#!/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

log = logging.getLogger(__name__)

class Error(Exception):
    pass


class Mac(object):
    def __init__(self):
        self.base_dir = "."

        self.prefix = 0x002000000000
        #self.prefix = "{:012x}".format(self._prefix)

        self.free    = self.read_file("mac-free")
        self.last    = self.read_file("mac-last")

    def read_file(self, filename):
        fname = os.path.join(self.base_dir, filename)
        ret = []

        try:
            with open(fname, "r") as fd:
                ret = fd.readlines()
        except Exception as e:
            pass

        return ret

    def append_to_file(self, text, filename):
        fname = os.path.join(self.base_dir, filename)
        with open(fname, "a+") as fd:
            fd.write("{}\n".format(text))

    @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 free_append(self, mac):
        if mac in self.free:
            raise Error("Mac already in free database: %s" % mac)

        self.append_to_file(mac, "mac-free")
        self.free    = self.read_file("mac-free")


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

    def getnext(self):
#        if self.free:
#            return self.free.pop()

#        if not self.prefix:
#            raise Error("Cannot generate address without prefix - use prefix-set")

        if self.last:
            last_number = int(self.last[0], 16)

            if last_number == int('0xffffff', 16):
                raise Error("Exhausted all possible mac addresses - try to free some")

            next_number = last_number + 1
        else:
            next_number = 0

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

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

        with open(os.path.join(self.base_dir, "mac-last"), "w+") as fd:
            fd.write("{}\n".format(next_number_string))

        return next_mac

    @classmethod
    def commandline(cls):
        pass


if __name__ == '__main__':
    m = Mac()
    m.commandline()
    # print(m.free)
    #print(m.last)
    print(m.getnext())