// Wire
// ====
// TCP on bytes: a List<U32> of octets in and out. After bend-kit-wire (MIT-0).

function gw_list(b, n) {
  let xs = { $: "Nil" };
  for (let i = n; i > 0; i -= 1) {
    xs = { $: "Con", head: b[i - 1], tail: xs };
  }
  return xs;
}

function wire_recv(socket, max, k) {
  const sys = io_sys();
  const fd = socket;
  const b = new Uint8Array(Math.max(Number(max), 1));
  const again = sys.mac ? 35 : 11;
  const go = () => {
    const n = Number(sys.recv(fd, sys.ptr(b), Number(max), 0));
    if (n < 0) {
      const code = sys.errno();
      if (code === again) {
        io_park_on(fd, false, k, go);
        return undefined;
      }
      return io_tup(socket, io_fail(code));
    }
    return io_tup(socket, io_done(gw_list(b, n)));
  };
  return go();
}

function wire_recv_need() {
  return { read: true };
}

// wire_recv with a deadline, as Base's TCP.poll: None past it
function wire_recv_timeout(socket, max, ms, k) {
  const sys = io_sys();
  const fd = socket;
  const b = new Uint8Array(Math.max(Number(max), 1));
  const again = sys.mac ? 35 : 11;
  const at = performance.now() + Number(ms);
  const go = () => {
    const n = Number(sys.recv(fd, sys.ptr(b), Number(max), 0));
    if (n >= 0) {
      return io_tup(socket, io_done({ $: "Some", value: gw_list(b, n) }));
    }
    const code = sys.errno();
    if (code !== again) {
      return io_tup(socket, io_fail(code));
    }
    if (performance.now() >= at) {
      return io_tup(socket, io_done({ $: "None" }));
    }
    io_park_on(fd, false, k, go, at);
    return undefined;
  };
  return go();
}

function wire_send(socket, data, k) {
  const sys = io_sys();
  const fd = socket;
  const bytes = [];
  for (let xs = data; xs.$ === "Con"; xs = xs.tail) {
    bytes.push(xs.head);
  }
  if (bytes.some((x) => x > 255)) {
    return io_tup(socket, io_fail(22));
  }
  const b = Uint8Array.from(bytes);
  const again = sys.mac ? 35 : 11;
  const go = (at) => {
    while (at < b.length) {
      const part = b.subarray(at);
      const n = Number(sys.send(fd, sys.ptr(part), part.length, 0));
      if (n < 0) {
        const code = sys.errno();
        if (code === again) {
          io_park_on(fd, true, k, () => go(at));
          return undefined;
        }
        return io_tup(socket, io_fail(code));
      }
      at += n;
    }
    return io_tup(socket, io_done({ $: "Unit" }));
  };
  return go(0);
}