""" Various utils """

from . import settings
import uuid

import subprocess
import sys
import asyncio
import functools


class NumberedClass:
    """ A class that counts its current instance number """

    next_id = 1  # Count from 1: IP addresses and id 0 are not a good mix.

    @classmethod
    def get_id(cls):
        out = cls.next_id
        cls.next_id += 1
        return out

    def __init__(self):
        self.id = self.get_id()


class LibvirtObject(NumberedClass):
    """ A class that has the basic attributes of a libvirt objects:
    * id
    * uuid
    and the applicable restrictions
    """

    class TooMany(Exception):
        def __init__(self, count):
            self.count = count

        def __str__(self):
            return (
                "Limit number reached. The current instance #{} does not fit in IPv4"
            ).format(self.count)

    def __init__(self, conn):
        super().__init__()

        self.conn = conn

        if self.id > 250:
            raise self.TooMany(self.id)

        self.uuid = uuid.uuid4()


class MACAddress:
    """ A MAC address for a NIC or bridge """

    def __init__(self, link_id, dev_id=None):
        """ link_id: id of the current link
            dev_id: id of the current NIC. If the device is a bridge, use None
        """
        if dev_id is None:
            dev_id = 0xFE

        self.link_id = link_id
        self.dev_id = dev_id

    def __str__(self):
        return "52:54:00:{nwid:02x}:{link_id:02x}:{dev_id:02x}".format(
            nwid=settings.NETWORK_ID, link_id=self.link_id, dev_id=self.dev_id
        )

    def __repr__(self):
        return str(self)


class Addrv4:
    """ An address in IPv4 """

    def __init__(self, link_id, dev_id=None, host_address=False):
        """ link_id: id of the current link
            dev_id: id of the current NIC. Use None to get the base address
            host_address: if True and dev_id is None, returns the host machine address
                on this network instead of the base address
        """

        self.host_address = host_address

        if dev_id is None:
            if host_address:
                dev_id = 0xFE
            else:
                dev_id = 0

        self.link_id = link_id
        self.dev_id = dev_id
        self.netmask = "255.255.255.0"
        self.prefix = 24

    def __str__(self):
        return "{base_range}.{link_id}.{dev_id}".format(
            base_range=settings.IPV4_RANGE, link_id=self.link_id, dev_id=self.dev_id,
        )

    def __repr__(self):
        return str(self)


class Addrv6:
    """ An address in IPv6 """

    def __init__(self, link_id, dev_id=None, host_address=False):
        """ link_id: id of the current link
            dev_id: id of the current NIC. Use None to get the base address
            host_address: if True and dev_id is None, returns the host machine address
                on this network instead of the base address
        """
        self.host_address = host_address

        if dev_id is None:
            if host_address:
                dev_id = 0xFE
            else:
                dev_id = 0

        self.link_id = link_id
        self.dev_id = dev_id
        self.prefix = 64

    def __str__(self):
        return "{base_range}:{link_id:04x}::{dev_id:04x}".format(
            base_range=settings.IPV6_RANGE, link_id=self.link_id, dev_id=self.dev_id,
        )


def run_cmd_retry(command, *args, **kwargs):
    rc = subprocess.run(command, *args, **kwargs)
    while rc.returncode != 0:
        print("Command failed. Try again:", file=sys.stderr)
        rc = subprocess.run(command, *args, **kwargs)
    return rc


def run_in_executor(f):
    """ Decorator: transforms a blocking function into an awaitable one """

    @functools.wraps(f)
    def inner(*args, **kwargs):
        loop = asyncio.get_running_loop()
        return loop.run_in_executor(None, functools.partial(f, *args, **kwargs))

    return inner


def ensure_sudo_rights():
    """ Updates sudo credentials to ensure that the user is logged in afterwards,
    without typing in a password """
    run_cmd_retry(["sudo", "-v"])


def drop_sudo_rights():
    """ Drop sudo credentials """
    run_cmd_retry(["sudo", "-k"])