class ROTP::OTP::URI

def parameters
  {
    secret: @otp.secret,
    issuer: issuer,
    algorithm: algorithm,
    digits: digits,
    period: period,
    counter: counter,
  }
    .merge(@otp.provisioning_params)
    .reject { |_, v| v.nil? }
    .map { |k, v| "#{k}=#{ERB::Util.url_encode(v)}" }
    .join('&')
end