worldhopper/lib/providers/navigation_provider.dart

import 'package:riverpod_annotation/riverpod_annotation.dart';
import 'package:shared_preferences/shared_preferences.dart';

part 'navigation_provider.g.dart';

/// Key for storing last tab index in SharedPreferences
const String _lastTabIndexKey = 'last_tab_index';

/// Default tab index (Library tab)
const int _defaultTabIndex = 0;

/// Provider for navigation state management and persistence
@riverpod
class NavigationState extends _$NavigationState {
  @override
  int build() {
    _loadLastTabIndex();
    return _defaultTabIndex; // Default value until loaded
  }

  /// Load last tab index from SharedPreferences
  Future<void> _loadLastTabIndex() async {
    final prefs = await SharedPreferences.getInstance();
    final lastIndex = prefs.getInt(_lastTabIndexKey);

    if (lastIndex != null && lastIndex >= 0 && lastIndex <= 2) {
      state = lastIndex;
    }
  }

  /// Set tab index and persist to SharedPreferences
  Future<void> setTabIndex(int index) async {
    if (index < 0 || index > 2) {
      return; // Invalid index, ignore
    }

    state = index;
    final prefs = await SharedPreferences.getInstance();
    await prefs.setInt(_lastTabIndexKey, index);
  }
}