add sqllite utils

lib/screens/chat_screen.dart

@@ -4,7 +4,9 @@ import '../widgets/chat_bubble.dart';
 import '../widgets/chat_input.dart';
 import '../widgets/gradient_background.dart';
 import '../models/chat_message.dart';
-import 'dart:convert';
+//import 'dart:convert';
+import '../config/database_helper.dart';
+import '../models/message_model.dart';
 
 class ChatScreen extends StatefulWidget {
   const ChatScreen({super.key});
@@ -18,6 +20,9 @@ class _ChatScreenState extends State<ChatScreen> {
   int? _currentStreamingMessageIndex;
   int _lastUserMessageCount = 0; // 添加这个变量跟踪用户消息数量
 
+  final DatabaseHelper _dbHelper = DatabaseHelper();
+  List<Message> _messagesDB = [];
+
   void _handleSendMessage(String text) {
     if (text.trim().isEmpty) return;
     setState(() {
@@ -41,6 +46,12 @@ class _ChatScreenState extends State<ChatScreen> {
       ));
       _lastUserMessageCount = _getUserMessageCount(); // 更新用户消息计数
       _currentStreamingMessageIndex = null; // 重置流索引，强制创建新气泡
+
+      _addMessage(Message(
+        role: 'user',
+        message: text,
+      ));
+
     });
   }
 
@@ -76,6 +87,11 @@ class _ChatScreenState extends State<ChatScreen> {
         }
       }
 
+      _addMessage(Message(
+        role: 'assistant',
+        message: text,
+      ));
+
       // 如果完成了，重置索引
       if (isComplete) {
         _currentStreamingMessageIndex = null;
@@ -83,6 +99,20 @@ class _ChatScreenState extends State<ChatScreen> {
     });
   }
 
+  Future<void> _loadMessages() async {
+    List<Map<String, dynamic>> records = await _dbHelper.getMessages();
+    setState(() {
+      _messagesDB = records.map((record) => Message(
+        role: record['role'],
+        message: record['message'],
+      )).toList();
+    });
+  }
+
+  Future<void> _addMessage(Message message) async {
+    await _dbHelper.insertMessage(message.toMap());
+  }
+
   @override
   Widget build(BuildContext context) {
     return Scaffold(