const crypto = require('crypto');
const Joi = require('joi');

// Define the expected webhook payload schema
const webhookSchema = Joi.object({
    // Add fields as needed
    mail: Joi.string().required(),
    // ...
});

// Define the secret token for webhook verification
const webhookSecret = 'your_secret_token';

// Webhook handler function
async function handleWebhook(req, res) {
    try {
        // Verify the webhook signature
        const signature = req.headers['x-webhook-signature'];
        const expectedSignature = crypto.createHmac('sha256', webhookSecret)
            .update(JSON.stringify(req.body))
            .digest('hex');
        if (signature !== expectedSignature) {
            return res.status(401).send('Invalid webhook signature');
        }

        // Validate the webhook payload
        const result = webhookSchema.validate(req.body);
        if (result.error) {
            return res.status(400).send('Invalid webhook payload');
        }

        // Process the mail
        // ...
        return res.status(200).send('Mail processed successfully');
    } catch (error) {
        return res.status(500).send('Error processing mail');
    }
}