Plant uml

export const proxy = async (returnEndpoint) => {
  const setup = (resolve, reject) => {
    if (typeof lit === "undefined") reject("No lit");
    else if (!window.__runkitCORSProxyEnpoint) {
      (async (fn) => {
        const rkEmbed = document.createElement("script");
        rkEmbed.onload = async (fn) => {
          const el = document.createElement("div");
          document.body.appendChild(el);
          el.setAttribute("style", "height:0;");
          RunKit.createNotebook({
            element: el,
            mode: "endpoint",
            onLoad: async (rk) => {
              const endpoint = await rk.getEndpointURL();
              window.__runkitCORSProxyEnpoint = endpoint;
              document.body.removeChild(el);
            },
            evaluateOnLoad: true,
            source: await lit.fs.readFile(
              "/testing/runkit-express-cors-proxy.js",
              {
                encoding: "utf8",
              }
            ),
          });
        };
        rkEmbed.setAttribute("src", "https://embed.runkit.com");
        document.body.appendChild(rkEmbed);
      })();
    } else {
      resolve(window.__runkitCORSProxyEnpoint);
    }
  };

  const endpoint = await new Promise(setup).then((e) => e);
  if (false && !window.__runkitCORSProxyEnpoint) {
    return "Still setting up proxy endpoint";
  } else {
    if (returnEndpoint) return endpoint;

    const getAndReplaceDomain = (originalUrl, newDomain) => {
      return newDomain + originalUrl.replace(/^https?:\/\//, "/");
    };

    const proxyFetch = async (url, opts = {}) => {
      const proxyUrl = getAndReplaceDomain(url, endpoint);
      return fetch(proxyUrl, opts);
    };

    return proxyFetch;
  }
};