database_helper.dart

import 'package:sqflite/sqflite.dart';
import 'package:path/path.dart';

class DatabaseHelper {
  static final DatabaseHelper instance = DatabaseHelper._init();
  static Database? _database;

  DatabaseHelper._init();

  Future<Database> get database async {
    if (_database != null) return _database!;
    _database = await _initDB('notes.db');
    return _database!;
  } 

  Future<Database> _initDB(String filePath) async {
    final dbPath = await getDatabasesPath();
    final path = join(dbPath, filePath);

    return await openDatabase(path, version: 1, onCreate: _createDB);
  }

  Future _createDB(Database db, int version) async {
    const idType = 'INTEGER PRIMARY KEY AUTOINCREMENT';
    const textType = 'TEXT NOT NULL';

    await db.execute('''
    CREATE TABLE notes ( 
      id $idType, 
      title $textType,
      content $textType
    )
    ''');
  }

  Future<void> insertNote(Map<String, dynamic> note) async {
    final db = await instance.database;
    await db.insert('notes', note);
  }

  Future<List<Map<String, dynamic>>> getNotes() async {
    final db = await instance.database;
    return await db.query('notes');
  }

  Future<int> updateNote(Map<String, dynamic> note) async {
    final db = await instance.database;
    final id = note['id'];
    return db.update(
      'notes',
      note,
      where: 'id = ?',
      whereArgs: [id],
    );
  }

  Future<int> deleteNote(int id) async {
    final db = await instance.database;
    return await db.delete(
      'notes',
      where: 'id = ?',
      whereArgs: [id],
    );
  }
}