#!/usr/bin/env python3
# -*- coding: utf-8 -*-
#
# 2012 Nico Schottelius (nico-cinv at schottelius.org)
#
# This file is part of cinv.
#
# cinv is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# cinv is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with cinv. If not, see <http://www.gnu.org/licenses/>.
#
#

import argparse
import logging
import os.path
import os
import re
import json

from uncloud import UncloudException
from uncloud.hack.db import DB

log = logging.getLogger(__name__)


class MAC(object):
    def __init__(self, config):
        self.config = config
        self.db = DB(config, prefix="/mac")

        self.prefix = 0x002000000000

    @staticmethod
    def validate_mac(mac):
        if not re.match(r'([0-9A-F]{2}[-:]){5}[0-9A-F]{2}$', mac, re.I):
            raise Error("Not a valid mac address: %s" % mac)

    def last_used_index(self):
        value = self.db.get("last_used_index")
        if not value:
            return 0
        return int(value)

    def last_used_mac(self):
        return self.int_to_mac(self.prefix + self.last_used_index())

    @staticmethod
    def int_to_mac(number):
        b = number.to_bytes(6, byteorder="big")
        return ':'.join(format(s, '02x') for s in b)

    def get_next(self, vmuuid=None, as_int=False):
        last_number = self.last_used_index()

        # FIXME: compare to 48bit minus prefix length
        if last_number == int('0xffffff', 16):
            raise UncloudException("Exhausted all possible mac addresses - try to free some")

        next_number = last_number + 1
        next_number_string = "{:012x}".format(next_number)

        next_mac_number = self.prefix + next_number
        next_mac = self.int_to_mac(next_mac_number)

        db_entry = {}
        db_entry['vm_uuid'] = vmuuid
        db_entry['index'] = next_number
        db_entry['mac_address'] = next_mac

        self.db.set("used/{}".format(next_mac),
                    db_entry, as_json=True)

        if as_int:
            return next_mac_number
        else:
            return next_mac