update dark mode handling

frontend/lib/pages/list.dart

@@ -2,6 +2,7 @@ import 'package:flutter/material.dart';
 
 import 'package:frontend/provider/quote_provider.dart';
 import 'package:frontend/model/quote.dart';
+import 'package:frontend/provider/theme_provider.dart';
 import 'package:frontend/values/strings.dart';
 import 'package:provider/provider.dart';
 
@@ -13,15 +14,16 @@ class ListPage extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     final provider = context.watch<QuoteProvider>();
+    final themeProvider = context.watch<ThemeProvider>();
     return RefreshIndicator(
       onRefresh: () async {
         await provider.readQuotes();
       },
-      child: _bodyBuilder(context, provider),
+      child: _bodyBuilder(context, provider, themeProvider),
     );
   }
 
-  Widget _bodyBuilder(BuildContext context, QuoteProvider provider) {   
+  Widget _bodyBuilder(BuildContext context, QuoteProvider provider, ThemeProvider themeProvider) {   
     if (provider.loading) {
       return Center(child: CircularProgressIndicator());
     }
@@ -51,7 +53,7 @@ class ListPage extends StatelessWidget {
               ),
             ),
           ),
-          filterBar(context, provider),
+          filterBar(context, provider, themeProvider),
           Expanded(
             child: ListView.builder(
               padding: EdgeInsets.all(Constants.edgeInset),
@@ -220,7 +222,7 @@ class ListPage extends StatelessWidget {
     );
   }
 
-  Widget filterBar(BuildContext context, QuoteProvider provider) {
+  Widget filterBar(BuildContext context, QuoteProvider provider, ThemeProvider themeProvider) {
     return Padding(
       padding: const EdgeInsets.all(Constants.edgeInset),
       child: Row(
@@ -246,7 +248,7 @@ class ListPage extends StatelessWidget {
           IconButton(
             icon: Icon(Icons.more_horiz),
             onPressed: () {
-              _showOptionsBottomSheet(context, provider);
+              _showOptionsBottomSheet(context, provider, themeProvider);
             },
           ),
         ],
@@ -254,7 +256,7 @@ class ListPage extends StatelessWidget {
     );
   }
 
-  void _showOptionsBottomSheet(BuildContext context, QuoteProvider provider) {
+  void _showOptionsBottomSheet(BuildContext context, QuoteProvider provider, ThemeProvider themeProvider) {
     showModalBottomSheet(
       context: context,
       builder: (context) {
@@ -284,6 +286,25 @@ class ListPage extends StatelessWidget {
                     );
                   }
                 ),
+                ListTile(
+                  title: Text(Strings.userPrefersDarkMode),
+                  onTap: () { themeProvider.setDarkMode(!themeProvider.isDark); },
+                  trailing: Row(
+                    mainAxisSize: MainAxisSize.min,
+                    children: [
+                      Padding(
+                        padding: const EdgeInsets.only(right: Constants.edgeInset),
+                        child: Switch(
+                          onChanged: (value) {
+                            themeProvider.setDarkMode(value);
+                          }, 
+                          value: themeProvider.isDark
+                        ),
+                      ),
+                      Icon(Icons.dark_mode),
+                    ],
+                  ),
+                ),
               ],
             ),
         );