refactor(frontend): Use TaggerPage to fix GetView issues

* This assures we don't end up without a controller instance (get loses it somehow)
* Also added theme persistence

frontend/lib/main.dart

@@ -3,6 +3,7 @@ import 'dart:io';
 import 'package:dio/dio.dart';
 import 'package:flutter/material.dart';
 import 'package:get/get.dart';
+import 'package:repo_tagger/tagger_preferences.dart';
 
 import 'api/tagger/repository_tagger_client.dart';
 import 'router.dart';
@@ -83,11 +84,19 @@ class TaggerApp extends StatelessWidget {
   final Dio dio;
   final RepositoryTaggerClient taggerClient;
 
+  void _initSetup() async {
+    await taggerPreferences.init();
+    final mode = taggerPreferences.themeMode();
+
+    Get.changeThemeMode(mode);
+  }
+
   @override
   Widget build(BuildContext context) {
+    _initSetup();
+
     return GetMaterialApp(
       title: 'Repo Tagger',
-      themeMode: ThemeMode.dark,
       theme: ThemeData.light().copyWith(
         primaryColor: Colors.blue,
       ),
@@ -96,7 +105,6 @@ class TaggerApp extends StatelessWidget {
         accentColor: Colors.lightBlueAccent,
       ),
       initialRoute: Routes.splash,
-      navigatorKey: Get.key,
       getPages: [
         GetPage(
           name: Routes.splash,
@@ -105,17 +113,14 @@ class TaggerApp extends StatelessWidget {
         GetPage(
           name: Routes.home,
           page: () => HomePage(),
-          binding: HomeBinding(),
         ),
         GetPage(
           name: Routes.repoDetails,
           page: () => RepositoryDetailsPage(),
-          binding: RepositoryDetailsBinding(),
         ),
         GetPage(
           name: Routes.tagRepositories,
           page: () => TagRepositoriesPage(),
-          binding: TagRepositoriesBinding(),
         ),
         GetPage(
           name: Routes.login,

frontend/lib/tagger_preferences.dart

@@ -0,0 +1,45 @@
+import 'package:flutter/material.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+const _themeModePref = 'THEME_MODE';
+
+final taggerPreferences = _TaggerPreferences();
+
+class _TaggerPreferences {
+  SharedPreferences _sharedInstance;
+
+  Future init() async {
+    _sharedInstance = await SharedPreferences.getInstance();
+  }
+
+  ThemeMode themeMode() {
+    final mode = _sharedInstance.getString(_themeModePref);
+
+    if (mode == 'dark') {
+      return ThemeMode.dark;
+    }
+
+    if (mode == 'light') {
+      return ThemeMode.light;
+    }
+
+    return ThemeMode.system;
+  }
+
+  Future setThemeMode(ThemeMode mode) async {
+    String modeString;
+    switch (mode) {
+      case ThemeMode.system:
+        modeString = 'system';
+        break;
+      case ThemeMode.light:
+        modeString = 'light';
+        break;
+      case ThemeMode.dark:
+        modeString = 'dark';
+        break;
+    }
+
+    await _sharedInstance.setString(_themeModePref, modeString);
+  }
+}

frontend/lib/ui/pages/home/home_page.dart

@@ -2,16 +2,19 @@ import 'package:flutter/material.dart';
 import 'package:get/get.dart';
 
 import '../../templates/three_slot_container.dart';
+import '../../utils/tagger_page.dart';
 import '../starred/starred_page.dart';
 import '../tags/tags_page.dart';
 import 'widgets/sidebar.dart';
 import 'widgets/sidebar_button.dart';
 
-part 'home_bindings.dart';
-
 part 'home_controller.dart';
 
-class HomePage extends GetView<HomeController> {
+class HomePage extends TaggerPage<HomeController> {
+
+  @override
+  HomeController provider() => HomeController();
+
   @override
   Widget build(BuildContext context) {
     return GetX(

frontend/lib/ui/pages/home/widgets/sidebar.dart

@@ -1,5 +1,6 @@
 import 'package:flutter/material.dart';
 import 'package:get/get.dart';
+import 'package:repo_tagger/tagger_preferences.dart';
 
 /// Side bar showed on home route
 /// it shows the given [content] and a logout button
@@ -38,10 +39,12 @@ class Sidebar extends StatelessWidget {
       title: const Text('Dark theme'),
       value: Get.isDarkMode,
       onChanged: (active) {
+        final mode = active ? ThemeMode.dark : ThemeMode.light;
         // Theme changing is good, but this is what makes us
         // see that flutter is not really ready for web, as changing
         // theme modes causes the page to hang a little
-        Get.changeThemeMode(active ? ThemeMode.dark : ThemeMode.light);
+        Get.changeThemeMode(mode);
+        taggerPreferences.setThemeMode(mode);
       },
     );
   }

frontend/lib/ui/pages/repository_details/repository_details_page.dart

@@ -10,14 +10,16 @@ import '../../../router.dart';
 import '../../molecules/detail_chip.dart';
 import '../../molecules/load_page_error.dart';
 import '../../utils/browser.dart';
+import '../../utils/tagger_page.dart';
 import 'widgets/readme_container.dart';
 import 'widgets/tags_container.dart';
 
-part 'repository_details_bindings.dart';
-
 part 'repository_details_controller.dart';
 
-class RepositoryDetailsPage extends GetView<RepositoryDetailsController> {
+class RepositoryDetailsPage extends TaggerPage<RepositoryDetailsController> {
+  @override
+  RepositoryDetailsController provider() => RepositoryDetailsController();
+
   @override
   Widget build(BuildContext context) {
     return GetX(

frontend/lib/ui/pages/repository_details/widgets/readme_container.dart

@@ -6,10 +6,10 @@ import 'package:markdown/markdown.dart' as md;
 import '../repository_details_page.dart';
 
 /// Controls exhibition of the repository readme
-/// [RepositoryDetailsController] is required to be injected.
-class ReadmeContainer extends GetView<RepositoryDetailsController> {
+class ReadmeContainer extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
+    final controller = Get.find<RepositoryDetailsController>();
     final repo = controller.repository.value;
     final readmeContents = repo.readmeContents;
 

frontend/lib/ui/pages/repository_details/widgets/tags_container.dart

@@ -1,13 +1,16 @@
 import 'package:flutter/material.dart';
-import 'package:get/get.dart';
+import 'package:repo_tagger/ui/utils/tagger_page.dart';
 
 import '../../../../api/tagger/repository_tagger_client.dart';
 import '../../../../external/taggable/taggable.dart';
 import '../repository_details_page.dart';
 
 /// Controls exhibition and creation UI for user tags
 /// [RepositoryDetailsController] is required to be injected.
-class TagsContainer extends GetView<RepositoryDetailsController> {
+class TagsContainer extends TaggerPage<RepositoryDetailsController> {
+  @override
+  RepositoryDetailsController provider() => RepositoryDetailsController();
+
   @override
   Widget build(BuildContext context) {
     // FIXME: underlying third party lib is applying a really

frontend/lib/ui/pages/starred/starred_page.dart

@@ -6,12 +6,14 @@ import '../../../router.dart';
 import '../../molecules/load_page_error.dart';
 import '../../molecules/page_title.dart';
 import '../../templates/repository_list.dart';
-
-part 'starred_bindings.dart';
+import '../../utils/tagger_page.dart';
 
 part 'starred_controller.dart';
 
-class StarredPage extends GetView<StarredController> {
+class StarredPage extends TaggerPage<StarredController> {
+  @override
+  StarredController provider() => StarredController();
+
   @override
   Widget build(BuildContext context) {
     return GetX(

frontend/lib/ui/pages/tag_repositories/tag_repositories_page.dart

@@ -1,17 +1,19 @@
 import 'package:flutter/material.dart';
 import 'package:get/get.dart';
+import 'package:repo_tagger/ui/utils/tagger_page.dart';
 
 import '../../../api/tagger/repository_tagger_client.dart';
 import '../../../router.dart';
 import '../../molecules/load_page_error.dart';
 import '../../molecules/page_title.dart';
 import '../../templates/repository_list.dart';
 
-part 'tag_repositories_bindings.dart';
-
 part 'tag_repositories_controller.dart';
 
-class TagRepositoriesPage extends GetView<TagRepositoriesController> {
+class TagRepositoriesPage extends TaggerPage<TagRepositoriesController> {
+  @override
+  TagRepositoriesController provider() => TagRepositoriesController();
+
   @override
   Widget build(BuildContext context) {
     return GetX(

frontend/lib/ui/pages/tags/tags_page.dart

@@ -5,12 +5,14 @@ import '../../../api/tagger/repository_tagger_client.dart';
 import '../../../router.dart';
 import '../../molecules/load_page_error.dart';
 import '../../molecules/page_title.dart';
-
-part 'tags_bindings.dart';
+import '../../utils/tagger_page.dart';
 
 part 'tags_controller.dart';
 
-class TagsPage extends GetView<TagsController> {
+class TagsPage extends TaggerPage<TagsController> {
+  @override
+  TagsController provider() => TagsController();
+
   @override
   Widget build(BuildContext context) {
     return GetX(

frontend/lib/ui/utils/tagger_page.dart

@@ -0,0 +1,12 @@
+import 'package:flutter/widgets.dart';
+import 'package:get/get.dart';
+
+/// Similar to GetView but this one forces a controller instance to be present
+/// (get loses itself sometimes)
+abstract class TaggerPage<T> extends StatelessWidget {
+  const TaggerPage({Key key}) : super(key: key);
+
+  T provider();
+
+  T get controller => Get.put<T>(provider());
+}