import { createHash, randomBytes } from "node:crypto";

export interface PkcePair {
  verifier: string;
  challenge: string;
}

/** Generate a PKCE verifier and its S256 challenge (RFC 7636). */
export function generatePkce(): PkcePair {
  const verifier = randomBytes(32).toString("base64url");
  const challenge = createHash("sha256").update(verifier).digest("base64url");
  return { verifier, challenge };
}