src/components/ai-elements/code-block.tsx

import { Button } from '@/components/ui/button';
import { cn } from '@/lib/utils';
import { CheckIcon, CopyIcon } from 'lucide-react';
import {
  type ComponentProps,
  createContext,
  type HTMLAttributes,
  useContext,
  useEffect,
  useRef,
  useState,
} from 'react';
import { type BundledLanguage, codeToHtml, type ShikiTransformer } from 'shiki';

type CodeBlockProps = HTMLAttributes<HTMLDivElement> & {
  code: string;
  language: BundledLanguage;
  showLineNumbers?: boolean;
};

type CodeBlockContextType = {
  code: string;
};

const CodeBlockContext = createContext<CodeBlockContextType>({
  code: '',
});

const lineNumberTransformer: ShikiTransformer = {
  name: 'line-numbers',
  line(node, line) {
    node.children.unshift({
      type: 'element',
      tagName: 'span',
      properties: {
        className: [
          'inline-block',
          'min-w-10',
          'mr-4',
          'text-right',
          'select-none',
          'text-muted-foreground',
        ],
      },
      children: [{ type: 'text', value: String(line) }],
    });
  },
};

export async function highlightCode(
  code: string,
  language: BundledLanguage,
  showLineNumbers = false,
) {
  const transformers: ShikiTransformer[] = showLineNumbers ? [lineNumberTransformer] : [];

  return await Promise.all([
    codeToHtml(code, {
      lang: language,
      theme: 'one-light',
      transformers,
    }),
    codeToHtml(code, {
      lang: language,
      theme: 'one-dark-pro',
      transformers,
    }),
  ]);
}

export const CodeBlock = ({
  code,
  language,
  showLineNumbers = false,
  className,
  children,
  ...props
}: CodeBlockProps) => {
  const [html, setHtml] = useState<string>('');
  const [darkHtml, setDarkHtml] = useState<string>('');
  const mounted = useRef(false);

  useEffect(() => {
    highlightCode(code, language, showLineNumbers).then(([light, dark]) => {
      if (!mounted.current) {
        setHtml(light);
        setDarkHtml(dark);
        mounted.current = true;
      }
    });

    return () => {
      mounted.current = false;
    };
  }, [code, language, showLineNumbers]);

  return (
    <CodeBlockContext.Provider value={{ code }}>
      <div
        className={cn(
          'group relative w-full overflow-hidden rounded-md border bg-background text-foreground',
          className,
        )}
        {...props}
      >
        <div className="relative">
          <div
            className="overflow-auto dark:hidden [&>pre]:m-0 [&>pre]:bg-background! [&>pre]:p-4 [&>pre]:text-foreground! [&>pre]:text-sm [&_code]:font-mono [&_code]:text-sm"
            // biome-ignore lint/security/noDangerouslySetInnerHtml: "this is needed."
            dangerouslySetInnerHTML={{ __html: html }}
          />
          <div
            className="hidden overflow-auto dark:block [&>pre]:m-0 [&>pre]:bg-background! [&>pre]:p-4 [&>pre]:text-foreground! [&>pre]:text-sm [&_code]:font-mono [&_code]:text-sm"
            // biome-ignore lint/security/noDangerouslySetInnerHtml: "this is needed."
            dangerouslySetInnerHTML={{ __html: darkHtml }}
          />
          {children && (
            <div className="absolute top-2 right-2 flex items-center gap-2">{children}</div>
          )}
        </div>
      </div>
    </CodeBlockContext.Provider>
  );
};

export type CodeBlockCopyButtonProps = ComponentProps<typeof Button> & {
  onCopy?: () => void;
  onError?: (error: Error) => void;
  timeout?: number;
};

export const CodeBlockCopyButton = ({
  onCopy,
  onError,
  timeout = 2000,
  children,
  className,
  ...props
}: CodeBlockCopyButtonProps) => {
  const [isCopied, setIsCopied] = useState(false);
  const { code } = useContext(CodeBlockContext);

  const copyToClipboard = async () => {
    if (typeof window === 'undefined' || !navigator?.clipboard?.writeText) {
      onError?.(new Error('Clipboard API not available'));
      return;
    }

    try {
      await navigator.clipboard.writeText(code);
      setIsCopied(true);
      onCopy?.();
      setTimeout(() => setIsCopied(false), timeout);
    } catch (error) {
      onError?.(error as Error);
    }
  };

  const Icon = isCopied ? CheckIcon : CopyIcon;

  return (
    <Button
      className={cn('shrink-0', className)}
      onClick={copyToClipboard}
      size="icon"
      variant="ghost"
      {...props}
    >
      {children ?? <Icon size={14} />}
    </Button>
  );
};