import mysql from 'mysql2/promise';
import dotenv from 'dotenv';
import * as xlsx from 'xlsx';
import fs from 'fs';

dotenv.config();

const { DB_HOST, DB_USER, DB_PASS, DB_NAME, DB_PORT } = process.env;

async function backup() {
  const connection = await mysql.createConnection({
    host: DB_HOST,
    user: DB_USER,
    password: DB_PASS,
    database: DB_NAME,
    port: parseInt(DB_PORT || '3306')
  });

  console.log('🚀 Starting Database Backup Process...');

  const tables = [
    'asset_pc', 'asset_server', 'asset_storage', 'asset_remote', 
    'asset_equipment', 'asset_office_supplies', 'asset_survey', 'asset_vip'
  ];
  
  const wb = xlsx.utils.book_new();

  for (const table of tables) {
    try {
      // 1. Create table backup
      await connection.query(`DROP TABLE IF EXISTS ${table}_backup`);
      await connection.query(`CREATE TABLE ${table}_backup AS SELECT * FROM ${table}`);
      console.log(`✅ Table backup created: ${table} -> ${table}_backup`);

      // 2. Fetch data for Excel
      const [rows] = await connection.query(`SELECT * FROM ${table}`);
      if (rows.length > 0) {
          const ws = xlsx.utils.json_to_sheet(rows);
          // Sheet names max length is 31 chars
          const sheetName = table.substring(0, 31);
          xlsx.utils.book_append_sheet(wb, ws, sheetName);
      }
    } catch (e) {
      console.warn(`⚠️ Skipped ${table}: ${e.message}`);
    }
  }

  // 3. Write Excel file
  const fileName = 'backupDB_20260608.xlsx';
  xlsx.writeFile(wb, fileName);
  console.log(`✅ Excel data exported successfully to ${fileName}`);
  
  await connection.end();
}

backup().catch(err => {
  console.error('❌ Backup Failed:', err);
  process.exit(1);
});