/** RFC 8785 JCS の UTF-8 対象文字列を生成する。T-12。 */
export function canonicalize(value: unknown): string {
  return encode(value);
}
function encode(v: unknown): string {
  if (v === null) return "null";
  if (typeof v === "string") return JSON.stringify(v);
  if (typeof v === "boolean") return v ? "true" : "false";
  if (typeof v === "number") {
    if (!Number.isFinite(v)) throw new TypeError("JCS does not support non-finite numbers");
    return JSON.stringify(Object.is(v, -0) ? 0 : v);
  }
  if (Array.isArray(v)) return `[${v.map(encode).join(",")}]`;
  if (typeof v === "object") {
    const o = v as Record<string, unknown>;
    const keys = Object.keys(o).sort();
    return `{${keys.map((k) => `${JSON.stringify(k)}:${encode(o[k])}`).join(",")}}`;
  }
  throw new TypeError(`Unsupported JCS value: ${typeof v}`);
}
/** JCS正規化したUTF-8をSHA-256し、指定形式で返す。T-12。 */
export async function sha256Jcs(value: unknown): Promise<string> {
  const bytes = new TextEncoder().encode(canonicalize(value));
  const digest = await globalThis.crypto.subtle.digest("SHA-256", bytes);
  return `sha256-jcs:${Array.from(new Uint8Array(digest), (b) => b.toString(16).padStart(2, "0")).join("")}`;
}