// Shared hooks
const { useState, useEffect, useRef, useCallback, useMemo } = React;

// Reveal on scroll via IntersectionObserver
function useReveal(options = {}) {
  const ref = useRef(null);
  const [visible, setVisible] = useState(false);
  useEffect(() => {
    if (!ref.current) return;
    const io = new IntersectionObserver(
      (entries) => {
        entries.forEach((e) => {
          if (e.isIntersecting) {
            setVisible(true);
            io.unobserve(e.target);
          }
        });
      },
      { threshold: 0.15, rootMargin: "0px 0px -60px 0px", ...options }
    );
    io.observe(ref.current);
    return () => io.disconnect();
  }, []);
  return [ref, visible];
}

// Count-up a number to a target over `duration` ms, starting when `active` is true.
function useCountUp(target, duration = 2200, active = true) {
  const [val, setVal] = useState(0);
  useEffect(() => {
    if (!active) return;
    let raf;
    const start = performance.now();
    const tick = (now) => {
      const t = Math.min(1, (now - start) / duration);
      // ease-out cubic
      const e = 1 - Math.pow(1 - t, 3);
      setVal(target * e);
      if (t < 1) raf = requestAnimationFrame(tick);
    };
    raf = requestAnimationFrame(tick);
    return () => cancelAnimationFrame(raf);
  }, [target, duration, active]);
  return val;
}

// Scroll progress 0..1 for the whole document
function useScrollProgress() {
  const [p, setP] = useState(0);
  useEffect(() => {
    const handler = () => {
      const h = document.documentElement;
      const max = h.scrollHeight - h.clientHeight;
      setP(max > 0 ? h.scrollTop / max : 0);
    };
    handler();
    window.addEventListener("scroll", handler, { passive: true });
    window.addEventListener("resize", handler);
    return () => {
      window.removeEventListener("scroll", handler);
      window.removeEventListener("resize", handler);
    };
  }, []);
  return p;
}

// Format helpers
function msToClock(ms) {
  const totalSec = Math.floor(ms / 1000);
  const h = Math.floor(totalSec / 3600);
  const m = Math.floor((totalSec % 3600) / 60);
  const s = totalSec % 60;
  const cs = Math.floor((ms % 1000) / 10);
  const pad = (n, w = 2) => String(n).padStart(w, "0");
  return `${pad(h)}:${pad(m)}:${pad(s)}.${pad(cs)}`;
}

Object.assign(window, { useReveal, useCountUp, useScrollProgress, msToClock });