from __future__ import annotations

import os
from dataclasses import dataclass


@dataclass(frozen=True)
class Settings:
    admin_token: str
    secret_key: str
    base_url: str = "http://127.0.0.1:8080"
    database_path: str = "backend/vpnapp.db"

    @classmethod
    def from_env(cls) -> Settings:
        admin_token = os.getenv("VPNAPP_ADMIN_TOKEN", "")
        secret_key = os.getenv("VPNAPP_SECRET_KEY", "")
        if not admin_token:
            raise RuntimeError("VPNAPP_ADMIN_TOKEN must be set")
        if not secret_key:
            raise RuntimeError(
                "VPNAPP_SECRET_KEY must be set to a Fernet key; generate one with "
                "python -c 'from cryptography.fernet import Fernet; print(Fernet.generate_key().decode())'"
            )
        return cls(
            admin_token=admin_token,
            secret_key=secret_key,
            base_url=os.getenv("VPNAPP_BASE_URL", "http://127.0.0.1:8080").rstrip("/"),
            database_path=os.getenv("VPNAPP_DATABASE", "backend/vpnapp.db"),
        )