FolderListing: Use Provider to fetch the NotesFolder

This is our first use case of trying to use 'Provider' for state
management. Right now, we're doing state management quite horribly as
all the widgets are rebuilt whenever the state of the app changes.

With this, we can now start to refactor and only rebuild the widgets
whose data has changed.

There we many many different state management solutions to choose from,
I've settled on Provider, as it seems like the simplest to integrate
into the code base. Bloc/Redux seemed like they would add too much
complexity for me.

lib/app.dart

@@ -5,6 +5,7 @@ import 'package:fimber/fimber.dart';
 import 'package:firebase_analytics/firebase_analytics.dart';
 import 'package:firebase_analytics/observer.dart';
 import 'package:flutter/material.dart';
+import 'package:provider/provider.dart';
 
 import 'package:gitjournal/apis/git.dart';
 import 'package:gitjournal/settings.dart';
@@ -46,7 +47,10 @@ class JournalApp extends StatelessWidget {
 
     runApp(StateContainer(
       appState: appState,
-      child: JournalApp(),
+      child: ChangeNotifierProvider(
+        child: JournalApp(),
+        create: (_) => appState.notesFolder,
+      ),
     ));
   }
 

lib/screens/folder_listing.dart

@@ -1,4 +1,5 @@
 import 'package:flutter/material.dart';
+import 'package:provider/provider.dart';
 
 import 'package:gitjournal/widgets/app_bar_menu_button.dart';
 import 'package:gitjournal/widgets/app_drawer.dart';
@@ -18,11 +19,10 @@ class _FolderListingScreenState extends State<FolderListingScreen> {
 
   @override
   Widget build(BuildContext context) {
-    final container = StateContainer.of(context);
-    final appState = container.appState;
+    final notesFolder = Provider.of<NotesFolder>(context);
 
     var treeView = FolderTreeView(
-      rootFolder: appState.notesFolder,
+      rootFolder: notesFolder,
       onFolderEntered: (NotesFolder folder) {
         var route = MaterialPageRoute(
           builder: (context) => JournalListingScreen(
@@ -99,9 +99,9 @@ class _CreateFolderButtonState extends State<CreateFolderButton> {
             await showDialog(context: context, builder: _buildAlert);
         if (folderName is String) {
           final container = StateContainer.of(context);
-          final appState = container.appState;
+          final notesFolder = Provider.of<NotesFolder>(context);
 
-          container.createFolder(appState.notesFolder, folderName);
+          container.createFolder(notesFolder, folderName);
         }
       },
       child: Icon(Icons.add),

pubspec.lock

@@ -399,6 +399,13 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "3.0.11"
+  provider:
+    dependency: "direct main"
+    description:
+      name: provider
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "3.2.0"
   pub_semver:
     dependency: transitive
     description:

pubspec.yaml

@@ -29,6 +29,7 @@ dependencies:
   flushbar: ^1.9.0
   flutter_staggered_grid_view: ^0.3.0
   page_transition: "^1.1.5"
+  provider: ^3.2.0
 
 dev_dependencies:
   flutter_launcher_icons: "^0.7.2"