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 *   SPDX-FileCopyrightText: Copyright 2005-2026                            *
 *       - Pierre-Henri WUILLEMIN(_at_LIP6)                                 *
 *       - Christophe GONZALES(_at_AMU)                                     *
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 ****************************************************************************/


/**
 * @file
 * @brief Headers of the Variable Selector class.
 *
 * @author Jean-Christophe MAGNAN
 */

// =========================================================================
#ifndef GUM_VARIABLE_SELECTOR_H
#define GUM_VARIABLE_SELECTOR_H
// =========================================================================
#include <agrum/base/core/multiPriorityQueue.h>
// =========================================================================
#include <agrum/base/variables/discreteVariable.h>

// =========================================================================

namespace gum {

  /**
   * @class VariableSelector variableselector.h
   * <agrum/FMDP/planning/FunctionGraph/variableselector.h>
   * @brief
   * @ingroup fmdp_group
   *
   *
   *
   */

  class VariableSelector {
    public:
    // ==========================================================================
    /// @name Constructor & destructor.
    // ==========================================================================
    /// @{

    // ###################################################################
    /// Default constructor
    // ###################################################################
    explicit VariableSelector(const gum::VariableSet& startingSet);

    // ###################################################################
    /// Default destructor
    // ###################################################################
    ~VariableSelector();

    /// @}

    // ==========================================================================
    /// @name
    // ==========================================================================
    /// @{

    // ###################################################################
    ///
    // ###################################################################
    void updateScore(const DiscreteVariable* var, double score, double secondaryscore);
    void downdateScore(const DiscreteVariable* var, double score, double secondaryscore);


    // ###################################################################
    /// Select the most relevant variable
    // ###################################################################
    const DiscreteVariable* select();

    bool isEmpty() const;

    void begin();

    bool hasNext() const;

    void next();

    const DiscreteVariable* current() const;

    private:
    void _addVar_(const DiscreteVariable* var);
    void _removeVar_(const DiscreteVariable* var);

    /// The set of remaining vars to select among
    gum::VariableSet                           _remainingVars_;
    SetIteratorSafe< const DiscreteVariable* > _rvi_;

    /// Heap keeping best score on top for immediate access
    MultiPriorityQueue< double, double, std::greater< double > > _remainingScores_;

    /// HashTable associating to each score the set of variable having that
    /// score
    HashTable< double, gum::VariableSet* > _remainingVarsByScore_;

    /// HashTable associating to each variable its score
    HashTable< const DiscreteVariable*, double > _remainingVarsScore_;

    /// HashTable associating to each variable its 2nd score
    HashTable< const DiscreteVariable*, double > _remainingVarsOtherScore_;
  };

}   // namespace gum

#ifndef GUM_NO_INLINE
#  include <agrum/FMDP/learning/datastructure/variableselector_inl.h>
#endif   // GUM_NO_INLINE
#endif   // GUM_VARIABLE_SELECTOR_H
