/*
*
* Template Numerical Toolkit (TNT)
*
* Mathematical and Computational Sciences Division
* National Institute of Technology,
* Gaithersburg, MD USA
*
*
* This software was developed at the National Institute of Standards and
* Technology (NIST) by employees of the Federal Government in the course
* of their official duties. Pursuant to title 17 Section 105 of the
* United States Code, this software is not subject to copyright protection
* and is in the public domain. NIST assumes no responsibility whatsoever for
* its use by other parties, and makes no guarantees, expressed or implied,
* about its quality, reliability, or any other characteristic.
*
*/

#ifndef IMPALGEBRA_TNT_I_REFVEC_H
#define IMPALGEBRA_TNT_I_REFVEC_H

#include <IMP/algebra/algebra_config.h>
#include <cstdlib>
#include <iostream>

#ifdef TNT_BOUNDS_CHECK
#include <assert.h>
#endif


IMPALGEBRA_BEGIN_INTERNAL_NAMESPACE
namespace TNT
{
using namespace std;
/*
  Internal representation of ref-counted array.  The TNT
  arrays all use this building block.

  <p>
  If an array block is created by TNT, then every time
  an assignment is made, the left-hand-side reference
  is decreased by one, and the right-hand-side refernce
  count is increased by one.  If the array block was
  external to TNT, the refernce count is a nullptr pointer
  regardless of how many references are made, since the
  memory is not freed by TNT.



*/
template <class T>
class i_refvec
{


  private:
    T* data_;
    int *ref_count_;


  public:

       i_refvec();
  explicit i_refvec(int n);
  inline   i_refvec(T* data);
  inline   i_refvec(const i_refvec &v);
  inline   T*     begin();
  inline const T* begin() const;
  inline  T& operator[](int i);
  inline const T& operator[](int i) const;
  inline  i_refvec<T> & operator=(const i_refvec<T> &V);
        void copy_(T* p, const T* q, const T* e);
        void set_(T* p, const T* b, const T* e);
  inline   int   ref_count() const;
  inline  int is_null() const;
  inline  void destroy();
       ~i_refvec();

};

template <class T>
void i_refvec<T>::copy_(T* p, const T* q, const T* e)
{
  for (T* t=p; q<e; t++, q++)
    *t= *q;
}

template <class T>
i_refvec<T>::i_refvec() : data_(nullptr), ref_count_(nullptr) {}

/**
  In case n is 0 or negative, it does NOT call new.
*/
template <class T>
i_refvec<T>::i_refvec(int n) : data_(nullptr), ref_count_(nullptr)
{
  if (n >= 1)
  {
#ifdef TNT_DEBUG
    std::cout  << "new data storage.\n";
#endif
    data_ = new T[n];
    ref_count_ = new int;
    *ref_count_ = 1;
  }
}

template <class T>
inline   i_refvec<T>::i_refvec(const i_refvec<T> &V): data_(V.data_),
  ref_count_(V.ref_count_)
{
  if (V.ref_count_ != nullptr)
      (*(V.ref_count_))++;
}


template <class T>
i_refvec<T>::i_refvec(T* data) : data_(data), ref_count_(nullptr) {}

template <class T>
inline T* i_refvec<T>::begin()
{
  return data_;
}

template <class T>
inline const T& i_refvec<T>::operator[](int i) const
{
  return data_[i];
}

template <class T>
inline T& i_refvec<T>::operator[](int i)
{
  return data_[i];
}


template <class T>
inline const T* i_refvec<T>::begin() const
{
  return data_;
}



template <class T>
i_refvec<T> & i_refvec<T>::operator=(const i_refvec<T> &V)
{
  if (this == &V)
    return *this;


  if (ref_count_ != nullptr)
  {
    (*ref_count_) --;
    if ((*ref_count_) == 0)
      destroy();
  }

  data_ = V.data_;
  ref_count_ = V.ref_count_;

  if (V.ref_count_ != nullptr)
      (*(V.ref_count_))++;

  return *this;
}

template <class T>
void i_refvec<T>::destroy()
{
  if (ref_count_ != nullptr)
  {
#ifdef TNT_DEBUG
    std::cout << "destorying data... \n";
#endif
    delete ref_count_;

#ifdef TNT_DEBUG
    std::cout << "deleted ref_count_ ...\n";
#endif
    if (data_ != nullptr)
      delete []data_;
#ifdef TNT_DEBUG
    std::cout << "deleted data_[] ...\n";
#endif
    data_ = nullptr;
  }
}

/*
* return 1 is vector is empty, 0 otherwise
*
* if is_null() is false and ref_count() is 0, then
*
*/
template<class T>
int i_refvec<T>::is_null() const
{
  return (data_ == nullptr ? 1 : 0);
}

/*
*  returns -1 if data is external,
*  returns 0 if a is nullptr array,
*  otherwise returns the positive number of vectors sharing
*      this data space.
*/
template <class T>
int i_refvec<T>::ref_count() const
{
  if (data_ == nullptr)
    return 0;
  else
    return (ref_count_ != nullptr ? *ref_count_ : -1) ;
}

template <class T>
i_refvec<T>::~i_refvec()
{
  if (ref_count_ != nullptr)
  {
    (*ref_count_)--;

    if (*ref_count_ == 0)
    destroy();
  }
}


} /* namespace TNT */



IMPALGEBRA_END_INTERNAL_NAMESPACE

#endif /* IMPALGEBRA_TNT_I_REFVEC_H */