Add sample browser to catalog_gallery app (#567)

Author: gspencergoog

examples/catalog_gallery/.metadata

@@ -4,20 +4,20 @@
 # This file should be version controlled and should not be manually edited.
 
 version:
-  revision: "e11e2c11288b6a3f9f9bb3dcfb9bb459a75e048c"
-  channel: "main"
+  revision: "b45fa18946ecc2d9b4009952c636ba7e2ffbb787"
+  channel: "stable"
 
 project_type: app
 
 # Tracks metadata for the flutter migrate command
 migration:
   platforms:
     - platform: root
-      create_revision: e11e2c11288b6a3f9f9bb3dcfb9bb459a75e048c
-      base_revision: e11e2c11288b6a3f9f9bb3dcfb9bb459a75e048c
+      create_revision: b45fa18946ecc2d9b4009952c636ba7e2ffbb787
+      base_revision: b45fa18946ecc2d9b4009952c636ba7e2ffbb787
     - platform: macos
-      create_revision: e11e2c11288b6a3f9f9bb3dcfb9bb459a75e048c
-      base_revision: e11e2c11288b6a3f9f9bb3dcfb9bb459a75e048c
+      create_revision: b45fa18946ecc2d9b4009952c636ba7e2ffbb787
+      base_revision: b45fa18946ecc2d9b4009952c636ba7e2ffbb787
 
   # User provided section
 

examples/catalog_gallery/lib/main.dart

@@ -3,16 +3,45 @@
 // found in the LICENSE file.
 
 import 'dart:convert';
-
+import 'package:args/args.dart';
+import 'package:file/file.dart';
+import 'package:file/local.dart';
 import 'package:flutter/material.dart';
 import 'package:genui/genui.dart';
 
-void main() {
-  runApp(const CatalogGalleryApp());
+import 'samples_view.dart';
+
+void main(List<String> args) {
+  final parser = ArgParser()
+    ..addOption('samples', abbr: 's', help: 'Path to the samples directory');
+  final ArgResults results = parser.parse(args);
+
+  const FileSystem fs = LocalFileSystem();
+  Directory? samplesDir;
+  if (results.wasParsed('samples')) {
+    samplesDir = fs.directory(results['samples'] as String);
+  } else {
+    final Directory current = fs.currentDirectory;
+    final Directory defaultSamples = fs
+        .directory(current.path)
+        .childDirectory('samples');
+    if (defaultSamples.existsSync()) {
+      samplesDir = defaultSamples;
+    }
+  }
+
+  runApp(CatalogGalleryApp(samplesDir: samplesDir, fs: fs));
 }
 
 class CatalogGalleryApp extends StatefulWidget {
-  const CatalogGalleryApp({super.key});
+  final Directory? samplesDir;
+  final FileSystem fs;
+
+  const CatalogGalleryApp({
+    super.key,
+    this.samplesDir,
+    this.fs = const LocalFileSystem(),
+  });
 
   @override
   State<CatalogGalleryApp> createState() => _CatalogGalleryAppState();
@@ -23,27 +52,51 @@ class _CatalogGalleryAppState extends State<CatalogGalleryApp> {
 
   @override
   Widget build(BuildContext context) {
+    final bool showSamples =
+        widget.samplesDir != null && widget.samplesDir!.existsSync();
+
     return MaterialApp(
       theme: ThemeData(
         colorScheme: ColorScheme.fromSeed(seedColor: Colors.blue),
       ),
-      home: Scaffold(
-        appBar: AppBar(
-          backgroundColor: Theme.of(context).colorScheme.inversePrimary,
-          title: const Text('Catalog items that has "exampleData" field set'),
-        ),
-        body: DebugCatalogView(
-          catalog: catalog,
-          onSubmit: (message) {
-            ScaffoldMessenger.of(context).showSnackBar(
-              SnackBar(
-                content: Text(
-                  'User action: '
-                  '${jsonEncode(message.parts.last)}',
-                ),
+      home: DefaultTabController(
+        length: showSamples ? 2 : 1,
+        child: Scaffold(
+          appBar: AppBar(
+            backgroundColor: Theme.of(context).colorScheme.inversePrimary,
+            title: const Text('Catalog Gallery'),
+            bottom: showSamples
+                ? const TabBar(
+                    tabs: [
+                      Tab(text: 'Catalog'),
+                      Tab(text: 'Samples'),
+                    ],
+                  )
+                : null,
+          ),
+          body: TabBarView(
+            children: [
+              DebugCatalogView(
+                catalog: catalog,
+                onSubmit: (message) {
+                  ScaffoldMessenger.of(context).showSnackBar(
+                    SnackBar(
+                      content: Text(
+                        'User action: '
+                        '${jsonEncode(message.parts.last)}',
+                      ),
+                    ),
+                  );
+                },
               ),
-            );
-          },
+              if (showSamples)
+                SamplesView(
+                  samplesDir: widget.samplesDir!,
+                  catalog: catalog,
+                  fs: widget.fs,
+                ),
+            ],
+          ),
         ),
       ),
     );

examples/catalog_gallery/lib/sample_parser.dart

@@ -0,0 +1,62 @@
+// Copyright 2025 The Flutter Authors.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:convert';
+
+import 'package:file/file.dart';
+import 'package:genui/genui.dart';
+import 'package:yaml/yaml.dart';
+
+class Sample {
+  final String name;
+  final String description;
+  final Stream<A2uiMessage> messages;
+
+  Sample({
+    required this.name,
+    required this.description,
+    required this.messages,
+  });
+}
+
+class SampleParser {
+  static Future<Sample> parseFile(File file) async {
+    final String content = await file.readAsString();
+    return parseString(content);
+  }
+
+  static Sample parseString(String content) {
+    final List<String> lines = const LineSplitter().convert(content);
+    final int separatorIndex = lines.indexOf('---');
+
+    if (separatorIndex == -1) {
+      throw const FormatException(
+        'Sample file must contain a YAML header and a JSONL body separated '
+        'by "---"',
+      );
+    }
+
+    final String yamlHeader = lines.sublist(0, separatorIndex).join('\n');
+    final String jsonlBody = lines.sublist(separatorIndex + 1).join('\n');
+
+    final header = loadYaml(yamlHeader) as YamlMap;
+    final String name = header['name'] as String? ?? 'Untitled Sample';
+    final String description = header['description'] as String? ?? '';
+
+    final Stream<A2uiMessage> messages = Stream.fromIterable(
+      const LineSplitter()
+          .convert(jsonlBody)
+          .where((line) => line.trim().isNotEmpty)
+          .map((line) {
+            final dynamic json = jsonDecode(line);
+            if (json is Map<String, dynamic>) {
+              return A2uiMessage.fromJson(json);
+            }
+            throw FormatException('Invalid JSON line: $line');
+          }),
+    );
+
+    return Sample(name: name, description: description, messages: messages);
+  }
+}