first commit

lib/providers/theme.dart

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+import 'package:flutter/material.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+class ThemeProvider extends ChangeNotifier {
+  final SharedPreferences _prefs;
+  static const String _themeKey = 'theme_mode';
+
+  ThemeMode _themeMode = ThemeMode.system;
+  ThemeMode get themeMode => _themeMode;
+
+  ThemeProvider(this._prefs) {
+    _loadTheme();
+  }
+
+  void _loadTheme() {
+    final themeString = _prefs.getString(_themeKey);
+    switch (themeString) {
+      case 'light':
+        _themeMode = ThemeMode.light;
+        break;
+      case 'dark':
+        _themeMode = ThemeMode.dark;
+        break;
+      default:
+        _themeMode = ThemeMode.system;
+        break;
+    }
+  }
+
+  Future<void> setThemeMode(ThemeMode mode) async {
+    if (mode == _themeMode) return;
+    _themeMode = mode;
+    notifyListeners();
+
+    String themeString;
+    switch (mode) {
+      case ThemeMode.light:
+        themeString = 'light';
+        break;
+      case ThemeMode.dark:
+        themeString = 'dark';
+        break;
+      case ThemeMode.system:
+      default:
+        themeString = 'system';
+        break;
+    }
+    await _prefs.setString(_themeKey, themeString);
+  }
+}