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#ifndef LOCA_MULTICONTINUATION_ABSTRACTGROUP_H
#define LOCA_MULTICONTINUATION_ABSTRACTGROUP_H

#include "NOX_Abstract_Group.H" // base class
#include "NOX_Abstract_MultiVector.H"
#include "LOCA_Abstract_Iterator.H"
#include <vector>
#include <string>

namespace LOCA {
  class ParameterVector;
}

namespace LOCA {

  //! Groups and vectors for multi-parameter continuation
  namespace MultiContinuation {

    /*!
     * \brief %LOCA abstract interface for continuation, derived from the
     * NOX::Abstract::Group.  This abstract class provides
     * the interface necessary to perform continuation, i.e., compute
     * families of solutions to \f$ F(x,p) = 0 \f$.
    */
    /*!
     * Concrete implemenations of this interface must provide implementations
     * of all of the methods in the NOX::Abstract::Group interface as well as
     * the additional interface defined here.
    */

    class AbstractGroup : public virtual NOX::Abstract::Group {

    public:

      //! Default constructor.
      AbstractGroup() {}

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

      /*!
       * @name Pure virtual methods
       * These methods must be defined by any concrete implementation
       */
      //@{

      //! Copy the group (replaces operator = )
      virtual void copy(const NOX::Abstract::Group& source) = 0;

      //! Set parameters indexed by (integer) paramIDs
      virtual void setParamsMulti(const std::vector<int>& paramIDs,
                  const NOX::Abstract::MultiVector::DenseMatrix& vals) = 0;

      //! Set the parameter vector in the group to p (pVector = p).
      virtual void setParams(const LOCA::ParameterVector& p) = 0;

       //! Set parameter indexed by (integer) paramID
      virtual void setParam(int paramID, double val) = 0;

      //! Set parameter indexed by (std::string) paramID
      virtual void setParam(std::string paramID, double val) = 0;

      //! Return a const reference to the ParameterVector owned by the group.
      virtual const LOCA::ParameterVector& getParams() const = 0;

      //! Return copy of parameter indexed by (integer) paramID
      virtual double getParam(int paramID) const = 0;

      //! Return copy of parameter indexed by (std::string) paramID
      virtual double getParam(std::string paramID) const = 0;

      /*!
       * Compute \f$\partial F/\partial p\f$ for each parameter \f$ p\f$
       * indexed by paramIDs.  The first column of \em dfdp holds F,
       * which is valid if \em isValidF is true.  Otherwise F must be
       * computed.
       */
      virtual NOX::Abstract::Group::ReturnType
      computeDfDpMulti(const std::vector<int>& paramIDs,
               NOX::Abstract::MultiVector& dfdp,
               bool isValidF) = 0;

      //@}


      /*!
       * @name Virtual methods with default implementations
       * These methods should be overloaded in a concrete implementation
       * if more appropriate/efficient approaches are available.
       */
      //@{

      //! Perform any preprocessing before a continuation step starts.
      /*!
       * The \c stepStatus argument indicates whether the previous step was
       * successful.  The default implementation to empty.
       */
      virtual void
      preProcessContinuationStep(
                 LOCA::Abstract::Iterator::StepStatus stepStatus);

      //! Perform any postprocessing after a continuation step finishes.
      /*!
       * The \c stepStatus argument indicates whether the step was
       * successful.  The default implementation to empty.
       */
      virtual void
      postProcessContinuationStep(
                 LOCA::Abstract::Iterator::StepStatus stepStatus);

      //! Projects solution to a few scalars for multiparameter continuation
      /*!
       * This method is called every time a solution is saved by the
       * multiparameter continuation code MF for later visualization
       * and should project the solution vector down to a few scalars.
       * The array \c px will be preallocated to the proper length
       * given by projectToDrawDimension().
       *
       * The default implementation is the max norm of the vector.
       */
      virtual void projectToDraw(const NOX::Abstract::Vector& x,
                 double *px) const;

      //! Returns the dimension of the project to draw array
      /*!
       * The default implementation is to return 1 since the default
       * projection is the max norm of the vector (a scalar).
       */
      virtual int projectToDrawDimension() const;

      //! Compute a scaled dot product
      /*!
       * The default implementation here just computes a.dot(b) but should
       * be overloaded for any problem that his difficult scaling.
       */
      virtual double
      computeScaledDotProduct(const NOX::Abstract::Vector& a,
                  const NOX::Abstract::Vector& b) const;

      //@}

      /*!
       * @name Virtual methods with empty or trivial implementations
       * These methods should be overloaded in a concrete implementation
       * but their implementation is not critical to the rest of %LOCA and
       * therefore have empty or trivial implementations.
       */
      //@{

      //! Function to print out solution and parameter after successful step
      /*!
       * Empty default definition.
       */
      virtual void printSolution(const double /* conParam */) const {};

      //! Function to print out a vector and parameter after successful step
      /*!
       * Empty default definition.
       */
      virtual void printSolution(const NOX::Abstract::Vector& /* x_ */,
                                 const double /* conParam */) const  {}

      //! Scales a vector using scaling vector
      /*!
       * The default definition here is to do nothing, i.e., no scaling
       */
      virtual void
      scaleVector(NOX::Abstract::Vector& x) const;

      //@}

      //! Bring NOX::Abstract::Group::operator=() into scope
      using NOX::Abstract::Group::operator=;

    };
  } // namespace MultiContinuation
} // namespace LOCA

#endif
