import path from "node:path";

export default function replaceUrl(url: string): string {
 if (typeof url !== "string" || !url.trim()) return "";
 let cleanedPath = "";
 try {
 const pathname = new URL(url).pathname;
 cleanedPath = pathname;
 } catch (e) {
 // 如果不是有效的URL,则直接使用原字符串
 cleanedPath = url;
 }
 cleanedPath = cleanedPath.replace(/^\/oss/, "").replace(/^\/smallImage/, "");
 // 去除 query 参数
 cleanedPath = cleanedPath.split("?")[0];
 // 防止路径穿越:对路径进行规范化后,确保不含上溯分量
 // 使用 posix 规范化(保持 / 分隔符),去除所有 .. 和 .
 const normalized = path.posix.normalize(cleanedPath);

 // 规范化后若路径以 ../ 开头或等于 .. 则说明发生了路径穿越,拒绝并返回空字符串
 if (normalized.startsWith("../") || normalized === "..") {
 return "";
 }

 // 去除前导斜杠,保证返回的是相对路径
 return normalized.replace(/^\/+/, "");
}