IA 迁移与别名策略

# 由 CI 把 redirects.json 转成 map（jq -r '.redirects[] | "\(.from) \(.to);"'）
map $uri $im_alias_target {
  include /etc/nginx/im-aliases.map;
}

server {
  listen 443 ssl;
  location /docs/ {
    if ($im_alias_target) { return 301 $im_alias_target; }
    try_files $uri $uri/index.html $uri.html =404;
  }
}

// 最小静态服务器（Node）：先查别名，再回落到文件
import { readFileSync, existsSync, statSync } from 'node:fs';
import { join, extname } from 'node:path';
import { createServer } from 'node:http';

const root = 'docs-site';
const { redirects } = JSON.parse(readFileSync(join(root, 'redirects.json'), 'utf8'));
const alias = new Map(redirects.map((entry) => [entry.from, entry.to]));

createServer((req, res) => {
  const path = decodeURIComponent(new URL(req.url, 'http://x').pathname);
  if (alias.has(path)) {
    res.writeHead(301, { location: alias.get(path) });
    res.end();
    return;
  }
  const rel = path.replace(/^\/docs\/?/, '');
  const candidates = [join(root, rel), join(root, rel, 'index.html'), extname(rel) ? null : join(root, rel + '.html')].filter(Boolean);
  const file = candidates.find((candidate) => existsSync(candidate) && statSync(candidate).isFile());
  if (!file) { res.writeHead(404).end('not found'); return; }
  res.writeHead(200, { 'content-type': 'text/html; charset=utf-8' });
  res.end(readFileSync(file));
}).listen(8080);