"""Flask-Login user loader — registered with login_manager in models.py."""

from app.extensions import login_manager


@login_manager.user_loader
def load_user(user_id):
    """Load a user by ID for Flask-Login session management.

    Returns the correct polymorphic subclass (Admin, Coach, Player, etc.)
    automatically because SQLAlchemy resolves the identity column.

    Returns None for deactivated accounts so that disabling a user also
    invalidates the sessions they already hold. Flask-Login only consults
    is_active when login_user() is called, never when restoring a session
    from the cookie, so the check has to happen here.
    """
    from app.extensions import db
    from app.models.user_model.user import User

    try:
        pk = int(user_id)
    except (TypeError, ValueError):
        return None

    user = db.session.get(User, pk)
    if user is None or not user.is_active_account:
        return None
    return user