"use client";

import { memo } from "react";
import ReactMarkdown from "react-markdown";
import remarkGfm from "remark-gfm";
import type { Components } from "react-markdown";
import { BookOpen, BrainCircuit, ArrowRight } from "lucide-react";
import { useRouter } from "next/navigation";
import type { Chunk } from "@/lib/types";

const mdComponents: Components = {
  h1: ({ children }) => (
    <h1 className="text-lg font-bold text-primary border-b-2 border-primary/20 pb-2 mb-3 mt-4 first:mt-0">
      {children}
    </h1>
  ),
  h2: ({ children }) => (
    <h2 className="text-base font-bold text-primary/90 border-l-3 border-primary pl-3 mb-2 mt-4">
      {children}
    </h2>
  ),
  h3: ({ children }) => (
    <h3 className="text-sm font-bold text-foreground mb-1.5 mt-3 flex items-center gap-1.5">
      <span className="inline-block w-1.5 h-1.5 rounded-full bg-primary shrink-0" />
      {children}
    </h3>
  ),
  p: ({ children }) => <p className="text-sm leading-7 text-foreground/90 my-2">{children}</p>,
  ul: ({ children }) => <ul className="my-2 ml-1 space-y-1">{children}</ul>,
  ol: ({ children }) => (
    <ol className="my-2 ml-1 space-y-1 list-decimal list-inside">{children}</ol>
  ),
  li: ({ children }) => (
    <li className="text-sm leading-6 text-foreground/90 flex items-start gap-1.5">
      <span className="inline-block w-1 h-1 rounded-full bg-primary/60 mt-2.5 shrink-0" />
      <span className="flex-1">{children}</span>
    </li>
  ),
  blockquote: ({ children }) => (
    <blockquote className="my-3 border-l-3 border-amber-400 bg-amber-50/60 dark:bg-amber-950/20 px-4 py-2 rounded-r-lg text-sm">
      {children}
    </blockquote>
  ),
  table: ({ children }) => (
    <div className="my-3 overflow-x-auto rounded-lg border">
      <table className="w-full text-sm">{children}</table>
    </div>
  ),
  thead: ({ children }) => <thead className="bg-primary/5 border-b">{children}</thead>,
  th: ({ children }) => (
    <th className="px-3 py-2 text-left text-xs font-semibold text-primary/80 uppercase tracking-wider">
      {children}
    </th>
  ),
  td: ({ children }) => <td className="px-3 py-2 text-sm border-b border-muted">{children}</td>,
  hr: () => <hr className="my-4 border-t-2 border-dashed border-primary/10" />,
  strong: ({ children }) => <strong className="font-semibold text-foreground">{children}</strong>,
  em: ({ children }) => <em className="text-primary/80 not-italic font-medium">{children}</em>,
  a: ({ href, children }) => {
    if (href === "#cite-kb") {
      const label = String(children).replace(/^知识库:/, "");
      return (
        <span className="inline-flex items-center gap-1.5 px-2.5 py-1 mx-0.5 text-xs font-semibold rounded bg-blue-100 text-blue-700 border border-blue-300 align-middle hover:bg-blue-200 transition-colors cursor-pointer">
          <BookOpen className="h-3.5 w-3.5 shrink-0" />
          <span>{label}</span>
        </span>
      );
    }
    if (href === "#cite-ai") {
      return (
        <span className="inline-flex items-center gap-1.5 px-2.5 py-1 mx-0.5 text-xs font-semibold rounded bg-orange-100 text-orange-700 border border-orange-300 align-middle whitespace-nowrap hover:bg-orange-200 transition-colors cursor-pointer">
          <BrainCircuit className="h-3.5 w-3.5 shrink-0" />
          <span>AI建议</span>
        </span>
      );
    }
    // 推荐应用：渲染为可点击的应用跳转卡片
    if (href?.startsWith("#cite-app:")) {
      const slug = href.replace("#cite-app:", "");
      const appName = String(children);
      return <AppLinkBadge slug={slug} name={appName} />;
    }
    return (
      <a
        href={href}
        target="_blank"
        rel="noopener noreferrer"
        className="text-primary underline underline-offset-2 hover:text-primary/80"
      >
        {children}
      </a>
    );
  },
  code: ({ className, children }) => {
    const lang = className?.replace("language-", "") || "";
    const isBlock = className?.includes("language-");
    if (isBlock && (lang === "markdown" || lang === "md")) {
      const text = String(children).replace(/\n$/, "");
      return (
        <ReactMarkdown remarkPlugins={[remarkGfm]} components={mdComponents}>
          {text}
        </ReactMarkdown>
      );
    }
    if (isBlock) {
      return (
        <div className="my-3 rounded-lg overflow-hidden border bg-slate-50 dark:bg-slate-900">
          <div className="px-3 py-1.5 bg-slate-100 dark:bg-slate-800 text-xs text-muted-foreground border-b">
            {lang || "代码"}
          </div>
          <pre className="p-3 overflow-x-auto text-xs leading-5">
            <code>{children}</code>
          </pre>
        </div>
      );
    }
    return (
      <code className="text-xs font-mono bg-primary/5 text-primary px-1.5 py-0.5 rounded border border-primary/10">
        {children}
      </code>
    );
  },
  pre: ({ children }) => <>{children}</>,
};

/**
 * 推荐应用跳转徽章组件：点击后跳转到同机构内的其他应用
 */
function AppLinkBadge({ slug, name }: { slug: string; name: string }) {
  const router = useRouter();
  return (
    <button
      type="button"
      onClick={() => router.push(`/chat/${slug}`)}
      className="inline-flex items-center gap-1 px-2.5 py-1 mx-0.5 text-xs font-medium rounded-lg bg-emerald-50 text-emerald-700 border border-emerald-200 align-middle cursor-pointer hover:bg-emerald-100 hover:border-emerald-300 transition-colors whitespace-nowrap"
    >
      <ArrowRight className="h-3 w-3 shrink-0" />
      <span>{name}</span>
    </button>
  );
}

interface GovMarkdownProps {
  content: string;
  className?: string;
  chunks?: Chunk[];
}

function stripOuterCodeFence(text: string): string {
  const trimmed = text.trim();
  const match = trimmed.match(/^```[\w]*\s*\n([\s\S]*?)```\s*$/);
  if (match) return match[1].trim();
  return text;
}

/**
 * 预处理 markdown 内容：将来源标注转为特殊链接格式，由 ReactMarkdown 的 a 组件拦截渲染
 *
 * 支持的标注格式：
 * - [[chunk:N]] → 知识库引用（使用 chunks 映射表解析为文档名）
 * - [[知识库:文档名]] → 知识库引用徽章
 * - [[AI建议]] → AI建议徽章
 * - [[推荐应用:名称:slug]] → 可点击跳转链接
 */
function preprocessCitations(content: string, chunks?: Chunk[]): string {
  let result = content;
  console.log("[preprocessCitations] chunks:", chunks);

  // 先处理 chunk 编号引用 [[chunk:N]]
  result = result.replace(/\[\[chunk:(\d+)\]\]/g, (_, idx) => {
    const i = parseInt(idx, 10);
    if (chunks && chunks[i]) {
      // 使用 chunks 映射表，转换为带文档名的知识库引用
      const docName = chunks[i].doc_name || chunks[i].content?.slice(0, 20) || "知识库片段";
      console.log(`[preprocessCitations] chunk[${i}]:`, docName);
      return `[知识库:${docName}](#cite-kb)`;
    }
    // 无映射时显示后备文本
    console.log(`[preprocessCitations] chunk[${i}] not found, chunks length:`, chunks?.length);
    return `[知识库片段](#cite-kb)`;
  });

  // 知识库引用：[[知识库:文献名称]] 或 [[知识库:文献名称:条款]]
  result = result.replace(/\[\[(知识库:[^\]]+)\]\]/g, (_, label) => `[${label}](#cite-kb)`);

  // AI建议：标准格式 [[AI建议]]
  result = result.replace(/\[\[AI建议\]\]/g, "[AI建议](#cite-ai)");

  // AI建议：来源说明块中的 **AI建议：** 或 **AI建议** 标题（仅匹配行首或 > 后）
  result = result.replace(/^(\s*\>?\s*)\*\*AI建议[：:]\*\*/gm, "$1[AI建议](#cite-ai)");

  // AI建议：无加粗的 AI建议： 标题行（仅匹配行首或 > 后）
  result = result.replace(/^(\s*\>?\s*)AI建议[：:]\s*$/gm, "$1[AI建议](#cite-ai)");

  // 推荐应用：[[推荐应用:应用名称:slug]] → 可点击跳转链接
  result = result.replace(
    /\[\[推荐应用:([^:]+):([^\]]+)\]\]/g,
    (_, name, slug) => `[${name}](#cite-app:${slug})`,
  );

  return result;
}

const GovMarkdown = memo(function GovMarkdown({ content, className, chunks }: GovMarkdownProps) {
  if (!content) {
    return (
      <div className="flex items-center gap-2 text-sm text-muted-foreground py-1">
        <span className="inline-block w-2 h-2 rounded-full bg-primary/60 animate-pulse" />
        正在检索知识库并生成回复...
      </div>
    );
  }
  const cleaned = preprocessCitations(stripOuterCodeFence(content), chunks);
  return (
    <div className={`gov-markdown ${className || ""}`}>
      <ReactMarkdown remarkPlugins={[remarkGfm]} components={mdComponents}>
        {cleaned}
      </ReactMarkdown>
    </div>
  );
});

export default GovMarkdown;