const http = require('http');
const https = require('https');
const url = require('url');
const querystring = require('querystring');

const apiEndpoint = process.env.url || 'https://oss.x-php.com/alist/link';
const requestTimeout = 10000; // 10 seconds
const cache = {};

// Get port from environment variable or default to 9001
const PORT = process.env.PORT || 9001;

const server = http.createServer((req, res) => {
    if (req.url === '/favicon.ico') {
        res.writeHead(204);
        res.end();
        return;
    }

    const parsedUrl = url.parse(req.url, true);
    const path = parsedUrl.pathname;
    const sign = parsedUrl.query.sign || '';

    // Check if the data is in cache and not expired
    const cacheEntry = cache[path];
    if (cacheEntry && cacheEntry.expiration > Date.now()) {
        // 清理所有过期的缓存
        Object.keys(cache).forEach(key => {
            if (cache[key].expiration < Date.now()) {
                delete cache[key];
            }
        });

        serveFromCache(cacheEntry, res);
        return;
    } else {
        delete cache[path]; // Remove expired cache entry if exists
    }

    // Construct the POST data
    const postData = querystring.stringify({ path, sign });

    // Request the real URL from the API
    const apiReq = https.request(apiEndpoint, {
        method: 'POST',
        headers: {
            'Content-Type': 'application/x-www-form-urlencoded',
            'Accept': 'application/json',
            'Content-Length': Buffer.byteLength(postData),
            'sign': sign
        },
        timeout: requestTimeout
    }, (apiRes) => {
        let data = '';
        apiRes.on('data', chunk => data += chunk);
        apiRes.on('end', () => {
            try {
                const apiData = JSON.parse(data);
                if (apiData.code === 200 && apiData.data && apiData.data.url) {
                    const { url: realUrl, cloudtype, expiration } = apiData.data;

                    // Cache the response if expiration is greater than 0
                    if (expiration > 0) {
                        cache[path] = {
                            realUrl,
                            cloudtype,
                            expiration: Date.now() + expiration * 1000
                        };
                    }

                    fetchAndServe(realUrl, cloudtype, res);
                } else {
                    res.writeHead(502, { 'Content-Type': 'text/plain' });
                    res.end(apiData.message || 'Bad Gateway');
                }
            } catch (error) {
                res.writeHead(502, { 'Content-Type': 'text/plain' });
                res.end('Bad Gateway: Failed to decode JSON');
            }
        });
    });

    apiReq.on('error', (e) => {
        if (e.code === 'ETIMEDOUT') {
            res.writeHead(504, { 'Content-Type': 'text/plain' });
            res.end('Gateway Timeout');
        } else {
            res.writeHead(500, { 'Content-Type': 'text/plain' });
            res.end('Internal Server Error');
        }
    });

    apiReq.write(postData);
    apiReq.end();
});

function fetchAndServe(realUrl, cloudtype, res) {
    const realReq = https.get(realUrl, { timeout: requestTimeout * 10 }, (realRes) => {
        res.writeHead(realRes.statusCode, {
            ...realRes.headers,
            'cloudtype': cloudtype
        });
        realRes.pipe(res);
    });

    realReq.on('error', (e) => {
        res.writeHead(502, { 'Content-Type': 'text/plain' });
        res.end(`Bad Gateway: ${realUrl}`);
    });
}

function serveFromCache(cacheEntry, res) {
    fetchAndServe(cacheEntry.realUrl, cacheEntry.cloudtype, res);
}

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

// Graceful shutdown
process.on('SIGINT', () => {
    console.log('Received SIGINT. Shutting down gracefully...');
    server.close(() => {
        console.log('Server closed.');
        process.exit(0);
    });

    // Force shutdown after 10 seconds if not closed
    setTimeout(() => {
        console.error('Forcing shutdown...');
        process.exit(1);
    }, 10000);
});