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

/*

 Copyright (C) 2008 Andreas Gaida

 Copyright (C) 2008 Ralph Schreyer

 Copyright (C) 2008 Klaus Spanderen

 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.

*/

#include <ql/methods/finitedifferences/meshers/fdmmesher.hpp>

#include <ql/methods/finitedifferences/operators/fdmlinearoplayout.hpp>

#include <ql/methods/finitedifferences/utilities/fdmdirichletboundary.hpp>

#include <ql/methods/finitedifferences/utilities/fdmindicesonboundary.hpp>

namespace QuantLib {

    FdmDirichletBoundary::FdmDirichletBoundary(

                            const ext::shared_ptr<FdmMesher>& mesher,

                            Real valueOnBoundary, Size direction,

                            FdmDirichletBoundary::Side side)

    : side_(side),

      valueOnBoundary_(valueOnBoundary),

      indices_(FdmIndicesOnBoundary(mesher->layout(),

                                    direction, side).getIndices()) {

        if (side_ == Lower) {

            xExtreme_ = mesher->locations(direction)[0];

        }

        else if (side_ == Upper) {

            xExtreme_ = mesher

                ->locations(direction)[mesher->layout()->dim()[direction]-1];

        }

        else {

            QL_FAIL("internal error");

        }

    }

    void FdmDirichletBoundary::applyBeforeApplying(operator_type&) const {

    }

    void FdmDirichletBoundary::applyAfterApplying(Array& x) const {

        for (unsigned long indice : indices_) {

            x[indice] = valueOnBoundary_;

        }

    }

    void FdmDirichletBoundary::applyBeforeSolving(operator_type&,

                                                  array_type&) const {

    }

    void FdmDirichletBoundary::applyAfterSolving(Array& rhs) const {

        this->applyAfterApplying(rhs);

    }

    Real FdmDirichletBoundary::applyAfterApplying(Real x, Real value) const {

        return (   (side_ == Lower && x < xExtreme_) 

                || (side_ == Upper && x > xExtreme_)) ? valueOnBoundary_ : value;

    }

}