/**
 * S3 Backup Script for Weight Tracker
 * 
 * This script creates automated backups of the Weight Tracker data
 * and uploads them to an S3-compatible storage (like Minio)
 */

const fs = require('fs');
const path = require('path');
const { S3Client, PutObjectCommand, ListObjectsV2Command, DeleteObjectCommand } = require('@aws-sdk/client-s3');
const cron = require('node-cron');

// Configuration (can be overridden by environment variables)
const config = {
  // S3 Configuration
  s3: {
    endpoint: process.env.S3_ENDPOINT || 'https://your-minio-server.example.com',
    region: process.env.S3_REGION || 'us-east-1', // Default region, can be any value for Minio
    bucket: process.env.S3_BUCKET || 'weight-tracker-backups',
    accessKey: process.env.S3_ACCESS_KEY || 'your-access-key',
    secretKey: process.env.S3_SECRET_KEY || 'your-secret-key',
    useSSL: process.env.S3_USE_SSL !== 'false' // Default to true unless explicitly set to 'false'
  },
  
  // Backup Configuration
  backup: {
    dataPath: process.env.DATA_PATH || '/data/weight-tracker-data.json',
    schedule: process.env.BACKUP_SCHEDULE || '0 0 * * *', // Default: daily at midnight
    retention: parseInt(process.env.BACKUP_RETENTION || '7') // Default: keep 7 backups
  }
};

// Initialize S3 client
const s3Client = new S3Client({
  endpoint: config.s3.endpoint,
  region: config.s3.region,
  credentials: {
    accessKeyId: config.s3.accessKey,
    secretAccessKey: config.s3.secretKey
  },
  forcePathStyle: true, // Required for Minio
  tls: config.s3.useSSL
});

/**
 * Create a backup and upload to S3
 */
async function createBackup() {
  try {
    // Check if data file exists
    if (!fs.existsSync(config.backup.dataPath)) {
      console.error(`Data file not found: ${config.backup.dataPath}`);
      return;
    }
    
    // Read data file
    const data = fs.readFileSync(config.backup.dataPath, 'utf8');
    
    // Generate backup filename with timestamp
    const timestamp = new Date().toISOString().replace(/[:.]/g, '-');
    const backupFilename = `weight-tracker-backup-${timestamp}.json`;
    
    // Upload to S3
    const uploadParams = {
      Bucket: config.s3.bucket,
      Key: backupFilename,
      Body: data,
      ContentType: 'application/json'
    };
    
    const uploadCommand = new PutObjectCommand(uploadParams);
    await s3Client.send(uploadCommand);
    
    console.log(`Backup created successfully: ${backupFilename}`);
    
    // Cleanup old backups
    await cleanupOldBackups();
    
  } catch (error) {
    console.error('Error creating backup:', error);
  }
}

/**
 * Clean up old backups based on retention policy
 */
async function cleanupOldBackups() {
  try {
    // List all backups
    const listParams = {
      Bucket: config.s3.bucket,
      Prefix: 'weight-tracker-backup-'
    };
    
    const listCommand = new ListObjectsV2Command(listParams);
    const response = await s3Client.send(listCommand);
    
    if (!response.Contents || response.Contents.length <= config.backup.retention) {
      return; // No cleanup needed
    }
    
    // Sort by date (oldest first)
    const backups = response.Contents.sort((a, b) => 
      new Date(a.LastModified) - new Date(b.LastModified)
    );
    
    // Delete oldest backups that exceed retention count
    const backupsToDelete = backups.slice(0, backups.length - config.backup.retention);
    
    for (const backup of backupsToDelete) {
      const deleteParams = {
        Bucket: config.s3.bucket,
        Key: backup.Key
      };
      
      const deleteCommand = new DeleteObjectCommand(deleteParams);
      await s3Client.send(deleteCommand);
      
      console.log(`Deleted old backup: ${backup.Key}`);
    }
    
  } catch (error) {
    console.error('Error cleaning up old backups:', error);
  }
}

/**
 * Initialize the backup system
 */
function init() {
  console.log('Starting Weight Tracker S3 backup system');
  console.log(`Backup schedule: ${config.backup.schedule}`);
  console.log(`Backup retention: ${config.backup.retention} backups`);
  console.log(`S3 endpoint: ${config.s3.endpoint}`);
  console.log(`S3 bucket: ${config.s3.bucket}`);
  
  // Schedule regular backups
  cron.schedule(config.backup.schedule, () => {
    console.log('Running scheduled backup...');
    createBackup();
  });
  
  // Create initial backup
  console.log('Creating initial backup...');
  createBackup();
}

// Start the backup system
init();