function createWebUpgradeRegistry() {
  const handlers = [];
  let attachedServer = null;

  function add(pathname, handler) {
    const path = normalizePath(pathname);
    if (typeof handler !== "function") throw new Error("An upgrade handler is required.");
    const entry = { path, handler };
    handlers.push(entry);
    return () => {
      const index = handlers.indexOf(entry);
      if (index >= 0) handlers.splice(index, 1);
    };
  }

  function dispatch(request, socket, head) {
    let pathname = "/";
    try {
      pathname = new URL(request.url || "/", "http://lumi.local").pathname;
    } catch {}
    const entry = handlers.find((candidate) => candidate.path === pathname);
    if (!entry) {
      socket.write("HTTP/1.1 404 Not Found\r\nConnection: close\r\n\r\n");
      socket.destroy();
      return;
    }
    try {
      entry.handler(request, socket, head);
    } catch {
      if (!socket.destroyed) {
        socket.write("HTTP/1.1 500 Internal Server Error\r\nConnection: close\r\n\r\n");
        socket.destroy();
      }
    }
  }

  function attach(server) {
    if (!server || typeof server.on !== "function") throw new Error("An HTTP server is required.");
    if (attachedServer === server) return;
    if (attachedServer) attachedServer.off("upgrade", dispatch);
    attachedServer = server;
    server.on("upgrade", dispatch);
  }

  function close() {
    if (attachedServer) attachedServer.off("upgrade", dispatch);
    attachedServer = null;
    handlers.length = 0;
  }

  return { add, attach, close, count: () => handlers.length };
}

function normalizePath(value) {
  const path = String(value || "").trim();
  if (!path.startsWith("/") || path.includes("?") || path.includes("#")) {
    throw new Error("Upgrade paths must be absolute URL paths.");
  }
  return path;
}

module.exports = { createWebUpgradeRegistry };