// 对象存储签名工具:浏览器直传用查询串签名(浏览器无法设置 Date 请求头)
import crypto from "node:crypto";

const REGION = process.env.OSS_REGION ?? "oss-cn-hangzhou";
const BUCKET = process.env.OSS_BUCKET ?? "";
const ID = process.env.OSS_ACCESS_KEY_ID ?? "";
const SECRET = process.env.OSS_ACCESS_KEY_SECRET ?? "";

const HOST = `${BUCKET}.${REGION}.aliyuncs.com`;

// 生成带签名的临时访问地址
function signUrl(method: string, key: string, seconds: number, contentType = "") {
  const expires = Math.floor(Date.now() / 1000) + seconds;
  const resource = `/${BUCKET}/${key}`;
  const str = `${method}\n\n${contentType}\n${expires}\n${resource}`;
  const signature = crypto.createHmac("sha1", SECRET).update(str).digest("base64");
  const qs = new URLSearchParams({
    OSSAccessKeyId: ID,
    Expires: String(expires),
    Signature: signature,
  });
  return `https://${HOST}/${encodeURIComponent(key)}?${qs}`;
}

// 直传地址:浏览器收到后直接 fetch PUT,有效期 10 分钟
export function uploadUrl(key: string, contentType: string) {
  return signUrl("PUT", key, 600, contentType);
}

// 展示地址:签名 GET,有效期 5 分钟,用完由页面刷新重新签发
export function viewUrl(key: string) {
  return signUrl("GET", key, 300);
}

// 照片键名:photos/孩子ID/日期/随机16进制.jpg
export function photoKey(childId: number, date: string) {
  return `photos/${childId}/${date}/${crypto.randomBytes(8).toString("hex")}.jpg`;
}