import re
import json
import requests
import hashlib
import ipaddress
import os

from app import app
from distutils.version import StrictVersion
from urllib.parse import urlparse
from datetime import datetime, timedelta
from threading import Thread

from .certutil import KEY_FILE, CERT_FILE
import logging as logger

logging = logger.getLogger(__name__)


if app.config['SAML_ENABLED']:
    from onelogin.saml2.auth import OneLogin_Saml2_Auth
    from onelogin.saml2.idp_metadata_parser import OneLogin_Saml2_IdPMetadataParser
    idp_timestamp = datetime(1970, 1, 1)
    idp_data = None
    if 'SAML_IDP_ENTITY_ID' in app.config:
        idp_data = OneLogin_Saml2_IdPMetadataParser.parse_remote(app.config['SAML_METADATA_URL'], entity_id=app.config.get('SAML_IDP_ENTITY_ID', None), required_sso_binding=app.config['SAML_IDP_SSO_BINDING'])
    else:
        idp_data = OneLogin_Saml2_IdPMetadataParser.parse_remote(app.config['SAML_METADATA_URL'], entity_id=app.config.get('SAML_IDP_ENTITY_ID', None))
    if idp_data is None:
        print('SAML: IDP Metadata initial load failed')
        exit(-1)
    idp_timestamp = datetime.now()


def get_idp_data():
    global idp_data, idp_timestamp
    lifetime = timedelta(minutes=app.config['SAML_METADATA_CACHE_LIFETIME'])
    if idp_timestamp+lifetime < datetime.now():
        background_thread = Thread(target=retrieve_idp_data)
        background_thread.start()
    return idp_data


def retrieve_idp_data():
    global idp_data, idp_timestamp
    if 'SAML_IDP_SSO_BINDING' in app.config:
        new_idp_data = OneLogin_Saml2_IdPMetadataParser.parse_remote(app.config['SAML_METADATA_URL'], entity_id=app.config.get('SAML_IDP_ENTITY_ID', None), required_sso_binding=app.config['SAML_IDP_SSO_BINDING'])
    else:
        new_idp_data = OneLogin_Saml2_IdPMetadataParser.parse_remote(app.config['SAML_METADATA_URL'], entity_id=app.config.get('SAML_IDP_ENTITY_ID', None))
    if new_idp_data is not None:
        idp_data = new_idp_data
        idp_timestamp = datetime.now()
        print("SAML: IDP Metadata successfully retrieved from: " + app.config['SAML_METADATA_URL'])
    else:
        print("SAML: IDP Metadata could not be retrieved")


if 'TIMEOUT' in app.config.keys():
    TIMEOUT = app.config['TIMEOUT']
else:
    TIMEOUT = 10


def auth_from_url(url):
    auth = None
    parsed_url = urlparse(url).netloc
    if '@' in parsed_url:
        auth = parsed_url.split('@')[0].split(':')
        auth = requests.auth.HTTPBasicAuth(auth[0], auth[1])
    return auth


def fetch_remote(remote_url, method='GET', data=None, accept=None, params=None, timeout=None, headers=None):
    if data is not None and type(data) != str:
        data = json.dumps(data)

    if timeout is None:
        timeout = TIMEOUT

    verify = False

    our_headers = {
        'user-agent': 'powerdnsadmin/0',
        'pragma': 'no-cache',
        'cache-control': 'no-cache'
    }
    if accept is not None:
        our_headers['accept'] = accept
    if headers is not None:
        our_headers.update(headers)

    r = requests.request(
        method,
        remote_url,
        headers=headers,
        verify=verify,
        auth=auth_from_url(remote_url),
        timeout=timeout,
        data=data,
        params=params
        )
    try:
        if r.status_code not in (200, 201, 204, 400, 422):
            r.raise_for_status()
    except Exception as e:
        msg = "Returned status {0} and content {1}"
        logging.error(msg.format(r.status_code, r.content))
        raise RuntimeError('Error while fetching {0}'.format(remote_url))

    return r


def fetch_json(remote_url, method='GET', data=None, params=None, headers=None):
    r = fetch_remote(remote_url, method=method, data=data, params=params, headers=headers,
                     accept='application/json; q=1')

    if method == "DELETE":
        return True

    if r.status_code == 204:
        return {}

    try:
        assert('json' in r.headers['content-type'])
    except Exception as e:
        raise RuntimeError('Error while fetching {0}'.format(remote_url)) from e

    # don't use r.json here, as it will read from r.text, which will trigger
    # content encoding auto-detection in almost all cases, WHICH IS EXTREMELY
    # SLOOOOOOOOOOOOOOOOOOOOOOW. just don't.
    data = None
    try:
        data = json.loads(r.content.decode('utf-8'))
    except Exception as e:
        raise RuntimeError('Error while loading JSON data from {0}'.format(remote_url)) from e
    return data


def display_record_name(data):
    record_name, domain_name = data
    if record_name == domain_name:
        return '@'
    else:
        return re.sub('\.{}$'.format(domain_name), '', record_name)


def display_master_name(data):
    """
    input data: "[u'127.0.0.1', u'8.8.8.8']"
    """
    matches = re.findall(r'\'(.+?)\'', data)
    return ", ".join(matches)


def display_time(amount, units='s', remove_seconds=True):
    """
    Convert timestamp to normal time format
    """
    amount = int(amount)
    INTERVALS = [(lambda mlsec:divmod(mlsec, 1000), 'ms'),
                 (lambda seconds:divmod(seconds, 60), 's'),
                 (lambda minutes:divmod(minutes, 60), 'm'),
                 (lambda hours:divmod(hours, 24), 'h'),
                 (lambda days:divmod(days, 7), 'D'),
                 (lambda weeks:divmod(weeks, 4), 'W'),
                 (lambda years:divmod(years, 12), 'M'),
                 (lambda decades:divmod(decades, 10), 'Y')]

    for index_start, (interval, unit) in enumerate(INTERVALS):
        if unit == units:
            break

    amount_abrev = []
    last_index = 0
    amount_temp = amount
    for index, (formula, abrev) in enumerate(INTERVALS[index_start: len(INTERVALS)]):
        divmod_result = formula(amount_temp)
        amount_temp = divmod_result[0]
        amount_abrev.append((divmod_result[1], abrev))
        if divmod_result[1] > 0:
            last_index = index
    amount_abrev_partial = amount_abrev[0: last_index + 1]
    amount_abrev_partial.reverse()

    final_string = ''
    for amount, abrev in amount_abrev_partial:
        final_string += str(amount) + abrev + ' '

    if remove_seconds and 'm' in final_string:
        final_string = final_string[:final_string.rfind(' ')]
        return final_string[:final_string.rfind(' ')]

    return final_string


def pdns_api_extended_uri(version):
    """
    Check the pdns version
    """
    if StrictVersion(version) >= StrictVersion('4.0.0'):
        return "/api/v1"
    else:
        return ""


def email_to_gravatar_url(email="", size=100):
    """
    AD doesn't necessarily have email
    """
    if email is None:
        email = ""

    hash_string = hashlib.md5(email.encode('utf-8')).hexdigest()
    return "https://s.gravatar.com/avatar/{0}?s={1}".format(hash_string, size)


def prepare_flask_request(request):
    # If server is behind proxys or balancers use the HTTP_X_FORWARDED fields
    url_data = urlparse(request.url)
    return {
        'https': 'on' if request.scheme == 'https' else 'off',
        'http_host': request.host,
        'server_port': url_data.port,
        'script_name': request.path,
        'get_data': request.args.copy(),
        'post_data': request.form.copy(),
        # Uncomment if using ADFS as IdP, https://github.com/onelogin/python-saml/pull/144
        'lowercase_urlencoding': True,
        'query_string': request.query_string
    }


def init_saml_auth(req):
    own_url = ''
    if req['https'] == 'on':
        own_url = 'https://'
    else:
        own_url = 'http://'
    own_url += req['http_host']
    metadata = get_idp_data()
    settings = {}
    settings['sp'] = {}
    if 'SAML_NAMEID_FORMAT' in app.config:
      settings['sp']['NameIDFormat'] = app.config['SAML_NAMEID_FORMAT']
    else:
        settings['sp']['NameIDFormat'] = idp_data.get('sp', {}).get('NameIDFormat', 'urn:oasis:names:tc:SAML:1.1:nameid-format:unspecified')
    settings['sp']['entityId'] = app.config['SAML_SP_ENTITY_ID']
    if os.path.isfile(CERT_FILE):
      cert = open(CERT_FILE, "r").readlines()
      settings['sp']['x509cert'] = "".join(cert)
    if os.path.isfile(KEY_FILE):
      key = open(KEY_FILE, "r").readlines()
      settings['sp']['privateKey'] = "".join(key)
    settings['sp']['assertionConsumerService'] = {}
    settings['sp']['assertionConsumerService']['binding'] = 'urn:oasis:names:tc:SAML:2.0:bindings:HTTP-POST'
    settings['sp']['assertionConsumerService']['url'] = own_url+'/saml/authorized'
    settings['sp']['attributeConsumingService'] = {}
    settings['sp']['singleLogoutService'] = {}
    settings['sp']['singleLogoutService']['binding'] = 'urn:oasis:names:tc:SAML:2.0:bindings:HTTP-Redirect'
    settings['sp']['singleLogoutService']['url'] = own_url+'/saml/sls'
    settings['idp'] = metadata['idp']
    settings['strict'] = True
    settings['debug'] = app.config['SAML_DEBUG']
    settings['security'] = {}
    settings['security']['digestAlgorithm'] = 'http://www.w3.org/2001/04/xmldsig-more#rsa-sha256'
    settings['security']['metadataCacheDuration'] = None
    settings['security']['metadataValidUntil'] = None
    settings['security']['requestedAuthnContext'] = True
    settings['security']['signatureAlgorithm'] = 'http://www.w3.org/2001/04/xmldsig-more#rsa-sha256'
    settings['security']['wantAssertionsEncrypted'] = False
    settings['security']['wantAttributeStatement'] = True
    settings['security']['wantNameId'] = True
    settings['security']['authnRequestsSigned'] = app.config['SAML_SIGN_REQUEST']
    settings['security']['logoutRequestSigned'] = app.config['SAML_SIGN_REQUEST']
    settings['security']['logoutResponseSigned'] = app.config['SAML_SIGN_REQUEST']
    settings['security']['nameIdEncrypted'] = False
    settings['security']['signMetadata'] = True
    settings['security']['wantAssertionsSigned'] = True
    settings['security']['wantMessagesSigned'] = app.config.get('SAML_WANT_MESSAGE_SIGNED', True)
    settings['security']['wantNameIdEncrypted'] = False
    settings['contactPerson'] = {}
    settings['contactPerson']['support'] = {}
    settings['contactPerson']['support']['emailAddress'] = app.config['SAML_SP_CONTACT_NAME']
    settings['contactPerson']['support']['givenName'] = app.config['SAML_SP_CONTACT_MAIL']
    settings['contactPerson']['technical'] = {}
    settings['contactPerson']['technical']['emailAddress'] = app.config['SAML_SP_CONTACT_NAME']
    settings['contactPerson']['technical']['givenName'] = app.config['SAML_SP_CONTACT_MAIL']
    settings['organization'] = {}
    settings['organization']['en-US'] = {}
    settings['organization']['en-US']['displayname'] = 'PowerDNS-Admin'
    settings['organization']['en-US']['name'] = 'PowerDNS-Admin'
    settings['organization']['en-US']['url'] = own_url
    auth = OneLogin_Saml2_Auth(req, settings)
    return auth


def display_setting_state(value):
    if value == 1:
        return "ON"
    elif value == 0:
        return "OFF"
    else:
        return "UNKNOWN"


def validate_ipaddress(address):
        try:
            ip = ipaddress.ip_address(address)
        except ValueError:
            pass
        else:
            if isinstance(ip, (ipaddress.IPv4Address, ipaddress.IPv6Address)):
                return [ip]
        return []