ext.py

# -*- coding: utf-8 -*-
#
# This file is part of Invenio.
# Copyright (C) 2017-2018 CERN.
#
# Invenio is free software; you can redistribute it and/or modify it
# under the terms of the MIT License; see LICENSE file for more details.

"""Cache module for Invenio."""

from __future__ import absolute_import, print_function

import pkg_resources
from flask_caching import Cache
from werkzeug.utils import import_string

from . import config
from ._compat import string_types


class InvenioCache(object):
    """Invenio-Cache extension."""

    def __init__(self, app=None):
        """Extension initialization."""
        if app:
            self.init_app(app)

    def init_app(self, app):
        """Flask application initialization."""
        self.init_config(app)
        self.cache = Cache(app)
        self.is_authenticated_callback = _callback_factory(
            app.config["CACHE_IS_AUTHENTICATED_CALLBACK"]
        )
        app.extensions["invenio-cache"] = self

    def build_redis_url(self, app, db=0):
        """Return the redis connection string if configured or build it from its parts.

        If set, then ``CACHE_REDIS_URL`` will be returned.
        Otherwise, the URI will be pieced together by the configuration items
        ``KV_CACHE_{PASSWORD,HOST,PORT,NAME,PROTOCOL}``.
        If that cannot be done (e.g. because required values are missing), then
        ``None`` will be returned.

        Note: see: https://docs.celeryq.dev/en/stable/userguide/configuration.html#new-lowercase-settings
        """
        if url := app.config.get("CACHE_REDIS_URL", None):
            return url

        params = {}
        for config_name in ["HOST", "PORT", "PASSWORD", "PROTOCOL"]:
            params[config_name] = app.config.get(f"KV_CACHE_{config_name}", None)

        if params.get("HOST") and params.get("PORT"):
            protocol = params.get("PROTOCOL", "redis")
            password = f":{params['PASSWORD']}@" if params.get("PASSWORD") else ""
            cache_url = f"{protocol}://{password}{params['HOST']}:{params['PORT']}/{db}"
            return cache_url

        return None

    def init_config(self, app):
        """Initialize configuration."""
        for k in dir(config):
            if k.startswith("CACHE_"):
                app.config.setdefault(k, getattr(config, k))


def _callback_factory(callback_imp):
    """Factory for creating a is authenticated callback."""
    if callback_imp is None:
        try:
            pkg_resources.get_distribution("flask-login")
            from flask_login import current_user

            return lambda: current_user.is_authenticated
        except pkg_resources.DistributionNotFound:
            return lambda: False
    elif isinstance(callback_imp, string_types):
        return import_string(callback_imp)
    else:
        return callback_imp