/****************************************************************************
 *   This file is part of the aGrUM/pyAgrum library.                        *
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 *   Copyright (c) 2005-2026 by                                             *
 *       - Pierre-Henri WUILLEMIN(_at_LIP6)                                 *
 *       - Christophe GONZALES(_at_AMU)                                     *
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 *   SPDX-FileCopyrightText: Copyright 2005-2026                            *
 *       - Pierre-Henri WUILLEMIN(_at_LIP6)                                 *
 *       - Christophe GONZALES(_at_AMU)                                     *
 *   SPDX-License-Identifier: LGPL-3.0-or-later OR MIT                      *
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 *   Contact  : info_at_agrum_dot_org                                       *
 *   homepage : http://agrum.gitlab.io                                      *
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/** @file
 * @brief the class for computing G2 scores
 *
 * @author Christophe GONZALES(_at_AMU) and Pierre-Henri WUILLEMIN(_at_LIP6)
 */

#ifndef GUM_LEARNING_INDEP_TEST_G2_H
#define GUM_LEARNING_INDEP_TEST_G2_H

#include <agrum/base/stattests/independenceTest.h>
#include <agrum/BN/learning/priors/noPrior.h>

namespace gum {

  namespace learning {

    /**
     * @class IndepTestG2
     * @headerfile indepTestG2.h <agrum/BN/learning/scores/indepTestG2.h>
     * @brief the class for computing G2 independence test scores
     * @ingroup learning_scores
     */
    // clang-format on

    class IndepTestG2: public IndependenceTest {
      public:
      // ##########################################################################
      /// @name Constructors / Destructors
      // ##########################################################################
      /// @{

      /// default constructor
      /** @param parser the parser used to parse the database
       * @param external_prior An prior that we add to the computation
       * of the score (this should come from expert knowledge): this consists in
       * adding numbers to counts in the contingency tables
       * @param ranges a set of pairs {(X1,Y1),...,(Xn,Yn)} of database's rows
       * indices. The counts are then performed only on the union of the
       * rows [Xi,Yi), i in {1,...,n}. This is useful, e.g, when performing
       * cross validation tasks, in which part of the database should be ignored.
       * An empty set of ranges is equivalent to an interval [X,Y) ranging over
       * the whole database.
       * @param nodeId2Columns a mapping from the ids of the nodes in the
       * graphical model to the corresponding column in the DatabaseTable
       * parsed by the parser. This enables estimating from a database in
       * which variable A corresponds to the 2nd column the parameters of a BN
       * in which variable A has a NodeId of 5. An empty nodeId2Columns
       * bijection means that the mapping is an identity, i.e., the value of a
       * NodeId is equal to the index of the column in the DatabaseTable.
       * @warning If nodeId2columns is not empty, then only the scores over the
       * ids belonging to this bijection can be computed: applying method
       * score() over other ids will raise exception NotFound. */
      IndepTestG2(const DBRowGeneratorParser&                                 parser,
                  const Prior&                                                external_prior,
                  const std::vector< std::pair< std::size_t, std::size_t > >& ranges,
                  const Bijection< NodeId, std::size_t >&                     nodeId2columns
                  = Bijection< NodeId, std::size_t >());


      /// default constructor
      /** @param parser the parser used to parse the database
       * @param prior An prior that we add to the computation of the score
       * @param nodeId2Columns a mapping from the ids of the nodes in the
       * graphical model to the corresponding column in the DatabaseTable
       * parsed by the parser. This enables estimating from a database in
       * which variable A corresponds to the 2nd column the parameters of a BN
       * in which variable A has a NodeId of 5. An empty nodeId2Columns
       * bijection means that the mapping is an identity, i.e., the value of a
       * NodeId is equal to the index of the column in the DatabaseTable.
       * @warning If nodeId2columns is not empty, then only the scores over the
       * ids belonging to this bijection can be computed: applying method
       * score() over other ids will raise exception NotFound. */
      IndepTestG2(const DBRowGeneratorParser&             parser,
                  const Prior&                            prior,
                  const Bijection< NodeId, std::size_t >& nodeId2columns
                  = Bijection< NodeId, std::size_t >());

      /// copy constructor
      IndepTestG2(const IndepTestG2& from);

      /// move constructor
      IndepTestG2(IndepTestG2&& from) noexcept;

      /// virtual copy constructor
      [[nodiscard]] IndepTestG2* clone() const override;

      /// destructor
      ~IndepTestG2() override;

      /// @}


      // ##########################################################################
      /// @name Operators
      // ##########################################################################

      /// @{

      /// copy operator
      IndepTestG2& operator=(const IndepTestG2& from);

      /// move operator
      IndepTestG2& operator=(IndepTestG2&& from) noexcept;

      /// get the pair <G2statistic,pvalue> for a test var1 indep var2 given
      /// rhs_ids
      std::pair< double, double >
          statistics(NodeId var1, NodeId var2, const std::vector< NodeId >& rhs_ids = {}) override;

      /// @}


      protected:
      /// compute the pair <G2 statistic,pvalue>
      std::pair< double, double > statistics_(const IdCondSet& idset);

#ifndef DOXYGEN_SHOULD_SKIP_THIS
#endif /* DOXYGEN_SHOULD_SKIP_THIS */
    };

  } /* namespace learning */

} /* namespace gum */

// include the inlined functions if necessary
#ifndef GUM_NO_INLINE
#  include <agrum/base/stattests/indepTestG2_inl.h>
#endif /* GUM_NO_INLINE */

#endif /* GUM_LEARNING_INDEP_TEST_G2_H */
