destructor
  virtual ~Ifpack_OverlapGraph() {};
  //@}

  //@{ \name Attribute access methods.
    
  //! Set parameters using a Teuchos::ParameterList object.
  /* This method is only available if the configure argument
     '--enable-ifpack-teuchos' was used.
     This method recognizes the name: level_overlap, which is case insensitive.
     The ParameterEntry must have type int.
  */
  int SetParameters(const Teuchos::ParameterList& parameterlist,
                    bool cerr_warning_if_unused=false);

  //! Returns the overlap graph object.
  const Epetra_CrsGraph & OverlapGraph() const {return(*OverlapGraph_);}
    
  //! Returns the RowMap associated with the overlap graph.
  const Epetra_BlockMap & OverlapRowMap() const {return(*OverlapRowMap_);}
    
  //! Returns the overlap graph object.
  const Epetra_Import & OverlapImporter() const {return(*OverlapImporter_);}
    
  //! Returns the level of overlap used to create this graph.
  /*! The graph created by this class uses a recursive definition 0f overlap.
      Level one overlap is created by copying all off-processor rows that are
      reached to be at least one column of the rows that are on processor.
      Level two overlap is the same process used on the level one graph.
  */
  int OverlapLevel() const {return(OverlapLevel_);}
  //@}

  //@{ \name Epetra_Object print method (allows use of << operator with this class).

  void Print(ostream& os) const {
    os << endl;
    if (UserMatrix_!=Teuchos::null) 
      os << "Overlap Graph created using the user's Epetra_RowMatrix object" << endl;
    else
      os << "Overlap Graph created using the user's Epetra_CrsGraph object" << endl;
    
    os << " Level of Overlap = " << OverlapLevel_ << endl;
    OverlapGraph_->Print(os);
    return;
  }
  //@}

 protected:

  int ConstructOverlapGraph(const Teuchos::RefCountPtr<const Epetra_CrsGraph>& UserMatrixGraph);
  Teuchos::RefCountPtr<Epetra_CrsGraph> OverlapGraph_;
  Teuchos::RefCountPtr<const Epetra_CrsGraph> UserMatrixGraph_;
  Teuchos::RefCountPtr<const Epetra_RowMatrix> UserMatrix_;
  Teuchos::RefCountPtr<Epetra_BlockMap> OverlapRowMap_;
  Teuchos::RefCountPtr<Epetra_Import> OverlapImporter_;
  int OverlapLevel_;
  bool IsOverlapped_;
};
#endif // IFPACK_OVERLAPGRAPH_H
