/****************************************************************************
 Copyright (c) 2020-2023 Xiamen Yaji Software Co., Ltd.

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 of this software and associated documentation files (the "Software"), to deal
 in the Software without restriction, including without limitation the rights to
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 of the Software, and to permit persons to whom the Software is furnished to do so,
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 The above copyright notice and this permission notice shall be included in
 all copies or substantial portions of the Software.

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****************************************************************************/

#pragma once

#include <cstdint>
#include <limits>
#include <type_traits>

namespace cc {

template <typename Index, typename Enable = std::enable_if_t<std::is_integral<Index>::value>>
class IndexHandle {
public:
    struct Hasher {
        inline std::size_t operator()(IndexHandle const &s) const noexcept { return s._index; }
    };

    using IndexType = Index;

    IndexHandle() noexcept = default;
    explicit IndexHandle(IndexType index) noexcept : _index(index) {}

    inline bool isValid() const noexcept;
    inline void clear() noexcept;

    inline bool operator<(IndexHandle const &rhs) const noexcept;
    inline bool operator==(IndexHandle const &rhs) const noexcept;
    inline bool operator!=(IndexHandle const &rhs) const noexcept;
    inline operator IndexType() const noexcept; // NOLINT(google-explicit-constructor) we need this implicitly

    static IndexType constexpr UNINITIALIZED{std::numeric_limits<IndexType>::max()};

private:
    IndexType _index{UNINITIALIZED};
};

template <typename Index, typename Enable>
bool IndexHandle<Index, Enable>::isValid() const noexcept {
    return _index != UNINITIALIZED;
}

template <typename Index, typename Enable>
void IndexHandle<Index, Enable>::clear() noexcept {
    _index = UNINITIALIZED;
}

template <typename Index, typename Enable>
bool IndexHandle<Index, Enable>::operator<(IndexHandle const &rhs) const noexcept {
    return _index < rhs._index;
}

template <typename Index, typename Enable>
bool IndexHandle<Index, Enable>::operator==(IndexHandle const &rhs) const noexcept {
    return (_index == rhs._index);
}

template <typename Index, typename Enable>
bool IndexHandle<Index, Enable>::operator!=(IndexHandle const &rhs) const noexcept {
    return !operator==(rhs);
}

template <typename Index, typename Enable>
IndexHandle<Index, Enable>::operator IndexType() const noexcept {
    return _index;
}

} // namespace cc
