const axios = require("axios");
const cache = require("memory-cache");
const crypto = require("crypto");

const APPID = "wxaebc7f284686a36f";
const APPSECRET = "44d74fc4e8c6a97a79c2eef23ca50123";

/**
 * 获取 access_token（缓存 7000 秒）
 */
async function getAccessToken() {
  const key = "access_token";
  let token = cache.get(key);
  if (!token) {
    const { data } = await axios.get(
      `https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=${APPID}&secret=${APPSECRET}`
    );
    if (data.errcode) throw new Error(JSON.stringify(data));
    token = data.access_token;
    console.log("🚀 ~ getAccessToken ~ token:", token);
    cache.put(key, token, 7000 * 1000); // 毫秒
  }
  return token;
}

/**
 * 获取 jsapi_ticket（缓存 7000 秒）
 */
async function getJsapiTicket() {
  const key = "jsapi_ticket";
  let ticket = cache.get(key);
  if (!ticket) {
    const token = await getAccessToken();
    const { data } = await axios.get(
      `https://api.weixin.qq.com/cgi-bin/ticket/getticket?access_token=${token}&type=jsapi`
    );
    if (data.errcode !== 0) throw new Error(JSON.stringify(data));
    ticket = data.ticket;
    cache.put(key, ticket, 7000 * 1000);
  }
  return ticket;
}

/**
 * 生成签名
 */
function createSignature(ticket, url) {
  const nonceStr = Math.random().toString(36).substr(2, 15);
  const timestamp = Math.floor(Date.now() / 1000);
  const raw = `jsapi_ticket=${ticket}&noncestr=${nonceStr}&timestamp=${timestamp}&url=${url}`;
  const signature = crypto.createHash("sha1").update(raw).digest("hex");
  return { appId: APPID, timestamp, nonceStr, signature };
}

/**
 * 验证微信服务器 Token（用于公众号后台配置）
 * @param {string} token - 公众号后台配置的 Token
 * @param {string} signature - 微信请求中的签名
 * @param {string} timestamp - 微信请求中的时间戳
 * @param {string} nonce - 微信请求中的随机数
 * @returns {boolean} 是否验证通过
 */
function verifyWechatToken(token, signature, timestamp, nonce) {
  const arr = [token, timestamp, nonce].sort().join("");
  const sha1 = crypto.createHash("sha1").update(arr).digest("hex");
  return sha1 === signature;
}

module.exports = { getJsapiTicket, createSignature, verifyWechatToken };