/* AI / Claude Code Course - Landing Page hooks */

function useScroll() {
  const [y, setY] = React.useState(0);
  React.useEffect(() => {
    let raf = 0;
    const onScroll = () => {
      cancelAnimationFrame(raf);
      raf = requestAnimationFrame(() => setY(window.scrollY));
    };
    window.addEventListener('scroll', onScroll, { passive: true });
    onScroll();
    return () => { window.removeEventListener('scroll', onScroll); cancelAnimationFrame(raf); };
  }, []);
  return y;
}

function useReveal(threshold = 0.18) {
  const ref = React.useRef(null);
  const [shown, setShown] = React.useState(false);
  React.useEffect(() => {
    if (!ref.current) return;
    const io = new IntersectionObserver(([e]) => { if (e.isIntersecting) setShown(true); }, { threshold });
    io.observe(ref.current);
    return () => io.disconnect();
  }, [threshold]);
  return [ref, shown];
}

/* useSectionProgress - 0..1 across a tall sticky section */
function useSectionProgress(ref) {
  const [p, setP] = React.useState(0);
  React.useEffect(() => {
    let raf = 0;
    const onScroll = () => {
      cancelAnimationFrame(raf);
      raf = requestAnimationFrame(() => {
        if (!ref.current) return;
        const rect = ref.current.getBoundingClientRect();
        const total = ref.current.offsetHeight - window.innerHeight;
        const scrolled = clamp(-rect.top, 0, total);
        setP(total > 0 ? scrolled / total : 0);
      });
    };
    window.addEventListener('scroll', onScroll, { passive: true });
    onScroll();
    return () => { window.removeEventListener('scroll', onScroll); cancelAnimationFrame(raf); };
  }, [ref]);
  return p;
}

const lerp = (a, b, t) => a + (b - a) * t;
const clamp = (v, a, b) => Math.max(a, Math.min(b, v));
const smoothstep = (e0, e1, x) => { const t = clamp((x - e0) / (e1 - e0), 0, 1); return t * t * (3 - 2 * t); };

/* useIsMobile - re-renders when viewport crosses the mobile breakpoint */
function useIsMobile(maxWidth = 767) {
  const [isMobile, setIsMobile] = React.useState(
    () => typeof window !== 'undefined' && window.matchMedia(`(max-width: ${maxWidth}px)`).matches
  );
  React.useEffect(() => {
    const mq = window.matchMedia(`(max-width: ${maxWidth}px)`);
    const onChange = () => setIsMobile(mq.matches);
    mq.addEventListener('change', onChange);
    return () => mq.removeEventListener('change', onChange);
  }, [maxWidth]);
  return isMobile;
}

window.useScroll = useScroll;
window.useReveal = useReveal;
window.useSectionProgress = useSectionProgress;
window.useIsMobile = useIsMobile;
window.lerp = lerp;
window.clamp = clamp;
window.smoothstep = smoothstep;