Fix Column spacing, clean up summary.dart, lower SDK constraint, and …

examples/fwe/wikipedia_reader/lib/main.dart

@@ -0,0 +1,170 @@
+import 'dart:convert';
+import 'dart:io';
+
+import 'package:flutter/material.dart';
+import 'package:http/http.dart';
+
+import 'summary.dart';
+
+void main() {
+  runApp(const MainApp());
+}
+
+class MainApp extends StatelessWidget {
+  const MainApp({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return const MaterialApp(home: ArticleView());
+  }
+}
+
+class ArticleModel {
+  Future<Summary> getRandomArticleSummary() async {
+    final uri = Uri.https(
+      'en.wikipedia.org',
+      '/api/rest_v1/page/random/summary',
+    );
+    final response = await get(uri);
+
+    if (response.statusCode != 200) {
+      throw const HttpException('Failed to update resource');
+    }
+
+    return Summary.fromJson(jsonDecode(response.body) as Map<String, Object?>);
+  }
+}
+
+class ArticleViewModel extends ChangeNotifier {
+  ArticleViewModel(this.model);
+  final ArticleModel model;
+
+  Summary? summary;
+
+  bool isLoading = false;
+
+  Exception? error;
+
+  Future<void> fetchArticle() async {
+    isLoading = true;
+    error = null;
+    notifyListeners();
+
+    try {
+      summary = await model.getRandomArticleSummary();
+      error = null;
+    } on Exception catch (e) {
+      error = e;
+    } finally {
+      isLoading = false;
+      notifyListeners();
+    }
+  }
+}
+
+class ArticleView extends StatefulWidget {
+  const ArticleView({super.key});
+
+  @override
+  State<ArticleView> createState() => _ArticleViewState();
+}
+
+class _ArticleViewState extends State<ArticleView> {
+  late final ArticleViewModel viewModel;
+
+  @override
+  void initState() {
+    super.initState();
+    viewModel = ArticleViewModel(ArticleModel());
+    viewModel.fetchArticle();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(title: const Text('Wikipedia Flutter')),
+      body: Center(
+        child: ListenableBuilder(
+          listenable: viewModel,
+          builder: (context, _) {
+            return switch ((
+              viewModel.isLoading,
+              viewModel.summary,
+              viewModel.error,
+            )) {
+              (true, _, _) => const CircularProgressIndicator(),
+              (_, final summary?, _) => ArticlePage(
+                summary: summary,
+                nextArticleCallback: viewModel.fetchArticle,
+              ),
+              (_, _, final Exception e) => Text('Error: $e'),
+              _ => const Text('Something went wrong!'),
+            };
+          },
+        ),
+      ),
+    );
+  }
+}
+
+class ArticlePage extends StatelessWidget {
+  const ArticlePage({
+    super.key,
+    required this.summary,
+    required this.nextArticleCallback,
+  });
+
+  final Summary summary;
+  final VoidCallback nextArticleCallback;
+
+  @override
+  Widget build(BuildContext context) {
+    return SingleChildScrollView(
+      child: Column(
+        children: [
+          ArticleWidget(summary: summary),
+          ElevatedButton(
+            onPressed: nextArticleCallback,
+            child: const Text('Next random article'),
+          ),
+        ],
+      ),
+    );
+  }
+}
+
+class ArticleWidget extends StatelessWidget {
+  const ArticleWidget({super.key, required this.summary});
+
+  final Summary summary;
+
+  @override
+  Widget build(BuildContext context) {
+    return Padding(
+      padding: const EdgeInsets.all(8.0),
+      child: Column(
+        children: [
+          if (summary.hasImage) ...[
+            Image.network(summary.originalImage!.source),
+            const SizedBox(height: 10.0),
+          ],
+          Text(
+            summary.titles.normalized,
+            overflow: TextOverflow.ellipsis,
+            style: Theme.of(context).textTheme.displaySmall,
+          ),
+          const SizedBox(height: 10.0),
+          if (summary.description != null) ...[
+            Text(
+              summary.description!,
+              overflow: TextOverflow.ellipsis,
+              style: Theme.of(context).textTheme.bodySmall,
+            ),
+            const SizedBox(height: 10.0),
+          ],
+          Text(summary.extract),
+        ],
+      ),
+    );
+  }
+}