ADC/net/adc_netservice_asio.h

#pragma once

/*

            ABSTRACT DEVICE COMPONENTS LIBRARY

    ASIO-library implementation of network service

 */


#include <future>
#ifdef USE_ASIO_LIBRARY

#include <asio/awaitable.hpp>
#include <asio/basic_datagram_socket.hpp>
#include <asio/basic_seq_packet_socket.hpp>
#include <asio/basic_stream_socket.hpp>
#include <asio/compose.hpp>
#include <asio/experimental/awaitable_operators.hpp>
#include <asio/read_until.hpp>
#include <asio/steady_timer.hpp>
#include <asio/streambuf.hpp>
#include <asio/use_future.hpp>
#include <asio/write.hpp>

#include <concepts>

namespace adc::impl
{


template <typename NetMessageT, typename InetProtoT>
class AdcNetServiceASIO : public InetProtoT
{
public:
    using socket_t = typename InetProtoT::socket;
    using endpoint_t = typename InetProtoT::endpoint;

    using streambuff_iter_t = asio::buffers_iterator<asio::streambuf::const_buffers_type>;

    template <typename... CtorArgTs>
    AdcNetServiceASIO(socket_t& sock, CtorArgTs&&... ctor_args)
        : InetProtoT(std::forward<CtorArgTs>(ctor_args)...), _socket(sock)
    {
    }

    virtual ~AdcNetServiceASIO() = default;


    template <typename TimeoutT, asio::completion_token_for<void(std::error_code)> CompletionTokenT>
    auto asyncConnect(const endpoint_t& endpoint, const TimeoutT& timeout, CompletionTokenT&& token)
    {
        auto timer = getDeadlineTimer(timeout);

        enum { starting, cancel_timer };

        // wrapper
        return asio::async_compose<CompletionTokenT, void(std::error_code)>(
            [timer = std::move(timer), state = starting, &endpoint, this](auto& self,
                                                                          const std::error_code& ec = {}) mutable {
                if (!ec) {
                    switch (state) {
                        case starting:
                            state = cancel_timer;
                            return _socket.async_connect(endpoint, std::move(self));
                            break;
                        case cancel_timer:
                            timer->cancel();
                            break;
                        default:
                            break;
                    }
                }

                self.complete(ec);
            },
            token, _socket);
    }

    template <typename TimeoutT, asio::completion_token_for<void(std::error_code)> CompletionTokenT>
    auto asynSend(const NetMessageT& msg, const TimeoutT& timeout, CompletionTokenT&& token)
    {
        enum { starting, cancel_timer };

        // create buffer sequence
        std::vector<asio::const_buffer> buff;
        std::ranges::for_each(msg.template bytesView<std::vector<std::string_view>>(),
                              [&buff](const auto& el) { buff.emplace_back(el); });

        auto timer = getDeadlineTimer(timeout);

        // wrapper
        return asio::async_compose<CompletionTokenT, void(std::error_code)>(
            [buff = std::move(buff), timer = std::move(timer), state = starting, this](
                auto& self, const std::error_code& ec = {}, size_t sz = 0) mutable {
                if (!ec) {
                    switch (state) {
                        case starting:
                            if constexpr (std::derived_from<
                                              socket_t, asio::basic_stream_socket<typename socket_t::protocol_type>>) {
                                return asio::async_write(_socket, buff, std::move(self));
                            } else if constexpr (std::derived_from<socket_t, asio::basic_datagram_socket<
                                                                                 typename socket_t::protocol_type>>) {
                                return _socket.async_send(buff, std::move(self));
                            } else if constexpr (std::derived_from<socket_t, asio::basic_seq_packet_socket<
                                                                                 typename socket_t::protocol_type>>) {
                                return _socket.async_send(buff, std::move(self));
                            } else {
                                static_assert(false, "UNKNOWN ASIO-LIBRARY SOCKET TYPE!!!");
                            }
                            break;
                        case cancel_timer:
                            timer->cancel();
                            break;
                        default:
                            break;
                    }
                }

                self.complete(ec);
            },
            token, _socket);
    }


    template <typename TimeoutT, typename CompletionTokenT>
    auto asyncReceive(const TimeoutT& timeout, CompletionTokenT&& token)
    {
        enum { starting, cancel_timer };

        std::unique_ptr<asio::socket_base::message_flags> out_flags;

        auto timer = getDeadlineTimer(timeout);  // armed timer

        return asio::async_compose<CompletionTokenT, void(const std::error_code&, const NetMessageT&)>(
            [timer = std::move(timer), out_flags = std::move(out_flags), state = starting, this](
                auto& self, const std::error_code& ec = {}, size_t sz = 0) mutable {
                if (!ec) {
                    switch (state) {
                        case starting:
                            if constexpr (std::derived_from<
                                              socket_t, asio::basic_stream_socket<typename socket_t::protocol_type>>) {
                                return asio::async_read_until(
                                    _socket, _streamBuffer,
                                    [this](auto begin, auto end) { this->matchCondition(begin, end); },
                                    std::move(self));
                            } else if constexpr (std::derived_from<socket_t, asio::basic_datagram_socket<
                                                                                 typename socket_t::protocol_type>>) {
                                return _socket.receive(_streamBuffer,
                                                       std::move(self));  // datagram, so it should be received at once
                            } else if constexpr (std::derived_from<socket_t, asio::basic_seq_packet_socket<
                                                                                 typename socket_t::protocol_type>>) {
                                return _socket.receive(_streamBuffer, *out_flags,
                                                       std::move(self));  // datagram, so it should be received at once
                            } else {
                                static_assert(false, "UNKNOWN ASIO-LIBRARY SOCKET TYPE!!!");
                            }
                            break;
                        case cancel_timer:
                            timer->cancel();
                            break;
                        default:
                            break;
                    }

                    auto begin_it = streambuff_iter_t::begin(_streamBuffer.data());
                    auto end_it = begin_it + _streamBuffer.data().size();

                    // check for byte sequence is valid byte sequence and find the limits
                    // (stream buffer may contain number of bytes more than requred by protocol)
                    auto res = this->matchCondition(begin_it, end_it);

                    if (!res.second) {
                        self.complete(std::make_error_code(std::errc::protocol_error),
                                      NetMessageT());  // return an empty message
                    } else {
                        auto nbytes = std::distance(begin_it, res.first);
                        NetMessageT msg;

                        auto msg_it = this->fromLowLevel(begin_it, res.first);
                        msg.setFromBytes(msg_it.first, msg_it.second);

                        _streamBuffer.consume(nbytes);

                        self.complete(ec, msg);
                    }
                } else {
                    self.complete(ec, NetMessageT());  // return an empty message
                    return;
                }
            },
            token, _socket);
    }

    template <typename TimeoutT>
    auto connect(const endpoint_t& endpoint, const TimeoutT& timeout)
    {
        std::future<void> ftr = asyncConnect(endpoint, timeout, asio::use_future);
        ftr.get();
    }

    template <typename TimeoutT>
    auto send(const NetMessageT& msg, const TimeoutT& timeout)
    {
        std::future<void> ftr = asyncSend(msg, timeout, asio::use_future);
        ftr.get();
    }

    template <typename TimeoutT>
    auto receive(const TimeoutT& timeout)
    {
        std::future<NetMessageT> ftr = asyncReceive(timeout, asio::use_future);
        return ftr.get();
    }

protected:
    socket_t& _socket;

    asio::streambuf _streamBuffer;

    template <typename TimeoutT>
    std::unique_ptr<asio::steady_timer> getDeadlineTimer(const TimeoutT& timeout, bool arm = true)
    {
        std::unique_ptr<asio::steady_timer> timer(_socket.get_executor());

        if (arm) {
            timer->expires_after(timeout);

            timer->async_wait([this](const std::error_code& ec) {
                if (!ec) {
                    _socket.cancel(std::make_error_code(std::errc::timed_out));
                }
            });
        }

        return timer;
    }
};


}  // namespace adc::impl


#endif