import json
import logging

from google.oauth2 import service_account
from google.auth.transport.requests import Request as GoogleAuthRequest
import httpx

from app.core.config import Settings

logger = logging.getLogger(__name__)


class PushService:
    def __init__(self, settings: Settings):
        self.settings = settings

    async def send_challenge(self, fcm_token: str | None, challenge_id: str) -> None:
        if not fcm_token:
            logger.info("Skipping push: device has no FCM token for challenge %s", challenge_id)
            return
        if not self.settings.fcm_project_id or not self.settings.fcm_service_account_json:
            logger.info("Skipping push: FCM credentials not configured for challenge %s", challenge_id)
            return

        credentials = service_account.Credentials.from_service_account_info(
            json.loads(self.settings.fcm_service_account_json),
            scopes=["https://www.googleapis.com/auth/firebase.messaging"],
        )
        credentials.refresh(GoogleAuthRequest())
        payload = {
            "message": {
                "token": fcm_token,
                "data": {"challenge_id": challenge_id},
                "android": {"priority": "high"},
            }
        }
        logger.debug("Prepared FCM payload: %s", json.dumps(payload))
        async with httpx.AsyncClient(timeout=10) as client:
            response = await client.post(
                f"https://fcm.googleapis.com/v1/projects/{self.settings.fcm_project_id}/messages:send",
                json=payload,
                headers={"Authorization": f"Bearer {credentials.token}"},
            )
            response.raise_for_status()