from pathlib import Path
from cryptography.fernet import Fernet

path = Path('.env')
lines = path.read_text(encoding='utf-8').splitlines() if path.exists() else []
key_name = 'DEVICE_CREDENTIAL_KEY'
found = any(line.strip().startswith(key_name + '=') for line in lines)
if not found:
    lines.append(f'{key_name}={Fernet.generate_key().decode("ascii")}')
    path.write_text('\n'.join(lines) + '\n', encoding='utf-8')
print('existing' if found else 'created')