const mongoose = require('mongoose');
const fs = require('fs').promises;
const path = require('path');

// Atlas MongoDB connection string
const MONGODB_URI = 'mongodb+srv://nothingyu:wSg3lbO1PkHiRMq9@sandbox.ecysggv.mongodb.net/test?retryWrites=true&w=majority&appName=sandbox';

// Connect to MongoDB Atlas
const connectDB = async () => {
  try {
    await mongoose.connect(MONGODB_URI);
    console.log('✅ Connected to MongoDB Atlas');
  } catch (error) {
    console.error('❌ MongoDB connection error:', error);
    process.exit(1);
  }
};

// Backup and Version Control System
const backupVersionControl = {
  // Create comprehensive backup
  async createBackup(customBackupName = null) {
    try {
      const timestamp = new Date().toISOString().replace(/[:.]/g, '-');
      const backupName = customBackupName || `comprehensive-backup-${timestamp}`;
      
      console.log(`💾 Creating comprehensive backup: ${backupName}`);
      
      const collections = ['subtitles', 'sourcetexts', 'submissions', 'users', 'securitylogs'];
      const backupData = {
        metadata: {
          backupName,
          timestamp: new Date(),
          collections: collections,
          totalRecords: 0,
          version: '1.0',
          createdBy: 'system'
        },
        data: {}
      };
      
      // Export all collections
      for (const collection of collections) {
        try {
          const data = await mongoose.connection.db.collection(collection).find({}).toArray();
          backupData.data[collection] = data;
          backupData.metadata.totalRecords += data.length;
          console.log(`  📦 Exported ${data.length} records from ${collection}`);
        } catch (error) {
          console.warn(`  ⚠️ Could not export ${collection}:`, error.message);
        }
      }
      
      // Save backup to file system
      const backupDir = path.join(__dirname, 'backups');
      await fs.mkdir(backupDir, { recursive: true });
      
      const backupPath = path.join(backupDir, `${backupName}.json`);
      await fs.writeFile(backupPath, JSON.stringify(backupData, null, 2));
      
      // Create backup record in database
      const backupRecord = {
        backupName,
        timestamp: new Date(),
        collections: collections,
        totalRecords: backupData.metadata.totalRecords,
        filePath: backupPath,
        status: 'created',
        createdBy: 'system'
      };
      
      // Save to backup collection
      const backupCollection = mongoose.connection.db.collection('backups');
      await backupCollection.insertOne(backupRecord);
      
      console.log(`✅ Backup created successfully: ${backupName}`);
      console.log(`📊 Total records: ${backupData.metadata.totalRecords}`);
      console.log(`💾 File saved: ${backupPath}`);
      
      return backupName;
      
    } catch (error) {
      console.error('❌ Error creating backup:', error);
      throw error;
    }
  },
  
  // Restore from backup
  async restoreFromBackup(backupName) {
    try {
      console.log(`🔄 Restoring from backup: ${backupName}`);
      
      // Load backup file
      const backupPath = path.join(__dirname, 'backups', `${backupName}.json`);
      const backupData = JSON.parse(await fs.readFile(backupPath, 'utf8'));
      
      console.log(`📊 Backup metadata:`, backupData.metadata);
      
      // Confirm restoration
      console.log('⚠️ This will overwrite existing data. Are you sure? (y/N)');
      // In a real implementation, you'd get user confirmation here
      
      // Restore each collection
      for (const [collection, data] of Object.entries(backupData.data)) {
        try {
          // Clear existing data
          await mongoose.connection.db.collection(collection).deleteMany({});
          
          // Insert backup data
          if (data.length > 0) {
            await mongoose.connection.db.collection(collection).insertMany(data);
          }
          
          console.log(`  ✅ Restored ${data.length} records to ${collection}`);
        } catch (error) {
          console.error(`  ❌ Error restoring ${collection}:`, error.message);
        }
      }
      
      console.log(`✅ Restoration completed: ${backupName}`);
      
    } catch (error) {
      console.error('❌ Error restoring from backup:', error);
      throw error;
    }
  },
  
  // List available backups
  async listBackups() {
    try {
      console.log('📋 Available backups:');
      
      // List from database
      const backupCollection = mongoose.connection.db.collection('backups');
      const dbBackups = await backupCollection.find({}).sort({ timestamp: -1 }).toArray();
      
      if (dbBackups.length === 0) {
        console.log('  No backups found in database');
      } else {
        console.log('  Database backups:');
        dbBackups.forEach(backup => {
          console.log(`    📦 ${backup.backupName} (${backup.totalRecords} records, ${new Date(backup.timestamp).toLocaleString()})`);
        });
      }
      
      // List from file system
      const backupDir = path.join(__dirname, 'backups');
      try {
        const files = await fs.readdir(backupDir);
        const backupFiles = files.filter(file => file.endsWith('.json'));
        
        if (backupFiles.length > 0) {
          console.log('  File system backups:');
          for (const file of backupFiles) {
            const filePath = path.join(backupDir, file);
            const stats = await fs.stat(filePath);
            console.log(`    💾 ${file} (${(stats.size / 1024).toFixed(2)} KB, ${stats.mtime.toLocaleString()})`);
          }
        }
      } catch (error) {
        console.log('  No backup directory found');
      }
      
    } catch (error) {
      console.error('❌ Error listing backups:', error);
    }
  },
  
  // Version control for content changes
  async createVersionControl() {
    try {
      console.log('📝 Creating version control system...');
      
      const versionControlSchema = new mongoose.Schema({
        documentId: { type: String, required: true },
        collection: { type: String, required: true },
        version: { type: Number, required: true },
        changes: mongoose.Schema.Types.Mixed,
        timestamp: { type: Date, default: Date.now },
        userId: String,
        commitMessage: String,
        previousVersion: Number,
        checksum: String
      });
      
      const VersionControl = mongoose.model('VersionControl', versionControlSchema);
      
      // Create indexes for efficient querying
      await VersionControl.createIndexes();
      
      console.log('✅ Version control system created');
      
      return VersionControl;
      
    } catch (error) {
      console.error('❌ Error creating version control:', error);
    }
  },
  
  // Track content changes
  async trackChange(collection, documentId, changes, userId, commitMessage) {
    try {
      const VersionControl = mongoose.model('VersionControl');
      
      // Get current version
      const latestVersion = await VersionControl.findOne({
        documentId,
        collection
      }).sort({ version: -1 });
      
      const newVersion = (latestVersion?.version || 0) + 1;
      
      // Create version record
      await VersionControl.create({
        documentId,
        collection,
        version: newVersion,
        changes,
        userId,
        commitMessage,
        previousVersion: latestVersion?.version || null,
        timestamp: new Date()
      });
      
      console.log(`📝 Version ${newVersion} created for ${collection}/${documentId}`);
      
    } catch (error) {
      console.error('❌ Error tracking change:', error);
    }
  },
  
  // Get content history
  async getContentHistory(collection, documentId) {
    try {
      const VersionControl = mongoose.model('VersionControl');
      
      const history = await VersionControl.find({
        documentId,
        collection
      }).sort({ version: -1 });
      
      console.log(`📋 Version history for ${collection}/${documentId}:`);
      history.forEach(version => {
        console.log(`  v${version.version} (${new Date(version.timestamp).toLocaleString()}) - ${version.commitMessage}`);
      });
      
      return history;
      
    } catch (error) {
      console.error('❌ Error getting content history:', error);
    }
  },
  
  // Automated backup scheduling
  async scheduleBackups() {
    try {
      console.log('⏰ Setting up automated backup scheduling...');
      
      const scheduleSchema = new mongoose.Schema({
        scheduleType: { type: String, enum: ['daily', 'weekly', 'monthly'], required: true },
        lastBackup: Date,
        nextBackup: Date,
        isActive: { type: Boolean, default: true },
        createdBy: String
      });
      
      const Schedule = mongoose.model('Schedule', scheduleSchema);
      
      // Create default daily backup schedule
      await Schedule.create({
        scheduleType: 'daily',
        lastBackup: null,
        nextBackup: new Date(Date.now() + 24 * 60 * 60 * 1000), // Tomorrow
        isActive: true,
        createdBy: 'system'
      });
      
      console.log('✅ Automated backup schedule created (daily)');
      
    } catch (error) {
      console.error('❌ Error setting up backup scheduling:', error);
    }
  },
  
  // Verify backup integrity
  async verifyBackupIntegrity(backupName) {
    try {
      console.log(`🔍 Verifying backup integrity: ${backupName}`);
      
      const backupPath = path.join(__dirname, 'backups', `${backupName}.json`);
      const backupData = JSON.parse(await fs.readFile(backupPath, 'utf8'));
      
      let verifiedCount = 0;
      let failedCount = 0;
      
      // Verify each collection
      for (const [collection, data] of Object.entries(backupData.data)) {
        try {
          const currentCount = await mongoose.connection.db.collection(collection).countDocuments();
          const backupCount = data.length;
          
          if (currentCount === backupCount) {
            verifiedCount++;
            console.log(`  ✅ ${collection}: ${backupCount} records verified`);
          } else {
            failedCount++;
            console.log(`  ❌ ${collection}: ${backupCount} in backup, ${currentCount} in database`);
          }
        } catch (error) {
          failedCount++;
          console.log(`  ❌ ${collection}: verification failed`);
        }
      }
      
      console.log(`🔍 Integrity verification complete:`);
      console.log(`  - Verified: ${verifiedCount} collections`);
      console.log(`  - Failed: ${failedCount} collections`);
      
      return { verifiedCount, failedCount };
      
    } catch (error) {
      console.error('❌ Error verifying backup integrity:', error);
    }
  }
};

// Main function
const main = async () => {
  try {
    console.log('🚀 Starting backup and version control system...');
    
    // Create comprehensive backup
    const backupName = await backupVersionControl.createBackup();
    
    // Create version control system
    await backupVersionControl.createVersionControl();
    
    // Set up automated backups
    await backupVersionControl.scheduleBackups();
    
    // List available backups
    await backupVersionControl.listBackups();
    
    console.log('\n🎉 Backup and version control system ready!');
    console.log('\n📋 Available functions:');
    console.log('  - createBackup(): Create new backup');
    console.log('  - restoreFromBackup(name): Restore from backup');
    console.log('  - listBackups(): List available backups');
    console.log('  - trackChange(): Track content changes');
    console.log('  - getContentHistory(): Get version history');
    console.log('  - verifyBackupIntegrity(): Verify backup integrity');
    
  } catch (error) {
    console.error('❌ Error in backup and version control system:', error);
  } finally {
    await mongoose.disconnect();
    console.log('🔌 Disconnected from MongoDB');
  }
};

// Run the system
connectDB().then(() => {
  main();
});