"""Shared extension instances and accessors.

Extensions are created here (unbound to any app) and initialized against the
app inside ``create_app()``. This lets blueprints/services import the single
shared ``login_manager`` / ``oauth`` without importing ``app`` itself.

``filter_engine`` and ``polling_service`` are accessed lazily so importing this
module (or ``app``) has no side effects.
"""

import logging

from flask_login import LoginManager
from authlib.integrations.flask_client import OAuth

logger = logging.getLogger(__name__)

# Flask-Login: bound to the app in create_app().
login_manager = LoginManager()
login_manager.login_view = "login"
login_manager.login_message = "Please log in to access this page."

# Authlib OAuth: bound to the app in create_app().
oauth = OAuth()


def get_filter_engine():
    """Return the singleton FilterEngine instance (lazy).

    ``FilterEngine.get_instance()`` is itself a lazy singleton, so this is
    cheap to call from routes/services. Kept as a function (not a module
    global) so importing this module never triggers filter-engine init.
    """
    from filter_pipeline import FilterEngine

    return FilterEngine.get_instance()


def get_polling_service():
    """Return the shared polling service singleton (lazy import)."""
    from polling_service import polling_service

    return polling_service