import 'dart:convert';

import 'package:flutter/services.dart';

import '../models/nutrient.dart';

class NutrientDataService {
  static final NutrientDataService _instance = NutrientDataService._internal();

  factory NutrientDataService() {
    return _instance;
  }

  NutrientDataService._internal();

  List<Nutrient>? _nutrients;

  Future<List<Nutrient>> get nutrients async {
    if (_nutrients != null) {
      return _nutrients!;
    }
    await _loadNutrientData();
    return _nutrients!;
  }

  Future<void> _loadNutrientData() async {
    try {
      final String response = await rootBundle.loadString('assets/canada_health.json');
      final data = await json.decode(response);
      final nutrientsData = data['nutrients'] as Map<String, dynamic>;

      _nutrients = nutrientsData.entries.map((entry) {
        return Nutrient.fromJson(entry.key, entry.value);
      }).toList();
    } catch (e) {
      print('Error loading nutrient data: $e');
      _nutrients = [];
    }
  }
}