ai_chat_assistant/lib/screens/chat_screen.dart

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
              ),
            ],
          ),
        ),
      ),
    );
  }
}