/***************************************************************************
 *  GModelSpectralMultiplicative.hpp - Multiplicative spectral model class *
 * ----------------------------------------------------------------------- *
 *  copyright (C) 2016-2017 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 GModelSpectralMultiplicative.hpp
 * @brief Multiplicative spectral model class interface definition
 * @author Michael Mayer
 */

#ifndef GMODELSPECTRALMULTIPLICATIVE_HPP
#define GMODELSPECTRALMULTIPLICATIVE_HPP

/* __ Includes ___________________________________________________________ */
#include <string>
#include <vector>
#include "GModelSpectral.hpp"
#include "GEnergy.hpp"
#include "GModelSpectralNodes.hpp"
#include "GFunction.hpp"

/* __ Forward declarations _______________________________________________ */
class GRan;
class GTime;
class GXmlElement;


/***********************************************************************//**
 * @class GModelSpectralMultiplicative
 *
 * @brief Multiplicative spectral model class
 *
 * This class implements a spectral model that is a multiplication spectral
 * model components. The spectral model components can be defined in an
 * XML file, or added using the append() method.
 ***************************************************************************/
class GModelSpectralMultiplicative : public GModelSpectral {

public:
    // Constructors and destructors
    GModelSpectralMultiplicative(void);
    explicit GModelSpectralMultiplicative(const GXmlElement& xml);
    GModelSpectralMultiplicative(const GModelSpectralMultiplicative& model);
    virtual ~GModelSpectralMultiplicative(void);

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

    // Implemented pure virtual methods
    virtual void                          clear(void);
    virtual GModelSpectralMultiplicative* clone(void) const;
    virtual std::string                   classname(void) const;
    virtual std::string                   type(void) const;
    virtual double                        eval(const GEnergy& srcEng,
                                               const GTime&   srcTime = GTime(),
                                               const bool&    gradients = false) const;
    virtual double                        flux(const GEnergy& emin,
                                               const GEnergy& emax) const;
    virtual double                        eflux(const GEnergy& emin,
                                                const GEnergy& emax) const;
    virtual GEnergy                       mc(const GEnergy& emin,
                                             const GEnergy& emax,
                                             const GTime&   time,
                                             GRan&          ran) const;
    virtual void                          read(const GXmlElement& xml);
    virtual void                          write(GXmlElement& xml) const;
    virtual std::string                   print(const GChatter& chatter = NORMAL) const;

    // Other methods
    void                  append(const GModelSpectral& spec, const std::string& name="");
    int                   components(void) const;
    const GModelSpectral* component(const int& index) const;
    const GModelSpectral* component(const std::string& name) const;

protected:
    // Protected methods
    void init_members(void);
    void copy_members(const GModelSpectralMultiplicative& model);
    void free_members(void);
    void update_mc_cache(const GEnergy& emin, const GEnergy& emax) const;

    // Class to determine the integral photon flux
    class flux_kern : public GFunction {
    public:
        // Constructor
        flux_kern(std::vector<GModelSpectral*> spec) : m_spec(spec) {}

        // Method
        double eval(const double& x) {
            GEnergy energy(x, "MeV");
            double value = m_spec[0]->eval(energy);
            for (size_t i = 1 ; i < m_spec.size(); ++i) {
                value *= m_spec[i]->eval(energy);
            }
            return value;
        }

    protected:
        // Protected members
        std::vector<GModelSpectral*> m_spec; //!< Spectral models
    };

    // Class to determine the integral energy flux, derived from flux_kern
    class eflux_kern : public flux_kern {
    public:
        // Constructor
        eflux_kern(std::vector<GModelSpectral*> spec) : flux_kern(spec) {}

        // Method
        double eval(const double& x) {
            return x * flux_kern::eval(x);
        }
    };

    // Protected members
    std::string                  m_type;        //!< Model type
    std::vector<GModelSpectral*> m_spectral;    //!< Container of spectral models
    std::vector<std::string>     m_components;  //!< Names of components

    // MC cache
    mutable GModelSpectralNodes  m_mc_spectrum; //!< MC spectrum cache
    mutable GEnergy              m_mc_emin;     //!< Last minimum energy
    mutable GEnergy              m_mc_emax;     //!< Last maximum energy
    mutable std::vector<double>  m_mc_values;   //!< Parameter values
};


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


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


/***********************************************************************//**
 * @brief Return number of spectral components
 *
 * @return Number of model components.
 *
 * Returns the number of spectral components.
 ***************************************************************************/
inline
int GModelSpectralMultiplicative::components(void) const
{
    return (m_spectral.size());
}

#endif /* GMODELSPECTRALMULTIPLICATIVE_HPP */