/*
 * FunctionArgument.hpp
 *
 *  Created on: 02.10.2012
 *      Author: heber
 */

#ifndef FUNCTIONARGUMENT_HPP_
#define FUNCTIONARGUMENT_HPP_

// include config.h
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <utility>
#include <iosfwd>

/** This class encapsulates all information with respect to a single argument
 *  for a high-dimensional model function.
 *
 *  We restrict ourselves here to a function that dependent on a set of
 *  three-dimensional vectors, i.e. a set of positions in space. And for
 *  the moment to distances in between these sets.
 *
 */
struct argument_t
{
  //!> grant operator access to private parts
  friend std::ostream& operator<<(std::ostream &ost, const argument_t &arg);

  //!> typedef for the two indices of the argument
  typedef std::pair<size_t, size_t> indices_t;

  /** Default constructor for class argument_t.
   *
   */
  argument_t() :
    indices( std::make_pair(0,1) ),
    distance(0.),
    globalid(-1)
  {}

  /** Constructor for class argument_t.
   *
   * This constructors uses the index pair (0,1) as default.
   *
   * \param _distance distance argument
   */
  argument_t(const double &_distance) :
    indices( std::make_pair(0,1) ),
    distance(_distance),
    globalid(-1)
  {}

  /** Constructor for class argument_t.
   *
   * \param _indices pair of indices associated with the \a _distance
   * \param _distance distance argument
   */
  argument_t(const indices_t &_indices, const double &_distance) :
    indices( _indices ),
    distance(_distance),
    globalid(-1)
  {}

  /** Comparator with respect to the distance.
   *
   * \note We'll have this as static function to allow usage in e.g. STL's sort.
   *
   * \param one first argument
   * \param other other argument to compare to \a one to
   * \return true - first distance is less
   */
  static bool DistanceComparator(const argument_t &one, const argument_t &other)
  {
    return one.distance < other.distance;
  }

  /** Comparator with respect to the pair of indices.
   *
   * \note We'll have this as static function to allow usage in e.g. STL's sort.
   *
   * \param one first argument
   * \param other other argument to compare to \a one to
   * \return true - first index is less or if equal, second index is less, else
   */
  bool static IndexComparator(const argument_t &one, const argument_t &other)
  {
    if (one.indices.first < other.indices.first)
      return true;
    else if (one.indices.first > other.indices.first)
      return false;
    else
      return one.indices.second < other.indices.second;
  }

  //!> indices between which the distance is given
  indices_t indices;
  //!> distance
  double distance;
  //!> global id refers to some global index, e.g. the configuration id in training set
  size_t globalid;
};

/** Print given \a arg to stream \a ost.
 *
 * \param ost output stream to print to
 * \param arg argument to print
 * \return output stream for concatenation
 */
std::ostream& operator<<(std::ostream &ost, const argument_t &arg);


#endif /* FUNCTIONARGUMENT_HPP_ */