import binascii
import ipaddress
import random
import subprocess as sp
import logging
import requests

from pyotp import TOTP

from ucloud.config import vm_pool, config


logger = logging.getLogger("ucloud.api.helper")

def check_otp(name, realm, token):
    try:
        data = {
            "auth_name": config['otp']['auth_name'],
            "auth_token": TOTP(config['otp']['auth_seed']).now(),
            "auth_realm": config['otp']['auth_realm'],
            "name": name,
            "realm": realm,
            "token": token,
        }
    except binascii.Error as err:
        logger.error(
            "Cannot compute OTP for seed: {}".format(config['otp']['auth_seed'])
        )
        return 400

    response = requests.post(
        "{OTP_SERVER}{OTP_VERIFY_ENDPOINT}".format(
            OTP_SERVER=config['otp']['server'],
            OTP_VERIFY_ENDPOINT=config['otp']['verify_endpoint']
        ),
        json=data,
    )
    return response.status_code


def resolve_vm_name(name, owner):
    """Return UUID of Virtual Machine of name == name and owner == owner

    Input: name of vm, owner of vm.
    Output: uuid of vm if found otherwise None
    """
    result = next(
        filter(
            lambda vm: vm.value["owner"] == owner and vm.value["name"] == name,
            vm_pool.vms,
        ),
        None,
    )
    if result:
        return result.key.split("/")[-1]

    return None


def resolve_image_name(name, etcd_client):
    """Return image uuid given its name and its store

       * If the provided name is not in correct format
         i.e {store_name}:{image_name} return ValueError
       * If no such image found then return KeyError

    """

    seperator = ":"

    # Ensure, user/program passed valid name that is of type string
    try:
        store_name_and_image_name = name.split(seperator)

        """
        Examples, where it would work and where it would raise exception
        "images:alpine" --> ["images", "alpine"]

        "images" --> ["images"] it would raise Exception as non enough value to unpack

        "images:alpine:meow" --> ["images", "alpine", "meow"] it would raise Exception
                                                              as too many values to unpack
        """
        store_name, image_name = store_name_and_image_name
    except Exception:
        raise ValueError("Image name not in correct format i.e {store_name}:{image_name}")

    images = etcd_client.get_prefix(config['etcd']['image_prefix'], value_in_json=True)

    # Try to find image with name == image_name and store_name == store_name
    try:
        image = next(filter(lambda im: im.value['name'] == image_name
                            and im.value['store_name'] == store_name, images))
    except StopIteration:
        raise KeyError("No image with name {} found.".format(name))
    else:
        image_uuid = image.key.split('/')[-1]

    return image_uuid


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 get_ip_addr(mac_address, device):
    """Return IP address of a device provided its mac address / link local address
       and the device with which it is connected.

       For Example, if we call get_ip_addr(mac_address="52:54:00:12:34:56", device="br0")
       the following two scenarios can happen
       1. It would return None if we can't be able to find device whose mac_address is equal
          to the arg:mac_address or the mentioned arg:device does not exists or the ip address
          we found is local.
       2. It would return ip_address of device whose mac_address is equal to arg:mac_address
          and is connected/neighbor of arg:device
    """
    try:
        output = sp.check_output(['ip', '-6', 'neigh', 'show', 'dev', device], stderr=sp.PIPE)
    except sp.CalledProcessError:
        return None
    else:
        result = []
        output = output.strip().decode("utf-8")
        output = output.split("\n")
        for entry in output:
            entry = entry.split()
            if entry:
                ip = ipaddress.ip_address(entry[0])
                mac = entry[2]
                if ip.is_global and mac_address == mac:
                    result.append(ip)
        return result


def mac2ipv6(mac, prefix):
    # only accept MACs separated by a colon
    parts = mac.split(":")

    # modify parts to match IPv6 value
    parts.insert(3, "ff")
    parts.insert(4, "fe")
    parts[0] = "%x" % (int(parts[0], 16) ^ 2)

    # format output
    ipv6_parts = [str(0)] * 4
    for i in range(0, len(parts), 2):
        ipv6_parts.append("".join(parts[i:i + 2]))

    lower_part = ipaddress.IPv6Address(":".join(ipv6_parts))
    prefix = ipaddress.IPv6Address(prefix)
    return str(prefix + int(lower_part))