// Copyright (c) 1997-2007  ETH Zurich (Switzerland).
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org).
//
// $URL: https://github.com/CGAL/cgal/blob/v5.6.1/QP_solver/include/CGAL/QP_solver/QP_exact_bland_pricing.h $
// $Id: QP_exact_bland_pricing.h 0779373 2020-03-26T13:31:46+01:00 Sébastien Loriot
// SPDX-License-Identifier: GPL-3.0-or-later OR LicenseRef-Commercial
//
//
// Author(s)     : Sven Schoenherr
//                 Bernd Gaertner <gaertner@inf.ethz.ch>
//                 Franz Wessendorp
//                 Kaspar Fischer

#ifndef CGAL_QP_EXACT_BLAND_PRICING_H
#define CGAL_QP_EXACT_BLAND_PRICING_H

#include <CGAL/license/QP_solver.h>


// includes
#include <CGAL/QP_solver/QP_pricing_strategy.h>

namespace CGAL {

// =================
// class declaration
// =================
template < typename Q, typename ET, typename Tags >
class QP_exact_bland_pricing;

// ===============
// class interface
// ===============
template < typename Q, typename ET, typename Tags >
class QP_exact_bland_pricing : public QP_pricing_strategy<Q,ET,Tags> {

  // self
  typedef  QP_pricing_strategy<Q,ET,Tags>    Base;
  typedef  QP_exact_bland_pricing<Q,ET,Tags>  Self;

  // types from the base class
  typedef  typename Tags::Is_nonnegative     Is_nonnegative;
  typedef  typename CGAL::QP_solver<Q,ET,Tags>    QP_solver;

 public:

  // creation
  QP_exact_bland_pricing();

  // operations
  int  pricing(int& direction );

  // cleanup
  ~QP_exact_bland_pricing() { };

 private:
  int pricing_helper(int& direction, Tag_true  /*is_in_standard_form*/);
  int pricing_helper(int& direction, Tag_false /*is_in_standard_form*/);
};

// ----------------------------------------------------------------------------

// =============================
// class implementation (inline)
// =============================

// construction
template < typename Q, typename ET, typename Tags >  inline
QP_exact_bland_pricing<Q,ET,Tags>::
QP_exact_bland_pricing()
  : QP_pricing_strategy<Q,ET,Tags>("full exact")
{ }

// operations
template < typename Q, typename ET, typename Tags >
int  QP_exact_bland_pricing<Q,ET,Tags>::
pricing(int& direction )
{
  return (pricing_helper(direction, Is_nonnegative()));
}

template < typename Q, typename ET, typename Tags >
int  QP_exact_bland_pricing<Q,ET,Tags>::
pricing_helper(int& /*direction*/, Tag_true /*is_in_standard_form*/)
{
  // get properties of quadratic program:
  int  w = this->solver().number_of_working_variables();

  // loop over all non-basic variables:
  int  j;
  ET   mu;
  for (j = 0; j < w; ++j) {

    // variable non-basic?
    if (!this->solver().is_basic(j)) {

      // don't price artificial variables:
      if (this->solver().is_artificial(j)) {
        CGAL_qpe_debug {
          this->vout() << "mu_" << j << ": artificial [ not priced ]"
                       << std::endl;
        }
        continue;
      }

      // compute mu_j:
      mu = this->mu_j(j);

      CGAL_qpe_debug {
        this->vout() << "mu_" << j << ": " << mu << std::endl;
      }

      // negative?
      if (mu < this->et0) return j;
    }
  }
  CGAL_qpe_debug {
    this->vout() << std::endl;
  }

  // fallback option
  return -1;

}

template < typename Q, typename ET, typename Tags >
int  QP_exact_bland_pricing<Q,ET,Tags>::
pricing_helper(int& direction, Tag_false /*is_in_standard_form*/)
{

  // get properties of quadratic program:
  int  w = this->solver().number_of_working_variables();

  // loop over all non-basic variables:
  int  j,  min_j  = -1;
  ET min_mu = this->et0;
  //
  for (j = 0; j < w; ++j) {

    // variable non-basic?
    if (!this->solver().is_basic(j)) {

      // don't price artificial variables:
      if (this->solver().is_artificial(j)) {
        CGAL_qpe_debug {
          this->vout() << "mu_" << j << ": artificial [ not priced ]"
                       << std::endl;
        }
        continue;
      }

      const ET mu = this->mu_j(j);
      // from pricing strategy base class
      this->price_dantzig (j, mu, this->et0, min_j, min_mu, direction);
      if (min_j >= 0) return j;
    }
  }
  CGAL_qpe_debug {
    this->vout() << std::endl;
  }
  // fallback option
  return -1;

}


} //namespace CGAL

#endif // CGAL_QP_EXACT_BLAND_PRICING_H

// ===== EOF ==================================================================

