flutter create ai_chatbot_app
cd ai_chatbot_app

dependencies:
  flutter:
    sdk: flutter
  http: ^0.13.4

flutter pub get

import 'dart:convert';
import 'package:http/http.dart' as http;

Future<String> fetchAIResponse(String prompt) async {
  final response = await http.post(
    Uri.parse('https://api.openai.com/v1/chat/completions'),
    headers: {
      'Content-Type': 'application/json',
      'Authorization': 'Bearer YOUR_API_KEY',
    },
    body: jsonEncode({
      'model': 'gpt-3.5-turbo',
      'messages': [
        {'role': 'user', 'content': prompt}
      ]
    }),
  );

  if (response.statusCode == 200) {
    final data = jsonDecode(response.body);
    return data['choices'][0]['message']['content'];
  } else {
    throw Exception('Failed to fetch response');
  }
}

class ChatScreen extends StatefulWidget {
  @override
  _ChatScreenState createState() => _ChatScreenState();
}

class _ChatScreenState extends State<ChatScreen> {
  final TextEditingController _controller = TextEditingController();
  final List<String> _messages = [];

  void _sendMessage() async {
    final input = _controller.text;
    if (input.isEmpty) return;

    setState(() {
      _messages.add('Bạn: $input');
    });
    _controller.clear();

    final response = await fetchAIResponse(input);

    setState(() {
      _messages.add('AI: $response');
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('AI Chatbot')),
      body: Column(
        children: [
          Expanded(
            child: ListView.builder(
              itemCount: _messages.length,
              itemBuilder: (context, index) {
                return ListTile(
                  title: Text(_messages[index]),
                );
              },
            ),
          ),
          Padding(
            padding: EdgeInsets.all(8),
            child: Row(
              children: [
                Expanded(
                  child: TextField(
                    controller: _controller,
                    decoration: InputDecoration(hintText: 'Nhập tin nhắn...'),
                  ),
                ),
                IconButton(
                  icon: Icon(Icons.send),
                  onPressed: _sendMessage,
                )
              ],
            ),
          )
        ],
      ),
    );
  }
}

bool isLoading = false;

void _sendMessage() async {
  final input = _controller.text;
  if (input.isEmpty) return;

  setState(() {
    _messages.add('Bạn: $input');
    isLoading = true;
  });
  _controller.clear();

  final response = await fetchAIResponse(input);

  setState(() {
    _messages.add('AI: $response');
    isLoading = false;
  });
}