"use client";

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

/** Fades content up when it scrolls into view (IntersectionObserver). */
export function Reveal({
  children,
  delay = 0,
  className = "",
}: {
  children: ReactNode;
  delay?: number;
  className?: string;
}) {
  const ref = useRef<HTMLDivElement>(null);
  const [visible, setVisible] = useState(false);

  useEffect(() => {
    const el = ref.current;
    if (!el) return;
    if (typeof IntersectionObserver === "undefined") {
      requestAnimationFrame(() => setVisible(true));
      return;
    }
    const observer = new IntersectionObserver(
      (entries) => {
        for (const entry of entries) {
          if (entry.isIntersecting) {
            setVisible(true);
            observer.disconnect();
          }
        }
      },
      { threshold: 0.12, rootMargin: "0px 0px -40px 0px" },
    );
    observer.observe(el);
    return () => observer.disconnect();
  }, []);

  return (
    <div
      ref={ref}
      className={`reveal ${visible ? "is-visible" : ""} ${className}`}
      style={{ ["--reveal-delay" as string]: `${delay}ms` }}
    >
      {children}
    </div>
  );
}