const express = require('express');
const axios = require('axios');
const crypto = require('crypto');
const qs = require('qs');


const app = express();
const port = 8181;

// OAuth2 参数
const CLIENT_ID = 'hi3geJYfTotoiR5S62u3rh4W5tSeC5UG';
const CLIENT_SECRET = 'VMPBVoAfOB5ojkGXRDEtzvDhRLENHpaN';
const REDIRECT_URI = 'http://localhost:8181/oauth2/callback';
const AUTHORIZATION_ENDPOINT = 'https://connect.linux.do/oauth2/authorize';
const TOKEN_ENDPOINT = 'https://connect.linux.do/oauth2/token';
const USER_ENDPOINT = 'https://connect.linux.do/api/user';

app.use(express.json());
app.use(express.urlencoded({ extended: true }));

// 使用 session 来保存 state 和其他 OAuth2 相关信息
const session = require('express-session');
app.use(session({
    secret: crypto.randomBytes(24).toString('hex'),
    resave: false,
    saveUninitialized: true
}));

app.get('/oauth2/initiate', (req, res) => {
    req.session.oauthState = crypto.randomBytes(16).toString('hex');
    const authorizationUrl = `${AUTHORIZATION_ENDPOINT}?client_id=${CLIENT_ID}&response_type=code&redirect_uri=${REDIRECT_URI}&state=${req.session.oauthState}`;
    res.redirect(authorizationUrl);
});

app.get('/oauth2/callback', async (req, res) => {
    const { code, state } = req.query;

    if (state !== req.session.oauthState) {
        console.error('State验证失败');
        return res.status(401).send('State value does not match');
    }

    try {
        const data = qs.stringify({
            grant_type: 'authorization_code',
            code: code,
            redirect_uri: REDIRECT_URI
        });

        const tokenResponse = await axios.post(TOKEN_ENDPOINT, data, {
            auth: {
                username: CLIENT_ID,
                password: CLIENT_SECRET
            },
            headers: { 'Content-Type': 'application/x-www-form-urlencoded' }
        });

        const userResponse = await axios.get(USER_ENDPOINT, {
            headers: { 'Authorization': `Bearer ${tokenResponse.data.access_token}` }
        });
        console.log('User response:', userResponse.data);
        res.json(userResponse.data);
    } catch (error) {
        console.error('Error during token fetch or user info retrieval:', error.message);

        // 更详细地输出错误信息
        if (error.response) {
            console.error('Error response data:', error.response.data);
            console.error('Error response status:', error.response.status);
            console.error('Error response headers:', error.response.headers);
        } else if (error.request) {
            console.error('No response received:', error.request);
        } else {
            console.error('Error', error.message);
        }

        return res.status(500).send('Failed to fetch access token');
    }

});

app.listen(port, () => {
    console.log(`App listening at http://localhost:${port}`);
});