import os
from dataclasses import dataclass
from typing import Mapping


@dataclass(frozen=True)
class Config:
    api_key: str
    api_secret: str
    api_passphrase: str
    trading_env: str = "demo"


def load_config(env: Mapping[str, str] | None = None) -> Config:
    source = os.environ if env is None else env
    api_key = source.get("OKX_API_KEY")
    api_secret = source.get("OKX_API_SECRET")
    api_passphrase = source.get("OKX_API_PASSPHRASE")
    if not api_key or not api_secret or not api_passphrase:
        raise ValueError("OKX credentials are required")
    trading_env = source.get("OKX_TRADING_ENV", "demo")
    if trading_env not in {"demo", "live"}:
        raise ValueError("OKX_TRADING_ENV must be demo or live")
    return Config(
        api_key=api_key,
        api_secret=api_secret,
        api_passphrase=api_passphrase,
        trading_env=trading_env,
    )