import subprocess as sp
import random
import logging
import socket
from contextlib import closing

logger = logging.getLogger(__name__)


def random_bytes(num=6):
    return [random.randrange(256) for _ in range(num)]


def generate_mac(uaa=False, multicast=False, oui=None, separator=':', byte_fmt='%02x'):
    mac = random_bytes()
    if oui:
        if type(oui) == str:
            oui = [int(chunk) for chunk in oui.split(separator)]
        mac = oui + random_bytes(num=6 - len(oui))
    else:
        if multicast:
            mac[0] |= 1  # set bit 0
        else:
            mac[0] &= ~1  # clear bit 0
        if uaa:
            mac[0] &= ~(1 << 1)  # clear bit 1
        else:
            mac[0] |= 1 << 1  # set bit 1
    return separator.join(byte_fmt % b for b in mac)


def create_dev(script, _id, dev, ip=None):
    command = ['sudo', '-p', 'Enter password to create network devices for vm: ',
               script, str(_id), dev]
    if ip:
        command.append(ip)
    try:
        output = sp.check_output(command, stderr=sp.PIPE)
    except Exception:
        logger.exception('Creation of interface %s failed.', dev)
        return None
    else:
        return output.decode('utf-8').strip()


def delete_network_interface(iface):
    try:
        sp.check_output(
            [
                'sudo', '-p', 'Enter password to remove {} network device: '.format(iface),
                'ip', 'link', 'del', iface
            ], stderr=sp.PIPE
        )
    except Exception:
        logger.exception('Interface %s Deletion failed', iface)


def find_free_port():
    with closing(socket.socket(socket.AF_INET, socket.SOCK_STREAM)) as s:
        try:
            s.bind(('', 0))
            s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
        except Exception:
            return None
        else:
            return s.getsockname()[1]