Umlaufbahn

'use client';

import { useEffect, useRef } from 'react';
import { cn, prefersReducedMotion, round } from '@/lib/kit';

export interface OrbitRing {
  /** Icons, logos or avatars, spread evenly around the ring */
  items: React.ReactNode[];
  /** Ring radius in % of the orbit size, 0 to 50 */
  radius: number;
  /** Seconds for one full turn, default 40 */
  duration?: number;
  /** Turn counterclockwise */
  reverse?: boolean;
  /** Start angle of the first item in degrees, default -90 (top) */
  offset?: number;
}

export interface OrbitProps {
  rings: OrbitRing[];
  /** What sits in the middle, e.g. your app mark */
  center?: React.ReactNode;
  /** Largest size in px, the orbit shrinks with its container below that. Default 520 */
  size?: number;
  /** Draw the rings as hairlines, default true */
  showRings?: boolean;
  /** Dashed rings instead of solid */
  dashed?: boolean;
  /** Degrees the rings turn on top of their run over a full scroll pass, items stay upright. Default 0 (off), 60 reads well. */
  scrollTurn?: number;
  /** Read out to screen readers, e.g. "Connects with 12 tools". Without it the orbit is decorative. */
  label?: string;
  className?: string;
}

const CSS = `
@keyframes kitfx-orbit-spin { to { transform: rotate(360deg); } }
.kitfx-orbit * { animation-play-state: var(--kitfx-play, running); }
.kitfx-orbit-turn { rotate: calc((var(--kitfx-p, 0.5) - 0.5) * var(--kitfx-turn)); transition: rotate .3s linear; }
.kitfx-orbit-upright { rotate: calc((var(--kitfx-p, 0.5) - 0.5) * var(--kitfx-turn) * -1); transition: rotate .3s linear; }
@media (prefers-reduced-motion: reduce) { .kitfx-orbit * { animation: none !important; } .kitfx-orbit-turn, .kitfx-orbit-upright { rotate: none; } }
`;

/**
 * Items circling a center on one or more rings. Items stay upright while
 * their ring turns. Each item wrapper carries data-orbit-item, e.g. to hide
 * the items on phones with max-sm:[&_[data-orbit-item]]:hidden. Square, responsive up to `size`. Pauses out of view and
 * stands still with reduced motion.
 */
export function Orbit({ rings, center, size = 520, showRings = true, dashed, scrollTurn = 0, label, className }: OrbitProps) {
  const ref = useRef<HTMLDivElement>(null);
  useEffect(() => {
    const el = ref.current;
    if (!el || typeof IntersectionObserver === 'undefined') return;
    const io = new IntersectionObserver(([e]) => el.style.setProperty('--kitfx-play', e.isIntersecting ? 'running' : 'paused'));
    io.observe(el);
    return () => io.disconnect();
  }, []);
  // Scroll pass: 0 when the orbit enters at the bottom, 1 when it leaves at the top
  useEffect(() => {
    const el = ref.current;
    if (!el || !scrollTurn || prefersReducedMotion()) return;
    let frame = 0;
    const update = () => {
      frame = 0;
      const r = el.getBoundingClientRect();
      el.style.setProperty('--kitfx-p', Math.min(1, Math.max(0, (window.innerHeight - r.top) / (r.height + window.innerHeight))).toFixed(4));
    };
    const onScroll = () => {
      if (!frame) frame = requestAnimationFrame(update);
    };
    update();
    window.addEventListener('scroll', onScroll, { passive: true });
    return () => {
      cancelAnimationFrame(frame);
      window.removeEventListener('scroll', onScroll);
    };
  }, [scrollTurn]);

  return (
    <div
      ref={ref}
      {...(label ? { role: 'img', 'aria-label': label } : { 'aria-hidden': true })}
      className={cn('kitfx-orbit relative mx-auto aspect-square w-full', className)}
      style={{ maxWidth: size, ...(scrollTurn ? { ['--kitfx-turn' as string]: `${scrollTurn}deg` } : {}) }}
    >
      <style dangerouslySetInnerHTML={{ __html: CSS }} />
      {showRings &&
        rings.map((r, i) => (
          <div
            key={`r${i}`}
            className={cn('absolute rounded-full border', dashed ? 'border-dashed border-[color-mix(in_oklch,var(--foreground)_16%,transparent)]' : 'border-[color-mix(in_oklch,var(--foreground)_11%,transparent)]')}
            style={{ left: `${50 - r.radius}%`, top: `${50 - r.radius}%`, width: `${r.radius * 2}%`, height: `${r.radius * 2}%` }}
          />
        ))}
      {rings.map((r, i) => {
        const dur = r.duration ?? 40;
        const dir = r.reverse ? 'reverse' : 'normal';
        const counter = r.reverse ? 'normal' : 'reverse';
        return (
          <div key={`o${i}`} className={cn('absolute inset-0', scrollTurn && 'kitfx-orbit-turn')} style={{ animation: `kitfx-orbit-spin ${dur}s linear infinite ${dir}`, ...(r.reverse && scrollTurn ? { ['--kitfx-turn' as string]: `${-scrollTurn}deg` } : {}) }}>
            {r.items.map((item, k) => {
              const a = round((r.offset ?? -90) + 90 + (360 / r.items.length) * k, 2);
              return (
                <div key={k} data-orbit-item="" className="absolute inset-0" style={{ transform: `rotate(${a}deg)` }}>
                  <div className="absolute left-1/2" style={{ top: `${50 - r.radius}%`, transform: `translate(-50%, -50%) rotate(${-a}deg)` }}>
                    <div className={scrollTurn ? 'kitfx-orbit-upright' : undefined} style={{ animation: `kitfx-orbit-spin ${dur}s linear infinite ${counter}` }}>{item}</div>
                  </div>
                </div>
              );
            })}
          </div>
        );
      })}
      {center && <div className="absolute left-1/2 top-1/2 -translate-x-1/2 -translate-y-1/2">{center}</div>}
    </div>
  );
}

/** A round chip for orbit items: an icon or initials on a card surface */
export function OrbitItem({ className, children }: { className?: string; children: React.ReactNode }) {
  return (
    <span className={cn('grid size-11 place-items-center rounded-full border border-border bg-card text-foreground shadow-[var(--highlight),var(--shadow-md)] sm:size-12', className)}>{children}</span>
  );
}