import os
from typing import Dict

_initialized = False
_use_mock = True

def init_firebase(credentials_path: str = None):
    global _initialized, _use_mock
    try:
        import firebase_admin
        from firebase_admin import credentials, messaging
    except Exception:
        _use_mock = True
        return

    if credentials_path is None:
        credentials_path = os.environ.get('FIREBASE_CREDENTIALS_PATH', 'backend/secrets/firebase-adminsdk.json')

    if not os.path.exists(credentials_path):
        _use_mock = True
        return

    try:
        cred = credentials.Certificate(credentials_path)
        firebase_admin.initialize_app(cred)
        _initialized = True
        _use_mock = False
    except Exception:
        _use_mock = True


def send_to_topic(topic: str, payload: Dict):
    """Sends a push to an FCM topic. Falls back to mock (prints) if not configured."""
    global _use_mock
    if _use_mock:
        print(f"[MOCK PUSH] topic={topic} payload={payload}")
        return {"mock": True, "topic": topic, "payload": payload}

    try:
        from firebase_admin import messaging
        message = messaging.Message(
            notification=messaging.Notification(title=payload.get('title'), body=payload.get('body')),
            topic=topic,
        )
        resp = messaging.send(message)
        return {"result": resp}
    except Exception as e:
        print(f"[PUSH ERROR] {e}")
        return {"error": str(e)}