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/feedData';
import { renderHeadTags } from '../src/ssr/head';
import { installServerDom } from '../src/ssr/serverDom';

// 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 }>;

/** 首帧主题脚本（localStorage j13-theme），与旧 index.html 保持一致 */
const THEME_INIT_SCRIPT
  = "(function(){var t=localStorage.getItem('j13-theme')||'light';document.documentElement.classList.toggle('dark',t==='dark');document.documentElement.style.colorScheme=t;})();";

/** 锁死手机/平板双指与手势缩放；头像裁剪 / 图片灯箱放行 pinch */
const ZOOM_BLOCK_SCRIPT
  = "(function(){function inZoomAllowArea(target){return !!(target&&target.closest&&target.closest('.avatar-crop-stage, .image-lightbox'));}function blockGesture(e){if(inZoomAllowArea(e.target))return;if(e.cancelable)e.preventDefault();}function blockMultiTouch(e){if(e.touches&&e.touches.length>1){if(inZoomAllowArea(e.target))return;if(e.cancelable)e.preventDefault();}}document.addEventListener('gesturestart',blockGesture,{passive:false});document.addEventListener('gesturechange',blockGesture,{passive:false});document.addEventListener('gestureend',blockGesture,{passive:false});document.addEventListener('touchstart',blockMultiTouch,{passive:false});document.addEventListener('touchmove',blockMultiTouch,{passive:false});})();";

/** 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, () => {
        // 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);
        return renderPageToString(<Page url={url} />);
      });
    } catch (err) {
      console.error('[j13] SSR 渲染失败，降级 SPA 壳:', err);
      pageHtml = '';
    }
  }

  const headTags = renderHeadTags(data?.head);

  // 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">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no" />
    ${dangerouslySkipEscape(headTags)}
    <script>${dangerouslySkipEscape(THEME_INIT_SCRIPT)}</script>
    <script>${dangerouslySkipEscape(ZOOM_BLOCK_SCRIPT)}</script>
  </head>
  <body>
    <div id="root">${dangerouslySkipEscape(pageHtml)}</div>
  </body>
</html>`;
}