/***************************************************************************
 *  GModelSpatialEllipticalGauss.hpp - Elliptical gauss source model class *
 * ----------------------------------------------------------------------- *
 *  copyright (C) 2015-2016 by Michael Mayer                               *
 * ----------------------------------------------------------------------- *
 *                                                                         *
 *  This program is free software: you can redistribute it and/or modify   *
 *  it under the terms of the GNU General Public License as published by   *
 *  the Free Software Foundation, either version 3 of the License, or      *
 *  (at your option) any later version.                                    *
 *                                                                         *
 *  This program 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 General Public License for more details.                           *
 *                                                                         *
 *  You should have received a copy of the GNU General Public License      *
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.  *
 *                                                                         *
 ***************************************************************************/
/**
 * @file GModelSpatialEllipticalGauss.hpp
 * @brief Elliptical gauss model class interface definition
 * @author Michael Mayer
 */

#ifndef GMODELSPATIALELLIPTICALGAUSS_HPP
#define GMODELSPATIALELLIPTICALGAUSS_HPP

/* __ Includes ___________________________________________________________ */
#include <string>
#include "GModelSpatialElliptical.hpp"
#include "GModelPar.hpp"
#include "GSkyDir.hpp"
#include "GXmlElement.hpp"


/**************************************************************************
 * @class GModelSpatialEllipticalGauss
 *
 * @brief Elliptical gauss source model class
 *
 * This class implements the spatial component of the factorised source
 * model for an elliptical gauss source, i.e. constant surface brightness
 * according to an asymmetric Gaussian.
 ***************************************************************************/
class GModelSpatialEllipticalGauss : public GModelSpatialElliptical {

public:
    // Constructors and destructors
    GModelSpatialEllipticalGauss(void);
    GModelSpatialEllipticalGauss(const bool& dummy, const std::string& type);
    GModelSpatialEllipticalGauss(const GSkyDir& dir,
                                 const double&  major,
                                 const double&  minor,
                                 const double&  posangle);
    explicit GModelSpatialEllipticalGauss(const GXmlElement& xml);
    GModelSpatialEllipticalGauss(const GModelSpatialEllipticalGauss& model);
    virtual ~GModelSpatialEllipticalGauss(void);

    // Operators
    virtual GModelSpatialEllipticalGauss& operator=(const GModelSpatialEllipticalGauss& model);

    // Implemented pure virtual base class methods
    virtual void                          clear(void);
    virtual GModelSpatialEllipticalGauss* clone(void) const;
    virtual std::string                   classname(void) const;
    virtual std::string                   type(void) const;
    virtual double                        eval(const double&  theta,
                                               const double&  posangle,
                                               const GEnergy& energy,
                                               const GTime&   time,
                                               const bool&    gradients = false) const;
    virtual GSkyDir                       mc(const GEnergy& energy,
                                             const GTime& time,
                                             GRan& ran) const;
    virtual bool                          contains(const GSkyDir& dir,
                                                   const double&  margin = 0.0) const;
    virtual double                        theta_max(void) const;
    virtual void                          read(const GXmlElement& xml);
    virtual void                          write(GXmlElement& xml) const;
    virtual std::string                   print(const GChatter& chatter = NORMAL) const;


protected:
    // Protected methods
    void init_members(void);
    void copy_members(const GModelSpatialEllipticalGauss& model);
    void free_members(void);
    void update(void) const;

    // Protected members
    std::string m_type;   //!< Model type

    // Cached members used for pre-computations
    mutable double m_last_minor;        //!< Last semi-minor axis
    mutable double m_last_major;        //!< Last semi-major axis
    mutable double m_last_posangle;     //!< Last position angle
    mutable double m_cospos2;           //!< squared cosine of position angle
    mutable double m_sinpos2;           //!< squared sine of position angle
    mutable double m_sin2pos;           //!< sine of twice the position angle
    mutable double m_minor2;            //!< square of minor axis
    mutable double m_major2;            //!< square of major axis
    mutable double m_minor_rad;         //!< Minor axis in radians
    mutable double m_major_rad;         //!< Major axis in radians
    mutable double m_norm;              //!< Normalization
    mutable double m_term1;             //!< Help term 1
    mutable double m_term2;             //!< Help term 2
    mutable double m_term3;             //!< Help term 3

};


/***********************************************************************//**
 * @brief Return class name
 *
 * @return String containing the class name ("GModelSpatialEllipticalGauss").
 ***************************************************************************/
inline
std::string GModelSpatialEllipticalGauss::classname(void) const
{
    return ("GModelSpatialEllipticalGauss");
}


/***********************************************************************//**
 * @brief Return model type
 *
 * @return Model type.
 *
 * Returns the type of the elliptical gauss model.
 ***************************************************************************/
inline
std::string GModelSpatialEllipticalGauss::type(void) const
{
    return (m_type);
}

#endif /* GMODELSPATIALELLIPTICALGAUSS_HPP */