import { createPublicKey, verify } from "crypto";

function getPublicKey() {
  const b64 = process.env.LICENSE_PUBLIC_KEY;
  if (!b64) {
    console.error("[revisione] LICENSE_PUBLIC_KEY is not set — license system not configured");
    throw createError({ statusCode: 500, message: "Internal server error" });
  }

  return createPublicKey({
    key: Buffer.from(b64, "base64"),
    format: "der",
    type: "spki",
  });
}

export function verifyLicenseKey(key: string): boolean {
  try {
    const pubKey = getPublicKey();
    const now = Math.floor(Date.now() / 1000 / 300);

    const sig = Buffer.from(key, "base64url");

    // accept current window and the one before (edge case tolerance)
    for (const window of [now, now - 1]) {
      const msg = Buffer.from(String(window));
      if (verify(null, msg, pubKey, sig)) return true;
    }

    return false;
  } catch {
    return false;
  }
}