vercel__workflow/docs/components/geistdocs/code-block.tsx

'use client';

import { CheckIcon, CopyIcon } from 'lucide-react';
import {
  type CSSProperties,
  type ReactNode,
  useCallback,
  useLayoutEffect,
  useRef,
  useState,
} from 'react';
import { toast } from 'sonner';
import { Button } from '@/components/ui/button';
import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card';
import { cn } from '@/lib/utils';

type CodeBlockProps = {
  children: ReactNode;
  className?: string;
  icon?: ReactNode;
  style?: CSSProperties;
  tabIndex?: number;
  title?: string;
  'data-line-numbers'?: string;
  'data-line-highlighting'?: string;
};

export const CodeBlock = ({
  children,
  className,
  icon,
  style,
  tabIndex,
  title,
  ...rest
}: CodeBlockProps) => {
  const ref = useRef<HTMLPreElement>(null);
  const [isCopied, setIsCopied] = useState(false);
  const { 'data-line-numbers': lineNumbers } = rest;

  // Filter out lines marked with `// @setup` using useLayoutEffect
  // useLayoutEffect runs synchronously after DOM mutations but before paint,
  // which minimizes the flash of @setup content
  useLayoutEffect(() => {
    if (!ref.current) return;

    const lines = Array.from(ref.current.querySelectorAll('.line'));

    // First pass: hide @setup lines
    for (const line of lines) {
      if (line.textContent?.includes('// @setup')) {
        (line as HTMLElement).style.display = 'none';
      }
    }

    // Second pass: hide leading empty lines (after @setup lines are hidden)
    for (const line of lines) {
      const htmlLine = line as HTMLElement;
      // Skip already hidden lines
      if (htmlLine.style.display === 'none') continue;
      // If this line is empty (no text content), hide it
      if (!line.textContent?.trim()) {
        htmlLine.style.display = 'none';
      } else {
        // Stop at first non-empty visible line
        break;
      }
    }
  }, [children]);

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

    const code = ref.current?.innerText;

    if (!code) {
      toast.error('No code to copy');
      return;
    }

    try {
      await navigator.clipboard.writeText(code);
      setIsCopied(true);
      setTimeout(() => setIsCopied(false), 2000);
    } catch (error) {
      const message = error instanceof Error ? error.message : 'Unknown error';

      toast.error(message);
    }
  }, []);

  const Icon = isCopied ? CheckIcon : CopyIcon;

  const CodeBlockComponent = useCallback(
    (props: { className?: string }) => (
      <pre
        className={cn(
          'not-prose flex-1 overflow-x-auto rounded-sm border bg-background py-3 text-sm outline-none',
          '[&>code]:grid [&>code]:min-w-max',
          className,
          props.className
        )}
        ref={ref}
        style={style}
        tabIndex={tabIndex}
      >
        {children}
      </pre>
    ),
    [children, style, tabIndex, className]
  );

  if (!title) {
    return (
      <div className="relative mb-6">
        <CodeBlockComponent
          className={cn(lineNumbers ? 'line-numbers' : '', className)}
        />
        <Button
          className="absolute top-[5px] right-[5px] bg-background/80 backdrop-blur-sm"
          onClick={copyToClipboard}
          size="icon"
          variant="ghost"
        >
          <Icon size={14} />
        </Button>
      </div>
    );
  }

  return (
    <Card className="not-prose mb-6 gap-0 overflow-hidden rounded-sm p-0 shadow-none border">
      <CardHeader className="flex items-center gap-2 border-b bg-sidebar py-1.5! pr-1.5 pl-4 text-muted-foreground">
        <div
          className="size-3.5 shrink-0"
          // biome-ignore lint/security/noDangerouslySetInnerHtml: "Required for icon prop."
          dangerouslySetInnerHTML={{ __html: icon as unknown as TrustedHTML }}
        />
        <CardTitle className="flex-1 font-mono font-normal text-sm tracking-tight">
          {title}
        </CardTitle>
        <Button
          className={cn('shrink-0', className)}
          onClick={copyToClipboard}
          size="icon"
          variant="ghost"
        >
          <Icon size={14} />
        </Button>
      </CardHeader>
      <CardContent className="p-0">
        <CodeBlockComponent
          className={cn(
            className,
            'rounded-none border-none',
            lineNumbers ? 'line-numbers' : ''
          )}
        />
      </CardContent>
    </Card>
  );
};