import { useEffect, useState } from 'react';
import type { Variants } from 'framer-motion';

// EaseOutExpo — smooth editorial deceleration
export const easeOutExpo = [0.22, 1, 0.36, 1] as const;

export const fadeInUp: Variants = {
  hidden: { opacity: 0, y: 20 },
  visible: { opacity: 1, y: 0, transition: { duration: 0.5, ease: easeOutExpo } },
};

export const fadeIn: Variants = {
  hidden: { opacity: 0 },
  visible: { opacity: 1, transition: { duration: 0.4, ease: easeOutExpo } },
};

export const staggerContainer: Variants = {
  hidden: {},
  visible: { transition: { staggerChildren: 0.1 } },
};

export const viewportOnce = { once: true, amount: 0.3 } as const;

// Hook: returns true if user prefers reduced motion. Components use this to
// disable Framer Motion animations (per spec, a11y requirement).
export function usePrefersReducedMotion() {
  const [reduced, setReduced] = useState(false);
  useEffect(() => {
    const mq = window.matchMedia('(prefers-reduced-motion: reduce)');
    setReduced(mq.matches);
    const handler = () => setReduced(mq.matches);
    mq.addEventListener('change', handler);
    return () => mq.removeEventListener('change', handler);
  }, []);
  return reduced;
}

// Pass to <motion.*> as motion-reduced guard. When reduced, variants resolve to visible immediately.
export const motionProps = (reduced: boolean) =>
  reduced
    ? { initial: 'visible' as const, animate: 'visible' as const, whileInView: undefined, viewport: undefined }
    : {};