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

/**
 * 요소가 뷰포트에 진입하면 inView = true 로 바뀌는 훅.
 * framer-motion의 whileInView({ once: true }) 와 동일한 동작.
 */
export function useInView<T extends HTMLElement = HTMLElement>(
  options?: IntersectionObserverInit,
) {
  const ref = useRef<T>(null);
  const [inView, setInView] = useState(false);

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

    const observer = new IntersectionObserver(
      ([entry]) => {
        if (entry.isIntersecting) {
          setInView(true);
          observer.disconnect(); // once: true
        }
      },
      { threshold: 0.15, ...options },
    );

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

  return { ref, inView };
}