#include "name_service.h"

namespace NSQLComplete {

namespace {

class TNameService: public INameService {
public:
    TNameService(IDocumentation::TPtr docs, INameService::TPtr origin)
        : Docs_(std::move(docs))
        , Origin_(std::move(origin))
    {
    }

    NThreading::TFuture<TNameResponse> Lookup(const TNameRequest& request) const override {
        return Origin_->Lookup(request).Apply([docs = Docs_, constraints = request.Constraints](auto f) {
            TNameResponse response = f.ExtractValue();
            for (TGenericName& name : response.RankedNames) {
                name = std::visit([&](auto&& name) -> TGenericName {
                    using T = std::decay_t<decltype(name)>;

                    if constexpr (std::is_base_of_v<TDescribed, T> &&
                                  std::is_base_of_v<TIdentifier, T>) {
                        T qualified = std::get<T>(constraints.Qualified(name));
                        name.Description = docs->Lookup(qualified.Identifier);
                    }

                    return std::forward<decltype(name)>(name);
                }, std::move(name));
            }
            return response;
        });
    }

private:
    IDocumentation::TPtr Docs_;
    INameService::TPtr Origin_;
};

} // namespace

INameService::TPtr MakeDocumentingNameService(IDocumentation::TPtr docs, INameService::TPtr origin) {
    return new TNameService(std::move(docs), std::move(origin));
}

} // namespace NSQLComplete