+-----------------+      +---------------------+      +----------------+
|  Admin / User   |----->| Node.js/Express API |----->|   PostgreSQL   |
| (e.g., Postman) |      |      (Backend)      |<-----|    Database    |
+-----------------+      +---------------------+      +----------------+
                           |          ^
                           |          | (Webhook Callbacks)
                           v          |
                      +-----------------+
                      | Vonage Messages |
                      |      API        |
                      +-----------------+
                           |          ^
                           | (SMS)    | (SMS)
                           v          |
                      +-----------------+
                      |   User's Phone  |
                      +-----------------+

# Create the project directory
mkdir vonage-sms-campaign-api
cd vonage-sms-campaign-api

# Initialize the Node.js project
npm init -y

npm install express @vonage/server-sdk dotenv pg uuid express-rate-limit

npm install --save-dev nodemon

// package.json
{
  // ... other settings
  "scripts": {
    "start": "node src/server.js"_
    "dev": "nodemon src/server.js"_
    "test": "echo \"Error: no test specified\" && exit 1"
  }_
  // ... other settings
}

.
├── src/
│   ├── config/
│   │   ├── db.js         # Database connection setup
│   │   └── vonage.js     # Vonage client initialization
│   ├── controllers/
│   │   ├── contactController.js
│   │   ├── campaignController.js
│   │   └── webhookController.js
│   ├── middleware/       # New directory for middleware
│   │   └── auth.js       # Authentication middleware
│   ├── models/
│   │   ├── contactModel.js
│   │   ├── campaignModel.js
│   │   └── messageModel.js
│   ├── routes/
│   │   ├── api.js        # Main API router
│   │   ├── contacts.js
│   │   ├── campaigns.js
│   │   └── webhooks.js
│   ├── services/
│   │   ├── vonageService.js # Logic for interacting with Vonage API
│   │   └── campaignService.js # Business logic for campaigns
│   ├── utils/
│   │   ├── logger.js     # Simple logger utility
│   │   └── errorHandler.js # Global error handler middleware
│   ├── server.js       # Express server entry point
│   └── app.js          # Express app configuration
├── .env                # Environment variables (DO NOT COMMIT)
├── .gitignore          # Git ignore file
├── package.json
└── package-lock.json

# .env

# Vonage API Credentials
VONAGE_API_KEY=YOUR_VONAGE_API_KEY
VONAGE_API_SECRET=YOUR_VONAGE_API_SECRET
VONAGE_APPLICATION_ID=YOUR_VONAGE_APPLICATION_ID
# SECURITY NOTE: Storing keys directly in the project folder is convenient for dev but not recommended for production.
# Consider storing it outside the project root or using a secrets manager. Update path accordingly.
VONAGE_PRIVATE_KEY_PATH=./private.key # Path relative to project root (or absolute path outside project)
VONAGE_NUMBER=YOUR_VONAGE_VIRTUAL_NUMBER # The number used for sending SMS

# Database Configuration
DATABASE_URL=postgresql://USER:PASSWORD@HOST:PORT/DATABASE_NAME

# Server Configuration
PORT=3000

# Basic API Key Authentication (Example)
API_KEY=your-secret-api-key # Change this to a strong_ random key

# .gitignore

# Dependencies
node_modules/

# Environment variables
.env
.env.*
!.env.example

# Logs
logs/
*.log
npm-debug.log*
yarn-debug.log*
yarn-error.log*

# Private key file (if stored in project - strongly recommended NOT to commit)
private.key

# OS generated files
.DS_Store
Thumbs.db

# Build output (if applicable)
dist/
build/

// src/utils/logger.js
const logger = {
    info: (message_ ...args) => {
        console.log(`[INFO] ${new Date().toISOString()} - ${message}`, ...args);
    },
    error: (message, ...args) => {
        console.error(`[ERROR] ${new Date().toISOString()} - ${message}`, ...args);
    },
    warn: (message, ...args) => {
        console.warn(`[WARN] ${new Date().toISOString()} - ${message}`, ...args);
    }
};

module.exports = logger;

// src/config/db.js
const { Pool } = require('pg');
const dotenv = require('dotenv');
const logger = require('../utils/logger');

dotenv.config();

const pool = new Pool({
    connectionString: process.env.DATABASE_URL,
    // Recommended for production environments with SSL
    // ssl: {
    //   rejectUnauthorized: false // Adjust based on your provider's requirements
    // }
});

pool.on('connect', () => {
    logger.info('Database connection established');
});

pool.on('error', (err) => {
    logger.error('Unexpected error on idle client', err);
    process.exit(-1); // Exit if the pool errors out
});

module.exports = {
    query: (text, params) => pool.query(text, params),
    pool // Export pool if direct access is needed
};

// src/config/vonage.js
const { Vonage } = require('@vonage/server-sdk');
const dotenv = require('dotenv');
const path = require('path');
const fs = require('fs');
const logger = require('../utils/logger');

dotenv.config();

// Resolve path relative to project root or use absolute path if provided
const privateKeyPath = path.resolve(process.env.VONAGE_PRIVATE_KEY_PATH || './private.key');

// Ensure the private key file exists before attempting to initialize
if (!fs.existsSync(privateKeyPath)) {
    logger.error(`Vonage private key file not found at path: ${privateKeyPath}`);
    logger.error('Please ensure the VONAGE_PRIVATE_KEY_PATH environment variable is set correctly and the file exists.');
    logger.error('Remember security best practices: avoid storing keys directly in the project folder in production.');
    // In a real app, you might handle this more gracefully, but exiting is clear during setup
    process.exit(1);
}

const vonage = new Vonage({
    apiKey: process.env.VONAGE_API_KEY,
    apiSecret: process.env.VONAGE_API_SECRET,
    applicationId: process.env.VONAGE_APPLICATION_ID,
    privateKey: privateKeyPath // Use the resolved path
}, {
    // Optional: Add custom logger or other options
    // logger: logger // You can potentially pass your custom logger here if needed
});

logger.info('Vonage client initialized.');

module.exports = vonage;

// src/app.js
const express = require('express');
const dotenv = require('dotenv');
const rateLimit = require('express-rate-limit');
const apiRouter = require('./routes/api');
const errorHandler = require('./utils/errorHandler');
const logger = require('./utils/logger');

dotenv.config();

const app = express();

// Middleware
app.use(express.json()); // Parse JSON bodies
app.use(express.urlencoded({ extended: true })); // Parse URL-encoded bodies

// Simple request logger middleware
app.use((req, res, next) => {
    logger.info(`${req.method} ${req.path}`);
    next();
});

// Apply rate limiting to API routes (excluding webhooks initially)
const apiLimiter = rateLimit({
    windowMs: 15 * 60 * 1000, // 15 minutes
    max: 100, // Limit each IP to 100 requests per windowMs for API routes
    message: 'Too many requests from this IP, please try again after 15 minutes'
});
// Apply limiter specifically to routes managed by apiRouter that are NOT webhooks
// Note: This requires apiRouter structure where webhooks are separate
// (as implemented in Section 4.2)
app.use('/api/v1', (req, res, next) => {
    // Check if the path starts with /webhooks to exclude them from this limiter
    if (req.path.startsWith('/webhooks')) {
        return next(); // Skip API limiter for webhooks
    }
    apiLimiter(req, res, next); // Apply limiter to other API routes
});
// Consider adding a separate, potentially more lenient, limiter for webhooks if needed

// Mount API routes
app.use('/api/v1', apiRouter); // Prefix routes with /api/v1

// Health check endpoint
app.get('/health', (req, res) => {
    res.status(200).json({ status: 'UP', timestamp: new Date().toISOString() });
});

// Global error handler - Must be the last middleware
app.use(errorHandler);

module.exports = app;

// src/server.js
const app = require('./app');
const logger = require('./utils/logger');
const db = require('./config/db'); // Import to potentially test connection on start

const PORT = process.env.PORT || 3000;

// Optional: Test database connection on startup
db.query('SELECT NOW()')
    .then(res => logger.info(`Database connectivity confirmed at: ${res.rows[0].now}`))
    .catch(err => {
        logger.error('Database connection failed on startup:', err);
        process.exit(1); // Exit if DB connection fails
    });

const server = app.listen(PORT, () => {
    logger.info(`Server running in ${process.env.NODE_ENV || 'development'} mode on port ${PORT}`);
    logger.info(`API available at http://localhost:${PORT}/api/v1`);
});

// Handle unhandled promise rejections
process.on('unhandledRejection', (err) => {
    logger.error('UNHANDLED REJECTION! Shutting down...');
    logger.error(err.name, err.message);
    server.close(() => {
        process.exit(1);
    });
});

// Handle SIGTERM signal (e.g., from Docker or Heroku)
process.on('SIGTERM', () => {
    logger.info('SIGTERM RECEIVED. Shutting down gracefully...');
    server.close(() => {
        logger.info('Process terminated.');
    });
});

-- Enable pgcrypto extension if not already enabled
CREATE EXTENSION IF NOT EXISTS pgcrypto;

-- contacts table
CREATE TABLE contacts (
    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    phone_number VARCHAR(20) UNIQUE NOT NULL, -- E.164 format recommended (e.g., +14155552671)
    first_name VARCHAR(100),
    last_name VARCHAR(100),
    opted_out BOOLEAN DEFAULT FALSE NOT NULL,
    created_at TIMESTAMPTZ DEFAULT NOW() NOT NULL,
    updated_at TIMESTAMPTZ DEFAULT NOW() NOT NULL
);

-- campaigns table
CREATE TABLE campaigns (
    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    name VARCHAR(255) NOT NULL,
    message_text TEXT NOT NULL,
    created_at TIMESTAMPTZ DEFAULT NOW() NOT NULL,
    scheduled_at TIMESTAMPTZ, -- For future scheduling feature
    status VARCHAR(20) DEFAULT 'draft' NOT NULL -- e.g., draft, sending, completed, failed
);

-- messages table (to track individual SMS status)
CREATE TABLE messages (
    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    campaign_id UUID REFERENCES campaigns(id) ON DELETE SET NULL, -- Allow campaign deletion without losing message history
    contact_id UUID REFERENCES contacts(id) ON DELETE CASCADE, -- If contact is deleted, remove their messages
    vonage_message_uuid VARCHAR(100) UNIQUE, -- UUID provided by Vonage on send
    status VARCHAR(20) DEFAULT 'submitted' NOT NULL, -- e.g., submitted, delivered, expired, failed, rejected, accepted, unknown
    status_timestamp TIMESTAMPTZ, -- Timestamp from Vonage status update
    error_code INTEGER,
    error_message TEXT,
    sent_at TIMESTAMPTZ DEFAULT NOW() NOT NULL,
    updated_at TIMESTAMPTZ DEFAULT NOW() NOT NULL
);

-- Add indexes for performance
CREATE INDEX idx_contacts_phone_number ON contacts(phone_number);
CREATE INDEX idx_messages_vonage_uuid ON messages(vonage_message_uuid);
CREATE INDEX idx_messages_campaign_id ON messages(campaign_id);
CREATE INDEX idx_messages_contact_id ON messages(contact_id);

-- Optional: Add triggers to automatically update updated_at timestamps
CREATE OR REPLACE FUNCTION update_updated_at_column()
RETURNS TRIGGER AS $$
BEGIN
   NEW.updated_at = NOW();
   RETURN NEW;
END;
$$ language 'plpgsql';

CREATE TRIGGER update_contacts_updated_at BEFORE UPDATE
ON contacts FOR EACH ROW EXECUTE FUNCTION
update_updated_at_column();

CREATE TRIGGER update_messages_updated_at BEFORE UPDATE
ON messages FOR EACH ROW EXECUTE FUNCTION
update_updated_at_column();

// src/models/contactModel.js
const db = require('../config/db');

const Contact = {
    create: async ({ phone_number, first_name, last_name, opted_out = false }) => { // Allow setting initial opt-out
        const query = `
            INSERT INTO contacts (phone_number, first_name, last_name, opted_out)
            VALUES ($1, $2, $3, $4)
            RETURNING *;
        `;
        const values = [phone_number, first_name, last_name, opted_out];
        const { rows } = await db.query(query, values);
        return rows[0];
    },

    findById: async (id) => {
        const { rows } = await db.query('SELECT * FROM contacts WHERE id = $1', [id]);
        return rows[0];
    },

    findByPhoneNumber: async (phone_number) => {
        const { rows } = await db.query('SELECT * FROM contacts WHERE phone_number = $1', [phone_number]);
        return rows[0];
    },

    getAll: async () => {
        const { rows } = await db.query('SELECT * FROM contacts ORDER BY created_at DESC');
        return rows;
    },

    updateOptOut: async (id, opted_out) => {
        const query = `
            UPDATE contacts
            SET opted_out = $1, updated_at = NOW()
            WHERE id = $2
            RETURNING *;
        `;
        const { rows } = await db.query(query, [opted_out, id]);
        return rows[0];
    },

    // Add delete function if needed
};

module.exports = Contact;

// src/models/campaignModel.js
const db = require('../config/db');

const Campaign = {
    create: async ({ name, message_text }) => {
        const query = `
            INSERT INTO campaigns (name, message_text)
            VALUES ($1, $2)
            RETURNING *;
        `;
        const values = [name, message_text];
        const { rows } = await db.query(query, values);
        return rows[0];
    },

    findById: async (id) => {
        const { rows } = await db.query('SELECT * FROM campaigns WHERE id = $1', [id]);
        return rows[0];
    },

    getAll: async () => {
        const { rows } = await db.query('SELECT * FROM campaigns ORDER BY created_at DESC');
        return rows;
    },

     updateStatus: async (id, status) => {
        const query = `
            UPDATE campaigns
            SET status = $1
            WHERE id = $2
            RETURNING *;
        `;
        const { rows } = await db.query(query, [status, id]);
        return rows[0];
    },
    // Add update, delete functions if needed
};

module.exports = Campaign;

// src/models/messageModel.js
const db = require('../config/db');

const Message = {
    create: async ({ campaign_id, contact_id, vonage_message_uuid, status = 'submitted', error_code = null, error_message = null }) => {
        const query = `
            INSERT INTO messages (campaign_id, contact_id, vonage_message_uuid, status, error_code, error_message, sent_at, updated_at)
            VALUES ($1, $2, $3, $4, $5, $6, NOW(), NOW())
            RETURNING *;
        `;
        const values = [campaign_id, contact_id, vonage_message_uuid, status, error_code, error_message];
        const { rows } = await db.query(query, values);
        return rows[0];
    },

    findByVonageUuid: async (vonage_message_uuid) => {
        const { rows } = await db.query('SELECT * FROM messages WHERE vonage_message_uuid = $1', [vonage_message_uuid]);
        return rows[0];
    },

    updateStatusByVonageUuid: async (vonage_message_uuid, status, status_timestamp, error_code = null, error_message = null) => {
        const query = `
            UPDATE messages
            SET status = $1,
                status_timestamp = $2,
                error_code = $3,
                error_message = $4,
                updated_at = NOW()
            WHERE vonage_message_uuid = $5
            RETURNING *;
        `;
        const values = [status, status_timestamp, error_code, error_message, vonage_message_uuid];
        const { rows } = await db.query(query, values);
        return rows[0];
    },

    getMessagesByCampaignId: async (campaign_id) => {
        const query = `
            SELECT m.*, c.phone_number
            FROM messages m
            JOIN contacts c ON m.contact_id = c.id
            WHERE m.campaign_id = $1
            ORDER BY m.sent_at ASC;
        `;
        const { rows } = await db.query(query, [campaign_id]);
        return rows;
    }
};

module.exports = Message;

// src/middleware/auth.js (Create this new file)
const logger = require('../utils/logger');

const authenticateApiKey = (req, res, next) => {
    const apiKey = req.headers['x-api-key'];

    if (!apiKey) {
        logger.warn('Authentication failed: No API key provided');
        return res.status(401).json({ message: 'Unauthorized: API key required' });
    }

    if (apiKey !== process.env.API_KEY) {
        logger.warn(`Authentication failed: Invalid API key provided: ${apiKey}`);
        return res.status(403).json({ message: 'Forbidden: Invalid API key' });
    }

    next(); // API key is valid
};

module.exports = authenticateApiKey;

// src/routes/api.js
const express = require('express');
const contactRoutes = require('./contacts');
const campaignRoutes = require('./campaigns');
const webhookRoutes = require('./webhooks');
const authenticateApiKey = require('../middleware/auth'); // Import the middleware

const router = express.Router();

// Apply API key authentication to all campaign and contact routes
router.use('/contacts', authenticateApiKey, contactRoutes);
router.use('/campaigns', authenticateApiKey, campaignRoutes);

// Webhook routes should generally NOT be authenticated with the API key,
// as they are called by Vonage. Security for webhooks is handled differently
// (e.g., signature verification if available, IP filtering).
router.use('/webhooks', webhookRoutes);

module.exports = router;

// src/routes/contacts.js
const express = require('express');
const contactController = require('../controllers/contactController');
// TODO: Add input validation middleware (e.g., using Joi or express-validator)

const router = express.Router();

router.post('/', contactController.createContact);
router.get('/', contactController.getAllContacts);
router.get('/:id', contactController.getContactById);
// Add routes for update, delete, opt-out update if needed

module.exports = router;

// src/controllers/contactController.js
const Contact = require('../models/contactModel');
const logger = require('../utils/logger');

exports.createContact = async (req, res, next) => {
    try {
        // Basic validation (implement more robust validation later, see Section 7 & 8)
        const { phone_number, first_name, last_name } = req.body;
        if (!phone_number) {
            return res.status(400).json({ message: 'Phone number is required' });
        }
        // TODO: Implement E.164 phone number format validation here (e.g., using libphonenumber-js)

        const existingContact = await Contact.findByPhoneNumber(phone_number);
        if (existingContact) {
            return res.status(409).json({ message: 'Contact with this phone number already exists' });
        }

        const contact = await Contact.create({ phone_number, first_name, last_name });
        logger.info(`Contact created: ${contact.id}`);
        res.status(201).json(contact);
    } catch (error) {
        next(error); // Pass error to the global error handler
    }
};

exports.getAllContacts = async (req, res, next) => {
    try {
        const contacts = await Contact.getAll();
        res.status(200).json(contacts);
    } catch (error) {
        next(error);
    }
};

exports.getContactById = async (req, res, next) => {
    try {
        const contact = await Contact.findById(req.params.id);
        if (!contact) {
            return res.status(404).json({ message: 'Contact not found' });
        }
        res.status(200).json(contact);
    } catch (error) {
        next(error);
    }
};

// Implement other handlers (update, delete) as needed

// src/routes/campaigns.js
const express = require('express');
const campaignController = require('../controllers/campaignController');
// TODO: Add input validation middleware
const router = express.Router();

router.post('/', campaignController.createCampaign);
router.get('/', campaignController.getAllCampaigns);
router.get('/:id', campaignController.getCampaignById);
router.post('/:id/send', campaignController.sendCampaign); // Endpoint to trigger sending
router.get('/:id/messages', campaignController.getCampaignMessages); // Endpoint to get message statuses for a campaign

module.exports = router;

// src/controllers/campaignController.js
const Campaign = require('../models/campaignModel');
const Message = require('../models/messageModel');
const CampaignService = require('../services/campaignService');
const logger = require('../utils/logger');

exports.createCampaign = async (req, res, next) => {
    try {
        // Basic validation (implement more robust validation later, see Section 7)
        const { name, message_text } = req.body;
        if (!name || !message_text) {
            return res.status(400).json({ message: 'Campaign name and message text are required' });
        }

        const campaign = await Campaign.create({ name, message_text });
        logger.info(`Campaign created: ${campaign.id}`);
        res.status(201).json(campaign);
    } catch (error) {
        next(error);
    }
};

exports.getAllCampaigns = async (req, res, next) => {
    try {
        const campaigns = await Campaign.getAll();
        res.status(200).json(campaigns);
    } catch (error) {
        next(error);
    }
};

exports.getCampaignById = async (req, res, next) => {
    try {
        const campaign = await Campaign.findById(req.params.id);
        if (!campaign) {
            return res.status(404).json({ message: 'Campaign not found' });
        }
        res.status(200).json(campaign);
    } catch (error) {
        next(error);
    }
};

exports.sendCampaign = async (req, res, next) => {
    try {
        const campaignId = req.params.id;
        // Optional: Specify target contact IDs in request body, or send to all non-opted-out contacts
        // const { targetContactIds } = req.body;

        const campaign = await Campaign.findById(campaignId);
        if (!campaign) {
            return res.status(404).json({ message: 'Campaign not found' });
        }
         if (campaign.status !== 'draft') {
            return res.status(400).json({ message: `Campaign cannot be sent, status is: ${campaign.status}` });
        }

        logger.info(`Initiating sending for campaign: ${campaignId}`);
        // Execute sending asynchronously (don't block the request)
        // Note: This function handles updating the campaign status internally
        CampaignService.sendCampaignToAll(campaignId)
            .then(() => logger.info(`Campaign ${campaignId} processing kicked off.`)) // Log kickoff
            .catch(err => logger.error(`Error during async campaign ${campaignId} processing:`, err)); // Log async errors

        // Immediately respond to the client, indicating the process has started
        res.status(202).json({ message: 'Campaign sending process initiated.' });

    } catch (error) {
        // Handle synchronous errors during setup/validation
        next(error);
    }
};

exports.getCampaignMessages = async (req, res, next) => {
    try {
        const campaignId = req.params.id;
        const messages = await Message.getMessagesByCampaignId(campaignId);
         if (!messages || messages.length === 0) {
             // Check if campaign exists at all to differentiate
            const campaign = await Campaign.findById(campaignId);
            if (!campaign) {
                return res.status(404).json({ message: 'Campaign not found' });
            }
            // Campaign exists, but no messages (yet or none sent)
            return res.status(200).json([]);
        }
        res.status(200).json(messages);
    } catch (error) {
        next(error);
    }
};

// src/routes/webhooks.js
const express = require('express');
const webhookController = require('../controllers/webhookController');
const router = express.Router();

// These routes are called BY Vonage, typically using POST for the Messages API
router.post('/inbound', webhookController.handleInboundSms);
router.post('/status', webhookController.handleMessageStatus);

module.exports = router;

// src/controllers/webhookController.js
const logger = require('../utils/logger');
const Contact = require('../models/contactModel');
const Message = require('../models/messageModel');
const vonageService = require('../services/vonageService'); // We'll create this next

exports.handleInboundSms = async (req, res) => {
    const params = req.body;
    logger.info('Received inbound SMS:', JSON.stringify(params, null, 2));

    // Vonage expects a 200 OK response quickly to prevent retries
    res.status(200).end();

    // Process the inbound message asynchronously
    try {
        // Basic validation for SMS via Messages API webhook format
        if (params.channel === 'sms' && params.message_type === 'text' && params.from?.number && params.text) {
            const fromNumber = params.from.number; // E.164 format
            const messageText = params.text.trim().toUpperCase();

            // Handle Opt-Out Keywords
            if (['STOP', 'UNSUBSCRIBE', 'CANCEL', 'END', 'QUIT'].includes(messageText)) {
                logger.info(`Opt-out request received from ${fromNumber}`);
                let contact = await Contact.findByPhoneNumber(fromNumber);
                if (contact) {
                    if (!contact.opted_out) {
                        await Contact.updateOptOut(contact.id, true);
                        logger.info(`Contact ${contact.id} (${fromNumber}) marked as opted-out.`);
                        // Optionally send confirmation SMS (use vonageService)
                        // await vonageService.sendSms(fromNumber, process.env.VONAGE_NUMBER, 'You have been unsubscribed.');
                    } else {
                        logger.info(`Contact ${contact.id} (${fromNumber}) was already opted-out.`);
                    }
                } else {
                    // Optionally create a contact record even if they opt-out immediately
                    // await Contact.create({ phone_number: fromNumber, opted_out: true });
                    logger.warn(`Opt-out request from unknown number: ${fromNumber}. Consider creating a record.`);
                }
            } else {
                // Handle other inbound messages (e.g., replies, help requests)
                logger.info(`Received other inbound text from ${fromNumber}: ""${params.text}""`);
                // Add logic here if needed (e.g., forward to support, auto-reply)
            }
        } else {
            logger.warn('Received non-SMS or malformed inbound message webhook:', params);
        }
    } catch (error) {
        logger.error('Error processing inbound SMS webhook:', error);
        // Don't send error response to Vonage here, as we already sent 200 OK
    }
};

exports.handleMessageStatus = async (req, res) => {
    const params = req.body;
    logger.info('Received message status update:', JSON.stringify(params, null, 2));

    // Vonage expects a 200 OK response quickly
    res.status(200).end();

    // Process the status update asynchronously
    try {
        // Basic validation for Messages API status webhook format
        if (params.message_uuid && params.status && params.timestamp) {
            const vonage_message_uuid = params.message_uuid;
            const status = params.status.toLowerCase(); // Normalize status
            const status_timestamp = params.timestamp;
            const error_code = params.error?.code;
            const error_message = params.error?.reason;

            const updatedMessage = await Message.updateStatusByVonageUuid(
                vonage_message_uuid,
                status,
                status_timestamp,
                error_code,
                error_message
            );

            if (updatedMessage) {
                logger.info(`Updated status for message ${vonage_message_uuid} to ${status}.`);
                // Optional: Add logic here based on status (e.g., update campaign status if all messages failed/delivered)
            } else {
                logger.warn(`Received status update for unknown message UUID: ${vonage_message_uuid}`);
            }
        } else {
            logger.warn('Received malformed message status webhook:', params);
        }
    } catch (error) {
        logger.error('Error processing message status webhook:', error);
        // Don't send error response to Vonage here, as we already sent 200 OK
    }
};