from typing import List as _List
from os.path import join as _join, isdir as _isdir, abspath as _abspath
from datetime import datetime as _datetime
from ipaddress import ip_network, ip_address
from subprocess import run as _run
from os import makedirs as _makedirs, unlink as _unlink
from shutil import rmtree as _rmtree
from glob import glob as _glob


_PKI_DIR = _abspath('pki/dnssec')
_ALGO = 'ECDSAP256SHA256'
_ZSK_LEN = 512
_KSK_LEN = _ZSK_LEN


def nsd_serial() -> str:
    return _datetime.now().strftime('%m%d%H%M%S')


def value_in(value: str,
             values: _List[str],
             ) -> bool:
    for val in values:
        if value == val:
            return True
    return False


def nsd_concat_lists(list1: _List[str],
                     list2: _List[str],
                     str1: str=None,
                     ) -> _List[str]:
    ret = list1 + list2
    if str1:
        ret.append(str1)
    return ret


def get_reverse_name(network: str) -> str:
    if not network:
        return
    network_obj = ip_network(network)
    if network_obj.prefixlen != 24:
        raise ValueError('only netmask "255.255.255.0" is supported for DNS reverse name')
    o1, o2, o3, o4 = network.split('.')
    return f'{o3}.{o2}.{o1}.in-addr.arpa.'


def _gen_key(cn:str,
             authority_cn: str,
             type: str,
             ) -> str:
    dir_name = _join(_PKI_DIR, cn, authority_cn, type)
    filename = None
    if _isdir(dir_name):
        filenames = _glob(_join(dir_name, f'K{authority_cn}.+*.key'))
        if filenames:
            filename = filenames[0].rsplit('.', 1)[0]
    if filename is None:
        if _isdir(dir_name):
            _rmtree(dir_name)
        _makedirs(dir_name)
        if type == 'zsk':
            cmd = ['ldns-keygen', '-a', _ALGO, '-b', str(_ZSK_LEN), authority_cn]
        else:
            cmd = ['ldns-keygen', '-a', _ALGO, '-b', str(_KSK_LEN), '-k', authority_cn]
        proc = _run(cmd,
                    cwd=dir_name,
                    capture_output=True,
                    )
        if proc.returncode != 0:
            raise Exception(f'cannot generate {type}: {proc.stdout.decode()}, {proc.stderr.decode()}')
        filename = _join(dir_name, proc.stdout.decode().strip())
    return filename


def _gen_keys(cn,
              authority_cn,
              ) -> str:
    zsk = _gen_key(cn, authority_cn, 'zsk')
    ksk = _gen_key(cn, authority_cn, 'ksk')
    return zsk, ksk


def gen_cert(cn: str,
             authority_cn: str,
             ) -> str:
    zsk, ksk = _gen_keys(cn, authority_cn)
    with open(f'{ksk}.key') as fh:
        content = fh.read().strip()
    scontent = content.split()
    infos = ' '.join(scontent[3:6])
    return f'"{authority_cn}." {infos} "{scontent[6]}";'


def sign(zone_filename: str,
         cn: str,
         ) -> str:
    authority_cn = zone_filename.rsplit('/', 1)[-1].rsplit('.', 1)[0]
    zsk, ksk = _gen_keys(cn, authority_cn)
    cmd = ['ldns-signzone', '-n', zone_filename, zsk, ksk]
    proc = _run(cmd, capture_output=True)
    if proc.returncode != 0:
        raise Exception(f'cannot sign {zone_filename}: {proc.stdout.decode()}, {proc.stderr.decode()}')
    signed_filename = f'{zone_filename}.signed'
    with open(signed_filename) as fh:
        content = fh.read().strip()
    _unlink(signed_filename)
    return content