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

/*

 Copyright (C) 2007, 2011 Ferdinando Ametrano

 Copyright (C) 2007 François du Vignaud

 Copyright (C) 2004, 2005, 2007, 2009 StatPro Italia srl

 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

 <http://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 settings.hpp

    \brief global repository for run-time library settings

*/

#ifndef quantlib_settings_hpp

#define quantlib_settings_hpp

#include <ql/patterns/singleton.hpp>

#include <ql/time/date.hpp>

#include <ql/utilities/observablevalue.hpp>

#include <ql/optional.hpp>

namespace QuantLib {

    //! global repository for run-time library settings

    class Settings : public Singleton<Settings> {

        friend class Singleton<Settings>;

      private:

        Settings();

        class DateProxy : public ObservableValue<Date> {

          public:

            DateProxy();

            DateProxy& operator=(const Date&);

            operator Date() const;

        };

        friend std::ostream& operator<<(std::ostream&, const DateProxy&);

      public:

        //! the date at which pricing is to be performed.

        /*! Client code can inspect the evaluation date, as in:

            \code

            Date d = Settings::instance().evaluationDate();

            \endcode

            where today's date is returned if the evaluation date is

            set to the null date (its default value;) can set it to a

            new value, as in:

            \code

            Settings::instance().evaluationDate() = d;

            \endcode

            and can register with it, as in:

            \code

            registerWith(Settings::instance().evaluationDate());

            \endcode

            to be notified when it is set to a new value.

            \warning a notification is not sent when the evaluation

                     date changes for natural causes---i.e., a date

                     was not explicitly set (which results in today's

                     date being used for pricing) and the current date

                     changes as the clock strikes midnight.

        */

        DateProxy& evaluationDate();

        const DateProxy& evaluationDate() const;

        /*! Call this to prevent the evaluation date to change at

            midnight (and, incidentally, to gain quite a bit of

            performance.)  If no evaluation date was previously set,

            it is equivalent to setting the evaluation date to

            Date::todaysDate(); if an evaluation date other than

            Date() was already set, it has no effect.

        */

        void anchorEvaluationDate();

        /*! Call this to reset the evaluation date to

            Date::todaysDate() and allow it to change at midnight.  It

            is equivalent to setting the evaluation date to Date().

            This comes at the price of losing some performance, since

            the evaluation date is re-evaluated each time it is read.

        */

        void resetEvaluationDate();

        /*! This flag specifies whether or not Events occurring on the reference

            date should, by default, be taken into account as not happened yet.

            It can be overridden locally when calling the Event::hasOccurred

            method.

        */

        bool& includeReferenceDateEvents();

        bool includeReferenceDateEvents() const;

        /*! If set, this flag specifies whether or not CashFlows

            occurring on today's date should enter the NPV.  When the

            NPV date (i.e., the date at which the cash flows are

            discounted) equals today's date, this flag overrides the

            behavior chosen for includeReferenceDate. It cannot be overridden

            locally when calling the CashFlow::hasOccurred method.

        */

        ext::optional<bool>& includeTodaysCashFlows();

        ext::optional<bool> includeTodaysCashFlows() const;

        bool& enforcesTodaysHistoricFixings();

        bool enforcesTodaysHistoricFixings() const;

      private:

        DateProxy evaluationDate_;

        bool includeReferenceDateEvents_ = false;

        ext::optional<bool> includeTodaysCashFlows_;

        bool enforcesTodaysHistoricFixings_ = false;

    };

    // helper class to temporarily and safely change the settings

    class SavedSettings { // NOLINT(cppcoreguidelines-special-member-functions)

      public:

        SavedSettings();

        ~SavedSettings();

      private:

        Date evaluationDate_;

        bool includeReferenceDateEvents_;

        ext::optional<bool> includeTodaysCashFlows_;

        bool enforcesTodaysHistoricFixings_;

    };

    // inline

    inline Settings::DateProxy::operator Date() const {

        if (value() == Date())

            return Date::todaysDate();

        else

            return value();

    }

    inline Settings::DateProxy& Settings::DateProxy::operator=(const Date& d) {

        if (value() != d) // avoid notifications if the date doesn't actually change

            ObservableValue<Date>::operator=(d);

        return *this;

    }

    inline Settings::DateProxy& Settings::evaluationDate() {

        return evaluationDate_;

    }

    inline const Settings::DateProxy& Settings::evaluationDate() const {

        return evaluationDate_;

    }

    inline bool& Settings::includeReferenceDateEvents() {

        return includeReferenceDateEvents_;

    }

    inline bool Settings::includeReferenceDateEvents() const {

        return includeReferenceDateEvents_;

    }

    inline ext::optional<bool>& Settings::includeTodaysCashFlows() {

        return includeTodaysCashFlows_;

    }

    inline ext::optional<bool> Settings::includeTodaysCashFlows() const {

        return includeTodaysCashFlows_;

    }

    inline bool& Settings::enforcesTodaysHistoricFixings() {

        return enforcesTodaysHistoricFixings_;

    }

    inline bool Settings::enforcesTodaysHistoricFixings() const {

        return enforcesTodaysHistoricFixings_;

    }

}

#endif