app.post('/send-otp', async (req, res) => {
  const { phoneNumber } = req.body;

  const apiKey = '3mW3hfluK8dpayQ53NXKdBhophrKP9sD8GKPi8qKqsMTZAAEsyq8HGMZCeSv';
  const otp = Math.floor(100000 + Math.random() * 900000); // Generate a 6-digit OTP
  const message = `${otp}`;

  const data = {
      sender_id: 'TKSOLV',
      message: '110131',
      variables_values: message,
      route: 'dlt',
      numbers: phoneNumber,
  };

  const options = {
      method: 'POST',
      headers: {
          'authorization': apiKey,
          'Content-Type': 'application/json'
      },
      data: JSON.stringify(data),
      url: 'https://www.fast2sms.com/dev/bulkV2',
  };

  try {
      const response = await axios(options);
      res.status(200).send({ success: true, message: 'OTP sent successfully', otp: otp });
  } catch (error) {
      res.status(500).send({ success: false, message: 'Failed to send OTP', error: error.message });
  }
});