import type { ComponentType, ReactElement } from 'react';
import { renderToReadableStream } from 'react-dom/server';
import { escapeInject, dangerouslySkipEscape } from 'vike/server';
import type { PageContextServer } from 'vike/types';
import { createHomeStore } from '../src/store/homeStore';
import { createRequestScope } from '../src/ssr/scopeTypes';
import { runWithScope } from '../src/ssr/scope';
import { seedFeedData, type FeedData } from '../src/ssr/feedSeed';
import { renderHeadTags } from '../src/ssr/head';
import { installServerDom } from '../src/ssr/serverDom';
import { readThemeFromCookie } from '../src/utils/theme';
import { createSsrApp } from '../src/App';

// 服务端 DOM polyfill：内容处理依赖 DOMParser/document，须在渲染前安装
installServerDom();

export { onRenderHtml };

type PageComponent = ComponentType<{ url?: string }>;

/** 等 lazy 页面全部渲染完成（allReady）后缓冲为完整 HTML，首字节语义与旧 Go 文档级 SSR 一致 */
async function renderPageToString(element: ReactElement): Promise<string> {
  const stream = await renderToReadableStream(element, {
    onError(err) {
      console.error('[j13] SSR 渲染错误:', err);
    },
  });
  await stream.allReady;
  return new Response(stream).text();
}

async function onRenderHtml(pageContext: PageContextServer) {
  const Page = pageContext.Page as PageComponent | undefined;
  const data = (pageContext as { data?: FeedData }).data;

  let pageHtml = '';
  if (Page) {
    // SSR feed 页：per-request 作用域 + hydrate 同构变体；渲染失败降级空壳（客户端自行接管），不 500
    const scope = createRequestScope(createHomeStore());
    scope.hydrating = true;
    const { pathname, searchOriginal } = pageContext.urlParsed;
    const url = pathname + (searchOriginal ?? '');
    try {
      pageHtml = await runWithScope(scope, async () => {
        // 渲染前把 +data 取回的数据 seed 进请求作用域（缓存层按 scope 隔离）
        seedFeedData(data);
        // 官方 SSR 路径：await 首导航后 StaticRouterProvider 同步渲染（避免 RouterProvider suspend
        // 导致内容落入 <div hidden>，禁 JS 爬虫不可见）
        const app = await createSsrApp(url);
        return renderPageToString(app);
      });
    } catch (err) {
      console.error('[j13] SSR 渲染失败，降级 SPA 壳:', err);
      pageHtml = '';
    }
  }

  const headTags = renderHeadTags(data?.head);

  // 主题从请求 Cookie 读取，首帧直接渲染到 <html> 上（深色用户无白屏闪烁，无需内联脚本）
  // headersOriginal 经 Vike 归一化为 pageContext.headers（键全小写）
  const cookieHeader = (pageContext as { headers?: Record<string, string> | null }).headers?.cookie;
  const dark = readThemeFromCookie(cookieHeader) === 'dark';
  const htmlAttrs = dark ? ' class="dark" style="color-scheme:dark"' : '';

  // 404/301 等状态码由 Vike abort 机制（throw render/redirect）原生处理
  return escapeInject`<!DOCTYPE html>
<html lang="zh-CN"${dangerouslySkipEscape(htmlAttrs)}>
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no" />
    ${dangerouslySkipEscape(headTags)}
  </head>
  <body>
    <div id="root">${dangerouslySkipEscape(pageHtml)}</div>
  </body>
</html>`;
}