/* Minimal static dev server for the component showcase site.
   Usage (from repo root):  node site/dev-server.js
   Then open:               http://127.0.0.1:3311/site/
   Serves the repo root so /site, /frameworks and /.design_library are all reachable. */
'use strict';
const http = require('http');
const fs = require('fs');
const path = require('path');

/* 默认端口 3311；AA_PORT 仅供验证脚本起独立实例（避免与正在运行的 3311 抢端口）。
   非法值（非整数 / 越界 / 空串）一律回落到 3311，保持既有行为。 */
const PORT = (() => {
  const raw = process.env.AA_PORT;
  if (raw === undefined || raw === '') return 3311;
  const n = Number(raw);
  return Number.isInteger(n) && n > 0 && n < 65536 ? n : 3311;
})();
const HOST = '127.0.0.1';
const ROOT = path.resolve(process.cwd());

const TYPES = {
  '.html': 'text/html; charset=utf-8',
  '.css': 'text/css; charset=utf-8',
  '.js': 'text/javascript; charset=utf-8',
  '.mjs': 'text/javascript; charset=utf-8',
  '.json': 'application/json; charset=utf-8',
  '.txt': 'text/plain; charset=utf-8',
  '.vue': 'text/plain; charset=utf-8',
  '.svg': 'image/svg+xml',
  '.png': 'image/png',
  '.ico': 'image/x-icon'
};

const SECURITY_HEADERS = {
  'Content-Security-Policy': [
    "default-src 'self'",
    "script-src 'self' 'unsafe-inline'",
    "style-src 'self' 'unsafe-inline'",
    "img-src 'self' data:",
    "font-src 'self' data:",
    "connect-src 'self'",
    "frame-src 'self'",
    "object-src 'none'",
    "base-uri 'self'",
    "frame-ancestors 'self'",
    "form-action 'self'"
  ].join('; '),
  'X-Content-Type-Options': 'nosniff',
  'Referrer-Policy': 'no-referrer',
  'Permissions-Policy': 'camera=(), microphone=(), geolocation=(), payment=(), usb=()'
};

const SENSITIVE_SEGMENT = /^(?:\.git|\.env(?:\..*)?|backup(?:s)?|log(?:s)?)$/i;
const SENSITIVE_FILE = /\.(?:bak|backup|log)$/i;

function isSensitivePath(relativePath) {
  if (!relativePath || relativePath === '..' || path.isAbsolute(relativePath)) return true;
  const segments = relativePath.split(path.sep);
  return segments.some((segment) => SENSITIVE_SEGMENT.test(segment) || SENSITIVE_FILE.test(segment));
}

const PUBLIC_ROOTS = new Set(['site', 'frameworks', '.design_library', 'tests', 'index.html', 'sitemap.xml']);
const PUBLIC_SPEC_FILES = new Set(Array.from({ length: 10 }, (_, i) => `组件${i + 1}.txt`));

function isPublicPath(relativePath) {
  if (!relativePath || relativePath === '.' || relativePath.startsWith(`..${path.sep}`) || path.isAbsolute(relativePath)) return false;
  const segments = relativePath.split(path.sep);
  const top = segments[0];
  if (top === 'index.html' || top === 'sitemap.xml') return segments.length === 1;
  if (top === 'site' || top === 'frameworks' || top === 'tests') return true;
  if (top === '.design_library') return true;
  // 兼容旧版文档站：仅允许仓库根的 10 份规范原文，其余根文件一律拒绝
  return segments.length === 1 && PUBLIC_SPEC_FILES.has(top);
}

function writeResponse(res, statusCode, headers, body) {
  res.writeHead(statusCode, { ...SECURITY_HEADERS, ...headers });
  res.end(body);
}

const server = http.createServer((req, res) => {
  const rawPath = req.url.split('?')[0];
  // 原始路径含编码形态的 「.」「/」或 NUL 一律拒绝：
  //  - %2e/%2f（含大小写变体与双重编码）解码后会把 /%2e%2e/x 归一化成合法根路径
  //  - %00 / %2500 解码后是 NUL，会让 fs.readFile 同步抛 TypeError 打挂进程
  if (/%(?:2e|2f|252e|252f|00|2500)/i.test(rawPath)) {
    writeResponse(res, 403, { 'Content-Type': 'text/plain; charset=utf-8' }, 'Forbidden');
    return;
  }
  let urlPath;
  try {
    urlPath = decodeURIComponent(rawPath).replace(/\\/g, '/');
  } catch (e) {
    writeResponse(res, 400, { 'Content-Type': 'text/plain; charset=utf-8' }, 'Bad request');
    return;
  }
  // 解码后再校验一次 NUL（双保险）：无论编码形态如何（含裸 NUL、平台解码差异），
  // 都不得把 NUL 带进后面的文件路径
  if (urlPath.indexOf('\u0000') !== -1) {
    writeResponse(res, 400, { 'Content-Type': 'text/plain; charset=utf-8' }, 'Bad request');
    return;
  }
  if (urlPath === '/' || urlPath === '') {
    writeResponse(res, 302, { Location: '/site/' });
    return;
  }
  if (urlPath.endsWith('/')) urlPath += 'index.html';
  // 根路径与常见入口自动跳转到站点，避免裸访问 404
  if (urlPath === '/index.html') {
    writeResponse(res, 302, { Location: '/site/' });
    return;
  }
  const filePath = path.resolve(ROOT, `.${urlPath}`);
  const relativePath = path.relative(ROOT, filePath);
  // 开发服务只开放站点运行所需的顶层目录；仓库元数据、配置、脚本一律拒绝
  if (!isPublicPath(relativePath) || isSensitivePath(relativePath)) {
    writeResponse(res, 403, { 'Content-Type': 'text/plain; charset=utf-8' }, 'Forbidden');
    return;
  }
  // fs.readFile 会对含 NUL 的路径**同步**抛 ERR_INVALID_ARG_VALUE；异常若逃逸出请求
  // 回调会打挂进程（单个畸形请求即可 DoS）。这里兜住同步抛错，转成 400 响应。
  try {
    fs.readFile(filePath, (err, buf) => {
      if (err) {
        writeResponse(res, 404, { 'Content-Type': 'text/plain; charset=utf-8' }, '404 Not Found: ' + urlPath);
        return;
      }
      writeResponse(res, 200, {
        'Content-Type': TYPES[path.extname(filePath).toLowerCase()] || 'application/octet-stream',
        'Cache-Control': 'no-cache'
      }, buf);
    });
  } catch (e) {
    writeResponse(res, 400, { 'Content-Type': 'text/plain; charset=utf-8' }, 'Bad request');
  }
});

server.listen(PORT, HOST, () => {
  console.log('Aurora Admin showcase serving at http://' + HOST + ':' + PORT + '/site/');
});
server.on('error', (e) => {
  console.error('Server error:', e.message);
  process.exit(1);
});