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

const PORT = 3456;
const UPSTREAM_URL = 'https://iplcsub.com/subscribe/36769/gVZJsFgUA7/surge/';

// 额外节点的 URI（VLESS 不被 Surge 支持，跳过）
const EXTRA_NODES_RAW = [
  // VLESS-Reality — Surge 不支持，以注释形式保留
  // 'vless://d42937a5-cf84-46c9-a304-36e0b6753c4c@coding.njcqtechaicoding.com:8443?...',
  'ss://MjAyMi1ibGFrZTMtYWVzLTEyOC1nY206L3lzcGo3RFFGSm9za0MvbkFvSDRNUT09Oi95c3BqN0RRRkpvc2tDL25Bb0g0TVE9PQ@coding.njcqtechaicoding.com:8446?type=tcp#Shadowsocks-2022-ss-2022%40x3ui',
  'vmess://ewogICJ2IjogIjIiLAogICJwcyI6ICJWTWVzcy1XUy1UTFMtdm1lc3Mtd3NAeDN1aSIsCiAgImFkZCI6ICJjb2RpbmcubmpjcXRlY2hhaWNvZGluZy5jb20iLAogICJwb3J0IjogMjA4MywKICAiaWQiOiAiNTI4ODkyMDUtNmY2ZC00ZWY2LTg4ZjItMmM2YTRmYThmOTJkIiwKICAic2N5IjogIiIsCiAgIm5ldCI6ICJ3cyIsCiAgInRscyI6ICJ0bHMiLAogICJwYXRoIjogIi92bWVzc3dzIiwKICAiaG9zdCI6ICJjb2RpbmcubmpjcXRlY2hhaWNvZGluZy5jb20iLAogICJzbmkiOiAiY29kaW5nLm5qY3F0ZWNoYWljb2RpbmcuY29tIiwKICAiZnAiOiAiY2hyb21lIiwKICAiYWxwbiI6ICJoMixodHRwLzEuMSIKfQ==',
  'trojan://1d834ec2-a09b-4f59-978e-bbd557f1ee3a@coding.njcqtechaicoding.com:2087?type=tcp&security=tls&fp=chrome&alpn=h2%2Chttp%2F1.1&sni=coding.njcqtechaicoding.com#Trojan-TLS-trojan-tls%40x3ui',
];

/**
 * 解析 ss:// URI 为 Surge 代理行
 */
function parseSS(uri) {
  const url = new URL(uri);
  const name = decodeURIComponent(url.hash.slice(1));
  const server = url.hostname;
  const port = url.port;

  // userinfo 是 base64(method:password)
  const decoded = Buffer.from(url.username, 'base64').toString();
  // SS 2022 格式: method:serverKey:userKey 或 method:password
  const firstColon = decoded.indexOf(':');
  const method = decoded.slice(0, firstColon);
  const password = decoded.slice(firstColon + 1);

  return `${name} = ss, ${server}, ${port}, encrypt-method=${method}, password=${password}`;
}

/**
 * 解析 vmess:// URI 为 Surge 代理行
 */
function parseVMess(uri) {
  const b64 = uri.replace('vmess://', '');
  const json = JSON.parse(Buffer.from(b64, 'base64').toString());

  const name = json.ps || 'VMess';
  const server = json.add;
  const port = json.port;
  const uuid = json.id;

  let line = `${name} = vmess, ${server}, ${port}, username=${uuid}, vmess-aead=true`;

  if (json.tls === 'tls') {
    line += ', tls=true';
    if (json.sni) line += `, sni=${json.sni}`;
    line += ', skip-cert-verify=true';
  }

  if (json.net === 'ws') {
    line += ', ws=true';
    if (json.path) line += `, ws-path=${json.path}`;
    if (json.host) line += `, ws-headers=Host:${json.host}`;
  }

  return line;
}

/**
 * 解析 trojan:// URI 为 Surge 代理行
 */
function parseTrojan(uri) {
  const url = new URL(uri);
  const name = decodeURIComponent(url.hash.slice(1));
  const server = url.hostname;
  const port = url.port;
  const password = url.username;
  const params = url.searchParams;
  const sni = params.get('sni') || server;

  let line = `${name} = trojan, ${server}, ${port}, password=${password}, sni=${sni}, skip-cert-verify=true`;

  return line;
}

/**
 * 将各协议的 URI 转为 Surge 代理行
 */
function convertToSurgeLine(uri) {
  if (uri.startsWith('ss://')) return parseSS(uri);
  if (uri.startsWith('vmess://')) return parseVMess(uri);
  if (uri.startsWith('trojan://')) return parseTrojan(uri);
  return null;
}

/**
 * 通过 HTTPS 获取上游订阅内容
 */
function fetchUpstream() {
  return new Promise((resolve, reject) => {
    https.get(UPSTREAM_URL, (res) => {
      let data = '';
      res.on('data', (chunk) => (data += chunk));
      res.on('end', () => resolve(data));
      res.on('error', reject);
    }).on('error', reject);
  });
}

/**
 * 将额外节点注入到 Surge 配置中
 */
function mergeNodes(config, extraLines) {
  if (extraLines.length === 0) return config;

  const extraNames = extraLines.map((l) => l.split(' = ')[0].trim());
  const lines = config.split('\n');
  const result = [];
  let inProxySection = false;
  let inProxyGroupSection = false;
  let proxyGroupHandled = false;

  for (let i = 0; i < lines.length; i++) {
    const line = lines[i];
    const trimmed = line.trim();

    // 检测 section 边界
    if (trimmed.startsWith('[') && trimmed.endsWith(']')) {
      // 如果正在 [Proxy] section，插入额外节点
      if (inProxySection) {
        result.push('# --- 自定义节点 ---');
        extraLines.forEach((l) => result.push(l));
        result.push('');
        inProxySection = false;
      }
      if (trimmed === '[Proxy]') {
        inProxySection = true;
      } else if (trimmed === '[Proxy Group]') {
        inProxyGroupSection = true;
      } else {
        inProxyGroupSection = false;
      }
    }

    // 处理 Proxy Group，在第一个 select 组中追加自定义节点名
    if (inProxyGroupSection && !proxyGroupHandled && trimmed.includes('= select,')) {
      const appended = line + ',' + extraNames.join(',');
      result.push(appended);
      proxyGroupHandled = true;
      continue;
    }

    result.push(line);
  }

  // 如果 [Proxy] 是最后一个 section
  if (inProxySection) {
    result.push('# --- 自定义节点 ---');
    extraLines.forEach((l) => result.push(l));
  }

  return result.join('\n');
}

/**
 * 替换 MANAGED-CONFIG URL 指向本地服务
 */
function rewriteManagedConfig(config, localUrl) {
  return config.replace(
    /^#!MANAGED-CONFIG\s+\S+/m,
    `#!MANAGED-CONFIG ${localUrl}`
  );
}

// 创建 HTTP 服务
const server = http.createServer(async (req, res) => {
  if (req.url === '/' || req.url === '/surge') {
    try {
      console.log(`[${new Date().toISOString()}] Fetching upstream subscription...`);
      const upstream = await fetchUpstream();

      // 解析额外节点
      const extraLines = EXTRA_NODES_RAW.map(convertToSurgeLine).filter(Boolean);

      // 合并配置
      let merged = mergeNodes(upstream, extraLines);

      // 替换 MANAGED-CONFIG URL
      const localUrl = `http://${req.headers.host || `127.0.0.1:${PORT}`}/surge`;
      merged = rewriteManagedConfig(merged, localUrl);

      console.log(`[${new Date().toISOString()}] Serving merged config (${extraLines.length} extra nodes)`);

      res.writeHead(200, {
        'Content-Type': 'text/plain; charset=utf-8',
        'Content-Disposition': 'attachment; filename=merged.conf',
      });
      res.end(merged);
    } catch (err) {
      console.error('Error:', err.message);
      res.writeHead(502, { 'Content-Type': 'text/plain' });
      res.end('Failed to fetch upstream subscription');
    }
  } else {
    res.writeHead(404);
    res.end('Not Found');
  }
});

server.listen(PORT, () => {
  console.log(`Sub-Router running at http://127.0.0.1:${PORT}/surge`);
  console.log('Use this URL in Surge as your subscription link.');
  console.log('');
  console.log('Note: VLESS-Reality node is skipped (not supported by Surge).');
});