mnemo_cards/mnemo_cards_backend/lib/cron/backup.dart

import 'dart:io';

import 'package:mnemo_cards_backend/cron/task.dart';

import '../main.dart';

class Backup with Task {
  final backupDir;

  static const _maxBackups = 6;
  static const _maxBackupAgeDays = 2;

  Backup(String dir) : backupDir = dir.endsWith('/') ? dir : '$dir/';

  @override
  String get name => 'backup';

  @override
  Future<void> task() async {
    print('$name waiting 5 seconds for other tasks to complete');
    await Future.delayed(Duration(seconds: 5));
    final t = DateTime.now();
    final timeString =
        '${t.year}_${t.month.toString().padLeft(2, '0')}_${t.day.toString().padLeft(2, '0')}_'
        '${t.hour.toString().padLeft(2, '0')}_${t.minute.toString().padLeft(2, '0')}';
    final filename = 'db_backup_$timeString.sql';
    final to = '${backupDir}$filename';
    final dir = Directory(backupDir)..createSync(recursive: true);
    await _deleteOldBackups(dir);
    // TODO: Implement PostgreSQL backup
    // await database.backupToFile(to);
    // print('$name database backup saved to $to');
  }

  Future<void> _deleteOldBackups(Directory dir) async {
    final now = DateTime.now();
    final backups = dir.listSync().whereType<File>();
    if (backups.length > _maxBackups) {
      final oldBackups = backups
          .where(
            (f) =>
                now.difference(f.lastModifiedSync()).inDays > _maxBackupAgeDays,
          )
          .toList();
      if (oldBackups.length != backups.length) {
        oldBackups.sort(
            (a, b) => a.lastModifiedSync().compareTo(b.lastModifiedSync()));
        oldBackups.take(backups.length - _maxBackups).forEach((b) {
          try {
            b.deleteSync();
          } catch (e) {
            print('$name error when deleting backup file $e');
          }
        });
      }
    }
  }

  @override
  int get intervalSeconds => 60 * 60 * 12;
}