/**
 * editor-api —— 只做「在线编辑文章」的轻量后端。
 *
 * 设计要点：
 *   · 零 npm 依赖，只用 node 内置模块 —— 镜像小、没有供应链风险、也不用 npm ci
 *   · 所有接口（除 /health）强制 X-Editor-Token，没有令牌一律 401。
 *     前端永远拿不到这个令牌 —— 它只存在于 Cloudflare Worker 的环境变量里，
 *     浏览器只跟 Worker 说话，Worker 鉴权通过后再加上令牌转发过来。
 *   · 端口只绑到宿主机的 127.0.0.1，由 nginx 反代出去，公网扫不到。
 *
 * 环境变量见 README.md。
 */
import http from 'node:http';
import fs from 'node:fs';
import path from 'node:path';
import crypto from 'node:crypto';
import { makePosts } from './src/posts.mjs';
import { makeGit } from './src/git.mjs';

// ------------------------------------------------------------------ 配置

const env = process.env;
const cfg = {
  port: Number(env.PORT || 8017),
  host: env.BIND_HOST || '0.0.0.0',
  token: env.EDITOR_TOKEN || '',
  repoRoot: path.resolve(env.BLOG_ROOT || '/blog'),
  contentDir: path.resolve(env.BLOG_ROOT || '/blog', 'content', 'posts'),
  trashDir: path.resolve(env.TRASH_DIR || '/app/trash'),
  branch: env.GIT_BRANCH || 'main',
  pushRemotes: (env.PUSH_REMOTES || 'origin,gh').split(',').map((s) => s.trim()).filter(Boolean),
  authorName: env.GIT_AUTHOR_NAME || 'blog-editor',
  authorEmail: env.GIT_AUTHOR_EMAIL || 'editor@localhost',
  defaultAuthor: env.DEFAULT_AUTHOR || '',
  maxUpload: Number(env.MAX_UPLOAD_MB || 20) * 1024 * 1024,
  gitPaths: (env.GIT_PATHS || 'content,static').split(',').map((s) => s.trim()).filter(Boolean),
  // 博客对外地址（如 https://usj.cc）。配了才返回绝对链接，列表「预览」按钮才能直接开新窗口。
  blogBase: (env.BLOG_BASE || '').replace(/\/+$/, ''),
};

if (!cfg.token) {
  console.error('[editor-api] 致命：没有设置 EDITOR_TOKEN。拒绝以无鉴权状态启动。');
  process.exit(1);
}

const posts = makePosts(cfg);
const git = makeGit({ ...cfg, repoRoot: cfg.repoRoot, paths: cfg.gitPaths });

// ------------------------------------------------------------------ HTTP 小工具

function json(res, status, data) {
  const body = JSON.stringify(data);
  res.writeHead(status, {
    'Content-Type': 'application/json; charset=utf-8',
    'Cache-Control': 'no-store',
    'Content-Length': Buffer.byteLength(body),
  });
  res.end(body);
}

function readBody(req, limit) {
  return new Promise((resolve, reject) => {
    const chunks = [];
    let size = 0;
    req.on('data', (c) => {
      size += c.length;
      if (size > limit) {
        reject(Object.assign(new Error('请求体超过上限 ' + Math.round(limit / 1048576) + 'MB'), { status: 413 }));
        req.destroy();
        return;
      }
      chunks.push(c);
    });
    req.on('end', () => resolve(Buffer.concat(chunks)));
    req.on('error', reject);
  });
}

async function readJson(req, limit = 2 * 1024 * 1024) {
  const buf = await readBody(req, limit);
  if (!buf.length) return {};
  try {
    return JSON.parse(buf.toString('utf8'));
  } catch {
    throw Object.assign(new Error('请求体不是合法 JSON'), { status: 400 });
  }
}

/** 定长比较，避免令牌被逐字节试探 */
function safeEqual(a, b) {
  const ba = Buffer.from(String(a));
  const bb = Buffer.from(String(b));
  if (ba.length !== bb.length) return false;
  return crypto.timingSafeEqual(ba, bb);
}

const safeName = (s) =>
  String(s || '')
    .replace(/[\\/]/g, '')
    .replace(/[^\w\u4e00-\u9fff.-]+/g, '_')
    .slice(0, 120);

// ------------------------------------------------------------------ 路由

const routes = [];
const route = (method, pattern, handler) => {
  routes.push({ method, segs: pattern.split('/').filter(Boolean), handler });
};

const R = '<param>';

const health = () => ({
  ok: true,
  repo: cfg.repoRoot,
  branch: cfg.branch,
  remotes: cfg.pushRemotes,
  time: new Date().toISOString(),
});

route('GET', '/health', health);

route('GET', '/posts', async ({ query }) => posts.listPosts({
  q: query.get('q') || '',
  page: Number(query.get('page') || 1),
  perPage: Number(query.get('perPage') || 20),
}));

route('POST', '/posts', async ({ req }) => {
  const body = await readJson(req);
  if (!body.frontMatter || !body.frontMatter.title) {
    throw Object.assign(new Error('缺少标题'), { status: 400 });
  }
  return posts.createPost(body);
});

route('GET', `/posts/${R}`, async ({ params }) => {
  const post = posts.getPost(params[0]);
  if (!post) throw Object.assign(new Error('文章不存在'), { status: 404 });
  return post;
});

route('PUT', `/posts/${R}`, async ({ req, params }) => {
  const body = await readJson(req, 4 * 1024 * 1024);
  const out = posts.savePost(params[0], body);
  if (!out) throw Object.assign(new Error('文章不存在'), { status: 404 });
  return { ok: true, ...out };
});

route('DELETE', `/posts/${R}`, async ({ params }) => {
  const out = posts.deletePost(params[0]);
  if (!out) throw Object.assign(new Error('文章不存在'), { status: 404 });
  return { ok: true, ...out };
});

// 图片：直接 POST 原始二进制，文件名走 query —— 不解析 multipart，零依赖也简单
route('POST', '/upload', async ({ req, query }) => {
  const type = req.headers['content-type'] || '';
  if (!type.startsWith('image/')) {
    throw Object.assign(new Error('只接受图片'), { status: 400 });
  }
  const buf = await readBody(req, cfg.maxUpload);
  if (!buf.length) throw Object.assign(new Error('空文件'), { status: 400 });

  const ext = (safeName(query.get('name')).split('.').pop() || 'png').toLowerCase().slice(0, 6);
  const base = Date.now().toString(36) + '-' + crypto.randomBytes(3).toString('hex');
  const fileName = base + '.' + ext;

  const target = posts.imageTargetDir(query.get('key') || '');
  fs.mkdirSync(target.dir, { recursive: true });
  fs.writeFileSync(path.join(target.dir, fileName), buf);

  return {
    ok: true,
    fileName,
    url: target.bare ? fileName : (target.urlPrefix || '/') + fileName,
    size: buf.length,
    dir: path.relative(cfg.repoRoot, target.dir).split(path.sep).join('/'),
  };
});

route('GET', '/git/status', async () => git.status());
route('POST', '/git/publish', async ({ req }) => {
  const body = await readJson(req);
  const out = await git.publish(body.message);
  if (!out.ok) {
    return { ...out, __status: out.conflict ? 409 : 500 };
  }
  return out;
});
route('POST', '/git/sync', async () => {
  const out = await git.sync();
  return out.ok ? out : { ...out, __status: out.conflict ? 409 : 500 };
});

// ------------------------------------------------------------------ 分发

function match(method, pathname) {
  const segs = pathname.split('/').filter(Boolean).map(decodeURIComponent);
  for (const r of routes) {
    if (r.method !== method) continue;
    if (r.segs.length !== segs.length) continue;
    const params = [];
    let ok = true;
    for (let i = 0; i < r.segs.length; i++) {
      if (r.segs[i] === R) params.push(segs[i]);
      else if (r.segs[i] !== segs[i]) {
        ok = false;
        break;
      }
    }
    if (ok) return { handler: r.handler, params };
  }
  return null;
}

const server = http.createServer(async (req, res) => {
  const url = new URL(req.url, 'http://localhost');

  try {
    // /health 免鉴权，供健康检查用；其余一律先验令牌
    if (url.pathname === '/health' && req.method === 'GET') {
      json(res, 200, health());
      return;
    }

    if (!safeEqual(req.headers['x-editor-token'] || '', cfg.token)) {
      json(res, 401, { error: '未授权' });
      return;
    }

    const hit = match(req.method, url.pathname);
    if (!hit) {
      json(res, 404, { error: 'Not Found: ' + req.method + ' ' + url.pathname });
      return;
    }

    const data = await hit.handler({ req, url, query: url.searchParams, params: hit.params });
    const status = data && data.__status ? data.__status : 200;
    if (data && data.__status) delete data.__status;
    json(res, status, data);
  } catch (e) {
    const status = e.status || 500;
    if (status >= 500) console.error('[editor-api]', req.method, url.pathname, e);
    json(res, status, { error: e.message || '服务端错误' });
  }
});

server.headersTimeout = 30_000;
server.requestTimeout = 120_000;

server.listen(cfg.port, cfg.host, () => {
  console.log('[editor-api] 已启动 http://' + cfg.host + ':' + cfg.port);
  console.log('[editor-api] 仓库     ' + cfg.repoRoot);
  console.log('[editor-api] 分支     ' + cfg.branch + '   推送远端 ' + cfg.pushRemotes.join(', '));
  console.log('[editor-api] 回收目录 ' + cfg.trashDir);
});