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

/*
 Copyright (C) 2007, 2008 Chris Kenyon
 Copyright (C) 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
 <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 interpolatedzeroinflationcurve.hpp
    \brief Inflation term structure based on the interpolation of zero rates.
*/

#ifndef quantlib_interpolated_zeroinflationcurve_hpp
#define quantlib_interpolated_zeroinflationcurve_hpp

#include <ql/termstructures/inflationtermstructure.hpp>
#include <ql/termstructures/interpolatedcurve.hpp>
#include <ql/math/interpolations/linearinterpolation.hpp>
#include <utility>

namespace QuantLib {

    //! Inflation term structure based on the interpolation of zero rates.
    /*! \ingroup inflationtermstructures */
    template<class Interpolator>
    class InterpolatedZeroInflationCurve
        : public ZeroInflationTermStructure,
          protected InterpolatedCurve<Interpolator> {
      public:
        InterpolatedZeroInflationCurve(const Date& referenceDate,
                                       std::vector<Date> dates,
                                       const std::vector<Rate>& rates,
                                       Frequency frequency,
                                       const DayCounter& dayCounter,
                                       const ext::shared_ptr<Seasonality>& seasonality = {},
                                       const Interpolator& interpolator = Interpolator());

        //! \name InflationTermStructure interface
        //@{
        Date maxDate() const override;
        //@}

        //! \name Inspectors
        //@{
        const std::vector<Date>& dates() const;
        const std::vector<Time>& times() const;
        const std::vector<Real>& data() const;
        const std::vector<Rate>& rates() const;
        std::vector<std::pair<Date,Rate> > nodes() const;
        //@}

      protected:
        //! \name ZeroInflationTermStructure Interface
        //@{
        Rate zeroRateImpl(Time t) const override;
        //@}
        mutable std::vector<Date> dates_;

        /*! Protected version for use when descendents don't want to
            (or can't) provide the points for interpolation on
            construction.
        */
        InterpolatedZeroInflationCurve(const Date& referenceDate,
                                       Date baseDate,
                                       Frequency frequency,
                                       const DayCounter& dayCounter,
                                       const ext::shared_ptr<Seasonality>& seasonality = {},
                                       const Interpolator &interpolator = Interpolator());
    };

    typedef InterpolatedZeroInflationCurve<Linear> ZeroInflationCurve;



    // template definitions

    template <class Interpolator>
    InterpolatedZeroInflationCurve<Interpolator>::InterpolatedZeroInflationCurve(
        const Date& referenceDate,
        std::vector<Date> dates,
        const std::vector<Rate>& rates,
        Frequency frequency,
        const DayCounter& dayCounter,
        const ext::shared_ptr<Seasonality>& seasonality,
        const Interpolator& interpolator)
    : ZeroInflationTermStructure(referenceDate, dates.at(0), frequency, dayCounter, seasonality),
      InterpolatedCurve<Interpolator>(std::vector<Time>(), rates, interpolator),
      dates_(std::move(dates)) {

        QL_REQUIRE(dates_.size() > 1, "too few dates: " << dates_.size());

        QL_REQUIRE(this->data_.size() == dates_.size(),
                   "indices/dates count mismatch: " << this->data_.size() << " vs "
                                                    << dates_.size());
        for (Size i = 1; i < dates_.size(); i++) {
            // must be greater than -1
            QL_REQUIRE(this->data_[i] > -1.0, "zero inflation data < -100 %");
        }

        this->setupTimes(dates_, referenceDate, dayCounter);
        this->setupInterpolation();
        this->interpolation_.update();
    }

    template <class Interpolator>
    InterpolatedZeroInflationCurve<Interpolator>::
    InterpolatedZeroInflationCurve(const Date& referenceDate,
                                   Date baseDate,
                                   Frequency frequency,
                                   const DayCounter& dayCounter,
                                   const ext::shared_ptr<Seasonality>& seasonality,
                                   const Interpolator& interpolator)
    :  ZeroInflationTermStructure(referenceDate, baseDate, frequency, dayCounter, seasonality),
       InterpolatedCurve<Interpolator>(interpolator) {
    }

    template <class T>
    Date InterpolatedZeroInflationCurve<T>::maxDate() const {
        if (this->maxDate_ != Date())
            return this->maxDate_;
        return dates_.back();
    }

    template <class T>
    inline Rate InterpolatedZeroInflationCurve<T>::zeroRateImpl(Time t) const {
        return this->interpolation_(t, true);
    }

    template <class T>
    inline const std::vector<Time>&
    InterpolatedZeroInflationCurve<T>::times() const {
        return this->times_;
    }

    template <class T>
    inline const std::vector<Date>&
    InterpolatedZeroInflationCurve<T>::dates() const {
        return dates_;
    }

    template <class T>
    inline const std::vector<Rate>&
    InterpolatedZeroInflationCurve<T>::rates() const {
        return this->data_;
    }

    template <class T>
    inline const std::vector<Real>&
    InterpolatedZeroInflationCurve<T>::data() const {
        return this->data_;
    }

    template <class T>
    inline std::vector<std::pair<Date,Rate> >
    InterpolatedZeroInflationCurve<T>::nodes() const {
        std::vector<std::pair<Date,Rate> > results(dates_.size());
        for (Size i=0; i<dates_.size(); ++i)
            results[i] = std::make_pair(dates_[i],this->data_[i]);
        return results;
    }

}


#endif
