import { TOTP, URI } from "otpauth";

export type TOTPAlgorithm = "SHA1" | "SHA256" | "SHA512";

export function generateTOTP(
  base32Secret: string,
  algorithm: TOTPAlgorithm = "SHA1"
): { code: string; remaining: number } {
  const totp = new TOTP({ secret: base32Secret, digits: 6, period: 30, algorithm });
  const code = totp.generate();
  const remaining = 30 - (Math.floor(Date.now() / 1000) % 30);
  return { code, remaining };
}

export function parseOtpauthURI(uri: string): { secret: string; algorithm?: TOTPAlgorithm } | null {
  try {
    const parsed = URI.parse(uri);
    if (parsed instanceof TOTP) {
      return { secret: parsed.secret.base32, algorithm: parsed.algorithm as TOTPAlgorithm };
    }
    return null;
  } catch {
    return null;
  }
}