#pragma once

#include <assert.h>
#include <iostream>

#include "utils.h"

//! @brief Base class for all waypoint managers.
template <class ElementType, template <class, class...> class Container /*e.g. QVector*/>
class GenericSlicer
{
public:
    typedef Container<ElementType> ContainerType;
    GenericSlicer();


    // Slicing.
    void slice      (const ContainerType &source, ContainerType &slice);
    void next       (const ContainerType &source, ContainerType &slice);
    void previous   (const ContainerType &source, ContainerType &slice);
    void reset      (const ContainerType &source, ContainerType &slice);


    // Slicing parameters.
    //! @brief Sets the overlap.
    //!
    //! @param overlap The number of overlapping vertices
    //! between on and the next slice.
    void setOverlap            (uint32_t overlap);
    //! @brief Sets the number of vertices per slice.
    //!
    //! @param N The number of vertices per slice.
    void setN   (std::uint32_t N);
    //! @brief Sets the start index.
    //!
    //! @param idxStart The start index.
    void setStartIndex         (int idxStart);

    //! @return Returns the overlap.
    uint32_t      overlap       ();
    //! @return Returns the number of vertices per slice N.
    uint32_t      N             ();
    //! @return Returns the start index.
    int           startIndex    ();


private:
    void _updateIdx(std::size_t size);

    long          _idxStart;
    long          _idxEnd;
    long          _idxNext;
    long          _idxPrevious;
    uint32_t      _overlap;
    uint32_t      _N;
    bool          _idxValid;
    bool          _atEnd;


};


template <class ElementType, template <class, class...> class Container /*e.g. QVector*/>
GenericSlicer<ElementType, Container>::GenericSlicer():
    _idxValid(false)
  , _atEnd(false)
{}

template <class ElementType, template <class, class...> class Container /*e.g. QVector*/>
void GenericSlicer<ElementType, Container>::setOverlap(std::uint32_t overlap)
{
    _idxValid = false;
    _overlap = overlap;
}

template <class ElementType, template <class, class...> class Container /*e.g. QVector*/>
void GenericSlicer<ElementType, Container>::setN(uint32_t N)
{
    _idxValid = false;
    _N = N > 0 ? N : 1;
}

template <class ElementType, template <class, class...> class Container /*e.g. QVector*/>
void GenericSlicer<ElementType, Container>::setStartIndex(int idxStart)
{
    _idxValid = false;
    _idxStart = idxStart;
}

template <class ElementType, template <class, class...> class Container /*e.g. QVector*/>
uint32_t GenericSlicer<ElementType, Container>::overlap()
{
    return _overlap;
}

template <class ElementType, template <class, class...> class Container /*e.g. QVector*/>
uint32_t GenericSlicer<ElementType, Container>::N()
{
    return _N;
}

template <class ElementType, template <class, class...> class Container /*e.g. QVector*/>
int GenericSlicer<ElementType, Container>::startIndex()
{
    return _idxStart;
}


template <class ElementType, template <class, class...> class Container /*e.g. QVector*/>
void GenericSlicer<ElementType, Container>::_updateIdx(std::size_t size)
{
    _idxValid = true;
    _atEnd    = false;
    if ( _idxStart >= size-1 ) {
        _idxStart   = size-1;
        _idxEnd     = _idxStart;
        _idxNext    = _idxStart;
        _atEnd      = true;
        return;
    }

    _idxStart < 0 ? 0 : _idxStart;

    _idxEnd = _idxStart + _N - 1;
    _idxEnd = _idxEnd < size ? _idxEnd : size-1;

    _idxNext = _idxEnd + 1 - _overlap;
    _idxNext = _idxNext < 0    ? 0        : _idxNext;
    _idxNext = _idxNext < size ? _idxNext : size-1;

    _idxPrevious = _idxStart - 1 + _overlap;
    _idxPrevious = _idxPrevious < 0    ? 0            : _idxPrevious;
    _idxPrevious = _idxPrevious < size ? _idxPrevious : size-1;
}

template <class ElementType, template <class, class...> class Container /*e.g. QVector*/>
void GenericSlicer<ElementType, Container>::slice(const ContainerType &source,
                                                  Container<ElementType> &slice){

    if ( !_idxValid)
        _updateIdx(source.size());

    WaypointManager::Utils::extract(source, slice, _idxStart, _idxEnd);
    // extract waypoints

}

template <class ElementType, template <class, class...> class Container /*e.g. QVector*/>
void GenericSlicer<ElementType, Container>::next(const ContainerType &source, Container<ElementType> &slice){
    setStartIndex(_idxNext);
    slice(source, slice);
}

template <class ElementType, template <class, class...> class Container /*e.g. QVector*/>
void GenericSlicer<ElementType, Container>::previous(const ContainerType &source, Container<ElementType> &slice){
    setStartIndex(_idxPrevious);
    slice(source, slice);
}

template <class ElementType, template <class, class...> class Container /*e.g. QVector*/>
void GenericSlicer<ElementType, Container>::reset(const ContainerType &source, Container<ElementType> &slice){
    setStartIndex(0);
    slice(source, slice);
}