#pragma once

#include "byte_size.h"

#include <library/cpp/threading/future/future.h>

#include <util/generic/ptr.h>
#include <util/datetime/base.h>

namespace NSQLComplete {

namespace NPrivate {

template <class T>
concept CHashable = requires(const T& x) {
    { THash<T>()(x) } -> std::convertible_to<std::size_t>;
};

template <class T>
concept CCacheKey = std::regular<T> && CHashable<T> && CByteSized<T>;

template <class T>
concept CCacheValue = std::copyable<T> && CByteSized<T>;

}; // namespace NPrivate

template <NPrivate::CCacheKey TKey, NPrivate::CCacheValue TValue>
class ICache: public TThrRefBase {
public:
    using TPtr = TIntrusivePtr<ICache>;

    struct TEntry {
        TMaybe<TValue> Value = Nothing();
        bool IsExpired = true;
    };

    ~ICache() override = default;
    virtual NThreading::TFuture<TEntry> Get(const TKey& key) const = 0;
    virtual NThreading::TFuture<void> Update(const TKey& key, TValue value) const = 0;
};

} // namespace NSQLComplete