// UFO.hxx -- interface to the "UFO" flight model
//
// Written by Curtis Olson, started October 1999.
// Slightly modified from MagicCarpet.hxx by Jonathan Polley, April 2002
//
// Copyright (C) 1999-2002  Curtis L. Olson  - http://www.flightgear.org/~curt
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License as
// published by the Free Software Foundation; either version 2 of the
// License, or (at your option) any later version.
//
// 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 GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
//


#ifndef _UFO_HXX
#define _UFO_HXX

#include "flight.hxx"


class FGUFO : public FGInterface
{
private:
    class lowpass
    {
    private:
        static double _dt;
        double _coeff;
        double _last;
        bool _initialized;

    public:
        lowpass(double coeff) : _coeff(coeff), _initialized(false) {}
        static inline void set_delta(double dt) { _dt = dt; }
        double filter(double value) {
            if (!_initialized) {
                _initialized = true;
                return _last = value;
            }
            double c = _dt / (_coeff + _dt);
            return _last = value * c + _last * (1.0 - c);
        }
    };

    lowpass *Throttle;
    lowpass *Aileron;
    lowpass *Elevator;
    lowpass *Rudder;
    lowpass *Aileron_Trim;
    lowpass *Elevator_Trim;
    lowpass *Rudder_Trim;
    SGPropertyNode_ptr Speed_Max;

public:
    FGUFO( double dt );
    ~FGUFO();

    // Subsystem API.
    void init() override;
    void update(double dt) override;

    // Subsystem identification.
    static const char* staticSubsystemClassId() { return "ufo"; }
};

#endif // _UFO_HXX
