from typing import Union, Optional
from core.models.session.SessionProfile import SessionProfile
from core.models.system.SystemProfile import SystemProfile
from core.Errors import MissingSubscriptionError, InvalidSubscriptionError
from core.services.WebServiceApiService import WebServiceApiService
from core.controllers.ConnectionController import ConnectionController
from core.observers.ConnectionObserver import ConnectionObserver

def activate_subscription(
    profile: Union[SessionProfile, SystemProfile], 
    connection_observer: Optional[ConnectionObserver] = None
) -> bool:
    """
    Purpose:
        Ensure subscription is ready.

    Features:
        Idempotent.
        Checks local first

    Confusion:
        This returns True both if was already active or just activated.

    Returns:
        Returns True if subscription was already active.
        Returns True if subscription was just activated.

    Errors:
        True.
        Raises if subscription is missing or invalid. (not false)
    """
    
    if not profile.has_subscription():
        raise MissingSubscriptionError()
    
    # Already activated—nothing to do
    if profile.subscription.has_been_activated():
        return True
    
    # Fetch and activate
    subscription = ConnectionController.with_preferred_connection(
        profile.subscription.billing_code, 
        task=WebServiceApiService.get_subscription, 
        connection_observer=connection_observer
    )
    
    if subscription is None:
        raise InvalidSubscriptionError()
    
    profile.subscription = subscription
    profile.save()
    return True


def is_subscription_ready(profile: Union[SessionProfile, SystemProfile]) -> bool:
    """Check if subscription exists and is activated (no side effects)."""
    return (
        profile.has_subscription() 
        and profile.subscription.has_been_activated()
    )