listeners.py

from collections import defaultdict
from typing import Callable


# Store all event listeners
LISTENERS_REGISTRY = defaultdict(list)

# events
PAYMENT_STATUS_CHANGED = 'payment_status_changed'
CONTACT_INFO = 'contact_info'


def call_listeners(event: str, **payload):
    """Call all listeners registered for an event"""
    listeners = LISTENERS_REGISTRY.get(event)

    for listener in listeners:
        listener(**payload)


def remove_listeners(event: str):
    """Remove all listeners registered for an event"""
    LISTENERS_REGISTRY[event].clear()
        

def register_listener(event: str) -> Callable:
    """Register a listener for an event"""
    def decorator(func: Callable) -> Callable:
        LISTENERS_REGISTRY[event].append(func)
        return func
    
    return decorator


add_payment_status_changed = register_listener(PAYMENT_STATUS_CHANGED)

add_contact_info_listener = register_listener(CONTACT_INFO)


# Better style for decorator usage
payment_status_changed = add_payment_status_changed
contact_info_listener = add_contact_info_listener