// To be deployed to Cloudflare Workers
// https://workers.cloudflare.com/

const PEER_URL = "https://service-6memx4r1-1251114981.sh.apigw.tencentcs.com/release/water-meter";

addEventListener("fetch", (event) => {
  event.respondWith(
    handleRequest(event.request).catch(
      (err) => new Response(err.stack, { status: 500 })
    )
  );
});

/**
 * Many more examples available at:
 *   https://developers.cloudflare.com/workers/examples
 * @param {Request} request
 * @returns {Promise<Response>}
 */
async function handleRequest(request) {
  const { pathname, origin } = new URL(request.url);
  switch (pathname) {
    case '/callback':
      return handleCallback(request);
    case '/':
      return new Response(`Usage: curl -L4 ${origin}
      
(If you seen this, it indicates your client does not follow HTTP redirections.)` , { status: 302, headers: { Location: PEER_URL } });
    default:
      return new Response(`Usage: curl -L4 ${origin}`);
  }
}

async function handleCallback(request) {
  const { searchParams: params } = new URL(request.url);
  const intraIp = params.get("ip");
  console.log(new URL(request.url))
  if (!intraIp) {
    return new Response("Wrong callback parameter" + request.url + intraIp, { status: 400 });
  }
  // if (!request.headers.get("Referer").includes((new URL(PEER_URL).host))) {
  //   return new Response("Invalid referer", { status: 400 })
  // }
  const interIp = request.headers.get("CF-Connecting-IP");
  let message;
  if (intraIp === interIp) {
    const geo = await getGeo(interIp);
    const notice = geo.country === "China" ? "你正在境内正常访问互联网。" : "现已识别到你属于境外势力。";
    message = `${callpolice(3)}${notice}${callpolice(3)}
你的IP地址是：${interIp}（${geo.organization}）。`;
  } else {
    const intraGeo = await getGeo(intraIp);
    const interGeo = await getGeo(interIp);
    if (intraGeo.country !== "China" || interGeo.country === "China") {
      return new Response("Unexpected network environment", { status: 400 });
    }
    message = `${callpolice(24)}
🚨🚨你正在使用非法定信道访问国际互联网！！！🚨🚨
${callpolice(24)}
你的境内IP地址是：${intraIp}（${intraGeo.organization}），
你的境外IP地址是：${interIp}（${interGeo.organization}）。
${callpolice(24)}
`;
  }
  return new Response(message);
}

async function getGeo(ip) {
  const resp = await fetch("https://api.ip.sb/geoip/" + ip);
  return await resp.json()
}

function callpolice(n, symbols = "🚔👮🚓🚨") {
  symbols = [...symbols];
  // Inspired by https://stackoverflow.com/a/68379909/5488616
  return Array.from(Array(n).keys()).map(() => symbols[Math.floor(Math.random() * symbols.length)]).join("");
}