1#
2# Copyright 2013 eNovance
3#
4#    Licensed under the Apache License, Version 2.0 (the "License"); you may
5#    not use this file except in compliance with the License. You may obtain
6#    a copy of the License at
7#
8#         http://www.apache.org/licenses/LICENSE-2.0
9#
10#    Unless required by applicable law or agreed to in writing, software
11#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13#    License for the specific language governing permissions and limitations
14#    under the License.
15
16import re
17
18
19class NotificationFilter(object):
20
21    r"""Filter notification messages
22
23    The NotificationFilter class is used to filter notifications that an
24    endpoint will received.
25
26    The notification can be filter on different fields: context,
27    publisher_id, event_type, metadata and payload.
28
29    The filter is done via a regular expression
30
31    filter_rule =  NotificationFilter(
32         publisher_id='^compute.*',
33         context={'tenant_id': '^5f643cfc-664b-4c69-8000-ce2ed7b08216$',
34                  'roles': 'private'},
35         event_type='^compute\.instance\..*',
36         metadata={'timestamp': 'Aug'},
37         payload={'state': '^active$')
38
39    """
40
41    def __init__(self, context=None, publisher_id=None, event_type=None,
42                 metadata=None, payload=None):
43        self._regex_publisher_id = None
44        self._regex_event_type = None
45
46        if publisher_id is not None:
47            self._regex_publisher_id = re.compile(publisher_id)
48        if event_type is not None:
49            self._regex_event_type = re.compile(event_type)
50        self._regexs_context = self._build_regex_dict(context)
51        self._regexs_metadata = self._build_regex_dict(metadata)
52        self._regexs_payload = self._build_regex_dict(payload)
53
54    @staticmethod
55    def _build_regex_dict(regex_list):
56        if regex_list is None:
57            return {}
58        return dict((k, re.compile(regex_list[k])) for k in regex_list)
59
60    @staticmethod
61    def _check_for_single_mismatch(data, regex):
62        if regex is None:
63            return False
64        if not isinstance(data, str):
65            return True
66        if not regex.match(data):
67            return True
68        return False
69
70    @classmethod
71    def _check_for_mismatch(cls, data, regex):
72        if isinstance(regex, dict):
73            for k in regex:
74                if k not in data:
75                    return True
76                if cls._check_for_single_mismatch(data[k], regex[k]):
77                    return True
78            return False
79        else:
80            return cls._check_for_single_mismatch(data, regex)
81
82    def match(self, context, publisher_id, event_type, metadata, payload):
83        if (self._check_for_mismatch(publisher_id, self._regex_publisher_id) or
84                self._check_for_mismatch(event_type, self._regex_event_type) or
85                self._check_for_mismatch(context, self._regexs_context) or
86                self._check_for_mismatch(metadata, self._regexs_metadata) or
87                self._check_for_mismatch(payload, self._regexs_payload)):
88            return False
89        return True
90