module std::net @if(os::SUPPORTS_INET);
import std::io, std::os, std::time, libc;

struct Socket (InStream, OutStream)
{
	NativeSocket sock;
	Socklen_t ai_addrlen;
	// TODO proper way to get the size of sockaddr_storage
	// https://learn.microsoft.com/en-us/previous-versions/windows/desktop/legacy/ms740504(v=vs.85)
	char[128] ai_addr_storage;
}

macro void @loop_over_ai(AddrInfo* ai; @body(NativeSocket fd, AddrInfo* ai))
{
	while (ai)
	{
		NativeSocket sockfd = os::socket(ai.ai_family, ai.ai_socktype, ai.ai_protocol);
		if (sockfd.is_valid())
		{
			@body(sockfd, ai);
		}
		ai = ai.ai_next;
	}
}

const Duration POLL_FOREVER = -1;

distinct PollSubscribes = ushort;
distinct PollEvents = ushort;

const PollSubscribes SUBSCRIBE_ANY_READ     = os::POLLIN;
const PollSubscribes SUBSCRIBE_PRIO_READ    = os::POLLPRI;
const PollSubscribes SUBSCRIBE_OOB_READ     = os::POLLRDBAND;
const PollSubscribes SUBSCRIBE_READ         = os::POLLRDNORM;
const PollSubscribes SUBSCRIBE_ANY_WRITE    = os::POLLOUT;
const PollSubscribes SUBSCRIBE_OOB_WRITE    = os::POLLWRBAND;
const PollSubscribes SUBSCRIBE_WRITE        = os::POLLWRNORM;

const PollEvents POLL_EVENT_READ_PRIO  = os::POLLPRI;
const PollEvents POLL_EVENT_READ_OOB   = os::POLLRDBAND;
const PollEvents POLL_EVENT_READ       = os::POLLRDNORM;
const PollEvents POLL_EVENT_WRITE_OOB  = os::POLLWRBAND;
const PollEvents POLL_EVENT_WRITE      = os::POLLWRNORM;
const PollEvents POLL_EVENT_DISCONNECT = os::POLLHUP;
const PollEvents POLL_EVENT_ERROR      = os::POLLERR;
const PollEvents POLL_EVENT_INVALID    = os::POLLNVAL;

struct Poll
{
	NativeSocket socket;
	PollSubscribes events;
	PollEvents revents;
}

fn ulong! poll_ms(Poll[] polls, long timeout_ms)
{
	return poll(polls, time::ms(timeout_ms)) @inline;
}

<*
 @param [inout] polls
 @param timeout "duration to poll."
*>
fn ulong! poll(Poll[] polls, Duration timeout)
{
	long time_ms = timeout.to_ms();
	if (time_ms > CInt.max) time_ms = CInt.max;
	$if env::WIN32:
		CInt result = win32_WSAPoll((Win32_LPWSAPOLLFD)polls.ptr, (Win32_ULONG)polls.len, (CInt)time_ms);
	$else
		CInt result = os::poll((Posix_pollfd*)polls.ptr, (Posix_nfds_t)polls.len, (CInt)time_ms);
	$endif
	return result < 0 ? os::socket_error()? : (ulong)result;
}

macro Socket new_socket(fd, ai)
{
	Socket sock = { .sock = fd, .ai_addrlen = ai.ai_addrlen };
	assert(sock.ai_addr_storage.len >= ai.ai_addrlen, "storage %d < addrlen %d", sock.ai_addr_storage.len, ai.ai_addrlen);
	mem::copy(&sock.ai_addr_storage, (void*)ai.ai_addr, ai.ai_addrlen);
	return sock;
}

enum SocketOption : char (CInt value)
{
	REUSEADDR                  = os::SO_REUSEADDR,
	REUSEPORT @if(!env::WIN32) = os::SO_REUSEPORT,
	KEEPALIVE                  = os::SO_KEEPALIVE,
	BROADCAST                  = os::SO_BROADCAST,
	OOBINLINE                  = os::SO_OOBINLINE,
	DONTROUTE                  = os::SO_DONTROUTE,
}

fn bool! Socket.get_broadcast(&self) => self.get_option(BROADCAST);
fn bool! Socket.get_keepalive(&self) => self.get_option(KEEPALIVE);
fn bool! Socket.get_reuseaddr(&self) => self.get_option(REUSEADDR);
fn bool! Socket.get_dontroute(&self) => self.get_option(DONTROUTE);
fn bool! Socket.get_oobinline(&self) => self.get_option(OOBINLINE);

fn void! Socket.set_broadcast(&self, bool value) => self.set_option(BROADCAST, value);
fn void! Socket.set_keepalive(&self, bool value) => self.set_option(KEEPALIVE, value);
fn void! Socket.set_reuseaddr(&self, bool value) => self.set_option(REUSEADDR, value);
fn void! Socket.set_dontroute(&self, bool value) => self.set_option(DONTROUTE, value);
fn void! Socket.set_oobinline(&self, bool value) => self.set_option(OOBINLINE, value);

fn void! Socket.set_option(&self, SocketOption option, bool value)
{
	CInt flag = (CInt)value;
	int errcode = os::setsockopt(self.sock, os::SOL_SOCKET, option.value, &flag, CInt.sizeof);
	if (errcode != 0) return NetError.SOCKOPT_FAILED?;
}

fn bool! Socket.get_option(&self, SocketOption option)
{
	CInt flag;
	int errcode = os::setsockopt(self.sock, os::SOL_SOCKET, option.value, &flag, CInt.sizeof);
	if (errcode != 0) return NetError.SOCKOPT_FAILED?;
	return (bool)flag;
}

fn usz! Socket.read(&self, char[] bytes) @dynamic
{
$if env::WIN32:
	isz n = libc::recv(self.sock, bytes.ptr, (int)bytes.len, 0);
$else
	isz n = libc::recv(self.sock, bytes.ptr, bytes.len, 0);
$endif
	if (n < 0) return os::socket_error()?;
	return (usz)n;
}

fn char! Socket.read_byte(&self) @dynamic => io::@read_byte_using_read(self);

fn usz! Socket.write(&self, char[] bytes) @dynamic
{
$if env::WIN32:
	isz n = libc::send(self.sock, bytes.ptr, (int)bytes.len, 0);
$else
	isz n = libc::send(self.sock, bytes.ptr, bytes.len, 0);
$endif
	if (n < 0) return os::socket_error()?;
	return (usz)n;
}

fn void! Socket.write_byte(&self, char byte) @dynamic => io::@write_byte_using_write(self, byte);

fn void! Socket.destroy(&self) @dynamic
{
	self.close()!;
}
fn void! Socket.close(&self) @inline @dynamic
{
	self.sock.close()!;
}