palmoil-mobile/lib/theme/theme_controller.dart

import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';

/// App-wide theme mode, persisted across launches. Defaults to
/// [ThemeMode.system] until a user preference is loaded/set.
class ThemeController {
  ThemeController._();

  static const _prefsKey = 'theme_mode';

  static final ValueNotifier<ThemeMode> themeMode = ValueNotifier(ThemeMode.system);

  static Future<void> load() async {
    final prefs = await SharedPreferences.getInstance();
    final stored = prefs.getString(_prefsKey);
    themeMode.value = switch (stored) {
      'light' => ThemeMode.light,
      'dark' => ThemeMode.dark,
      _ => ThemeMode.system,
    };
  }

  static Future<void> setThemeMode(ThemeMode mode) async {
    themeMode.value = mode;
    final prefs = await SharedPreferences.getInstance();
    await prefs.setString(_prefsKey, mode.name);
  }
}