Implement Gemini Chat app

Author: leehack

ios/Flutter/Debug.xcconfig

@@ -1 +1,2 @@
+#include? "Pods/Target Support Files/Pods-Runner/Pods-Runner.debug.xcconfig"
 #include "Generated.xcconfig"

ios/Flutter/Release.xcconfig

@@ -1 +1,2 @@
+#include? "Pods/Target Support Files/Pods-Runner/Pods-Runner.release.xcconfig"
 #include "Generated.xcconfig"

ios/Podfile

@@ -0,0 +1,44 @@
+# Uncomment this line to define a global platform for your project
+# platform :ios, '12.0'
+
+# CocoaPods analytics sends network stats synchronously affecting flutter build latency.
+ENV['COCOAPODS_DISABLE_STATS'] = 'true'
+
+project 'Runner', {
+  'Debug' => :debug,
+  'Profile' => :release,
+  'Release' => :release,
+}
+
+def flutter_root
+  generated_xcode_build_settings_path = File.expand_path(File.join('..', 'Flutter', 'Generated.xcconfig'), __FILE__)
+  unless File.exist?(generated_xcode_build_settings_path)
+    raise "#{generated_xcode_build_settings_path} must exist. If you're running pod install manually, make sure flutter pub get is executed first"
+  end
+
+  File.foreach(generated_xcode_build_settings_path) do |line|
+    matches = line.match(/FLUTTER_ROOT\=(.*)/)
+    return matches[1].strip if matches
+  end
+  raise "FLUTTER_ROOT not found in #{generated_xcode_build_settings_path}. Try deleting Generated.xcconfig, then run flutter pub get"
+end
+
+require File.expand_path(File.join('packages', 'flutter_tools', 'bin', 'podhelper'), flutter_root)
+
+flutter_ios_podfile_setup
+
+target 'Runner' do
+  use_frameworks!
+  use_modular_headers!
+
+  flutter_install_all_ios_pods File.dirname(File.realpath(__FILE__))
+  target 'RunnerTests' do
+    inherit! :search_paths
+  end
+end
+
+post_install do |installer|
+  installer.pods_project.targets.each do |target|
+    flutter_additional_ios_build_settings(target)
+  end
+end

lib/main.dart

@@ -1,19 +1,6 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:riverpod_annotation/riverpod_annotation.dart';
-part 'main.g.dart';
-
-@riverpod
-class Counter extends _$Counter {
-  @override
-  int build() {
-    return 0;
-  }
-
-  increment() {
-    return state++;
-  }
-}
+import 'package:riverpod_gemini/screens/chat_screen.dart';
 
 void main() {
   runApp(const ProviderScope(child: MyApp()));
@@ -26,48 +13,15 @@ class MyApp extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     return MaterialApp(
-      title: 'Riverpod Demo',
+      title: 'Riverpod Gemini Demo',
       theme: ThemeData(
         colorScheme: ColorScheme.fromSeed(
           seedColor: Colors.deepPurple,
           brightness: Brightness.dark,
         ),
         useMaterial3: true,
       ),
-      home: const MyHomePage(),
-    );
-  }
-}
-
-class MyHomePage extends ConsumerWidget {
-  const MyHomePage({super.key});
-
-  @override
-  Widget build(BuildContext context, WidgetRef ref) {
-    return Scaffold(
-      appBar: AppBar(
-        backgroundColor: Theme.of(context).colorScheme.inversePrimary,
-        title: const Text("Riverpod Demo"),
-      ),
-      body: Center(
-        child: Column(
-          mainAxisAlignment: MainAxisAlignment.center,
-          children: <Widget>[
-            const Text(
-              'You have pushed the button this many times:',
-            ),
-            Text(
-              ref.watch(counterProvider).toString(),
-              style: Theme.of(context).textTheme.headlineMedium,
-            ),
-          ],
-        ),
-      ),
-      floatingActionButton: FloatingActionButton(
-        onPressed: () => ref.read(counterProvider.notifier).increment(),
-        tooltip: 'Increment',
-        child: const Icon(Icons.add),
-      ),
+      home: const ChatScreen(title: 'Flutter + Generative AI'),
     );
   }
 }

lib/providers/api_key_provider.dart

@@ -0,0 +1,15 @@
+import 'package:riverpod_annotation/riverpod_annotation.dart';
+
+part 'api_key_provider.g.dart';
+
+@Riverpod(keepAlive: true)
+class ApiKey extends _$ApiKey {
+  @override
+  String? build() {
+    return null;
+  }
+
+  void setApiKey(String value) {
+    state = value;
+  }
+}

lib/main.g.dart renamed to lib/providers/api_key_provider.g.dart

@@ -0,0 +1,59 @@
+import 'package:google_generative_ai/google_generative_ai.dart';
+import 'package:riverpod_annotation/riverpod_annotation.dart';
+import 'package:riverpod_gemini/providers/api_key_provider.dart';
+
+part 'chat_provider.g.dart';
+
+@Riverpod(keepAlive: true)
+ChatSession chatSession(ChatSessionRef ref) {
+  return GenerativeModel(
+    model: 'gemini-pro',
+    apiKey: ref.watch(apiKeyProvider) ?? '',
+  ).startChat();
+}
+
+@riverpod
+class ChatMessage extends _$ChatMessage {
+  @override
+  Future<String> build() async {
+    return '';
+  }
+
+  Future<void> send(String text) async {
+    state = const AsyncValue.loading();
+    state = await AsyncValue.guard(() async {
+      final res =
+          await ref.read(chatSessionProvider).sendMessage(Content.text(text));
+      if (res.text == null) {
+        throw Exception('Empty response');
+      }
+      return res.text!;
+    });
+    if (state is! AsyncError) {
+      ref.invalidate(chatContentsProvider);
+    }
+  }
+}
+
+@riverpod
+List<ChatContent> chatContents(ChatContentsRef ref) {
+  return ref
+      .watch(chatSessionProvider)
+      .history
+      .map((content) => ChatContent.fromContent(content))
+      .toList();
+}
+
+class ChatContent {
+  final String role;
+  final String text;
+
+  ChatContent(this.role, this.text);
+
+  factory ChatContent.fromContent(Content content) {
+    return ChatContent(
+      content.role ?? '',
+      content.parts.whereType<TextPart>().map<String>((e) => e.text).join(''),
+    );
+  }
+}

lib/providers/chat_provider.dart

@@ -0,0 +1,47 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:riverpod_gemini/providers/api_key_provider.dart';
+import 'package:riverpod_gemini/widgets/api_key_widget.dart';
+import 'package:riverpod_gemini/widgets/chat_input_widget.dart';
+import 'package:riverpod_gemini/widgets/chat_list_widget.dart';
+
+class ChatScreen extends ConsumerWidget {
+  const ChatScreen({super.key, required this.title});
+
+  final String title;
+
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    return Scaffold(
+      appBar: AppBar(
+        title: Text(title),
+      ),
+      body: switch (ref.watch(apiKeyProvider)) {
+        _? => const ChatWidget(),
+        _ => const ApiKeyWidget(),
+      },
+    );
+  }
+}
+
+class ChatWidget extends StatelessWidget {
+  const ChatWidget({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return const Padding(
+      padding: EdgeInsets.all(8.0),
+      child: Column(
+        mainAxisAlignment: MainAxisAlignment.center,
+        crossAxisAlignment: CrossAxisAlignment.start,
+        children: [
+          Expanded(child: ChatListWidget()),
+          Padding(
+            padding: EdgeInsets.symmetric(vertical: 25, horizontal: 15),
+            child: ChatInputBoxWidget(),
+          ),
+        ],
+      ),
+    );
+  }
+}