from hashlib import sha1
import json
import re

import requests
from django.conf import settings
from django.core.exceptions import SuspiciousOperation

from desecapi.exceptions import PDNSException, PDNSValidationError, RequestEntityTooLarge

NSLORD = object()
NSMASTER = object()

_config = {
    NSLORD: {
        'base_url': settings.NSLORD_PDNS_API,
        'headers': {
            'Accept': 'application/json',
            'User-Agent': 'desecapi',
            'X-API-Key': settings.NSLORD_PDNS_API_TOKEN,
        }
    },
    NSMASTER: {
        'base_url': settings.NSMASTER_PDNS_API,
        'headers': {
            'Accept': 'application/json',
            'User-Agent': 'desecapi',
            'X-API-Key': settings.NSMASTER_PDNS_API_TOKEN,
        }
    }

}


def _pdns_request(method, *, server, path, data=None):
    if data is not None:
        data = json.dumps(data)
    if data is not None and len(data) > settings.PDNS_MAX_BODY_SIZE:
        raise RequestEntityTooLarge

    r = requests.request(method, _config[server]['base_url'] + path, data=data, headers=_config[server]['headers'])
    if r.status_code == PDNSValidationError.pdns_code:
        raise PDNSValidationError(response=r)
    elif r.status_code not in range(200, 300):
        raise PDNSException(response=r)

    return r


def _pdns_post(server, path, data):
    return _pdns_request('post', server=server, path=path, data=data)


def _pdns_patch(server, path, data):
    return _pdns_request('patch', server=server, path=path, data=data)


def _pdns_get(server, path):
    return _pdns_request('get', server=server, path=path)


def _pdns_put(server, path):
    return _pdns_request('put', server=server, path=path)


def _pdns_delete(server, path):
    return _pdns_request('delete', server=server, path=path)


def pdns_id(name):
    # See also pdns code, apiZoneNameToId() in ws-api.cc (with the exception of forward slash)
    if not re.match(r'^[a-zA-Z0-9_.-]+$', name):
        raise SuspiciousOperation('Invalid hostname ' + name)

    name = name.translate(str.maketrans({'/': '=2F', '_': '=5F'}))
    return name.rstrip('.') + '.'


def get_keys(domain):
    """
    Retrieves a dict representation of the DNSSEC key information
    """
    r = _pdns_get(NSLORD, '/zones/%s/cryptokeys' % pdns_id(domain.name))
    return [{k: key[k] for k in ('dnskey', 'ds', 'flags', 'keytype')}
            for key in r.json()
            if key['active'] and key['keytype'] in ['csk', 'ksk']]


def get_zone(domain):
    """
    Retrieves a dict representation of the zone from pdns
    """
    r = _pdns_get(NSLORD, '/zones/' + pdns_id(domain.name))

    return r.json()


def get_rrset_datas(domain):
    """
    Retrieves a dict representation of the RRsets in a given zone
    """
    return [{'domain': domain,
             'subname': rrset['name'][:-(len(domain.name) + 2)],
             'type': rrset['type'],
             'records': [record['content'] for record in rrset['records']],
             'ttl': rrset['ttl']}
            for rrset in get_zone(domain)['rrsets']]


def construct_catalog_rrset(zone=None, delete=False, subname=None, qtype='PTR', rdata=None):
    # subname can be generated from zone for convenience; exactly one needs to be given
    assert (zone is None) ^ (subname is None)
    # sanity check: one can't delete an rrset and give record data at the same time
    assert not (delete and rdata)

    if subname is None:
        zone = zone.rstrip('.') + '.'
        m_unique = sha1(zone.encode()).hexdigest()
        subname = f'{m_unique}.zones'

    if rdata is None:
        rdata = zone

    return {
        'name': f'{subname}.{settings.CATALOG_ZONE}'.strip('.') + '.',
        'type': qtype,
        'ttl': 0,  # as per the specification
        'changetype': 'REPLACE',
        'records': [] if delete else [{'content': rdata, 'disabled': False}],
    }