migrate-multi-instance.js

#!/usr/bin/env node

/**
 * Migration script for Multi-Instance MongoDB Solution
 * 
 * This script helps with:
 * 1. Creating necessary database indexes
 * 2. Cleaning up any existing pending responses
 * 3. Verifying the setup
 */

const { MongoClient } = require('mongodb');

const MONGO_URL = process.env.MONGO_URL || process.env.MONGODB_URI || 'mongodb://localhost:27017/meteor';

async function createIndexes(db) {
  console.log('Creating database indexes...');
  
  const collection = db.collection('pendingResponses');
  
  try {
    // Create username index
    await collection.createIndex({ username: 1 });
    console.log('✅ Created username index');
    
    // Create requestId index
    await collection.createIndex({ requestId: 1 });
    console.log('✅ Created requestId index');
    
    // Create TTL index for automatic cleanup
    await collection.createIndex({ expiresAt: 1 }, { expireAfterSeconds: 0 });
    console.log('✅ Created TTL index for automatic cleanup');
    
    // Create compound index for efficient queries
    await collection.createIndex({ username: 1, status: 1 });
    console.log('✅ Created compound index (username + status)');
    
  } catch (error) {
    console.error('❌ Error creating indexes:', error.message);
    throw error;
  }
}

async function cleanupExistingData(db) {
  console.log('Cleaning up existing pending responses...');
  
  const collection = db.collection('pendingResponses');
  
  try {
    const result = await collection.deleteMany({});
    console.log(`✅ Cleaned up ${result.deletedCount} existing pending responses`);
  } catch (error) {
    console.error('❌ Error cleaning up data:', error.message);
    throw error;
  }
}

async function verifySetup(db) {
  console.log('Verifying setup...');
  
  const collection = db.collection('pendingResponses');
  
  try {
    // Check indexes
    const indexes = await collection.indexes();
    const requiredIndexes = ['username_1', 'requestId_1', 'expiresAt_1'];
    
    const existingIndexNames = indexes.map(idx => idx.name);
    const missingIndexes = requiredIndexes.filter(name => !existingIndexNames.includes(name));
    
    if (missingIndexes.length === 0) {
      console.log('✅ All required indexes are present');
    } else {
      console.log('❌ Missing indexes:', missingIndexes);
      return false;
    }
    
    // Test insert and query
    const testDoc = {
      username: 'migration-test',
      requestId: 'test-123',
      status: 'pending',
      createdAt: new Date(),
      expiresAt: new Date(Date.now() + 30000)
    };
    
    await collection.insertOne(testDoc);
    console.log('✅ Test document inserted');
    
    const found = await collection.findOne({ username: 'migration-test' });
    if (found) {
      console.log('✅ Test document retrieved');
    } else {
      console.log('❌ Could not retrieve test document');
      return false;
    }
    
    // Clean up test document
    await collection.deleteOne({ username: 'migration-test' });
    console.log('✅ Test document cleaned up');
    
    return true;
    
  } catch (error) {
    console.error('❌ Error during verification:', error.message);
    return false;
  }
}

async function showCollectionStats(db) {
  console.log('Collection statistics:');
  
  const collection = db.collection('pendingResponses');
  
  try {
    const stats = await db.command({ collStats: 'pendingResponses' });
    console.log(`📊 Documents: ${stats.count || 0}`);
    console.log(`📊 Average document size: ${Math.round((stats.avgObjSize || 0) / 1024 * 100) / 100} KB`);
    console.log(`📊 Total collection size: ${Math.round((stats.size || 0) / 1024 / 1024 * 100) / 100} MB`);
    console.log(`📊 Indexes: ${stats.nindexes || 0}`);
  } catch (error) {
    // Collection might not exist yet
    console.log('📊 Collection does not exist yet (will be created on first use)');
  }
}

async function main() {
  console.log('🚀 Starting Multi-Instance MongoDB Migration\n');
  
  if (!MONGO_URL) {
    console.error('❌ MONGO_URL environment variable is required');
    process.exit(1);
  }
  
  console.log(`📡 Connecting to: ${MONGO_URL.replace(/\/\/.*@/, '//***:***@')}`);
  
  const client = new MongoClient(MONGO_URL);
  
  try {
    await client.connect();
    console.log('✅ Connected to MongoDB\n');
    
    const db = client.db();
    
    // Show current stats
    await showCollectionStats(db);
    console.log('');
    
    // Clean up existing data
    await cleanupExistingData(db);
    console.log('');
    
    // Create indexes
    await createIndexes(db);
    console.log('');
    
    // Verify setup
    const isValid = await verifySetup(db);
    console.log('');
    
    if (isValid) {
      console.log('🎉 Migration completed successfully!');
      console.log('');
      console.log('Next steps:');
      console.log('1. Deploy the updated application code');
      console.log('2. Monitor /api/pending-responses endpoint');
      console.log('3. Test with a sample notification');
      console.log('');
      console.log('Monitoring:');
      console.log('- Pending responses: GET /api/pending-responses');
      console.log('- Database cleanup runs automatically every minute');
      console.log('- TTL index will auto-delete expired documents');
    } else {
      console.log('❌ Migration failed verification');
      process.exit(1);
    }
    
  } catch (error) {
    console.error('❌ Migration failed:', error.message);
    process.exit(1);
  } finally {
    await client.close();
    console.log('📡 Database connection closed');
  }
}

// Handle CLI arguments
const args = process.argv.slice(2);

if (args.includes('--help') || args.includes('-h')) {
  console.log(`
Multi-Instance MongoDB Migration Script

Usage:
  node migrate-multi-instance.js [options]

Options:
  --help, -h     Show this help message
  --dry-run      Show what would be done without making changes
  --force        Skip confirmation prompts

Environment Variables:
  MONGO_URL      MongoDB connection string (required)

Examples:
  # Basic migration
  MONGO_URL="mongodb://localhost:27017/meteor" node migrate-multi-instance.js
  
  # With custom MongoDB Atlas connection
  MONGO_URL="mongodb+srv://user:pass@cluster.mongodb.net/myapp" node migrate-multi-instance.js
  
  # Dry run to see what would happen
  node migrate-multi-instance.js --dry-run
`);
  process.exit(0);
}

if (args.includes('--dry-run')) {
  console.log('🔍 DRY RUN MODE - No changes will be made\n');
  console.log('Would perform the following actions:');
  console.log('1. Clean up existing pendingResponses collection');
  console.log('2. Create indexes: username_1, requestId_1, expiresAt_1');
  console.log('3. Create compound index: username_1_status_1');
  console.log('4. Verify setup with test document');
  console.log('\nTo perform actual migration, run without --dry-run');
  process.exit(0);
}

// Run migration
main().catch(console.error);

module.exports = {
  createIndexes,
  cleanupExistingData,
  verifySetup
};