#pragma once

#include <iterator>
#include <concepts>
#include <utility>


///////////////////////////////////////////////////////////////////////////////
// C++ named requirements
namespace cruft::concepts::named {
    /// Corresponds to the "Container" named requirement.
    template <class T>
    concept container =
        std::default_initializable<T> and
        std::copy_constructible<T> and
        std::move_constructible<T> and
        std::destructible<T> and
        std::equality_comparable<T> and
        requires (T a, T b)
    {
        typename T::value_type;
        typename T::reference;
        typename T::const_reference;
        typename T::iterator;
        typename T::const_iterator;
        typename T::difference_type;
        typename T::size_type;

        { a = b } -> std::same_as<T&>;
        { a = std::move (b) } -> std::same_as<T&>;

        { a.begin  () } -> std::same_as<typename T::iterator>;
        { a.end    () } -> std::same_as<typename T::iterator>;
        { a.cbegin () } -> std::same_as<typename T::const_iterator>;
        { a.cend   () } -> std::same_as<typename T::const_iterator>;

        { a.swap (b)  } -> std::same_as<void>;
        { std::swap (a, b) } -> std::same_as<void>;

        { a.size () } -> std::same_as<typename T::size_type>;
        { a.max_size () } -> std::same_as<typename T::size_type>;
        { a.empty () } -> std::same_as<bool>;
    };


    template <typename T>
    concept move_assignable =
    requires (T a, T b)
    {
        { a = std::move (b) } -> std::same_as<T&>;
    };


    template <typename T>
    concept copy_assignable =
    move_assignable<T> &&
    requires (T a, T b)
    {
        { a = b } -> std::same_as<T&>;
    };


    template <typename T>
    concept legacy_iterator =
    std::copy_constructible<T> &&
    copy_assignable<T> &&
        std::destructible<T> &&
    std::swappable<T> &&
    requires (T t)
    {
        typename std::iterator_traits<T>::value_type;
        typename std::iterator_traits<T>::difference_type;
        typename std::iterator_traits<T>::reference;
        typename std::iterator_traits<T>::pointer;
        typename std::iterator_traits<T>::iterator_category;

        {  *t };
        { ++t } -> std::same_as<T&>;
    };

    template <typename T>
    concept legacy_input_iterator =
    legacy_iterator<T> &&
    std::equality_comparable<T> &&
    requires (T a, T b)
    {
        typename std::iterator_traits<T>::reference;
        typename std::iterator_traits<T>::value_type;
        { a != b } -> std::same_as<bool>;

        { ++a } -> std::same_as<T&>;
        { a++ };
    };
}