/*!
 * \file
 * \brief Circular_Buffer class (container)
 * \author Tobias Tynderfeldt
 *
 * -------------------------------------------------------------------------
 *
 * IT++ - C++ library of mathematical, signal processing, speech processing,
 *        and communications classes and functions
 *
 * Copyright (C) 1995-2007  (see AUTHORS file for a list of contributors)
 *
 * 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 St, Fifth Floor, Boston, MA 02110-1301 USA
 *
 * -------------------------------------------------------------------------
 *
 * This file is not separated into .h and .cpp files. The reason is
 * to avoid problems with template initializations of this class.
 * A \c Circular_Buffer<type> can contain any type and it is not
 * possible to initialize and pre-compile all types that might be put
 * into a \c Circular_Buffer.
 */

#ifndef CIRCULAR_BUFFER_H
#define CIRCULAR_BUFFER_H

#include <itpp/base/vec.h>
#include <itpp/base/array.h>


namespace itpp {

  /*!
    \brief General circular buffer class

    This class is a general circular buffer class for arbitrary types.

    For rarely used types you will need to instantiate the class by
    \code
    template class Circular_Buffer<type>;
    \endcode

    The following example shows how to define a Circular_Buffer of doubles:
    \code
    vec a = randn(3);
    vec b = randn(8);
    vec out_vec;
    Array <double> out_array;

    Circular_Buffer<double> cb1(10);

    //Put the elements of a to the buffer
    cb1.put(a);

    //Vector output: Peek at the two oldest elements of the buffer (the two first extracted)
    cb1.peek(out_vec,2);
    cout << "peek(out_vec,2) = " << out_vec << ": display 2 first elements of the buffer, without affecting the content"  << endl;

    //Vector output: Peek at all elements of the buffer in reverse order
    cb1.peek_reverse(out_vec);
    cout << "peek_reverse(out_vec,-1) = " << out_vec << ": display buffer, without affecting the content"  << endl;

    //Array output: Peek at all elements of the buffer in reverse order
    cb1.peek_reverse(out_array);
    cout << "peek_reverse(out_array,-1) = " << out_array << ": display buffer, without affecting the content"  << endl;

    //Put the elements of \c b to the buffer
    cb1.put(b);

    //Extract the oldest element of the buffer
    cb1.get(out_vec,1);
    cout << "get(out_vec,1) = " << out_vec << endl ;

    //Extract all element of the buffer
    cb1.get(out_vec);
    cout << "get(out_vec) = " << out_vec << endl ;
    \endcode
  */
  template<class T>
  class Circular_Buffer {
  public:
    //! Default constructor
    Circular_Buffer();

    //! Create a Circular_Buffer of size \c n
    Circular_Buffer(int n);

    //! Create a copy of \c s
    Circular_Buffer(const Circular_Buffer<T> &s);

    //! Default destructor
    virtual ~Circular_Buffer();

    //! Write the element \a in to the buffer
    void put(const T& in);

    //! Write the vector of elements \a in to the circular buffer
    void put(const Vec<T>& in);

    //! Write the vector of elements \a in to the circular buffer
    void put(const Array<T>& in);

    //! Get the oldest element in the circular buffer
    void get(T& out);

    //! Get the oldest element in the circular buffer
    T get();

    //! Get the N oldest element in the circular buffer. \c N=-1 returns all elements in the buffer
    void get(Vec<T>& out, const int N=-1);

    //! Get the N oldest element in the circular buffer. \c N=-1 returns all elements in the buffer
    void get(Array<T>& out, const int N=-1);

    //! Peek at the oldest element in the circular buffer, without removing it.
    void peek(T& out) const;

    //! Peek at the oldest element in the circular buffer, without removing it.
    T peek() const;

    //! Peek at the element with index \a index in the circular buffer, without removing it.
    void peek(const int index, T& out) const;

    //! Peek at the N first elements of the circular buffer, without removing them. \c N=-1 peeks all elements in the buffer
    void peek(Vec<T>& out, const int N=-1) const;

    //! Peek at the elements with index \a index in the circular buffer, without removing them.
    void peek(const ivec& index, Vec<T>& out) const;

    //! Peek at the N first elements of the circular buffer, without removing them. \c N=-1 peeks all elements in the buffer
    void peek(Array<T>& out, const int N=-1) const;

    //! Peek at the elements with index \a index in the circular buffer, without removing them.
    void peek(const ivec& index, Array<T>& out) const;

    //! Peek at the latest element in the circular buffer, without removing it.
    void peek_reverse(T& out) const;

    //! Peek at the latest element in the circular buffer, without removing it.
    T peek_reverse() const;

    //! Peek at the N latest elements of the circular buffer in reverse order, without removing them. \c N=-1 returns all elements in the buffer
    void peek_reverse(Vec<T>& out, const int N=-1) const;

    //! Peek at the N latest elements of the circular buffer in reverse order, without removing them. \c N=-1 returns all elements in the buffer
    void peek_reverse(Array<T>& out, const int N=-1) const;

    //! Empty the circular buffer
    void clear();

    //! Assignment operator
    void operator=(const Circular_Buffer<T> &s);

    //! Returns the maximum number of data elements the circular buffer can store
    int size() const { return _ndata; }

    //! Returns the number of data elements currently stored in the circular buffer
    int nrof_elements() const { return _rw_dist; }

    //! Resizing a Circular_Buffer<T>.
    void set_size(int n, bool copy=false);

  private:

    int _write;
    int _read;
    int _ndata;
    int _rw_dist;
    T *_data;

    void alloc(int n);
    void free();

  };

  // --------------------------- Implementation starts here ----------------------------------

  template<class T>
    Circular_Buffer<T>::Circular_Buffer()
    {
      _data    = 0;
      _ndata   = 0;
      _rw_dist = 0;
      _read    = 0;
      _write   = 0;
    }

  template<class T>
    Circular_Buffer<T>::Circular_Buffer(int n)
    {
      alloc(n);
      _read    = 0;
      _write   = 0;
      _rw_dist = 0;
    }

  template<class T>
    Circular_Buffer<T>::Circular_Buffer(const Circular_Buffer<T> &cb)
    {
      _data    = NULL;
      _ndata   = 0;
      _read    = cb._read;
      _write   = cb._write;
      _rw_dist = cb._rw_dist;

      alloc(cb._ndata);
      for (int i=0; i<cb._ndata; i++) { _data[i] = cb._data[i]; }
    }

  template<class T>
    Circular_Buffer<T>::~Circular_Buffer()
    {
      free();
    }

  template <class T>
    void Circular_Buffer<T>::get(T& out)
    {
      it_assert_debug(_rw_dist>0,"Buffer empty. No data left to read from the buffer.");
      out=_data[_read];
      _read++;
      _rw_dist--;

      if (_read==_ndata) { _read=0; }
    }

  template <class T>
    T Circular_Buffer<T>::get()
    {
      T out;

      get(out);
      return out;
    }

  template <class T>
    void Circular_Buffer<T>::get(Vec<T>& out, const int N)
    {
      int N_out;

      if (N==-1)
	N_out=_rw_dist;
      else
	N_out=N;

      out.set_size(N_out);

      for (int i=0;i<N_out;i++)
	{
	  it_assert_debug(_rw_dist>0,"Buffer empty. No data left to read from the buffer.");
	  out(i)=_data[_read];
	  _read++;
	  _rw_dist--;

	  if (_read==_ndata)
	    _read=0;
	}
    }

  template <class T>
    void Circular_Buffer<T>::get(Array<T>& out, const int N)
    {
      int N_out;

      if (N==-1)
	N_out=_rw_dist;
      else
	N_out=N;

      out.set_size(N_out);

      for (int i=0;i<N_out;i++)
	{
	  it_assert_debug(_rw_dist>0,"Buffer empty. No data left to read from the buffer.");
	  out(i)=_data[_read];
	  _read++;
	  _rw_dist--;

	  if (_read==_ndata)
	    _read=0;
	}
    }

  template <class T>
    void Circular_Buffer<T>::peek(T& out) const
    {
      it_assert_debug(_rw_dist>0,"Attempted to peek at an empty buffer.");
      out=_data[_read];
    }

  template <class T>
    T Circular_Buffer<T>::peek() const
    {
      T out;

      peek(out);
      return out;
    }

  template <class T>
    void Circular_Buffer<T>::peek(const int index, T& out) const
    {
      it_assert_debug(_rw_dist>index && index>=0,"The index exceeds the number of elements stored in the buffer.");
      out=_data[(_read+index)%_ndata];
    }

  template <class T>
    void Circular_Buffer<T>::peek(Vec<T>& out, const int N) const
    {
      int N_out;
      int read_tmp=_read;

      if (N==-1)
	N_out=_rw_dist;
      else
	N_out=N;

      it_assert_debug(_rw_dist>=N_out,"Attempted to peek at more elements than there are stored in the buffer.");
      out.set_size(N_out);

      for (int i=0;i<N_out;i++)
	{
	  out(i)=_data[read_tmp];
	  read_tmp++;
	  if (read_tmp==_ndata)
	    read_tmp=0;
	}
    }

  template <class T>
    void Circular_Buffer<T>::peek(const ivec& index, Vec<T>& out) const
    {
      out.set_size(index.size());

      for (int i=0;i<index.size();i++)
	{
	  it_assert_debug(_rw_dist>=index(i) && index(i)>=0,"Attempted to peek at an element, whose index exceeds the number of buffered elements.");
	  out(i)=_data[(_read+index(i))%_ndata];
	}
    }

  template <class T>
    void Circular_Buffer<T>::peek(Array<T>& out, const int N) const
    {
      int N_out;
      int read_tmp=_read;

      if (N==-1)
	N_out=_rw_dist;
      else
	N_out=N;

      it_assert_debug(_rw_dist>=N_out,"Attempted to peek at more elements than there are stored in the buffer.");
      out.set_size(N_out);

      for (int i=0;i<N_out;i++)
	{
	  out(i)=_data[read_tmp];
	  read_tmp++;
	  if (read_tmp==_ndata)
	    read_tmp=0;
	}
    }

  template <class T>
    void Circular_Buffer<T>::peek(const ivec& index, Array<T>& out) const
    {
      out.set_size(index.size());

      for (int i=0;i<index.size();i++)
	{
	  it_assert_debug(_rw_dist>=index(i) && index(i)>=0,"Attempted to peek at an element, whose index exceeds the number of buffered elements.");
	  out(i)=_data[(_read+index(i))%_ndata];
	}
    }

  template <class T>
    void Circular_Buffer<T>::peek_reverse(T& out) const
    {
      int read_tmp;

      it_assert_debug(_rw_dist>0,"Attempted to peek at an empty buffer.");

      if (_write>0)
	read_tmp=_write-1;
      else
	read_tmp=_ndata-1;

      out=_data[read_tmp];
    }

  template <class T>
    T Circular_Buffer<T>::peek_reverse() const
    {
      T out;

      peek_reverse(out);
      return out;
    }

  template <class T>
    void Circular_Buffer<T>::peek_reverse(Vec<T>& out, const int N) const
    {
      int N_out;
      int read_tmp;

      if (N==-1)
	N_out=_rw_dist;
      else
	N_out=N;

      it_assert_debug(_rw_dist>=N_out,"Attempted to peek at more elements than there are stored in the buffer.");
      out.set_size(N_out);

      if (_write>0)
	read_tmp=_write-1;
      else
	read_tmp=_ndata-1;

      for (int i=0;i<N_out;i++)
	{
	  out(i)=_data[read_tmp];
	  read_tmp--;
	  if (read_tmp<0)
	    read_tmp=_ndata-1;
	}
    }

  template <class T>
    void Circular_Buffer<T>::peek_reverse(Array<T>& out, const int N) const
    {
      int N_out;
      int read_tmp;

      if (N==-1)
	N_out=_rw_dist;
      else
	N_out=N;

      it_assert_debug(_rw_dist>=N_out,"Attempted to peek at more elements than there are stored in the buffer.");
      out.set_size(N_out);

      if (_write>0)
	read_tmp=_write-1;
      else
	read_tmp=_ndata-1;

      for (int i=0;i<N_out;i++)
	{
	  out(i)=_data[read_tmp];
	  read_tmp--;
	  if (read_tmp<0)
	    read_tmp=_ndata-1;
	}
    }

  template <class T>
    void Circular_Buffer<T>::put(const T& in)
    {
      //Remove the oldest element of the buffer if the buffer is full
      if (_rw_dist>=_ndata)
	{
	  T dummy;
	  get(dummy);
	}

      //Write data to the buffer and move the pointer to the next buffer slot
      _data[_write]=in;
      _write++;
      _rw_dist++;

      //Check if the pointer in the circular buffer should go back to zero
      if (_write>=_ndata)
	_write=0;

    }

  template <class T>
    void Circular_Buffer<T>::put(const Vec<T>& in)
    {
      for (int i=0;i<in.size();i++)
	{
	  //Remove the oldest element of the buffer if the buffer is full
	  if (_rw_dist>=_ndata)
	    {
	      T dummy;
	      get(dummy);
	    }

	  //Write data to the buffer and move the pointer to the next buffer slot
	  _data[_write]=in(i);
	  _write++;
	  _rw_dist++;

	  //Check if the pointer in the circular buffer should go back to zero
	  if (_write>=_ndata)
	    _write=0;
	}

    }

  template <class T>
    void Circular_Buffer<T>::put(const Array<T>& in)
    {
      for (int i=0;i<in.size();i++)
	{
	  //Remove the oldest element of the buffer if the buffer is full
	  if (_rw_dist>=_ndata)
	    {
	      T dummy;
	      get(dummy);
	    }

	  //Write data to the buffer and move the pointer to the next buffer slot
	  _data[_write]=in(i);
	  _write++;
	  _rw_dist++;

	  //Check if the pointer in the circular buffer should go back to zero
	  if (_write>=_ndata)
	    _write=0;
	}
    }

  template <class T>
    void Circular_Buffer<T>::clear()
    {
      _write   = 0;
      _read    = 0;
      _rw_dist = 0;
    }

  template<class T>
    void Circular_Buffer<T>::alloc(int n)
    {
      if (n == 0) {
	_ndata = 0;
	_data  = NULL;
      }
      else if (n>0) {
	_ndata = n;
	_data = new T[_ndata];
	it_assert(_data!=0, "Out of memory in Circular_Buffer::alloc");
      }
      else {
	it_error("Circular_Buffer<T>::alloc(int n): n must be positive");
      }
    }

  template<class T>
    void Circular_Buffer<T>::free()
    {
      delete [] _data;

      _data    = NULL;
      _ndata   = 0;
      _write   = 0;
      _read    = 0;
      _rw_dist = 0;
    }

  template<class T>
    void Circular_Buffer<T>::operator=(const Circular_Buffer<T> &s)
    {
      set_size(s._ndata);
      for (int i=0; i<_ndata; i++)
	_data[i] = s._data[i];
      _read=s._read;
      _write=s._write;
      _rw_dist=_write-_read;
    }

  template<class T>
    void Circular_Buffer<T>::set_size(int sz, bool copy)
    {
      int i, min_nrof_elem;
      //T *tmp;
      Vec<T> tmp;

      if (_ndata == sz)
	return;

      if (copy)
	{
	  peek_reverse(tmp,-1);
	  min_nrof_elem = _rw_dist < sz ? _rw_dist : sz;
	  alloc(sz);
	  clear();
	  for (i=0; i<min_nrof_elem; i++)
	    put(tmp(min_nrof_elem-1-i));
	}
      else
	{
	  free();
	  alloc(sz);
	}

      _ndata = sz;
    }

} // namespace itpp

#endif // #ifndef CIRCULAR_BUFFER_H