/* -*- mode: c++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */

/*
 Copyright (C) 2012, 2013 Klaus Spanderen
 Copyright (C) 2014 Johannes Göttker-Schnetmann


 This file is part of QuantLib, a free-software/open-source library
 for financial quantitative analysts and developers - http://quantlib.org/

 QuantLib is free software: you can redistribute it and/or modify it
 under the terms of the QuantLib license.  You should have received a
 copy of the license along with this program; if not, please email
 <quantlib-dev@lists.sf.net>. The license is also available online at
 <https://www.quantlib.org/license.shtml>.

 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 license for more details.
*/

/*! \file fdmblackscholesfwdop.hpp
    \brief Black Scholes linear operator for the Fokker-Planck forward equation
*/

#ifndef quantlib_fdm_black_scholes_fwd_op_hpp
#define quantlib_fdm_black_scholes_fwd_op_hpp

#include <ql/processes/blackscholesprocess.hpp>
#include <ql/methods/finitedifferences/operators/firstderivativeop.hpp>
#include <ql/methods/finitedifferences/operators/triplebandlinearop.hpp>
#include <ql/methods/finitedifferences/operators/fdmlinearopcomposite.hpp>

namespace QuantLib {

class FdmBlackScholesFwdOp : public FdmLinearOpComposite {
      public:
        FdmBlackScholesFwdOp(
            const ext::shared_ptr<FdmMesher>& mesher,
            const ext::shared_ptr<GeneralizedBlackScholesProcess>& process,
            Real strike, 
            bool localVol = false,
            Real illegalLocalVolOverwrite = -Null<Real>(),
            Size direction = 0);

        Size size() const override;
        void setTime(Time t1, Time t2) override;

        Array apply(const Array& r) const override;
        Array apply_mixed(const Array& r) const override;
        Array apply_direction(Size direction, const Array& r) const override;
        Array solve_splitting(Size direction, const Array& r, Real s) const override;
        Array preconditioner(const Array& r, Real s) const override;

        std::vector<SparseMatrix> toMatrixDecomp() const override;
      private:
        const ext::shared_ptr<FdmMesher> mesher_;
        const ext::shared_ptr<YieldTermStructure> rTS_, qTS_;
        const ext::shared_ptr<BlackVolTermStructure> volTS_;
        const ext::shared_ptr<LocalVolTermStructure> localVol_;
        const Array x_;
        const FirstDerivativeOp  dxMap_;
        const TripleBandLinearOp dxxMap_;
        TripleBandLinearOp mapT_;
        const Real strike_;
        const Real illegalLocalVolOverwrite_;
        const Size direction_;
    };
}

#endif
