/*=========================================================================

  Program:   Insight Segmentation & Registration Toolkit
  Module:    $RCSfile: itkNeighborhood.h,v $
  Language:  C++
  Date:      $Date: 2005/04/21 17:40:46 $
  Version:   $Revision: 1.40 $

  Copyright (c) Insight Software Consortium. All rights reserved.
  See ITKCopyright.txt or http://www.itk.org/HTML/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even 
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR 
     PURPOSE.  See the above copyright notices for more information.

=========================================================================*/
#ifndef __itkNeighborhood_h
#define __itkNeighborhood_h

#include <iostream>
#include "itkNeighborhoodAllocator.h"
#include "itkSize.h"
#include "itkIndent.h"
#include "itkSliceIterator.h"
#include "vnl/vnl_vector.h"
#include "itkOffset.h"
#include <vector>

namespace itk {
  
/** \class Neighborhood
 * \brief A light-weight container object for storing an N-dimensional
 * neighborhood of values. 
 *
 * This class serves as the base class for several other Itk objects such as
 * itk::NeighborhoodOperator and itk::NeighborhoodIterator.  Its purpose is to
 * store values and their relative spatial locations.
 *
 * A Neighborhood has an N-dimensional \em radius.  The radius is defined
 * separately for each dimension as the number of pixels that the neighborhood
 * extends outward from the center pixel.  For example, a 2D Neighborhood
 * object with a radius of 2x3 has sides of length 5x7.  Neighborhood objects
 * always have an unambiguous center because their side lengths are always odd.
 *
 * \sa Neighborhood
 * \sa NeighborhoodIterator
 * 
 * \ingroup Operators
 * \ingroup ImageIterators
 */

template<class TPixel, unsigned int VDimension = 2,
         class TAllocator = NeighborhoodAllocator<TPixel> >
class ITK_EXPORT Neighborhood 
{
public:
  /** Standard class typedefs. */
  typedef Neighborhood Self;

  /** External support for allocator type. */
  typedef TAllocator AllocatorType;

  /** External support for dimensionality. */
  itkStaticConstMacro(NeighborhoodDimension, unsigned int, VDimension);
  
  /** External support for pixel type. */
  typedef TPixel PixelType;
  
  /** Iterator typedef support. Note the naming is intentional, i.e.,
  * ::iterator and ::const_iterator, because the allocator may be a
  * vnl object or other type, which uses this form. */
  typedef typename AllocatorType::iterator Iterator;
  typedef typename AllocatorType::const_iterator ConstIterator;
  
  /** Size and value typedef support. */
  typedef Size<VDimension> SizeType;
  typedef typename SizeType::SizeValueType SizeValueType;
  
  /** Radius typedef support. */
  typedef Size<VDimension> RadiusType;

  /** Offset type used to reference neighbor locations */
  typedef Offset<VDimension> OffsetType;
  
  /** External slice iterator type typedef support. */
  typedef SliceIterator<TPixel, Self> SliceIteratorType;
  
  /** Default constructor. */
  Neighborhood() { m_Radius.Fill(0); m_Size.Fill(0);  }

  /** Default destructor. */
  virtual ~Neighborhood() {}
    
  /** Copy constructor. */
  Neighborhood(const Self& other);

  /** Assignment operator. */
  Self &operator=(const Self& other);

  /** Comparison operator. */
  bool
  operator==(const Self& other) const
  {
    return (m_Radius == other.m_Radius &&
            m_Size   == other.m_Size &&
            m_DataBuffer == other.m_DataBuffer);
  }

  /** Not Equal operator. */
  bool operator!=(const Self& other) const
  {
    return (m_Radius != other.m_Radius ||
            m_Size   != other.m_Size ||
            m_DataBuffer != other.m_DataBuffer);
  }

  /** Returns the radius of the neighborhood. */
  const SizeType GetRadius() const
    { return m_Radius; }

  /** Returns the radius of the neighborhood along a specified
   * dimension. */
  unsigned long GetRadius(const unsigned long n) const
    { return m_Radius[n]; }

  /** Returns the size (total length) of the neighborhood along
   * a specified dimension. */
  unsigned long GetSize(const unsigned long n) const
    { return m_Size[n]; }

  /** Returns the size (total length of sides) of the neighborhood. */
  SizeType GetSize() const
    { return m_Size; }
  
  /** Returns the stride length for the specified dimension. Stride
   * length is the number of pixels between adjacent pixels along the
   * given dimension. */
  unsigned GetStride(const unsigned axis) const
  {     return m_StrideTable[axis];  }
  
  /** STL-style iterator support. */
  Iterator End()
    { return m_DataBuffer.end(); }
  Iterator Begin()
    { return m_DataBuffer.begin(); }
  ConstIterator End() const
    { return m_DataBuffer.end(); }
  ConstIterator Begin() const
    { return m_DataBuffer.begin(); }
  
  /** More STL-style support. */
  unsigned int Size() const
    { return m_DataBuffer.size(); }
  
  /** Pass-through data access methods to the buffer. */
  TPixel &operator[](unsigned int i)
    { return m_DataBuffer[i]; }
  const TPixel &operator[](unsigned int i) const
  { return m_DataBuffer[i]; }
  TPixel &GetElement(unsigned int i) 
  { return m_DataBuffer[i]; }

  /** Returns the element at the center of the neighborhood. */
  TPixel GetCenterValue() const
  {    return (this->operator[]((this->Size())>>1)); }

  /** Sets the radius for the neighborhood, calculates size from the
   * radius, and allocates storage. */
  void SetRadius(const SizeType &);

  /** Sets the radius for the neighborhood. Overloaded to support an unsigned
   * long array. */
  void SetRadius(const unsigned long *rad)
  {
    SizeType s;
    memcpy(s.m_Size, rad, sizeof(unsigned long) * VDimension);
    this->SetRadius(s);
  }
  
  /** Overloads SetRadius to allow a single long integer argument
   * that is used as the radius of all the dimensions of the
   * Neighborhood (resulting in a "square" neighborhood). */
  void SetRadius(const unsigned long);

  /** Standard itk object method. */
  void Print(std::ostream& os) const
    { this->PrintSelf(os, Indent(0));  }

  /** Returns a reference to the data buffer structure. */
  AllocatorType &GetBufferReference()
    { return m_DataBuffer; }
  const AllocatorType &GetBufferReference() const
    { return m_DataBuffer; }

  /** Get pixel value by offset */
  TPixel &operator[](const OffsetType &o)
  {    return this->operator[](this->GetNeighborhoodIndex(o)); }
  const TPixel &operator[](const OffsetType &o) const
  { return this->operator[](this->GetNeighborhoodIndex(o)); }

  /** Returns the itk::Offset from the center of the Neighborhood to
      the requested neighbor index. */
  OffsetType GetOffset(unsigned int i) const
  {    return m_OffsetTable[i];  }

  virtual unsigned int GetNeighborhoodIndex(const OffsetType &) const;

  unsigned int GetCenterNeighborhoodIndex() const
  { return  static_cast<unsigned int>(this->Size()/2); }
    
  std::slice GetSlice(unsigned int) const;
  
protected:
  /** Sets the length along each dimension. */
  void SetSize()
  {
    for (unsigned int i=0; i<VDimension; ++i)
      { m_Size[i] = m_Radius[i]*2+1; }
  }

  /** Allocates the neighborhood's memory buffer. */
  virtual void Allocate(unsigned int i)
    { m_DataBuffer.set_size(i); }

  /** Standard itk object method. */
  virtual void PrintSelf(std::ostream&, Indent) const;

  /** Computes the entries for the stride table */
  virtual void ComputeNeighborhoodStrideTable();

  /** Fills entries into the offset lookup table. Called once on
      initialization. */
  virtual void ComputeNeighborhoodOffsetTable();

private:
  /** Number of neighbors to include (symmetrically) along each axis.
   * A neighborhood will always have odd-length axes (m_Radius[n]*2+1). */
  SizeType m_Radius;

  /** Actual length of each dimension, calculated from m_Radius.
   * A neighborhood will always have odd-length axes (m_Radius[n]*2+1). */
  SizeType m_Size;

  /** The buffer in which data is stored. */
  AllocatorType m_DataBuffer;

  /** A lookup table for keeping track of stride lengths in a neighborhood
      i.e. the memory offsets between pixels along each dimensional axis */
  unsigned int m_StrideTable[VDimension];

  /** */
  std::vector<OffsetType> m_OffsetTable;

};

template <class TPixel, unsigned int VDimension, class TContainer>
std::ostream & operator<<(std::ostream &os, const Neighborhood<TPixel,VDimension,TContainer> &neighborhood)
{
  os << "Neighborhood:" << std::endl;
  os << "    Radius:" << neighborhood.GetRadius() << std::endl;
  os << "    Size:" << neighborhood.GetSize() << std::endl;
  os << "    DataBuffer:" << neighborhood.GetBufferReference() << std::endl;

  return os;
}

} // namespace itk

#ifndef ITK_MANUAL_INSTANTIATION
#include "itkNeighborhood.txx"
#endif

#endif
