/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2003 Robert Osfield 
 *
 * This library is open source and may be redistributed and/or modified under  
 * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or 
 * (at your option) any later version.  The full license is in LICENSE file
 * included with this distribution, and on the openscenegraph.org website.
 * 
 * This library 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 
 * OpenSceneGraph Public License for more details.
*/

#ifndef OSGSIM_BLINKSQUENCE
#define OSGSIM_BLINKSQUENCE 1

#include <osgSim/Export>

#include <osg/Quat>
#include <osg/Vec3>
#include <osg/Vec4>
#include <osg/ref_ptr>

#include <vector>

namespace osgSim {

class OSGSIM_EXPORT BlinkSequence : public osg::Object
{
    public:

        /** sequence group which can be used to synchronize related blink sequences.*/
        class OSGSIM_EXPORT SequenceGroup : public osg::Referenced
        {
            public:

                SequenceGroup();
                SequenceGroup(double baseTime);

                double      _baseTime;
        };


        BlinkSequence();

        BlinkSequence(const BlinkSequence& bs, const osg::CopyOp& copyop = osg::CopyOp::SHALLOW_COPY);
        
        META_Object(osgSim,BlinkSequence);

        
        /** add a pulse of specified color and duration to the BlinkSequence.*/
        inline void addPulse(double length,const osg::Vec4& color);

        /** get the total pulse period of the blink sequence, which is equal to the sum of all the pulse periods.*/
        inline double getPulsePeriod() const { return _pulsePeriod; }

        /** set the sequence group which can be used to synchronize related blink sequences.*/
        inline void setSequenceGroup(SequenceGroup* sg) { _sequenceGroup = sg; }
        
        /** get the non const sequence group.*/
        inline SequenceGroup* getSequenceGroup() { return _sequenceGroup.get(); }
        
        /** get the const sequence group.*/
        inline const SequenceGroup* getSequenceGroup() const { return _sequenceGroup.get(); }

        /** set the phase shift of the blink sequence, this would be used to shift a sequence within a sequence group.*/
        inline void setPhaseShift(double ps) { _phaseShift = ps; }

        /** get the pahse shift.*/        
        inline double getPhaseShift() const { return _phaseShift; }
        


        /** compute the local time clamped to this BlinkSequences period, and accounting for the phase shift and sequence group.*/
        inline double localTime(double time) const;

        /** compute the color for the time interval sepecifed. Averages the colors if the length is greater than the current pulse.*/
        inline osg::Vec4 color(double time,double length) const;
        

    protected:


        typedef std::pair<double,osg::Vec4> IntervalColor;
        typedef std::vector<IntervalColor>  PulseData;
        
        double                      _pulsePeriod;
        double                      _phaseShift;
        PulseData                   _pulseData;
        osg::ref_ptr<SequenceGroup> _sequenceGroup;
};


inline double BlinkSequence::localTime(double time) const
{
    if (_sequenceGroup.valid()) time -= _sequenceGroup->_baseTime;
    time -= _phaseShift;
    return time - floor(time/_pulsePeriod)*_pulsePeriod;
}

inline void BlinkSequence::addPulse(double length,const osg::Vec4& color)
{
    _pulseData.push_back(IntervalColor(length,color));
    _pulsePeriod += length;
}

inline osg::Vec4 BlinkSequence::color(double time,double length) const
{
    if (_pulseData.empty()) return osg::Vec4(1.0f,1.0f,1.0f,1.0f);
    double lt = localTime(time);
    PulseData::const_iterator itr = _pulseData.begin();

    // find the first sample at this time point.
    while (lt>itr->first)
    {
        lt -= itr->first;
        ++itr;
        if (itr==_pulseData.end()) itr = _pulseData.begin();
    }

    // if time interval fits inside the current pulse 
    // then simply return this pulses color value.
    if (lt+length<=itr->first)
    {
        return itr->second;
    }

    // time length exceeds the current pulse therefore
    // we have to average out the pules to get the correct
    // results...

    // accumulate final part of the first active pulses.
    osg::Vec4 color(itr->second*(itr->first-lt));
    double len = length-(itr->first-lt);
    ++itr;
    if (itr==_pulseData.end()) itr = _pulseData.begin();

    // accumulate all the whole pluses pulses.
    while (len>itr->first)
    {
        len -= itr->first;
        color += itr->second*itr->first;
        ++itr;
        if (itr==_pulseData.end()) itr = _pulseData.begin();
    }

    // add remaining part of the final pulse.
    color += itr->second*len;

    // normalise the time waited color.   
    color /= length;

    return color;
}

}

#endif