'use client';

import { useEffect, useRef, useState } from 'react';

function cx(...args) {
  return args.filter(Boolean).join(' ');
}

export default function Reveal({ children, className, delay }) {
  const ref = useRef(null);
  const [visible, setVisible] = useState(false);

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

    let reduced = false;
    try {
      reduced = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
    } catch (e) {
      // matchMedia unavailable - fall back to animating
    }
    if (reduced) {
      setVisible(true);
      return undefined;
    }

    const observer = new IntersectionObserver(
      (entries) => {
        entries.forEach((entry) => {
          if (entry.isIntersecting) {
            setVisible(true);
            observer.disconnect();
          }
        });
      },
      { threshold: 0.15 }
    );
    observer.observe(node);
    return () => observer.disconnect();
  }, []);

  return (
    <div
      ref={ref}
      style={delay ? { transitionDelay: `${delay}ms` } : undefined}
      className={cx(
        className,
        'transition-all duration-700 ease-out',
        visible ? 'opacity-100 translate-y-0' : 'opacity-0 translate-y-6'
      )}
    >
      {children}
    </div>
  );
}