import os
from telethon import TelegramClient

API_ID = int(os.environ.get("TG_API_ID", "0"))
API_HASH = os.environ.get("TG_API_HASH", "")
SESSION_PREFIX = os.environ.get("TG_SESSION", "telethon_session")  # writes <prefix>.session in cwd

def _prompt_nonempty(prompt: str, default: str | None = None) -> str:
    while True:
        val = input(f"{prompt}{f' [{default}]' if default else ''}: ").strip()
        if not val and default is not None:
            return default
        if val:
            return val
        print("Please enter a value.")

def main():
    # If env vars are missing, ask interactively.
    global API_ID, API_HASH, SESSION_PREFIX
    if not API_ID:
        api_id_str = _prompt_nonempty("Enter TG_API_ID (from my.telegram.org)")
        try:
            API_ID = int(api_id_str)
        except ValueError:
            raise SystemExit("TG_API_ID must be an integer.")
    if not API_HASH:
        API_HASH = _prompt_nonempty("Enter TG_API_HASH (from my.telegram.org)")
    if not SESSION_PREFIX:
        SESSION_PREFIX = _prompt_nonempty("Enter session prefix (file will be <prefix>.session)", "telethon_session")

    client = TelegramClient(SESSION_PREFIX, API_ID, API_HASH)
    client.start()  # this will prompt for phone, code, and 2FA if needed
    print(f"Session created: {SESSION_PREFIX}.session")
    client.disconnect()


if __name__ == "__main__":
    main()