server.js

import express from 'express';
import dotenv from 'dotenv';
import { MongoClient } from 'mongodb';
import cookieParser from 'cookie-parser';
import path from 'path';
import { fileURLToPath } from 'url';

// Load environment variables
dotenv.config();

const { MONGO_URI, API_BASE_URL } = process.env;
const PORT = process.env.PORT || 3000;
const AUTH_COOKIE_NAME = 'auth_token';
const API_PREFIX = API_BASE_URL || '/api';

// ES Module equivalent of __dirname
const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);

const app = express();
app.use(express.json());
app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));


let db;

// --- Database Connection ---
async function connectToDb() {
    try {
        const client = new MongoClient(MONGO_URI,{
            serverSelectionTimeoutMS: 5000,
            heartbeatFrequencyMS: 1000,
            connectTimeoutMS: 30000,
            socketTimeoutMS: 360000,
            retryWrites: true,
            retryReads: true,
        });
        await client.connect();
        db = client.db('chat_ldata'); // Use the specific db from the URI
        console.log('Connected to MongoDB');
    } catch (error) {
        console.error('Failed to connect to MongoDB', error);
        process.exit(1);
    }
}

// --- Authentication Middleware ---
const authMiddleware = (req, res, next) => {
    const authToken = req.cookies[AUTH_COOKIE_NAME];
    if (authToken && authToken.startsWith('user_')) {
        // 从cookie中提取用户名
        req.currentUser = authToken.replace('user_', '');
        next();
    } else {
        res.status(401).json({ message: 'Unauthorized' });
    }
};

// --- API Routes ---
app.post('/login', async (req, res) => {
    const { username, password } = req.body;
    
    // 检查密码格式：用户名 + "123321"
    const expectedPassword = username + '123321';
    
    if (password === expectedPassword) {
        // 验证用户是否存在于数据库中
        try {
            const user = await db.collection('users').findOne({ username: username });
            if (user) {
                // 设置包含用户名的cookie
                res.cookie(AUTH_COOKIE_NAME, `user_${username}`, { httpOnly: true, maxAge: 3600 * 1000 }); // 1 hour cookie
                res.status(200).json({ message: 'Login successful' });
            } else {
                res.status(401).json({ message: '用户不存在' });
            }
        } catch (error) {
            console.error('Login error:', error);
            res.status(500).json({ message: '登录过程中发生错误' });
        }
    } else {
        res.status(401).json({ message: '用户名或密码错误' });
    }
});

app.post('/logout', (req, res) => {
    res.clearCookie(AUTH_COOKIE_NAME);
    res.status(200).json({ message: 'Logged out' });
});

// GET all users (except admin) and their linkMappings
app.get(`${API_PREFIX}/users`, authMiddleware, async (req, res) => {
    try {
        const currentUser = req.currentUser;
        
        // 构建查询条件：只返回当前登录用户的数据
        const query = { username: currentUser };

        const users = await db.collection('users').find(query).project({
            username: 1,
            'preferences.linkMappings': 1
        }).toArray();
        
        res.json(users);
    } catch (error) {
        console.error('Error fetching users:', error);
        res.status(500).json({ message: 'Error fetching data from database.' });
    }
});

// Update a user's linkMappings
app.post(`${API_PREFIX}/users/:username`, authMiddleware, async (req, res) => {
    const { username } = req.params;
    const { linkMappings: updatedMappingsFromClient } = req.body;

    if (!Array.isArray(updatedMappingsFromClient)) {
        return res.status(400).json({ message: 'linkMappings must be an array.' });
    }

    try {
        // Step 1: Read the user's full, original document from the database.
        const user = await db.collection('users').findOne({ username: username });

        if (!user) {
            return res.status(404).json({ message: 'User not found.' });
        }

        // Get the original mappings, ensuring it's an array.
        const originalMappings = user.preferences?.linkMappings || [];

        // Step 2: Modify the original data with the updates from the client.
        const newMappings = originalMappings.map((originalMapping, index) => {
            // If the client sent a corresponding mapping, update its 'links' property.
            if (updatedMappingsFromClient[index]) {
                return {
                    ...originalMapping,
                    links: updatedMappingsFromClient[index].links
                };
            }
            // Otherwise, return the original mapping untouched.
            return originalMapping;
        });

        // Step 3: Write the safely merged, complete data back to the database.
        const result = await db.collection('users').updateOne(
            { username: username },
            { $set: { 'preferences.linkMappings': newMappings } }
        );

        res.status(200).json({ message: 'User updated successfully.' });
    } catch (error) {
        console.error(`Error updating user ${username}:`, error);
        res.status(500).json({ message: 'Error updating data in database.' });
    }
});


// --- Serve Frontend ---
// For any other GET request, send the dashboard (if logged in) or login page
app.get('*', (req, res) => {
    const authToken = req.cookies[AUTH_COOKIE_NAME];
    if (authToken && authToken.startsWith('user_')) {
        res.sendFile(path.join(__dirname, 'public', 'dashboard.html'));
    } else {
        res.sendFile(path.join(__dirname, 'public', 'index.html'));
    }
});


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