Edge bucketing

addEventListener("fetch", event => event.respondWith(handleRequest(event.request)));

async function handleRequest(request) {
  // 1. Parse visitor ID from cookies
  const cookies = parseCookies(request.headers.get("cookie") || "");
  const visitorId = getMintedVisitorId(cookies);

  if (!visitorId) {
    return new Response("Missing visitor ID", { status: 400 });
  }

  // 2–4. Fetch flags from LaunchDarkly (via proxy or edge-compatible endpoint)
  const flags = await getFlagsForVisitor(visitorId);

  // 5. Add flags as headers
  const headers = new Headers(request.headers);
  for (const [flag, value] of Object.entries(flags)) {
    headers.set(`X-Minted-Experiment-${flag}`, String(value));
  }

  // 6. Forward request to origin (Minted)
  const upstreamUrl = new URL(request.url);
  upstreamUrl.hostname = "www.minted.com"; // or your actual origin

  const forwardedRequest = new Request(upstreamUrl.toString(), {
    method: request.method,
    headers,
    body: request.body,
  });

  return fetch(forwardedRequest);
}

function parseCookies(cookieHeader) {
  const cookies = {};
  cookieHeader.split(";").forEach(pair => {
    const [key, value] = pair.split("=").map(part => part.trim());
    if (key && value) cookies[key] = value;
  });
  return cookies;
}

function getMintedVisitorId(cookies) {
  // Return the first valid "Minted" visitor cookie
  for (const [key, value] of Object.entries(cookies)) {
    if (key.toLowerCase().includes("minted") && value) {
      return value;
    }
  }
  return null;
}

// This would ideally hit a LaunchDarkly-compatible edge API or gateway
async function getFlagsForVisitor(visitorId) {
  const res = await fetch(`https://your-proxy.example.com/flags?user=${visitorId}`);
  if (!res.ok) return {};
  return res.json();
}