const express = require('express');
const axios = require('axios');
const cors = require('cors');
const path = require('path');

const app = express();
const PORT = 3000;

// 中间件
app.use(cors());
app.use(express.json());
app.use(express.static(path.join(__dirname, 'public')));

// API路由
app.post('/api/chat', async (req, res) => {
    try {
        const { message, history } = req.body;
        
        // 构建消息数组，包含系统提示、历史对话和当前消息
        const messages = [
            { role: "system", content: "You are a helpful assistant." },
            ...(history || []),  // 添加历史对话
            { role: "user", content: message }  // 添加当前消息
        ];

        // 限制对话历史长度，防止超出token限制
        const maxHistoryLength = 10;  // 可根据实际情况调整
        if (messages.length > maxHistoryLength) {
            messages.splice(1, messages.length - maxHistoryLength);
        }

        const response = await axios.post('https://dashscope.aliyuncs.com/api/v1/services/aigc/text-generation/generation', {
            model: "farui-plus",
            input: {
                messages: messages
            }
        }, {
            headers: {
                'Authorization': `sk-24a6af9eea55494b8f465a01cb92d461`,
                'Content-Type': 'application/json'
            }
        });

        res.json({
            status: 'success',
            response: response.data
        });
    } catch (error) {
        console.error(error);
        res.status(500).json({
            status: 'error',
            message: 'Internal server error'
        });
    }
});

// 前端路由
app.get('*', (req, res) => {
    res.sendFile(path.join(__dirname, 'public', 'index.html'));
});

app.listen(PORT, () => {
    console.log(`Server is running on http://localhost:${PORT}`);
});