Phoenix/Phoenix/Common/Include/Common/CMS/ModManager.hpp

// Copyright 2019-20 Genten Studios
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#pragma once

#include <Common/Logger.hpp>

#include <sol/sol.hpp>

#include <functional>
#include <queue>
#include <vector>

namespace phx::cms
{
	/**
	 * @brief A class to handle all Mods that require loading.
	 *
	 * To be used in conjunction with saves. Each save stores a list of mods
	 * associated to the world stored.
	 */
	class ModManager
	{
	public:
		/**
		 * @brief The status of the ModManager during load.
		 *
		 * This will help tell if there was an error while loading mods.
		 */
		struct Status
		{
			/// @brief Boolean saying whether the operation was ok or not.
			bool ok;

			/// @brief If the operation failed, the error message will be stored
			/// in this.
			std::string what;
		};

		using ModList = std::vector<std::string>;

	public:
		ModManager() = delete;

		/**
		 * @brief Constructs the manager by initializing the Lua state.
		 * @param toLoad The list of mods to load.
		 * @param paths The list of directories a mod could be found in.
		 *
		 * The allowance for extra paths to be used makes sure that someone can
		 * have mods stored in different directories. This is especially helpful
		 * for developers since they can work on their mod and store it
		 * somewhere much more convenient for them while still being able to use
		 * it.
		 */
		explicit ModManager(const ModList& toLoad, const ModList& paths);

		/**
		 * @brief Registers a C++ function into Lua.
		 * @tparam F The function signature for the function being registered.
		 * @param funcName The name the function should have in the Lua.
		 * @param func The function itself, can be a lambda or std::function.
		 *
		 * FuncName should be laid out like so:
		 *		namespace.namespace.functionName
		 *
		 * Function hierarchies of greater than 3 sections are not allowed, so
		 * only two namespaces are allowed as of right now. For example:
		 *		core.block.register(...)
		 */
		template <typename F>
		void registerFunction(const std::string& funcName, F func);

		// unimplemented function, exists as a reminder for when we need it.
		template <typename T>
		void exposeVariable(const std::string& name, T var);

		/**
		 * @brief Loads the mods into the Lua state, ready for the game.
		 * @param The current progress of the loading.
		 * @return The status of the load, can dictate fail or success.
		 */
		Status load(float* progress);

		/**
		 * @brief Cleans up mods once ready.
		 *
		 * Currently unimplemented, but will be implemented with a mod.cleanup
		 * function registered in lua for safely shutting down the game.
		 */
		void cleanup();

		/**
		 * @brief Gets the list of mods being loaded.
		 * @return The list of loaded mods.
		 */
		const ModList&     getModList() const;

		/**
		 * @brief Gets the path of the currently loading mod.
		 * @return The path of the mod being currently loaded.
		 *
		 * This is useful when loading mods since some functions don't have
		 * information on the currently loading mod, making it difficult to use
		 * things like textures that are packaged with the mod.
		 */
		const std::string& getCurrentModPath() const;

	private:
		std::vector<std::string> m_modsRequired;
		std::vector<std::string> m_modPaths;
		std::string              m_currentModPath;

		sol::state m_luaState;
	};
} // namespace phx::cms

#include "ModManager.inl"