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

/*

 Copyright (C) 2009 Jose Aparicio

 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.

*/

#ifndef quantlib_recovery_rate_model_hpp

#define quantlib_recovery_rate_model_hpp

#include <ql/settings.hpp>

#include <ql/handle.hpp>

#include <ql/experimental/credit/defaultprobabilitykey.hpp>

#include <ql/experimental/credit/recoveryratequote.hpp>

namespace QuantLib {

    /*! Models of the recovery rate provide future values of a recovery

        rate in the event of a default.

    */

    class RecoveryRateModel : public virtual Observable {

      public:

        /*! returns the expected recovery rate at a future time conditional

            on some default event type and seniority.

        */

        virtual Real recoveryValue(const Date& defaultDate,

            const DefaultProbKey& defaultKey = DefaultProbKey()) const {

            // no check on dates...

            return recoveryValueImpl(defaultDate, defaultKey);

        }

        /*! Returns true if the model will return recovery rates for

            the requested seniority.

        */

        virtual bool appliesToSeniority(Seniority) const = 0;

        ~RecoveryRateModel() override = default;

      protected:

        /*! Returns Null<Real> if unable to produce a recovery for

            the requested seniority.

        */

        virtual Real recoveryValueImpl(const Date&,

                                       const DefaultProbKey& defaultKey

                                       ) const = 0;

    };

    /*! Simple Recovery Rate model returning the constant value of the quote

        independently of the date and the seniority.

    */

    class ConstantRecoveryModel : public RecoveryRateModel,

                                  public Observer {

      public:

        explicit ConstantRecoveryModel(const Handle<RecoveryRateQuote>& quote);

        explicit ConstantRecoveryModel(Real recovery,

                                       Seniority sen = NoSeniority);

        void update() override { notifyObservers(); }

        bool appliesToSeniority(Seniority) const override { return true; }

      protected:

        /*! Notice the quote's value is returned without a

            check on a match of the seniorties of the

            quote and the request.

        */

        Real recoveryValueImpl(const Date&, const DefaultProbKey&) const override {

            // no match on requested seniority, all pass

            return quote_->value();

        }

      private:

        Handle<RecoveryRateQuote> quote_;

    };

}

#endif