Errors

import requests
import time

def get_gex_levels(api_key, symbol="BTCUSDT", max_retries=3):
    for attempt in range(max_retries):
        resp = requests.get(
            "https://api.backquant.com/v2/gex/levels",
            params={"symbol": symbol},
            headers={"X-API-Key": api_key},
        )
        body = resp.json()

        if body["success"]:
            return body["data"]

        code = body["error"]["code"]

        if code == "UNAUTHORIZED":
            raise ValueError(
                "Invalid API key. Get/rotate at https://backquant.com/api-access"
            )
        if code == "RATE_LIMIT_EXCEEDED":
            retry_after = int(resp.headers.get("Retry-After", "60"))
            # Two different 429s. A burst clears within the minute; a monthly
            # quota 429 sends the seconds until the month rolls over, which
            # you must never sleep off - surface it instead.
            if resp.headers.get("X-Quota-Remaining") == "0":
                raise RuntimeError(body["error"]["message"])
            print(f"Rate limited; sleeping {retry_after}s")
            time.sleep(retry_after)
            continue
        if code == "NOT_FOUND":
            # 404 = no cache for this symbol/expiry. Don't retry - handle as no-data.
            return None
        if code == "UPSTREAM_ERROR":
            # Redis/DB blip - exponential backoff
            sleep = 2 ** attempt
            print(f"Upstream error; sleeping {sleep}s")
            time.sleep(sleep)
            continue
        if code == "VALIDATION_ERROR":
            raise ValueError(f"Invalid parameters: {body['error']}")

        raise RuntimeError(
            f"Unexpected error: {body['error']} "
            f"(request_id={body['meta'].get('request_id')})"
        )
    raise RuntimeError("Max retries exceeded")

async function getGexLevels(
  apiKey: string,
  symbol = "BTCUSDT",
  maxRetries = 3,
): Promise<unknown | null> {
  for (let attempt = 0; attempt < maxRetries; attempt++) {
    const resp = await fetch(
      `https://api.backquant.com/v2/gex/levels?symbol=${symbol}`,
      { headers: { "X-API-Key": apiKey } },
    );
    const body = await resp.json();

    if (body.success) return body.data;

    const code = body.error.code;

    if (code === "UNAUTHORIZED") {
      throw new Error(
        "Invalid API key. Get/rotate at https://backquant.com/api-access",
      );
    }
    if (code === "RATE_LIMIT_EXCEEDED") {
      const retryAfter = parseInt(resp.headers.get("Retry-After") ?? "60", 10);
      // Two different 429s. A burst clears within the minute; a monthly quota
      // 429 sends the seconds until the month rolls over, which you must
      // never sleep off - surface it instead.
      if (resp.headers.get("X-Quota-Remaining") === "0") {
        throw new Error(body.error.message);
      }
      console.log(`Rate limited; sleeping ${retryAfter}s`);
      await new Promise((r) => setTimeout(r, retryAfter * 1000));
      continue;
    }
    if (code === "NOT_FOUND") {
      return null; // no data, don't retry
    }
    if (code === "UPSTREAM_ERROR") {
      const sleep = 2 ** attempt;
      console.log(`Upstream error; sleeping ${sleep}s`);
      await new Promise((r) => setTimeout(r, sleep * 1000));
      continue;
    }
    if (code === "VALIDATION_ERROR") {
      throw new Error(`Invalid parameters: ${JSON.stringify(body.error)}`);
    }
    throw new Error(
      `Unexpected error: ${body.error.message} ` +
        `(request_id=${body.meta?.request_id})`,
    );
  }
  throw new Error("Max retries exceeded");
}