module;

#include <asio.hpp>

#include <format>
#include <span>
#include <vector>

export module ttwhy:io;

import :event;
import :scanner;

namespace ttwhy::io
{

  export template<typename Stream>
  auto handle_signals(Stream & stream) -> asio::awaitable<std::error_code>
  {
    auto executor = co_await asio::this_coro::executor;
    auto signals = asio::signal_set{executor, SIGINT, SIGTERM};

    auto [error, signal] = co_await signals.async_wait(asio::as_tuple(asio::use_awaitable));
    if (!error)
    {
      auto message = std::format("Received signal {}, exiting ...\n", signal);
      co_await asio::async_write(stream, asio::buffer(message), asio::use_awaitable);
    }
    co_return error;
  }

  export template<typename InputStream, typename AppRouter>
  auto read_events(InputStream & stream, AppRouter & router) -> asio::awaitable<void>
  {
    auto queue = std::vector<input_event>{};
    queue.reserve(16);

    auto scanner = ansi_scanner{queue};
    auto raw_buffer = std::array<char, 64>{};

    while (true)
    {
      auto [error, bytes_read] =
          co_await stream.async_read_some(asio::buffer(raw_buffer), asio::as_tuple(asio::use_awaitable));

      if (error)
      {
        co_return;
      }

      auto const byte_span = std::span<char const>{raw_buffer.data(), bytes_read};

      scanner.process(byte_span);

      for (auto const & event : queue)
      {
        co_await router.process(event);
      }

      queue.clear();
    }
  }

}  // namespace ttwhy::io