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"""
Copyright (c) 2024 Proton AG
This file is part of Proton VPN.
Proton VPN 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.
Proton VPN 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 ProtonVPN. If not, see <https://www.gnu.org/licenses/>.
"""
from __future__ import annotations
import os
from typing import TYPE_CHECKING
from pathlib import Path
from proton.utils.environment import VPNExecutionEnvironment
from proton.vpn.session.utils import RefreshCalculator, rest_api_request
from proton.vpn.core.cache_handler import CacheHandler
if TYPE_CHECKING:
from proton.vpn.session.api import VPNSession
REFRESH_INTERVAL = 2 * 60 * 60 # 2 hours
FF_ENV_VAR = "PROTON_VPN_FEATURE_FLAG_{flag}"
DEFAULT = {
"toggles": [
{
"name": "BinaryServerStatus",
"enabled": False,
"impressionData": False,
"variant": {
"name": "disabled",
"enabled": False
}
},
],
"ExpirationTime": 0
}
class FeatureFlags: # pylint: disable=too-few-public-methods
"""Contains a record of available features."""
def __init__(self, api_data: dict):
self._api_data = api_data
self._expiration_time = api_data.get(
"ExpirationTime",
RefreshCalculator.get_expiration_time(
refresh_interval=REFRESH_INTERVAL
)
)
def get(self, feature_flag_name: str) -> bool:
"""Get a feature flag by its name.
Always returns `False` if the feature flag is not found.
"""
# Allow environment variable override for feature flags
# this makes it easy to enable a feature flag for testing purposes
if self._search_for_env_var(feature_flag_name):
return True
return self._search_for_feature_flag(feature_flag_name)
def _search_for_env_var(self, feature_name: str) -> bool:
env_var = FF_ENV_VAR.format(flag=feature_name)
return env_var in os.environ
def _search_for_feature_flag(self, feature_name: str) -> bool:
feature_flag_dict = {}
for feature in self._api_data.get("toggles", {}):
if feature["name"] == feature_name:
feature_flag_dict = feature
break
return feature_flag_dict.get("enabled", False)
@property
def is_expired(self) -> bool:
"""Returns if data has expired"""
return RefreshCalculator.get_is_expired(self._expiration_time)
@property
def seconds_until_expiration(self) -> int:
"""Returns amount of seconds until it expires."""
return RefreshCalculator.get_seconds_until_expiration(self._expiration_time)
@staticmethod
def get_refresh_interval_in_seconds() -> int:
"""Returns refresh interval in seconds."""
return RefreshCalculator(REFRESH_INTERVAL).get_refresh_interval_in_seconds()
@staticmethod
def default() -> FeatureFlags:
"""Returns a feature object with default values"""
return FeatureFlags(DEFAULT)
class FeatureFlagsFetcher:
"""Fetches and caches features from Proton's REST API."""
ROUTE = "/feature/v2/frontend"
CACHE_PATH = Path(VPNExecutionEnvironment().path_cache) / "features.json"
def __init__(
self, session: "VPNSession",
refresh_calculator: RefreshCalculator = None,
cache_handler: CacheHandler = None
):
"""
:param session: session used to retrieve the client configuration.
"""
self._features = None
self._session = session
self._refresh_calculator = refresh_calculator or RefreshCalculator
self._cache_file = cache_handler or CacheHandler(self.CACHE_PATH)
def clear_cache(self):
"""Discards the cache, if existing."""
self._features = None
self._cache_file.remove()
async def fetch(self) -> FeatureFlags:
"""
Fetches the client configuration from the REST API.
:returns: the fetched client configuration.
"""
response = await rest_api_request(
self._session,
self.ROUTE,
)
response["ExpirationTime"] = self._refresh_calculator\
.get_expiration_time(refresh_interval=REFRESH_INTERVAL)
self._cache_file.save(response)
self._features = FeatureFlags(response)
return self._features
def load_from_cache(self) -> FeatureFlags:
"""
Loads the client configuration from persistence.
:returns: the persisted client configuration. If no persistence
was found then the default client configuration is returned.
"""
cache = self._cache_file.load()
self._features = FeatureFlags(cache) if cache else FeatureFlags.default()
return self._features
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