feat(ui_storage): add StorageListView and PaginatedLoadingController (#…

…11170)

* feat(ui_storage): add StorageListView and PaginatedLoadingController

* drop uuid

* license header

packages/firebase_ui_storage/README.md

@@ -139,3 +139,36 @@ class MyUploadProgress extends StatelessWidget {
   }
 }
 ```
+
+### StorageListView
+
+```dart
+StorageListView(
+  ref: storage.ref('images'),
+  itemBuilder: (context, ref) {
+    return AspectRatio(
+      aspectRatio: 1,
+      child: StorageImage(ref: ref),
+    );
+  },
+  loadingBuilder: (context) {
+    return const Center(
+      child: CircularProgressIndicator(),
+    );
+  },
+  errorBuilder: (context, error, controller) {
+    return Center(
+      child: Column(
+        mainAxisSize: MainAxisSize.min,
+        children: [
+          Text('Error: $error'),
+          TextButton(
+            onPressed: () => controller.load(),
+            child: const Text('Retry'),
+          ),
+        ],
+      ),
+    );
+  },
+);
+```

packages/firebase_ui_storage/example/lib/src/apps.dart

@@ -8,6 +8,7 @@ import 'package:flutter/material.dart';
 
 import 'progress_bar_app.dart';
 import 'upload_button_app.dart';
+import 'list_view_app.dart';
 
 abstract class App implements Widget {
   String get name;
@@ -17,6 +18,7 @@ const apps = <App>[
   UploadButtonApp(),
   ProgressBarApp(),
   StorageImageApp(),
+  StorageListViewApp(),
 ];
 
 class AppList extends StatelessWidget {

packages/firebase_ui_storage/example/lib/src/list_view_app.dart

@@ -0,0 +1,40 @@
+// Copyright 2023, the Chromium project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:firebase_storage/firebase_storage.dart';
+import 'package:firebase_ui_storage/firebase_ui_storage.dart';
+import 'package:flutter/material.dart';
+
+import 'apps.dart';
+
+class StorageListViewApp extends StatelessWidget implements App {
+  const StorageListViewApp({super.key});
+
+  @override
+  String get name => 'StorageListView';
+
+  @override
+  Widget build(BuildContext context) {
+    return StorageListView(
+      ref: FirebaseStorage.instance.ref('list'),
+      itemBuilder: (context, ref) {
+        return ListTile(
+          title: FutureBuilder(
+            future: ref.getData(),
+            builder: (context, snapshot) {
+              if (snapshot.hasError) {
+                return Text(snapshot.error.toString());
+              }
+              if (snapshot.hasData) {
+                return Text(snapshot.data.toString());
+              }
+
+              return const Text('Loading...');
+            },
+          ),
+        );
+      },
+    );
+  }
+}

packages/firebase_ui_storage/example/pubspec.yaml

@@ -4,7 +4,7 @@ publish_to: 'none'
 version: 0.1.0
 
 environment:
-  sdk: '>=2.19.5 <4.0.0'
+  sdk: '>=3.0.0 <4.0.0'
 
 dependencies:
   cupertino_icons: ^1.0.3

packages/firebase_ui_storage/lib/firebase_ui_storage.dart

@@ -20,3 +20,5 @@ export 'src/widgets/progress_indicator.dart'
     show TaskProgressIndicator, TaskProgressWidget, ErrorBuilder;
 
 export 'src/widgets/image.dart' show StorageImage, LoadingStateVariant;
+export 'src/paginated_loading_controller.dart';
+export 'src/widgets/list_view.dart';

packages/firebase_ui_storage/lib/src/paginated_loading_controller.dart

@@ -0,0 +1,104 @@
+// Copyright 2023, the Chromium project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:firebase_storage/firebase_storage.dart';
+import 'package:flutter/foundation.dart';
+
+/// A base class for loading states.
+sealed class PaginatedLoadingState {
+  const PaginatedLoadingState();
+}
+
+/// Indicates that the first page is loading.
+class InitialPageLoading extends PaginatedLoadingState {
+  const InitialPageLoading();
+}
+
+class PageLoading extends PaginatedLoadingState {
+  final List<Reference> items;
+
+  const PageLoading({required this.items});
+}
+
+class PageLoadComplete extends PaginatedLoadingState {
+  final List<Reference> pageItems;
+  final List<Reference> items;
+
+  const PageLoadComplete({
+    required this.pageItems,
+    required this.items,
+  });
+}
+
+class PageLoadError extends PaginatedLoadingState {
+  final Object? error;
+  final List<Reference>? items;
+
+  const PageLoadError({
+    required this.error,
+    this.items,
+  });
+}
+
+class PaginatedLoadingController extends ChangeNotifier {
+  int pageSize;
+  final Reference ref;
+
+  PaginatedLoadingController({
+    required this.ref,
+    this.pageSize = 50,
+  }) {
+    load();
+  }
+
+  PaginatedLoadingState? _state;
+  PaginatedLoadingState get state => _state!;
+
+  ListResult? _cursor;
+  List<Reference>? _items;
+
+  ListOptions get _listOptions {
+    return ListOptions(
+      maxResults: pageSize,
+      pageToken: _cursor?.nextPageToken,
+    );
+  }
+
+  Future<void> load() {
+    _state = _state == null
+        ? const InitialPageLoading()
+        : PageLoading(items: _items!);
+
+    notifyListeners();
+
+    return ref.list(_listOptions).then((value) {
+      _cursor = value;
+      (_items ??= []).addAll(value.items);
+
+      _state = PageLoadComplete(
+        pageItems: value.items,
+        items: _items!,
+      );
+
+      notifyListeners();
+    }).catchError((e) {
+      _state = PageLoadError(
+        error: e,
+        items: _items,
+      );
+
+      notifyListeners();
+    });
+  }
+
+  bool shouldLoadNextPage(int itemIndex) {
+    return switch (state) {
+      InitialPageLoading() => false,
+      PageLoading() => false,
+      PageLoadComplete(items: final items) =>
+        itemIndex == (items.length - pageSize + 1),
+      PageLoadError() => false,
+    };
+  }
+}