// This source code is released into the public domain.
export module nihil.config:store;

// The configuration store.  There should only be one of these.

import nihil.std;
import nihil.error;
import nihil.generator;

namespace nihil::config {

export struct option;

struct store final {
	/*
	 * Get the global config store.
	 */
	[[nodiscard]] static auto get() -> store &;

	/*
	 * Register a new value with the config store.
	 */
	[[nodiscard]] auto register_option(this store &, option *object)
		-> std::expected<void, error>;

	/*
	 * Remove a value from the config store.
	 */
	[[nodiscard]] auto unregister_option(this store &, option *object)
		-> std::expected<void, error>;

	/*
	 * Fetch an existing value in the config store.
	 */
	[[nodiscard]] auto fetch(this store const &, std::string_view name)
		-> std::expected<option const *, error>;
	[[nodiscard]] auto fetch(this store &, std::string_view name)
		-> std::expected<option *, error>;

	/*
	 * Fetch all values in the configuration store.
	 */
	[[nodiscard]] auto all(this store const &self)
		-> nihil::generator<option const *>;
	[[nodiscard]] auto all(this store &self)
		-> nihil::generator<option *>;

	// Not movable or copyable.
	store(store const &) = delete;
	store(store &&) = delete;
	auto operator=(store const &) -> store & = delete;
	auto operator=(store &&) -> store & = delete;

private:
	store();

	std::map<std::string_view, option *> m_options;
};

/*
 * The public API.
 */
export auto get_option(std::string_view option_name)
	-> std::expected<option *, error>;

} // namespace nihil::config