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lib/screens/chat_screen.dart

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+import 'package:flutter/material.dart';
+import '../widgets/ai_avatar.dart';
+import '../widgets/chat_bubble.dart';
+import '../widgets/chat_input.dart';
+import '../widgets/gradient_background.dart';
+import '../models/chat_message.dart';
+import 'dart:convert';
+
+class ChatScreen extends StatefulWidget {
+  const ChatScreen({super.key});
+
+  @override
+  State<ChatScreen> createState() => _ChatScreenState();
+}
+
+class _ChatScreenState extends State<ChatScreen> {
+  final List<ChatMessage> _messages = [];
+  int? _currentStreamingMessageIndex;
+  int _lastUserMessageCount = 0; // 添加这个变量跟踪用户消息数量
+
+  void _handleSendMessage(String text) {
+    if (text.trim().isEmpty) return;
+    setState(() {
+      _messages.add(ChatMessage(
+        text: text,
+        isUser: true,
+        timestamp: DateTime.now(),
+      ));
+      _lastUserMessageCount = _getUserMessageCount(); // 更新用户消息计数
+      _currentStreamingMessageIndex = null; // 重置流索引，强制创建新气泡
+    });
+  }
+
+  // 处理语音识别后的文本
+  void _handleAIResponse(String text) {
+    setState(() {
+      _messages.add(ChatMessage(
+        text: text,
+        isUser: true, // 用户的消息
+        timestamp: DateTime.now(),
+      ));
+      _lastUserMessageCount = _getUserMessageCount(); // 更新用户消息计数
+      _currentStreamingMessageIndex = null; // 重置流索引，强制创建新气泡
+    });
+  }
+
+  // 计算用户消息总数
+  int _getUserMessageCount() {
+    return _messages.where((msg) => msg.isUser).length;
+  }
+
+  // 处理 AI 流式响应
+  void _handleAIStreamResponse(String text, bool isComplete) {
+    // 检查是否有新的用户消息，如果有，应该创建新的AI响应
+    final currentUserMessageCount = _getUserMessageCount();
+    final hasNewUserMessage = currentUserMessageCount > _lastUserMessageCount;
+
+    setState(() {
+      if (hasNewUserMessage || _currentStreamingMessageIndex == null) {
+        // 有新用户消息或首次响应，创建新气泡
+        _messages.add(ChatMessage(
+          text: text,
+          isUser: false,
+          timestamp: DateTime.now(),
+        ));
+        _currentStreamingMessageIndex = _messages.length - 1;
+        _lastUserMessageCount = currentUserMessageCount; // 更新追踪
+      } else {
+        // 更新现有气泡
+        if (_currentStreamingMessageIndex! < _messages.length) {
+          _messages[_currentStreamingMessageIndex!] = ChatMessage(
+            text: text,
+            isUser: false,
+            timestamp: _messages[_currentStreamingMessageIndex!].timestamp,
+          );
+        }
+      }
+
+      // 如果完成了，重置索引
+      if (isComplete) {
+        _currentStreamingMessageIndex = null;
+      }
+    });
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      body: GradientBackground(
+        child: SafeArea(
+          child: Column(
+            children: [
+              // Header with AI avatar
+              SizedBox(
+                height: 140,
+                child: Stack(
+                  children: [
+                    // 背景渐变已由外层GradientBackground提供
+                    Row(
+                      crossAxisAlignment: CrossAxisAlignment.start,
+                      children: [
+                        // AI贴图
+                        const Padding(
+                          padding: EdgeInsets.only(left: 16, top: 0),
+                          child: AIAvatar(width: 120, height: 140),
+                        ),
+                        const SizedBox(width: 8),
+                        // 文字整体下移
+                        Padding(
+                          padding: const EdgeInsets.only(top: 48),
+                          child: Column(
+                            crossAxisAlignment: CrossAxisAlignment.start,
+                            children: [
+                              const Text(
+                                'Hi, 我是众众!',
+                                style: TextStyle(
+                                  fontSize: 22,
+                                  fontWeight: FontWeight.bold,
+                                  color: Colors.white,
+                                ),
+                              ),
+                              const SizedBox(height: 8),
+                              Text(
+                                '您的专属看、选、买、用车助手',
+                                style: TextStyle(
+                                  fontSize: 14,
+                                  color: Colors.white.withOpacity(0.8),
+                                ),
+                              ),
+                            ],
+                          ),
+                        ),
+                        // 可选：右上角关闭按钮
+                        const Spacer(),
+                        Padding(
+                          padding: const EdgeInsets.only(top: 16, right: 16),
+                          child: Icon(Icons.close, color: Colors.white),
+                        ),
+                      ],
+                    ),
+                    // 底部分割线
+                    Positioned(
+                      left: 0,
+                      right: 0,
+                      bottom: 0,
+                      child: Container(
+                        height: 1,
+                        color: Colors.white.withOpacity(0.15),
+                      ),
+                    ),
+                  ],
+                ),
+              ),
+
+              // Chat messages
+              Expanded(
+                child: ListView.builder(
+                  padding: const EdgeInsets.symmetric(horizontal: 16),
+                  itemCount: _messages.length,
+                  reverse: true,
+                  itemBuilder: (context, index) {
+                    final message = _messages[_messages.length - 1 - index];
+                    return ChatBubble(message: message);
+                  },
+                ),
+              ),
+
+              // Input area
+              ChatInput(
+                onSendMessage: _handleSendMessage,
+                onAIResponse: _handleAIResponse,
+                onAIStreamResponse: _handleAIStreamResponse, // 添加新回调
+              ),
+            ],
+          ),
+        ),
+      ),
+    );
+  }
+}