LinksUniquenessResolver.h

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namespace Platform::Data::Doublets::Decorators
{
    template <typename TFacade, typename TDecorated>
    struct LinksUniquenessResolver : DecoratorBase<TFacade, TDecorated>
    {
      public:
        using base = DecoratorBase<TFacade, TDecorated>;
        using base::Constants;
        using typename base::LinkAddressType;
        using typename base::LinkType;
        using typename base::ReadHandlerType;
        using typename base::WriteHandlerType;
 
      public:
        USE_ALL_BASE_CONSTRUCTORS(LinksUniquenessResolver, base);
 
      public:
        LinkAddressType Update(const LinkType& restriction, const LinkType& substitution,
                               const WriteHandlerType& handler)
        {
            auto newLinkAddress = SearchOrDefault(this->decorated(), substitution[Constants.SourcePart],
                                                  substitution[Constants.TargetPart]);
            if (newLinkAddress == LinkAddressType{})
            {
                return this->decorated().TDecorated::Update(restriction, substitution, handler);
            }
            return this->ResolveAddressChangeConflict(restriction[Constants.IndexPart], newLinkAddress, handler);
        }
 
      public:
        LinkAddressType ResolveAddressChangeConflict(LinkAddressType oldLinkAddress, LinkAddressType newLinkAddress,
                                                     const WriteHandlerType& handler)
        {
            if (oldLinkAddress != newLinkAddress && Exists(this->decorated(), oldLinkAddress))
            {
                this->facade().Delete(LinkType{oldLinkAddress}, handler);
            }
            return Constants.Continue;
        }
    };
} // namespace Platform::Data::Doublets::Decorators