import { createHash } from 'node:crypto';

const LBS_HOST = 'https://apis.map.qq.com';

/**
 * 腾讯位置服务 WebServiceAPI（GET）签名 URL。
 * 控制台开启 SN/签名校验后须附带 sig；SecretKey 仅服务端使用。
 *
 * sig = md5(请求路径 + "?" + 按参数名升序的原始 query + SK)
 * @see https://lbs.qq.com/FAQ/server_faq.html
 */
export function buildTencentLbsRequestUrl(
  path: string,
  params: Record<string, string>,
  options: { key: string; secretKey?: string },
): string {
  const key = options.key.trim();
  if (!key) {
    throw new Error('TENCENT_LBS_KEY 未配置');
  }

  const pathname = (path.startsWith('/') ? path : `/${path}`).replace(/\/+$/, '') || '/';
  const all: Record<string, string> = { ...params, key };
  const sortedKeys = Object.keys(all).sort();
  const rawQuery = sortedKeys.map((k) => `${k}=${all[k]}`).join('&');

  const search = new URLSearchParams();
  for (const k of sortedKeys) {
    search.set(k, all[k]);
  }

  const sk = options.secretKey?.trim();
  if (sk) {
    const sig = createHash('md5').update(`${pathname}?${rawQuery}${sk}`).digest('hex');
    search.set('sig', sig);
  }

  return `${LBS_HOST}${pathname}?${search.toString()}`;
}