// Copyright (c) 2001,2004  INRIA Sophia-Antipolis (France).
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org)
//
// $URL: https://github.com/CGAL/cgal/blob/v6.1/Filtered_kernel/include/CGAL/Filtered_kernel.h $
// $Id: include/CGAL/Filtered_kernel.h b26b07a1242 $
// SPDX-License-Identifier: LGPL-3.0-or-later OR LicenseRef-Commercial
//
//
// Author(s)     : Sylvain Pion

#ifndef CGAL_FILTERED_KERNEL_H
#define CGAL_FILTERED_KERNEL_H

#include <CGAL/Filtered_kernel_fwd.h>
#include <CGAL/basic.h>
#include <CGAL/Filtered_predicate.h>
#include <CGAL/Cartesian_converter.h>
#include <CGAL/Simple_cartesian.h>
#include <CGAL/Kernel/Type_equality_wrapper.h>
#include <CGAL/Exact_kernel_selector.h>

#include <CGAL/Filtered_kernel/internal/Static_filters/Static_filters.h>
#include <boost/type_traits.hpp>

// This file contains the definition of a generic kernel filter.
//
// TODO:
// - at the moment, only the predicates are filtered.
//   Constructions will come later.
// - the kernel provides the traits interface, as well as type equality.
//   Having the global functions working is another story...
// - The converters are more a property of the types rather than anything else,
//   so maybe they should not be passed as template parameter, but use a
//   traits-like mechanism ?

namespace CGAL {

// CK = eventually rebound construction kernel (gets Point_2 from).
// Exact_kernel = exact kernel called when needed by the filter.
// Approximate_kernel = filtering "interval" kernel
template < typename CK >
struct Filtered_kernel_base
  : public CK
{
  // Use Exact_kernel_selector as a base class?
    typedef typename Exact_kernel_selector<CK>::Exact_nt        Exact_nt;
    typedef typename Exact_kernel_selector<CK>::Exact_kernel    Exact_kernel;
    typedef typename Exact_kernel_selector<CK>::Exact_kernel_rt Exact_kernel_rt;
    typedef typename Exact_kernel_selector<CK>::C2E             C2E;
    typedef typename Exact_kernel_selector<CK>::C2E_rt          C2E_rt;

    typedef Simple_cartesian<Interval_nt_advanced>        Approximate_kernel;
    typedef Cartesian_converter<CK, Approximate_kernel>   C2F;

    enum { Has_filtered_predicates = true };
    typedef Boolean_tag<Has_filtered_predicates> Has_filtered_predicates_tag;

    template < typename Kernel2 >
    struct Base {
        typedef typename CK::template Base<Kernel2> CK2;
        typedef Filtered_kernel_base<CK2>  Type;
    };

    template < typename T >
    struct Ambient_dimension {
        typedef typename T::Ambient_dimension type; // maybe not the right way...
    };

    template < typename T >
    struct Feature_dimension {
        typedef typename T::Feature_dimension type; // maybe not the right way...
    };

    Exact_kernel exact_kernel() const { return {}; }
    Approximate_kernel approximate_kernel() const { return {}; }

    // We change the predicates.
#define CGAL_Kernel_pred_RT_or_FT(P, Pf) \
    typedef Filtered_predicate_RT_FT<typename Exact_kernel_rt::P, \
                                     typename Exact_kernel::P, \
                                     typename Approximate_kernel::P, \
                                    C2E_rt, \
                                    C2E, \
                                    C2F> P; \
    P Pf() const { return P(); }

#define CGAL_Kernel_pred(P, Pf) CGAL_Kernel_pred_RT_or_FT(P, Pf)

    // We don't touch the constructions.
#define CGAL_Kernel_cons(Y,Z)

#include <CGAL/Kernel/interface_macros.h>

};

template < typename CK >
struct Static_filters_base
  : public internal::Static_filters< Filtered_kernel_base<CK> >
{
    template < typename Kernel2 >
    struct Base {
        typedef typename CK::template Base<Kernel2>::Type  CK2;
        typedef Static_filters_base<CK2>                   Type;
    };
};

#ifdef CGAL_NO_STATIC_FILTERS
template < typename CK, bool UseStaticFilters = false >
#else
template < typename CK, bool UseStaticFilters = true >
#endif
struct Filtered_kernel_adaptor
  : public Filtered_kernel_base<CK>
{
        enum { Has_static_filters = false };
};

template < typename CK >
struct Filtered_kernel_adaptor<CK, true>
  : public Static_filters_base<CK>
{
        enum { Has_static_filters = true };
};

// UseStaticFilters has a default value, depending on
// CGAL_NO_STATIC_FILTERS. See in <CGAL/Filtered_kernel_fwd.h>.
template < typename CK, bool UseStaticFilters >
struct Filtered_kernel
  : public Filtered_kernel_adaptor<
               Type_equality_wrapper<
                   typename CK:: template Base< Filtered_kernel<CK, UseStaticFilters> >::Type,
                   Filtered_kernel<CK, UseStaticFilters> >,
               UseStaticFilters >
{};

} //namespace CGAL

#endif // CGAL_FILTERED_KERNEL_H

