import { timingSafeEqual } from "node:crypto";
import type { Context } from "hono";

export const ORIGIN_VERIFY_HEADER = "x-origin-verify";

export function originVerifyHeader(c: Context): string {
  return c.req.header(ORIGIN_VERIFY_HEADER)?.trim() ?? "";
}

/** When a secret is configured, only CloudFront's origin header is accepted. */
export function cloudFrontOriginAllowed(c: Context, secret: string | undefined): boolean {
  if (!secret) return true;
  const provided = originVerifyHeader(c);
  const a = Buffer.from(provided);
  const b = Buffer.from(secret);
  if (a.length !== b.length) return false;
  return timingSafeEqual(a, b);
}