"""Helper methods to tune a TCP connection"""

import asyncio
import socket
from contextlib import suppress
from typing import Optional  # noqa


__all__ = ('tcp_keepalive', 'tcp_nodelay', 'tcp_cork')


if hasattr(socket, 'TCP_CORK'):  # pragma: no cover
    CORK = socket.TCP_CORK  # type: Optional[int]
elif hasattr(socket, 'TCP_NOPUSH'):  # pragma: no cover
    CORK = socket.TCP_NOPUSH  # type: ignore
else:  # pragma: no cover
    CORK = None


if hasattr(socket, 'SO_KEEPALIVE'):
    def tcp_keepalive(transport: asyncio.Transport) -> None:
        sock = transport.get_extra_info('socket')
        if sock is not None:
            sock.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1)
else:
    def tcp_keepalive(
            transport: asyncio.Transport) -> None:  # pragma: no cover
        pass


def tcp_nodelay(transport: asyncio.Transport, value: bool) -> None:
    sock = transport.get_extra_info('socket')

    if sock is None:
        return

    if sock.family not in (socket.AF_INET, socket.AF_INET6):
        return

    value = bool(value)

    # socket may be closed already, on windows OSError get raised
    with suppress(OSError):
        sock.setsockopt(
            socket.IPPROTO_TCP, socket.TCP_NODELAY, value)


def tcp_cork(transport: asyncio.Transport, value: bool) -> None:
    sock = transport.get_extra_info('socket')

    if CORK is None:
        return

    if sock is None:
        return

    if sock.family not in (socket.AF_INET, socket.AF_INET6):
        return

    value = bool(value)

    with suppress(OSError):
        sock.setsockopt(
            socket.IPPROTO_TCP, CORK, value)