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

/*

 Copyright (C) 2008 J. Erik Radmall

 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 dateinterval.hpp

    \brief Date interval

*/

#ifndef quantlib_date_interval_hpp

#define quantlib_date_interval_hpp

#include <ql/time/date.hpp>

#include <ql/errors.hpp>

#include <algorithm>

namespace QuantLib {

    //! Date interval described by a number of a given time unit

    /*! \ingroup datetime */

    class DateInterval {

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

      private:

        Date startDate_;

        Date endDate_;

      public:

        DateInterval() = default;

        DateInterval(const Date& startDate, const Date& endDate)

        : startDate_(startDate), endDate_(endDate) {

            QL_REQUIRE(endDate_ >= startDate_,

                       "end date must be >= start date");

        }

        const Date& startDate() const { return startDate_; }

        const Date& endDate() const { return endDate_; }

        bool isDateBetween(Date date,

                           bool includeFirst = true,

                           bool includeLast = true) const {

            if (includeFirst && !(date >= startDate_))

                return false;

            else if (!(date > startDate_))

                return false;

            if (includeLast && !(date <= endDate_))

                return false;

            else if (!(date < endDate_))

                return false;

            return true;

        }

        DateInterval intersection(const DateInterval& di) const {

            if ((startDate_ < di.startDate_ && endDate_ < di.startDate_) ||

                (startDate_ > di.endDate_ && endDate_ > di.endDate_))

                return {};

            return {std::max(startDate_, di.startDate_), std::min(endDate_, di.endDate_)};

        }

        bool operator==(const DateInterval& rhs) const {

            return startDate_ == rhs.startDate_ && endDate_ == rhs.endDate_;

        }

        bool operator!=(const DateInterval& rhs) const {

            return !(*this == rhs);

        }

    };

}

#endif