/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     |
    \\  /    A nd           | Copyright (C) 2016 OpenFOAM Foundation
     \\/     M anipulation  |
-------------------------------------------------------------------------------
License
    This file is part of OpenFOAM.

    OpenFOAM 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.

    OpenFOAM 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 OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.

Class
    Foam::CrossSection

Description

SourceFiles
    CrossSectionI.H
    CrossSection.C
    CrossSectionIO.C

\*---------------------------------------------------------------------------*/

#ifndef CrossSection_H
#define CrossSection_H

#include "scalar.H"
#include "scalarField.H"
#include "Electron.H"
#include "Neutral.H"
#include "Interaction.H"

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

namespace Foam
{

// Forward declaration of classes
class Istream;
class Ostream;

// Forward declaration of friend functions and operators
class CrossSection;
Istream& operator>>(Istream&, CrossSection&);
Ostream& operator<<(Ostream&, const CrossSection&);


/*---------------------------------------------------------------------------*\
                         Class CrossSection Declaration
\*---------------------------------------------------------------------------*/

class CrossSection
    : public Interaction
{
    // Private data
    //
        //- Highest polynomial order of diffusivity fitting formular
        static constexpr label M = 7;

        //- Collision participant ion a
        const Electron &a_;

        //- Collision participant neutral b
        const Neutral &b_;

        //- p * Dej Fit Coefficient
        scalarField b11_;

        //- Buffer for polynomial feature
        static scalarField vec;

    // Private Member Functions

        //- Disallow default bitwise copy construct
        CrossSection(const CrossSection&);

        //- Disallow default bitwise assignment
        void operator=(const CrossSection&);

        // primary template
        template <label Order>
            struct UnivarPolyFeat
            {
                    static scalar transform (scalar x1, scalar *vec)
                    {
                        scalar highest = UnivarPolyFeat<Order-1>::transform(x1,vec) * x1;

                        *(vec+Order) = highest;

                        return highest;
                    }
            };

        // convenience function
        inline void transform (scalar x1, scalar *vec)
        {
            UnivarPolyFeat<M>::transform(x1,vec);
        }

        // primary template
        template <label N>
            struct ScalarProduct
            {
                static scalar product (const scalar* first, const scalar* second)
                {
                    return ScalarProduct<N-1>::product(first + 1, second + 1)
                        + *first * *second;
                }
            };

        // convenience function
        inline scalar scalarProduct (const scalar *x1, const scalar *x2)
        {
            return ScalarProduct<(M+1)>::product(x1,x2);
        }


public:

    // Static data members


    // Constructors

        //- Construct null
        CrossSection();

        //- Construct from components
        CrossSection(const Electron& a, const Neutral& b);

        //- Construct from Istream
        CrossSection(Istream&);

        //- Construct as copy
        // CrossSection(const CrossSection&);


    //- Destructor
    ~CrossSection();


    // Member Functions

        // Access

        // Check

        // Edit

        // Write

        inline scalar Dfit(const scalar T);


        inline scalar D(const scalar p, const scalar T);


    // Member Operators


    // Friend Functions

    // Friend Operators

    // IOstream Operators

        friend Istream& operator>>(Istream&, CrossSection&);
        friend Ostream& operator<<(Ostream&, const CrossSection&);
};

// partial specialization as end criteria
template <>
class CrossSection::UnivarPolyFeat<0>
{
    public:
        static scalar transform (scalar x1, scalar *vec)
        {
            *vec = 1.0;
            return 1.0;
        }
};

template <>
struct CrossSection::ScalarProduct<1>
{
    static scalar product (const scalar* first, const scalar* second) {
        return *first * *second;
    };
};


// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

} // End namespace Foam

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

#include "CrossSectionI.H"

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

#endif

// ************************************************************************* //