//                                               -*- C++ -*-
/**
 *
 *  Copyright 2005-2024 Airbus-EDF-IMACS-ONERA-Phimeca
 *
 *  This library is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Lesser General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with this library.  If not, see <http://www.gnu.org/licenses/>.
 *
 */
#ifndef OPENTURNS_DIRACCOVARIANCEMODEL_HXX
#define OPENTURNS_DIRACCOVARIANCEMODEL_HXX

#include "openturns/CovarianceModelImplementation.hxx"

BEGIN_NAMESPACE_OPENTURNS

/**
 * @class DiracCovarianceModel
 */

class OT_API DiracCovarianceModel
  : public CovarianceModelImplementation
{

  CLASSNAME

public:


  /** Default constructor */
  explicit DiracCovarianceModel(const UnsignedInteger inputDimension = 1);

  /** Parameters constructor */
  DiracCovarianceModel(const UnsignedInteger inputDimension,
                       const Point & amplitude);

  /** Parameters constructor */
  DiracCovarianceModel(const UnsignedInteger inputDimension,
                       const Point & amplitude,
                       const CorrelationMatrix & correlation);

  /** Parameters constructor */
  DiracCovarianceModel(const UnsignedInteger inputDimension,
                       const CovarianceMatrix & covariance);

  /** Virtual copy constructor */
  DiracCovarianceModel * clone() const override;

  /** Computation of the covariance function */
  using CovarianceModelImplementation::operator();
  SquareMatrix operator() (const Point & tau) const override;

  /** Computation of the covariance function */
  using CovarianceModelImplementation::computeAsScalar;
  Scalar computeAsScalar(const Point &tau) const override;
#ifndef SWIG
  Scalar computeAsScalar(const Collection<Scalar>::const_iterator &s_begin,
                         const Collection<Scalar>::const_iterator &t_begin) const override;
#endif
  Scalar computeAsScalar(const Scalar tau) const override;

  /** Discretize the covariance function */
  using CovarianceModelImplementation::discretize;
  CovarianceMatrix discretize(const Sample & vertices) const override;
  Sample discretizeRow(const Sample & vertices, const UnsignedInteger p) const override;

  using CovarianceModelImplementation::discretizeAndFactorize;
  TriangularMatrix discretizeAndFactorize(const Sample & vertices) const override;
  // discretize with use of HMatrix
  using CovarianceModelImplementation::discretizeHMatrix;
  HMatrix discretizeHMatrix(const Sample & vertices,
                            const HMatrixParameters & parameters) const override;
  HMatrix discretizeHMatrix(const Sample & vertices,
                            const Scalar nuggetFactor,
                            const HMatrixParameters & parameters) const;

  /** Gradient */
  Matrix partialGradient(const Point & s, const Point & t) const override;

  /** Scale/amplitude set accessors */
  void setScale(const Point & scale) override;
  void setAmplitude(const Point & amplitude) override;
  void setOutputCorrelation(const CorrelationMatrix & outputCorrelation) override;

  /** String converter */
  String __repr__() const override;

  /** String converter */
  String __str__(const String & offset = "") const override;

  /** Method save() stores the object through the StorageManager */
  void save(Advocate & adv) const override;

  /** Method load() reloads the object from the StorageManager */
  void load(Advocate & adv) override;

protected:
  /** Parameter accessor */
  void setFullParameter(const Point & parameter) override;
  Point getFullParameter() const override;
  Description getFullParameterDescription() const override;


  friend struct DiracCovarianceModelDiscretizePolicy;
  friend struct DiracCovarianceModelDiscretizeAndFactorizePolicy;
  mutable TriangularMatrix covarianceFactor_;
  void computeCovariance();

} ; /* class DiracCovarianceModel */

END_NAMESPACE_OPENTURNS

#endif
