/*
 * 支持 Range 请求的静态文件服务器(测试用)
 * python3 -m http.server 不支持 Range,会导致 mp4 无法 seek,故用此替代
 * 用法:node scripts/serve.js [端口]
 */
const http = require('http');
const fs = require('fs');
const path = require('path');

const root = path.resolve(__dirname, '..');
const port = parseInt(process.argv[2] || '8931', 10);
const mime = {
  '.html': 'text/html', '.js': 'text/javascript', '.css': 'text/css',
  '.png': 'image/png', '.mp4': 'video/mp4', '.json': 'application/json',
  '.map': 'application/json', '.ico': 'image/x-icon'
};

http.createServer((req, res) => {
  const urlPath = decodeURIComponent(req.url.split('?')[0]);
  let file = path.join(root, urlPath === '/' ? 'index.html' : urlPath);
  if (!file.startsWith(root)) { res.writeHead(403); res.end(); return; }
  fs.stat(file, (err, stat) => {
    if (err || !stat.isFile()) { res.writeHead(404); res.end('404'); return; }
    const type = mime[path.extname(file).toLowerCase()] || 'application/octet-stream';
    const range = req.headers.range;
    if (range) {
      const m = /bytes=(\d*)-(\d*)/.exec(range);
      let start = m && m[1] ? parseInt(m[1], 10) : 0;
      let end = m && m[2] ? parseInt(m[2], 10) : stat.size - 1;
      end = Math.min(end, stat.size - 1);
      res.writeHead(206, {
        'Content-Type': type,
        'Content-Range': `bytes ${start}-${end}/${stat.size}`,
        'Accept-Ranges': 'bytes',
        'Content-Length': end - start + 1
      });
      fs.createReadStream(file, { start, end }).pipe(res);
    } else {
      res.writeHead(200, { 'Content-Type': type, 'Accept-Ranges': 'bytes', 'Content-Length': stat.size });
      fs.createReadStream(file).pipe(res);
    }
  });
}).listen(port, () => console.log(`静态服务器(支持 Range): http://localhost:${port}`));