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

/*

 Copyright (C) 2008 Andrea Odetti

 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/experimental/mcbasket/mcpathbasketengine.hpp>

#include <utility>

namespace QuantLib {

    EuropeanPathMultiPathPricer::EuropeanPathMultiPathPricer(

        ext::shared_ptr<PathPayoff>& payoff,

        std::vector<Size> timePositions,

        std::vector<Handle<YieldTermStructure> > forwardTermStructures,

        Array discounts)

    : payoff_(payoff), timePositions_(std::move(timePositions)),

      forwardTermStructures_(std::move(forwardTermStructures)), discounts_(std::move(discounts)) {}

    Real EuropeanPathMultiPathPricer::operator()(const MultiPath& multiPath)

                                                                       const {

        Size n = multiPath.pathSize();

        QL_REQUIRE(n > 0, "the path cannot be empty");

        Size numberOfAssets = multiPath.assetNumber();

        QL_REQUIRE(numberOfAssets > 0, "there must be some paths");

        const Size numberOfTimes = timePositions_.size();

        Matrix path(numberOfAssets, numberOfTimes, Null<Real>());

        for (Size i = 0; i < numberOfTimes; ++i) {

            const Size pos = timePositions_[i];

            for (Size j = 0; j < numberOfAssets; ++j)

                path[j][i] = multiPath[j][pos];

        }

        Array values(numberOfTimes, 0.0);

        // ignored

        Array exercises;

        std::vector<Array> states;

        payoff_->value(path, forwardTermStructures_, values, exercises, states);

        // in this engine we ignore early exercise

        Real discountedPayoff = DotProduct(values, discounts_);

        return discountedPayoff;

    }

}