// backend/src/server.js (核心片段)
const express = require('express');
const axios = require('axios');
const { OpenAI } = require('openai');

const app = express();
app.use(express.json());

const openai = new OpenAI({ apiKey: process.env.OPENAI_API_KEY });
const GOOGLE_PLACES_API_KEY = process.env.GOOGLE_PLACES_API_KEY;

app.post('/api/recommend', async (req, res) => {
  try {
    const { location, budget, interests } = req.body;
    // 1. 获取附近POI（使用Google Places Nearby Search）
    const placesResponse = await axios.get(
      'https://maps.googleapis.com/maps/api/place/nearbysearch/json',
      {
        params: {
          location: location, // 如 "40.7128,-74.0060"
          radius: 50000,      // 50km ≈ 1小时车程（城市道路）
          type: 'tourist_attraction',
          key: GOOGLE_PLACES_API_KEY,
        },
      }
    );
    const places = placesResponse.data.results.slice(0, 5); // 取前5个

    // 2. 用LLM生成个性化推荐
    const prompt = `你是一个短途旅行规划师。用户位置：${location}，预算：${budget}元，兴趣：${interests}。以下是附近景点（名称+评分+地址）：\n${places.map(p => `${p.name} (评分${p.rating}, ${p.vicinity})`).join('\n')}\n请推荐1-2个最适合的去处，包含：总花费估算、路线建议、时间段分配。输出格式：用markdown列表，每一项以短横线开头。`;

    const stream = await openai.chat.completions.create({
      model: 'gpt-4o-mini',
      messages: [{ role: 'user', content: prompt }],
      stream: true,
    });

    res.setHeader('Content-Type', 'text/plain');
    for await (const chunk of stream) {
      res.write(chunk.choices[0]?.delta?.content || '');
    }
    res.end();
  } catch (error) {
    console.error(error);
    res.status(500).send('出错了，稍后再试');
  }
});

app.listen(process.env.PORT || 3001);

import { useState } from 'react';

function App() {
  const [location, setLocation] = useState('');
  const [budget, setBudget] = useState('200');
  const [interests, setInterests] = useState('');
  const [output, setOutput] = useState('');
  const [loading, setLoading] = useState(false);

  const handleSubmit = async (e) => {
    e.preventDefault();
    setOutput('');
    setLoading(true);

    // 用 fetch 读取流
    const response = await fetch('/api/recommend', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({
        location: location || '40.7128,-74.0060', // 默认纽约
        budget,
        interests,
      }),
    });

    const reader = response.body.getReader();
    const decoder = new TextDecoder();
    while (true) {
      const { done, value } = await reader.read();
      if (done) break;
      setOutput((prev) => prev + decoder.decode(value, { stream: true }));
    }
    setLoading(false);
  };

  return (
    <div className="max-w-2xl mx-auto p-4">
      <h1 className="text-2xl font-bold mb-4">本地短途旅行推荐</h1>
      <form onSubmit={handleSubmit} className="space-y-4">
        <input
          value={location}
          onChange={(e) => setLocation(e.target.value)}
          placeholder="地理位置 (如 40.7128,-74.0060)"
          className="w-full border p-2"
        />
        <input
          value={budget}
          onChange={(e) => setBudget(e.target.value)}
          placeholder="预算 (元)"
          className="w-full border p-2"
        />
        <input
          value={interests}
          onChange={(e) => setInterests(e.target.value)}
          placeholder="兴趣 (如徒步, 亲子, 美食)"
          className="w-full border p-2"
        />
        <button
          type="submit"
          disabled={loading}
          className="bg-blue-500 text-white px-4 py-2 rounded disabled:opacity-50"
        >
          {loading ? '生成中...' : '获取推荐'}
        </button>
      </form>
      <div className="mt-6 whitespace-pre-wrap">{output}</div>
    </div>
  );
}

export default App;

local-trip-recommender/
├── frontend/
│   ├── public/
│   ├── src/
│   │   ├── App.jsx
│   │   ├── main.jsx
│   │   └── index.css
│   ├── package.json
│   ├── vite.config.js
│   └── .env   (VITE_API_BASE_URL=http://localhost:3001)
├── backend/
│   ├── src/
│   │   └── server.js
│   ├── package.json
│   ├── .env   (OPENAI_API_KEY=..., GOOGLE_PLACES_API_KEY=...)
│   └── .gitignore
├── README.md
└── .gitignore

// vite.config.js
export default defineConfig({
  plugins: [react()],
  server: {
    proxy: {
      '/api': 'http://localhost:3001',
    },
  },
});

const overpassQuery = `[out:json];node["tourism"="attraction"](around:50000,${lat},${lon});out 5;`;

const controller = new AbortController();
setTimeout(() => controller.abort(), 30000); // 30秒超时