agentlens/apps/web/src/components/animate-on-scroll.tsx

"use client";

import { useEffect, useRef, ReactNode } from "react";

interface AnimateOnScrollProps {
  children: ReactNode;
  className?: string;
  delay?: number;
  threshold?: number;
}

export function AnimateOnScroll({
  children,
  className = "",
  delay = 0,
  threshold = 0.15,
}: AnimateOnScrollProps) {
  const ref = useRef<HTMLDivElement>(null);

  useEffect(() => {
    const el = ref.current;
    if (!el) return;

    const prefersReduced = window.matchMedia(
      "(prefers-reduced-motion: reduce)"
    ).matches;

    if (prefersReduced) {
      el.setAttribute("data-animate", "visible");
      return;
    }

    const observer = new IntersectionObserver(
      (entries) => {
        for (const entry of entries) {
          if (entry.isIntersecting) {
            entry.target.setAttribute("data-animate", "visible");
            observer.unobserve(entry.target);
          }
        }
      },
      { threshold }
    );

    observer.observe(el);

    return () => observer.disconnect();
  }, [threshold]);

  return (
    <div
      ref={ref}
      data-animate="hidden"
      className={className}
      style={{ animationDelay: delay ? `${delay}ms` : undefined }}
    >
      {children}
    </div>
  );
}