require('dotenv').config();
const sql = require('mssql');
const AWS = require('aws-sdk');
const fs = require('fs');
const path = require('path');
const SambaClient = require('samba-client');

// AWS S3 Configuration
const s3 = new AWS.S3({
  accessKeyId: process.env.AWS_ACCESS_KEY_ID,
  secretAccessKey: process.env.AWS_SECRET_ACCESS_KEY,
  region: process.env.AWS_REGION
});

// MSSQL Configuration
const config = {
  user: process.env.MSSQL_USER,
  password: process.env.MSSQL_PASSWORD,
  server: process.env.MSSQL_SERVER,
  port: parseInt(process.env.MSSQL_PORT) || 1433,
  database: process.env.MSSQL_DATABASE,
  options: {
    encrypt: true, // Use this if you're on Windows Azure
    trustServerCertificate: true // Change to true for local dev / self-signed certs
  }
};

// Backup file path
const backupFilePath = process.env.BACKUP_FILE_PATH;

// SMB Configuration
const smbConfig = {
  address: process.env.SMB_ADDRESS,
  username: process.env.SMB_USERNAME,
  password: process.env.SMB_PASSWORD,
  domain: process.env.SMB_DOMAIN || '', // optional
};

// Ensure download directory exists
const downloadFile = process.env.SMB_DOWNLOAD_FILE;
const localDownloadFile = process.env.SMB_LOCAL_DOWNLOAD_FILE;


// Function to create database backup
async function createDatabaseBackup() {
  try {
    console.log('Connecting to database...');
    await sql.connect(config);
    
    console.log('Creating database backup...');
    const backupQuery = `
      BACKUP DATABASE [${process.env.MSSQL_DATABASE}] 
      TO DISK = N'${backupFilePath}' 
      WITH NOFORMAT, NOINIT, NAME = N'${process.env.MSSQL_DATABASE}-Vollständig Datenbank Sichern', 
      SKIP, NOREWIND, NOUNLOAD, STATS = 10
    `;
    
    const result = await sql.query(backupQuery);
    console.log('Database backup created successfully');
    return backupFilePath;
  } catch (err) {
    console.error('Error creating database backup:', err);
    throw err;
  } finally {
    await sql.close();
  }
}

// Function to download backup file from SMB share
async function downloadBackupFile() {
  try {
    console.log('Downloading backup file from SMB share...');
    
    // Create SMB client
    const client = new SambaClient(smbConfig);
    
    // Download file from SMB share
    await client.getFile(downloadFile, localDownloadFile);
    
    console.log('Backup file downloaded successfully to:', localDownloadFile);
    return localDownloadFile;
  } catch (err) {
    console.error('Error downloading backup file from SMB share:', err);
    throw err;
  }
}

// Function to upload backup to S3
async function uploadBackupToS3(filePath) {
  try {
    console.log('Uploading backup to S3...');
    
    // Create a read stream for the file
    const fileStream = fs.createReadStream(filePath);
    
    // Handle stream errors
    fileStream.on('error', (err) => {
      console.error('File stream error:', err);
      throw err;
    });
    
    // Create S3 upload parameters using stream
    const params = {
      Bucket: process.env.S3_BUCKET_NAME,
      Key: `backups/${process.env.MSSQL_DATABASE}_${new Date().toISOString().replace(/[:.]/g, '-')}.bak`,
      Body: fileStream
    };
    
    // Upload file to S3 using stream
    const data = await s3.upload(params).promise();
    console.log('Backup uploaded successfully to S3:', data.Location);
    return data.Location;
  } catch (err) {
    console.error('Error uploading backup to S3:', err);
    throw err;
  }
}

// Function to run backup process
async function runBackupProcess() {
  try {
    console.log('Starting backup process at', new Date().toISOString());
    
    // Create database backup
    await createDatabaseBackup();
    
    // Download backup file from SMB share
    const localBackupFile = await downloadBackupFile();
    
    // Upload backup to S3
    const s3Url = await uploadBackupToS3(localBackupFile);
    
    console.log('Backup process completed successfully at', new Date().toISOString());
    console.log('Backup available at:', s3Url);
  } catch (err) {
    console.error('Backup process failed:', err);
  }
}

// Run backup immediately when starting
runBackupProcess();

// Schedule backup to run every 24 hours (86400000 milliseconds)
// You can adjust this interval as needed
setInterval(runBackupProcess, 86400000);

console.log('Database backup service started. Running backups every 24 hours.');