import json
from datetime import datetime
from typing import Optional

from google.oauth2.credentials import Credentials
from google_auth_oauthlib.flow import Flow

from app.core.config import settings

def build_flow(state: Optional[str] = None) -> Flow:
    flow = Flow.from_client_secrets_file(
        settings.GOOGLE_CLIENT_SECRET_FILE,
        scopes=settings.scopes_list(),
        state=state,
    )
    flow.redirect_uri = settings.GOOGLE_REDIRECT_URI
    return flow

def creds_from_token_json(token_json: str) -> Credentials:
    data = json.loads(token_json)
    # google.oauth2.credentials.Credentials acepta kwargs del token JSON
    return Credentials(**data)

def token_json_from_creds(creds: Credentials) -> str:
    # Convertimos a dict estándar
    data = {
        "token": creds.token,
        "refresh_token": creds.refresh_token,
        "token_uri": creds.token_uri,
        "client_id": creds.client_id,
        "client_secret": creds.client_secret,
        "scopes": creds.scopes,
        "id_token": getattr(creds, "id_token", None),
    }
    # Algunos campos pueden ser None; igual está ok.
    return json.dumps(data, ensure_ascii=False)