#include <DB/Interpreters/Dictionaries.h>
#include <DB/Dictionaries/DictionaryFactory.h>
#include <Poco/Util/XMLConfiguration.h>


namespace DB
{

namespace
{
	template <typename T> struct release
	{
		void operator()(const T * const ptr) { ptr->release(); }
	};
	template <typename T> using config_ptr_t = std::unique_ptr<T, release<T>>;
};

void Dictionaries::reloadExternalDictionaries()
{
	const auto config_path = Poco::Util::Application::instance().config().getString("dictionaries_config");
	const config_ptr_t<Poco::Util::XMLConfiguration> config{new Poco::Util::XMLConfiguration{config_path}};

	/// get all dictionaries' definitions
	Poco::Util::AbstractConfiguration::Keys keys;
	config->keys(keys);

	/// for each dictionary defined in xml config
	for (const auto & key : keys)
	{
		if (0 != strncmp(key.data(), "dictionary", strlen("dictionary")))
		{
			/// @todo maybe output a warning
			continue;
		}

		std::cout << key << std::endl;
		const auto & prefix = key + '.';

		const auto & name = config->getString(prefix + "name");
		if (name.empty())
		{
			/// @todo handle error, dictionary name cannot be empty
		}

		auto dict_ptr = DictionaryFactory::instance().create();
		const auto it = external_dictionaries.find(name);
		if (it == std::end(external_dictionaries))
		{
			external_dictionaries.emplace(name, std::make_shared<MultiVersion<IDictionary>>(dict_ptr.release()));
		}
		else
		{
			it->second->set(dict_ptr.release());
		}
	}
};

}