/* NIA — shared scroll & motion hooks */

const { useState, useEffect, useRef } = React;

/* Reveal on scroll — adds .is-revealed class */
function useReveal(threshold = 0.12) {
  const ref = useRef();
  useEffect(() => {
    const el = ref.current; if (!el) return;
    const io = new IntersectionObserver((entries) => {
      entries.forEach(e => { if (e.isIntersecting) el.classList.add("is-revealed"); });
    }, { threshold, rootMargin: "0px 0px -10% 0px" });
    io.observe(el);
    return () => io.disconnect();
  }, [threshold]);
  return ref;
}
window.useReveal = useReveal;

/* Parallax — returns ref + y offset */
function useParallax(speed = 0.2) {
  const ref = useRef();
  const [y, setY] = useState(0);
  useEffect(() => {
    let raf;
    const onScroll = () => {
      cancelAnimationFrame(raf);
      raf = requestAnimationFrame(() => {
        const el = ref.current; if (!el) return;
        const r = el.getBoundingClientRect();
        const center = r.top + r.height / 2 - window.innerHeight / 2;
        setY(-center * speed);
      });
    };
    window.addEventListener("scroll", onScroll, { passive: true });
    onScroll();
    return () => { window.removeEventListener("scroll", onScroll); cancelAnimationFrame(raf); };
  }, [speed]);
  return [ref, y];
}
window.useParallax = useParallax;

/* Count-up when element enters viewport */
function useCountUp(end, duration = 1600) {
  const [val, setVal] = useState(0);
  const ref = useRef();
  const started = useRef(false);
  useEffect(() => {
    const el = ref.current; if (!el) return;
    const io = new IntersectionObserver((entries) => {
      entries.forEach(e => {
        if (e.isIntersecting && !started.current) {
          started.current = true;
          const t0 = performance.now();
          const tick = (now) => {
            const p = Math.min(1, (now - t0) / duration);
            const eased = 1 - Math.pow(1 - p, 3);
            setVal(end * eased);
            if (p < 1) requestAnimationFrame(tick);
          };
          requestAnimationFrame(tick);
        }
      });
    }, { threshold: 0.4 });
    io.observe(el);
    return () => io.disconnect();
  }, [end, duration]);
  return [ref, val];
}
window.useCountUp = useCountUp;

/* Scroll progress 0..1 over page */
function useScrollProgress() {
  const [p, setP] = useState(0);
  useEffect(() => {
    const on = () => {
      const h = document.documentElement.scrollHeight - window.innerHeight;
      setP(h > 0 ? window.scrollY / h : 0);
    };
    window.addEventListener("scroll", on, { passive: true });
    on();
    return () => window.removeEventListener("scroll", on);
  }, []);
  return p;
}
window.useScrollProgress = useScrollProgress;

/* Section-relative scroll progress 0..1 */
function useSectionProgress(ref) {
  const [p, setP] = useState(0);
  useEffect(() => {
    const on = () => {
      const el = ref.current; if (!el) return;
      const r = el.getBoundingClientRect();
      const total = r.height + window.innerHeight;
      const pos = window.innerHeight - r.top;
      setP(Math.max(0, Math.min(1, pos / total)));
    };
    window.addEventListener("scroll", on, { passive: true });
    on();
    return () => window.removeEventListener("scroll", on);
  }, [ref]);
  return p;
}
window.useSectionProgress = useSectionProgress;

/* Mouse position normalized -1..1 */
function useMouse() {
  const [m, setM] = useState({ x: 0, y: 0 });
  useEffect(() => {
    const on = (e) => setM({
      x: (e.clientX / window.innerWidth - 0.5) * 2,
      y: (e.clientY / window.innerHeight - 0.5) * 2,
    });
    window.addEventListener("mousemove", on);
    return () => window.removeEventListener("mousemove", on);
  }, []);
  return m;
}
window.useMouse = useMouse;