import 'package:sqflite_common_ffi/sqflite_ffi.dart';
import 'package:path/path.dart';
import '../models/product.dart';

class DatabaseHelper {
  static final DatabaseHelper _instance = DatabaseHelper._internal();
  static Database? _database;

  factory DatabaseHelper() {
    return _instance;
  }

  DatabaseHelper._internal();

  Future<Database> get database async {
    if (_database != null) {
      return _database!;
    }
    _database = await _initDatabase();
    return _database!;
  }

  Future<Database> _initDatabase() async {
    String documentsDirectory = await getDatabasesPath();
    String path = join(documentsDirectory, 'product_database.db');

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

  Future<void> _onCreate(Database db, int version) async {
    await db.execute('''
      CREATE TABLE products(
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        name TEXT NOT NULL,
        code TEXT NOT NULL,
        quantity INTEGER NOT NULL,
        price REAL NOT NULL,
        description TEXT
      )
      ''');
  }

  Future<int> insertProduct(Product product) async {
    final db = await database;
    return await db.insert(
      'products',
      product.toMap(),
      conflictAlgorithm: ConflictAlgorithm.replace,
    );
  }

  Future<List<Product>> getProducts() async {
    final db = await database;
    final List<Map<String, dynamic>> maps = await db.query('products');

    return List.generate(maps.length, (i) {
      return Product.fromMap(maps[i]);
    });
  }

  Future<int> updateProduct(Product product) async {
    final db = await database;
    return await db.update(
      'products',
      product.toMap(),
      where: 'id = ?',
      whereArgs: [product.id],
    );
  }

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