/**
 * Correlation ids for iframe postMessage. `crypto.randomUUID` is Safari
 * 15.4+ / Chrome 92+; `getRandomValues` covers the SDK's older floor.
 */
export function randomRequestId(): string {
  const cryptoObj = globalThis.crypto;
  if (typeof cryptoObj?.randomUUID === "function") {
    return cryptoObj.randomUUID();
  }

  const bytes = new Uint8Array(16);
  if (typeof cryptoObj?.getRandomValues === "function") {
    cryptoObj.getRandomValues(bytes);
  } else {
    for (let i = 0; i < 16; i++) {
      bytes[i] = Math.floor(Math.random() * 256);
    }
  }

  const version = bytes[6] ?? 0;
  const variant = bytes[8] ?? 0;
  bytes[6] = (version & 0x0f) | 0x40;
  bytes[8] = (variant & 0x3f) | 0x80;

  const hex = Array.from(bytes, (byte) =>
    byte.toString(16).padStart(2, "0"),
  ).join("");
  return `${hex.slice(0, 8)}-${hex.slice(8, 12)}-${hex.slice(12, 16)}-${hex.slice(16, 20)}-${hex.slice(20)}`;
}