/**
 * Deterministic JSON serializer used by idempotentAppend's byte-compare.
 * Sorts object keys lexicographically at every depth; preserves array order;
 * round-trips numbers/strings/booleans/null. Throws on circular structures.
 *
 * NOT a general-purpose canonical-JSON impl (no RFC 8785 number normalisation,
 * no Unicode escape rewriting). Sufficient for comparing two Message envelopes
 * we wrote ourselves moments apart.
 */
export function canonicalJSON(value: unknown): string {
  return JSON.stringify(canonicalize(value));
}

export function canonicalBytes(value: unknown): Uint8Array {
  return new TextEncoder().encode(canonicalJSON(value));
}

function canonicalize(v: unknown, seen: WeakSet<object> = new WeakSet()): unknown {
  if (v === null || typeof v !== "object") return v;
  if (v instanceof Uint8Array) {
    // Stable representation: array-of-bytes. Symmetric with envelope.ts replacer.
    return Array.from(v);
  }
  if (seen.has(v as object)) throw new Error("canonicalJSON: circular");
  seen.add(v as object);
  if (Array.isArray(v)) return v.map((x) => canonicalize(x, seen));
  const src = v as Record<string, unknown>;
  const out: Record<string, unknown> = {};
  for (const k of Object.keys(src).sort()) {
    out[k] = canonicalize(src[k], seen);
  }
  return out;
}