Endpoint.h

/*
	This file is part of duckOS.

	duckOS is free software: you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation, either version 3 of the License, or
	(at your option) any later version.

	duckOS is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with duckOS.  If not, see <https://www.gnu.org/licenses/>.

	Copyright (c) Byteduck 2016-2021. All rights reserved.
*/

#pragma once

#include <string>
#include <functional>
#include <optional>
#include "BusConnection.h"
#include <libduck/Log.h>

namespace River {
	class IFunction;
	template<typename RetT, typename... ArgTs>
	class Function;
	class BusConnection;
	class IMessage;
	template<typename T>
	class Message;

	template<typename T>
	struct type_identity {
		using type = T;
	};

	class Endpoint: public std::enable_shared_from_this<Endpoint> {
	public:
		enum ConnectionType { PROXY, HOST };

		Endpoint(std::shared_ptr<BusConnection> bus, const std::string& name, ConnectionType type);

		template<typename RetT, typename... ParamTs>
		Duck::ResultRet<Function<RetT, ParamTs...>> register_function(const std::string& path, typename type_identity<std::function<RetT(sockid_t, ParamTs...)>>::type callback) {
			auto stringname = Function<RetT, ParamTs...>::stringname_of(path);

			if(_functions[stringname])
				return *std::dynamic_pointer_cast<Function<RetT, ParamTs...>>(_functions[path]);

			_bus->send_packet({
				REGISTER_FUNCTION,
				_name,
				stringname
			});

			auto packet = _bus->await_packet(REGISTER_FUNCTION, _name, stringname);
			if(packet.error) {
				Duck::Log::err("[River] Couldn't register function ", _name, ":", path, ": ", error_str(packet.error));
				return Duck::Result(packet.error);
			}

			auto ret = std::make_shared<Function<RetT, ParamTs...>>(path, shared_from_this(), callback);
			_functions[stringname] = ret;
			return *ret;
		}

		template<typename RetT, typename... ParamTs, typename FuncT, typename ClassT>
		Duck::Result bind_function(const std::string& path, FuncT func, ClassT* obj) {
			auto ret = register_function<RetT, ParamTs...>(path, [=](auto&&... args) {
				return (obj->*func)(std::forward<decltype(args)>(args)...);
			});

			return ret.result();
		}

		template<typename RetT, typename... ParamTs>
		Duck::ResultRet<Function<RetT, ParamTs...>> get_function(const std::string& path) {
			auto stringname = Function<RetT, ParamTs...>::stringname_of(path);

			if(_functions[stringname])
				return *std::dynamic_pointer_cast<Function<RetT, ParamTs...>>(_functions[path]);

			_bus->send_packet({
				GET_FUNCTION,
				_name,
				stringname
			});

			auto packet = _bus->await_packet(River::GET_FUNCTION, _name, stringname);
			if(packet.error) {
				Duck::Log::err("[River] Couldn't get function ", _name, ":", path, ": ", error_str(packet.error));
				return Duck::Result(packet.error);
			}

			auto ret = std::make_shared<Function<RetT, ParamTs...>>(path, shared_from_this());
			_functions[stringname] = ret;
			return *ret;
		}

		template<typename RetT, typename... ParamTs>
		Duck::Result get_function(const std::string& path, Function<RetT, ParamTs...>& storage) {
			auto res = get_function<RetT, ParamTs...>(path);
			if(res.is_error())
				return res.result();
			storage = res.value();
			return Duck::Result::SUCCESS;
		}

		template<typename RetT, typename... ParamTs>
		Duck::Result get_function(Function<RetT, ParamTs...>& storage) {
			auto res = get_function<RetT, ParamTs...>(storage.path());
			if(res.is_error())
				return res.result();
			storage = res.value();
			return Duck::Result::SUCCESS;
		}

		template<typename T>
		Duck::ResultRet<Message<T>> register_message(const std::string& path) {
			auto stringname = Message<T>::stringname_of(path);

			if(_messages[stringname])
				return *std::dynamic_pointer_cast<Message<T>>(_messages[path]);

			_bus->send_packet({
				REGISTER_MESSAGE,
				_name,
				stringname
			});

			auto packet = _bus->await_packet(River::REGISTER_MESSAGE, _name, stringname);
			if(packet.error) {
				Duck::Log::err("[River] Couldn't register message ", _name, ":", path, ": ", error_str(packet.error));
				return Duck::Result(packet.error);
			}

			auto ret = std::make_shared<Message<T>>(path, shared_from_this());
			_messages[stringname] = ret;
			return *ret;
		}

		template<typename T>
		Duck::Result send_message(const std::string& path, sockid_t recipient, const T& data) {
			auto stringname = Message<T>::stringname_of(path);
			auto msg = _messages[stringname];
			if(!msg) {
				Duck::Log::err("[River] Couldn't send unregistered message ", _name, ":", path);
				return MESSAGE_DOES_NOT_EXIST;
			}
			return std::dynamic_pointer_cast<Message<T>>(msg)->send(recipient, data);
		}

		template<typename T>
		Duck::Result set_message_handler(const std::string& path, typename type_identity<std::function<void(T)>>::type callback) {
			auto stringname = Message<T>::stringname_of(path);

			if(_messages[stringname])
				return Duck::Result(MESSAGE_HANDLER_ALREADY_SET);

			_bus->send_packet({
				GET_MESSAGE,
				_name,
				stringname
			});

			auto packet = _bus->await_packet(River::GET_MESSAGE, _name, stringname);
			if(packet.error) {
				Duck::Log::err("[River] Couldn't get message ", _name, ":", path, ": ", error_str(packet.error));
				return Duck::Result(packet.error);
			}

			auto ret = std::make_shared<Message<T>>(path, shared_from_this(), callback);
			_messages[stringname] = ret;
			return Duck::Result(SUCCESS);
		}

		std::shared_ptr<IFunction> get_ifunction(const std::string& path);
		std::shared_ptr<IMessage> get_imessage(const std::string& path);

		const std::string& name();
		ConnectionType type() const;
		const std::shared_ptr<BusConnection>& bus();

		std::function<void(sockid_t, pid_t)> on_client_connect = nullptr;
		std::function<void(sockid_t, pid_t)> on_client_disconnect = nullptr;
	private:
		std::map<std::string, std::shared_ptr<IFunction>> _functions;
		std::map<std::string, std::shared_ptr<IMessage>> _messages;
		std::string _name;
		ConnectionType _type;
		std::shared_ptr<BusConnection> _bus;
	};
}