import httpx


class Backend:
    def __init__(self, url: str, login: str, password: str, transport=None):
        self.client = httpx.AsyncClient(base_url=url.rstrip("/"), auth=(login, password), timeout=8,
                                       limits=httpx.Limits(max_connections=4, max_keepalive_connections=4),
                                       transport=transport, trust_env=False)

    async def close(self):
        await self.client.aclose()

    async def request(self, method: str, path: str, **kwargs):
        try:
            response = await self.client.request(method, path, **kwargs)
        except httpx.HTTPError:
            raise ValueError("BACKEND_UNAVAILABLE: request failed; writes may have committed, check current state before retry") from None
        codes = {400: "INVALID_ARGUMENT", 401: "BACKEND_AUTH_FAILED", 403: "BACKEND_AUTH_FAILED",
                 404: "NOT_FOUND", 409: "CONFLICT", 429: "BUSY", 503: "BUSY"}
        if response.is_error:
            # Never send stack traces, SQL or backend credentials into an agent's context.
            raise ValueError(f"{codes.get(response.status_code, 'BACKEND_ERROR')}: HTTP {response.status_code}")
        return response.json() if response.content else {"ok": True}