Advanced chat management via UI

frontend/lib/create_chat_screen.dart

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+import 'package:flutter/material.dart';
+import 'backend.dart';
+import 'chat_screen.dart';
+
+class AgentEntry {
+  final int id;
+  final String name;
+
+  AgentEntry({required this.id, required this.name});
+}
+
+class CreateChatScreen extends StatefulWidget {
+  @override
+  _CreateChatScreenState createState() => _CreateChatScreenState();
+}
+
+class _CreateChatScreenState extends State<CreateChatScreen> {
+  final TextEditingController nameController = TextEditingController();
+
+  // Track selected participants
+  final Set<int> selectedParticipants = {};
+
+  void _submit() async {
+    Backend.invalidateCache(chat: true);
+    final response = await Backend.sendAction("create-chat", {
+        'name': nameController.text,
+        'members': selectedParticipants.toList(),
+    });
+    Navigator.push(
+        context,
+        MaterialPageRoute(
+            builder: (context) => ChatScreen(chatId: response['chatId']),
+        ),
+    );
+  }
+
+  void _toggleParticipant(int id) {
+    setState(() {
+      if (selectedParticipants.contains(id)) {
+        selectedParticipants.remove(id);
+      } else {
+        selectedParticipants.add(id);
+      }
+    });
+  }
+
+  // TODO: Agents should only be retrieved once, then the same future is reused in `build`
+  static Future<List<AgentEntry>> getAgents() async {
+    final response = await Backend.sendAction("get-agents", {});
+    List<dynamic> chatObjects = response['agents'];
+    List<AgentEntry> chats = chatObjects
+        .map((msg) => AgentEntry(
+              id: msg['id'],
+              name: msg['name']?.isNotEmpty == true ? msg['name'] : '[Chat ${msg['id']}]',
+            ))
+        .toList();
+    return chats;
+  }
+
+  Widget _buildParticipantTile(AgentEntry entry) {
+    final isSelected = selectedParticipants.contains(entry.id);
+    return GestureDetector(
+      onTap: () => _toggleParticipant(entry.id),
+      child: Container(
+        padding: EdgeInsets.symmetric(vertical: 12, horizontal: 16),
+        margin: EdgeInsets.symmetric(vertical: 4),
+        decoration: BoxDecoration(
+          color: isSelected ? Colors.blue.shade100 : Colors.grey.shade200,
+          border: Border.all(
+            color: isSelected ? Colors.blue : Colors.transparent,
+            width: 2,
+          ),
+          borderRadius: BorderRadius.circular(8),
+        ),
+        child: Text(
+          entry.name,
+          style: TextStyle(
+            fontWeight: FontWeight.w600,
+            color: isSelected ? Colors.blue.shade900 : Colors.black87,
+          ),
+        ),
+      ),
+    );
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(title: Text('Create Chat')),
+      body: Center(
+        child: Padding(
+          padding: const EdgeInsets.all(16.0),
+          child: Column(
+            children: [
+              TextField(
+                controller: nameController,
+                decoration: InputDecoration(labelText: 'Title'),
+              ),
+              SizedBox(height: 20),
+              Align(
+                alignment: Alignment.centerLeft,
+                child: Text('Select Participants:',
+                    style: TextStyle(
+                        fontSize: 16, fontWeight: FontWeight.bold)),
+              ),
+              SizedBox(height: 8),
+              Expanded(
+                child: FutureBuilder<List<AgentEntry>>(
+                    future: getAgents(),
+                    builder: (context, snapshot) {
+                        if (snapshot.hasData) {
+                            final agents = snapshot.data!;
+                            return ListView.builder(
+                                itemCount: agents.length,
+                                itemBuilder: (context, index) {
+                                    return _buildParticipantTile(agents[index]);
+                                },
+                            );
+                        } else {
+                            return ListView.builder(
+                                itemCount: 0,
+                                itemBuilder: (context, index) {
+                                    return ListTile();
+                                },
+                            );
+                        }
+                    },
+                ),
+              ),
+              ElevatedButton(
+                onPressed: _submit,
+                child: Text('Create Chat'),
+              ),
+            ],
+          ),
+        ),
+      ),
+    );
+  }
+}