'use client';

import { memo, useMemo } from 'react';
import ReactMarkdown from 'react-markdown';
import remarkGfm from 'remark-gfm';
import { CodeBlock } from './CodeBlock';
import { cn } from '@/lib/utils';

interface MarkdownRendererProps {
  content: string;
  className?: string;
  /** 图片链接点击回调，用于在灯箱中打开图片 */
  onImageLinkClick?: (url: string) => void;
}

/**
 * 判断 URL 是否为图片链接
 */
function isImageUrl(url: string): boolean {
  const imageExtensions = ['.jpg', '.jpeg', '.png', '.gif', '.webp', '.bmp', '.svg', '.ico'];
  const urlLower = url.toLowerCase();
  // 检查扩展名（忽略查询参数）
  const urlWithoutQuery = urlLower.split('?')[0];
  return imageExtensions.some(ext => urlWithoutQuery.endsWith(ext));
}

/**
 * 创建 Markdown 组件配置
 * 使用工厂函数以支持传入回调
 */
function createMarkdownComponents(onImageLinkClick?: (url: string) => void) {
  return {
    // 代码块
    code({ className, children, ...props }: { className?: string; children?: React.ReactNode }) {
      const match = /language-(\w+)/.exec(className || '');
      const isInline = !match && !className;

      if (isInline) {
        // 行内代码 - 无特殊样式，仅等宽字体
        return (
          <code
            className="font-mono"
            {...props}
          >
            {children}
          </code>
        );
      }

      // 代码块
      return (
        <CodeBlock
          code={String(children).replace(/\n$/, '')}
          language={match ? match[1] : 'text'}
        />
      );
    },

    // 段落
    p({ children }: { children?: React.ReactNode }) {
      return (
        <p className="mb-3 last:mb-0 leading-[1.7]">
          {children}
        </p>
      );
    },

    // 标题 - 使用相对单位保持与全局字体的比例
    h1({ children }: { children?: React.ReactNode }) {
      return (
        <h1 className="text-[1.25em] font-bold mt-5 mb-3 text-[var(--color-text-primary)]">
          {children}
        </h1>
      );
    },
    h2({ children }: { children?: React.ReactNode }) {
      return (
        <h2 className="text-[1.125em] font-bold mt-4 mb-2 text-[var(--color-text-primary)]">
          {children}
        </h2>
      );
    },
    h3({ children }: { children?: React.ReactNode }) {
      return (
        <h3 className="text-[1em] font-semibold mt-3 mb-2 text-[var(--color-text-primary)]">
          {children}
        </h3>
      );
    },
    h4({ children }: { children?: React.ReactNode }) {
      return (
        <h4 className="text-[1em] font-semibold mt-2 mb-1 text-[var(--color-text-primary)]">
          {children}
        </h4>
      );
    },

    // 列表
    ul({ children }: { children?: React.ReactNode }) {
      return (
        <ul className="list-disc pl-5 my-2 space-y-1 marker:text-[#E06B3E]">
          {children}
        </ul>
      );
    },
    ol({ children }: { children?: React.ReactNode }) {
      return (
        <ol className="list-decimal pl-5 my-2 space-y-1 marker:text-[#E06B3E]">
          {children}
        </ol>
      );
    },
    li({ children }: { children?: React.ReactNode }) {
      return (
        <li className="leading-relaxed">
          {children}
        </li>
      );
    },

    // 链接 - 支持图片链接在灯箱中打开
    a({ href, children }: { href?: string; children?: React.ReactNode }) {
      // 如果是图片链接且有回调，则拦截点击事件
      if (href && onImageLinkClick && isImageUrl(href)) {
        return (
          <a
            href={href}
            onClick={(e) => {
              e.preventDefault();
              onImageLinkClick(href);
            }}
            className="text-[var(--color-primary)] hover:underline cursor-pointer"
          >
            {children}
          </a>
        );
      }
      // 非图片链接保持原有行为
      return (
        <a
          href={href}
          target="_blank"
          rel="noopener noreferrer"
          className="text-[var(--color-primary)] hover:underline"
        >
          {children}
        </a>
      );
    },

    // 粗体
    strong({ children }: { children?: React.ReactNode }) {
      return (
        <strong className="font-semibold">
          {children}
        </strong>
      );
    },

    // 斜体
    em({ children }: { children?: React.ReactNode }) {
      return (
        <em className="italic">
          {children}
        </em>
      );
    },

    // 引用
    blockquote({ children }: { children?: React.ReactNode }) {
      return (
        <blockquote className="border-l-3 border-[var(--color-primary)] pl-3 my-3 italic text-[var(--color-text-secondary)]">
          {children}
        </blockquote>
      );
    },

    // 分割线
    hr() {
      return (
        <hr className="my-4 border-[var(--color-border)]" />
      );
    },

    // 表格
    table({ children }: { children?: React.ReactNode }) {
      return (
        <div className="overflow-x-auto my-3">
          <table className="min-w-full border border-[var(--color-border)] rounded-lg overflow-hidden text-[0.9em]">
            {children}
          </table>
        </div>
      );
    },
    thead({ children }: { children?: React.ReactNode }) {
      return (
        <thead className="bg-[var(--color-bg-tertiary)]">
          {children}
        </thead>
      );
    },
    tbody({ children }: { children?: React.ReactNode }) {
      return (
        <tbody className="divide-y divide-[var(--color-border)]">
          {children}
        </tbody>
      );
    },
    tr({ children }: { children?: React.ReactNode }) {
      return (
        <tr className="hover:bg-[var(--color-bg-hover)] transition-colors">
          {children}
        </tr>
      );
    },
    th({ children }: { children?: React.ReactNode }) {
      return (
        <th className="px-3 py-1.5 text-left text-[0.85em] font-semibold text-[var(--color-text-primary)]">
          {children}
        </th>
      );
    },
    td({ children }: { children?: React.ReactNode }) {
      return (
        <td className="px-3 py-1.5 text-[0.85em] text-[var(--color-text-secondary)]">
          {children}
        </td>
      );
    },

    // 图片
    img(props: React.ImgHTMLAttributes<HTMLImageElement>) {
      return (
        <img
          {...props}
          alt={props.alt || ''}
          className="max-w-full h-auto rounded-lg my-3"
        />
      );
    },
  };
}

// 使用 memo 包裹组件，避免不必要的重渲染
export const MarkdownRenderer = memo(function MarkdownRenderer({ content, className, onImageLinkClick }: MarkdownRendererProps) {
  // 使用 useMemo 缓存 components 配置，仅在 onImageLinkClick 变化时重新创建
  const components = useMemo(
    () => createMarkdownComponents(onImageLinkClick),
    [onImageLinkClick]
  );

  return (
    <div className={cn('markdown-content', className)}>
      <ReactMarkdown
        remarkPlugins={[remarkGfm]}
        components={components}
      >
        {content}
      </ReactMarkdown>
    </div>
  );
});