/**
 * SEO/GEO 构建期钩子（仅 Node 构建时运行，不进客户端 bundle）：
 *   - transformPageData：每页独立 title（去编号前缀）与 description（取 :::tip 首句）
 *   - transformHead：canonical / Open Graph / twitter 卡片 / JSON-LD 结构化数据
 *   - sitemap.transformItems：注入 lastmod（git 最后提交时间）并过滤 404
 *
 * 由 config/index.ts 通过 createSeoHooks(zhConfig.themeConfig?.sidebar) 挂载。
 * 依赖 extract.mjs（纯 ESM，同被 scripts/generate-llms-txt.mjs 复用）。
 */
import fs from "node:fs";
import path from "node:path";
import { execSync } from "node:child_process";
import {
  SITE_URL,
  extractDescription,
  extractFaqs,
  stripNumberPrefix,
} from "./extract.mjs";

/** 与 vitepress HeadConfig 同构：[tag, attrs, innerHTML?] */
type HeadTuple = [string, Record<string, any>, string?];

interface SideItem {
  text?: string;
  link?: string;
  items?: SideItem[];
}

interface PageDataLike {
  relativePath?: string;
  title?: string;
  description?: string;
  frontmatter?: Record<string, any>;
  [k: string]: any;
}

interface TransformCtx {
  pageData?: PageDataLike;
  title?: string;
  description?: string;
  content?: string;
  siteConfig?: { root?: string; srcDir?: string };
}

const ORG = {
  "@type": "Organization",
  name: "RXThinkCMF",
  url: "https://www.rxthink.cn",
  logo: `${SITE_URL}/logo.png`,
  sameAs: [
    "https://gitee.com/rxthinkcmf/RXThinkCMF_Laravel13_AntdVue",
    "https://www.rxthink.cn",
  ],
};

/** 相对路径 → 站内路由（cleanUrls 关闭，正文页带 .html） */
function routeOf(relativePath: string): string {
  if (relativePath === "index.md") return "/";
  if (relativePath === "404.md") return "/404.html";
  return `/${relativePath.replace(/\.md$/, ".html")}`;
}

/** 去掉侧边栏文案前导 emoji/符号，保留 "1.1 项目介绍" 这类编号文字 */
function cleanLabel(s?: string): string {
  return (s || "").replace(/^[^\p{L}\p{N}]+/u, "").trim();
}

/** 从侧边栏构建 route → 面包屑文案链（含分组小节） */
function buildCrumbMap(sidebar: unknown): Map<string, string[]> {
  const map = new Map<string, string[]>();
  const groups: SideItem[] = Array.isArray(sidebar)
    ? sidebar
    : ((sidebar as Record<string, SideItem[]>)?.["/zh/"] ?? []);
  const walk = (items: SideItem[], trail: string[]) => {
    for (const item of items) {
      if (item.link && item.link.startsWith("/")) {
        map.set(item.link, [...trail, cleanLabel(item.text)]);
      } else if (item.items?.length) {
        walk(item.items, [...trail, cleanLabel(item.text)]);
      }
    }
  };
  for (const group of groups) {
    walk(group.items ?? [], [cleanLabel(group.text)].filter(Boolean));
  }
  return map;
}

/** 从渲染后的 HTML 提取 H1 纯文本（JSON-LD headline 须与页面 H1 一致） */
function h1OfHtml(html?: string): string {
  const m = (html || "").match(/<h1[^>]*>([\s\S]*?)<\/h1>/i);
  if (!m) return "";
  return m[1]
    .replace(/<[^>]+>/g, "")
    .replace(/&amp;/g, "&")
    .replace(/&lt;/g, "<")
    .replace(/&gt;/g, ">")
    .replace(/&quot;/g, '"')
    .replace(/&#39;/g, "'")
    .trim();
}

/** 从 Markdown 源提取 H1 纯文本（去除行内 markdown 标记） */
function h1OfMd(md: string): string {
  const m = md.match(/^# (?!#)(.+)$/m);
  if (!m) return "";
  return m[1]
    .replace(/`([^`]+)`/g, "$1")
    .replace(/\*\*([^*]+)\*\*/g, "$1")
    .trim();
}

export function createSeoHooks(sidebar: unknown) {
  const crumbs = buildCrumbMap(sidebar);
  const projectDirs: string[] = [];
  let gitDates: Map<string, string> | null = null;

  const readMd = (relativePath: string, srcDir?: string): string => {
    try {
      return fs.readFileSync(
        path.resolve(srcDir || process.cwd(), relativePath),
        "utf8",
      );
    } catch {
      return "";
    }
  };

  /**
   * 项目内每个文件最后一次 git 提交的 ISO 时间。
   * 单次 git log 调用构建全量映射（key = 相对路径，与 pageData.relativePath 一致）；
   * git 不可用时静默降级（sitemap 无 lastmod、JSON-LD 无 dateModified）。
   */
  const getGitDates = (root: string): Map<string, string> => {
    if (gitDates) return gitDates;
    gitDates = new Map<string, string>();
    try {
      const out = execSync(
        "git log --format=:::%cI --name-only --relative -n 500 -- .",
        {
          cwd: root,
          encoding: "utf8",
          maxBuffer: 64 * 1024 * 1024,
          stdio: ["ignore", "pipe", "ignore"],
        },
      );
      let current = "";
      for (const line of out.split(/\r?\n/)) {
        if (line.startsWith(":::")) {
          current = line.slice(3).trim();
          continue;
        }
        const file = line.trim();
        if (file && current && !gitDates.has(file)) {
          gitDates.set(file, current);
        }
      }
    } catch {
      // 降级：无 lastmod / dateModified
    }
    return gitDates;
  };

  /** 每页独立 title（去 "5.10 " 编号前缀，关键词前置）与 description（:::tip 首句） */
  function transformPageData(pageData: PageDataLike, ctx?: any): Record<string, unknown> {
    const srcDir: string | undefined = ctx?.siteConfig?.srcDir;
    const root: string | undefined = ctx?.siteConfig?.root;
    if (root && !projectDirs.includes(root)) projectDirs.push(root);

    const out: Record<string, unknown> = {};
    const rel = pageData.relativePath;
    if (rel && !pageData.frontmatter?.description) {
      const desc = extractDescription(readMd(rel, srcDir));
      if (desc) out.description = desc;
    }
    if (pageData.title) {
      out.title = stripNumberPrefix(pageData.title);
    }
    return out;
  }

  /** 构建期注入 canonical / OG / twitter / JSON-LD */
  function transformHead(ctx: TransformCtx): HeadTuple[] {
    const rel = ctx?.pageData?.relativePath || "";
    if (!rel || rel === "404.md") return [];

    const route = routeOf(rel);
    const url = `${SITE_URL}${route}`;
    const title = ctx.pageData?.title || ctx.title || "";
    const desc = ctx.description || "";
    const isHome = rel === "index.md";
    const image = `${SITE_URL}/logo.png`;

    const heads: HeadTuple[] = [
      ["link", { rel: "canonical", href: url }],
      ["meta", { property: "og:type", content: isHome ? "website" : "article" }],
      ["meta", { property: "og:site_name", content: "RXThinkCMF" }],
      ["meta", { property: "og:locale", content: "zh_CN" }],
      ["meta", { property: "og:title", content: title }],
      ["meta", { property: "og:description", content: desc }],
      ["meta", { property: "og:url", content: url }],
      ["meta", { property: "og:image", content: image }],
      ["meta", { property: "twitter:title", content: title }],
      ["meta", { property: "twitter:description", content: desc }],
      ["meta", { property: "twitter:url", content: url }],
      ["meta", { property: "twitter:image", content: image }],
    ];

    // ---- JSON-LD ----
    const root = ctx.siteConfig?.root || projectDirs[0] || process.cwd();
    const srcDir = ctx.siteConfig?.srcDir || root;
    const lastMod = getGitDates(root).get(rel);
    const blocks: Record<string, any>[] = [];

    if (isHome) {
      blocks.push({
        "@context": "https://schema.org",
        "@type": "WebSite",
        name: "RXThinkCMF 开发文档",
        url: `${SITE_URL}/`,
        inLanguage: "zh-CN",
        description: desc,
      });
      blocks.push({ "@context": "https://schema.org", ...ORG });
    } else {
      const md = readMd(rel, srcDir);
      const article: Record<string, any> = {
        "@context": "https://schema.org",
        "@type": "TechArticle",
        headline: h1OfMd(md) || h1OfHtml(ctx.content) || title,
        description: desc,
        url,
        inLanguage: "zh-CN",
        mainEntityOfPage: { "@type": "WebPage", "@id": url },
        publisher: ORG,
      };
      if (lastMod) article.dateModified = lastMod;
      blocks.push(article);

      const trail = crumbs.get(route);
      if (trail?.length) {
        const items: Record<string, any>[] = [
          { "@type": "ListItem", position: 1, name: "首页", item: `${SITE_URL}/` },
        ];
        trail.forEach((name, i) => {
          const node: Record<string, any> = {
            "@type": "ListItem",
            position: i + 2,
            name,
          };
          if (i === trail.length - 1) node.item = url;
          items.push(node);
        });
        blocks.push({
          "@context": "https://schema.org",
          "@type": "BreadcrumbList",
          itemListElement: items,
        });
      }

      const faqs = extractFaqs(md);
      if (faqs.length) {
        blocks.push({
          "@context": "https://schema.org",
          "@type": "FAQPage",
          mainEntity: faqs.map((f) => ({
            "@type": "Question",
            name: f.q,
            acceptedAnswer: { "@type": "Answer", text: f.a },
          })),
        });
      }
    }

    // 转义 "<"，防止内容中出现 </script> 破坏注入
    const json = JSON.stringify(blocks).replace(/</g, "\\u003c");
    heads.push(["script", { type: "application/ld+json" }, json]);
    return heads;
  }

  /** sitemap.xml：过滤 404/README，注入 git lastmod */
  const sitemap = {
    hostname: SITE_URL,
    transformItems(items: { url: string; lastmod?: string }[]) {
      const root = projectDirs[0] || process.cwd();
      const dates = getGitDates(root);
      const out: { url: string; lastmod?: string }[] = [];
      for (const item of items) {
        // ⚠ vitepress 传入的 item.url 是相对路径（"404.html"、"zh/x.html"、""），
        //   无前导斜杠也无域名——hostname 由 SitemapStream 事后拼接。
        if (/(^|\/)404\.html$/.test(item.url)) continue;   // 404 页不收录
        if (/(^|\/)README\.html$/.test(item.url)) continue; // 仓库 README 非文档页
        const p = item.url.replace(/^\//, "");
        const rel =
          p === "" || p === "index.html" ? "index.md" : p.replace(/\.html$/, ".md");
        const lastmod = dates.get(rel);
        out.push(lastmod ? { ...item, lastmod } : item);
      }
      return out;
    },
  };

  return { transformPageData, transformHead, sitemap };
}