import type { Context } from "@oak/oak";
import { verifyJWT } from "./jwt.ts";

/** Extracts the userId from an optional Bearer token. Returns null if absent or invalid. */
export async function parseOptionalAuth(ctx: Context): Promise<string | null> {
  const authHeader = ctx.request.headers.get("Authorization");
  if (!authHeader?.startsWith("Bearer ")) return null;
  const payload = await verifyJWT(authHeader.substring(7));
  return payload?.userId ?? null;
}