import JSONBig from 'json-bigint';

const jsonParser = JSONBig({
  storeAsString: true,
  useNativeBigInt: false,
});

function looksLikeJsonPayload(data: string) {
  const trimmed = data.trim();
  return trimmed.startsWith('{') || trimmed.startsWith('[');
}

export function parseJsonPreservingLong<T>(data: unknown, contentType?: string): T | unknown {
  if (typeof data !== 'string' || !looksLikeJsonPayload(data)) {
    return data;
  }
  if (contentType && !contentType.toLowerCase().includes('application/json')) {
    return data;
  }
  return jsonParser.parse(data) as T;
}