//
// echo_server.cpp
// ~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2022 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//

#include <boost/asio.hpp>

#include <cstdio>
#include <iostream>
#if defined(BOOST_ASIO_HAS_CO_AWAIT)

namespace net = boost::asio;
namespace this_coro = net::this_coro;
using net::ip::tcp;
using net::detached;
using executor_type = net::io_context::executor_type;
using socket_type = net::basic_stream_socket<net::ip::tcp, executor_type>;
using tcp_socket = net::use_awaitable_t<executor_type>::as_default_on_t<socket_type>;
using acceptor_type = net::basic_socket_acceptor<net::ip::tcp, executor_type>;
using tcp_acceptor = net::use_awaitable_t<executor_type>::as_default_on_t<acceptor_type>;
using awaitable_type = net::awaitable<void, executor_type>;
constexpr net::use_awaitable_t<executor_type> use_awaitable;

awaitable_type echo(tcp_socket socket)
{
   try {
      char data[1024];
      for (;;) {
         std::size_t n = co_await socket.async_read_some(net::buffer(data), use_awaitable);
         co_await async_write(socket, net::buffer(data, n), use_awaitable);
      }
   } catch (std::exception const&) {
      //std::printf("echo Exception: %s\n", e.what());
   }
}

awaitable_type listener()
{
   auto ex = co_await this_coro::executor;
   tcp_acceptor acceptor(ex, {tcp::v4(), 55555});
   for (;;) {
      tcp_socket socket = co_await acceptor.async_accept(use_awaitable);
      co_spawn(ex, echo(std::move(socket)), detached);
   }
}

int main()
{
   try {
      net::io_context io_context{BOOST_ASIO_CONCURRENCY_HINT_UNSAFE_IO};
      co_spawn(io_context, listener(), detached);
      io_context.run();
   } catch (std::exception const& e) {
      std::printf("Exception: %s\n", e.what());
   }
}
#else   // defined(BOOST_ASIO_HAS_CO_AWAIT)
auto main() -> int
{
   std::cout << "Requires coroutine support." << std::endl;
   return 1;
}
#endif  // defined(BOOST_ASIO_HAS_CO_AWAIT)