from typing import Dict

from fastapi import BackgroundTasks, FastAPI

app = FastAPI()


def write_notification(email: str, message: str = "") -> None:
    with open("log.txt", mode="w") as email_file:
        content = f"notification for {email}: {message}"
        email_file.write(content)


@app.post("/send-notification/{email}")
async def send_notification(
    email: str, background_tasks: BackgroundTasks
) -> Dict[str, str]:
    background_tasks.add_task(write_notification, email, message="some notification")
    return {"message": "Notification sent in the background"}