Feiern

'use client';

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

/*
 * Moments of joy: confetti, fireworks, side cannons, a gentle rain and
 * sparkles. Drawn as small DOM pieces in one fixed layer over the page that
 * moves only transform and opacity and cleans itself up, so nothing ever
 * widens the page or blocks a click.
 *
 *   useCelebrate()   fire(kind, origin) from your own code, e.g. after a payment
 *   <Celebrate>      fires on click, when it scrolls into view, or when you say
 *   <Sparkles>       small stars that twinkle around its children on hover and in view
 *
 * Colors come from the theme: the accent, its neighbour, success, warning and
 * the text color. With reduced motion nothing flies, the moment stays calm.
 */

export type CelebrateKind = 'burst' | 'rain' | 'fireworks' | 'cannons' | 'pop';

export interface FireOptions {
  /** Where it starts: an element, a point in window pixels, or the center of the window */
  origin?: Element | { x: number; y: number } | null;
  /** Number of pieces, capped at 160 */
  count?: number;
  /** Colors as CSS values, default the theme colors */
  colors?: string[];
  /** 1 is the designed force */
  power?: number;
}

const THEME_COLORS = ['var(--primary)', 'var(--primary-2)', 'var(--success)', 'var(--warning)', 'color-mix(in oklab, var(--foreground) 80%, transparent)', 'color-mix(in oklab, var(--primary) 45%, var(--background))'];

let layer: HTMLDivElement | null = null;
/** One fixed, clipped layer for every piece on the page */
function getLayer() {
  if (layer && document.body.contains(layer)) return layer;
  layer = document.createElement('div');
  layer.setAttribute('aria-hidden', 'true');
  layer.setAttribute('data-clip-ok', '');
  Object.assign(layer.style, { position: 'fixed', inset: '0', overflow: 'hidden', pointerEvents: 'none', zIndex: '60', contain: 'strict' });
  document.body.appendChild(layer);
  return layer;
}

function originPoint(origin: FireOptions['origin']) {
  if (!origin) return { x: window.innerWidth / 2, y: window.innerHeight / 2, w: 0, h: 0 };
  if ('getBoundingClientRect' in origin) {
    const r = origin.getBoundingClientRect();
    return { x: r.left + r.width / 2, y: r.top + r.height / 2, w: r.width, h: r.height };
  }
  return { ...origin, w: 0, h: 0 };
}

interface Piece {
  x: number;
  y: number;
  vx: number;
  vy: number;
  spin: number;
  size: number;
  shape: 'rect' | 'strip' | 'dot' | 'spark';
  color: string;
  life: number;
  delay: number;
  gravity: number;
  drag: number;
}

/** Throws pieces with a simple ballistic path, sampled into keyframes */
function launch(pieces: Piece[]) {
  const root = getLayer();
  for (const p of pieces) {
    const el = document.createElement('span');
    const w = p.shape === 'strip' ? p.size * 0.45 : p.shape === 'spark' ? 2.5 : p.size;
    const h = p.shape === 'strip' ? p.size * 1.6 : p.shape === 'spark' ? p.size * 2.2 : p.shape === 'dot' ? p.size : p.size * 0.6;
    Object.assign(el.style, {
      position: 'absolute',
      left: `${p.x}px`,
      top: `${p.y}px`,
      width: `${w}px`,
      height: `${h}px`,
      marginLeft: `${-w / 2}px`,
      marginTop: `${-h / 2}px`,
      background: p.color,
      borderRadius: p.shape === 'dot' || p.shape === 'spark' ? '999px' : '1.5px',
      willChange: 'transform, opacity',
    });
    root.appendChild(el);
    const frames: Keyframe[] = [];
    const steps = 8;
    for (let i = 0; i <= steps; i++) {
      const t = i / steps;
      // velocity fades with drag, gravity pulls down
      const k = (1 - Math.exp(-p.drag * t)) / p.drag;
      const dx = p.vx * k;
      const dy = p.vy * k + 0.5 * p.gravity * t * t;
      const flutter = p.shape === 'spark' ? 0 : Math.sin(t * 9 + p.spin) * 6 * t;
      const rot = p.shape === 'spark' ? Math.atan2(p.vy + p.gravity * t, p.vx) * (180 / Math.PI) + 90 : p.spin * 360 * t;
      frames.push({
        transform: `translate(${(dx + flutter).toFixed(1)}px, ${dy.toFixed(1)}px) rotate(${rot.toFixed(1)}deg) rotateX(${(t * 720 * (p.spin > 0 ? 1 : -1)).toFixed(0)}deg)`,
        opacity: t < 0.75 ? 1 : 1 - (t - 0.75) / 0.25,
      });
    }
    const anim = el.animate(frames, { duration: p.life, delay: p.delay, easing: 'linear', fill: 'both' });
    anim.onfinish = () => el.remove();
    anim.oncancel = () => el.remove();
  }
}

/**
 * Fire confetti from code.
 *   const fire = useCelebrate();
 *   fire('burst', { origin: buttonRef.current })
 */
export function useCelebrate() {
  return useCallback((kind: CelebrateKind = 'burst', opts: FireOptions = {}) => {
    if (typeof window === 'undefined' || prefersReducedMotion()) return;
    const colors = opts.colors?.length ? opts.colors : THEME_COLORS;
    const power = opts.power ?? 1;
    const o = originPoint(opts.origin);
    const r = Math.random;
    const pick = () => colors[Math.floor(r() * colors.length)];
    const shapes: Piece['shape'][] = ['rect', 'rect', 'strip', 'dot'];
    const shape = () => shapes[Math.floor(r() * shapes.length)];
    const pieces: Piece[] = [];
    const cap = (n: number) => Math.min(160, Math.max(1, Math.round(opts.count ?? n)));
    const H = window.innerHeight;

    if (kind === 'burst' || kind === 'pop') {
      const n = cap(kind === 'pop' ? 28 : 70);
      for (let i = 0; i < n; i++) {
        const a = -Math.PI / 2 + (r() - 0.5) * (kind === 'pop' ? Math.PI * 2 : Math.PI * 1.1);
        const v = (kind === 'pop' ? 160 : 520) * power * (0.45 + r() * 0.75);
        pieces.push({ x: o.x + (r() - 0.5) * o.w * 0.6, y: o.y, vx: Math.cos(a) * v, vy: Math.sin(a) * v, spin: (r() - 0.5) * 4, size: 7 + r() * 6, shape: shape(), color: pick(), life: (kind === 'pop' ? 900 : 1900) + r() * 700, delay: r() * 60, gravity: kind === 'pop' ? 180 : 900, drag: 2.2 });
      }
    } else if (kind === 'rain') {
      const n = cap(90);
      const left = opts.origin ? o.x - o.w / 2 : 0;
      const width = opts.origin ? o.w : window.innerWidth;
      const top = opts.origin ? o.y - o.h / 2 : 0;
      for (let i = 0; i < n; i++) {
        pieces.push({ x: left + r() * width, y: top - 20 - r() * 40, vx: (r() - 0.5) * 60, vy: 40 + r() * 60, spin: (r() - 0.5) * 3, size: 7 + r() * 5, shape: shape(), color: pick(), life: 2600 + r() * 1600, delay: r() * 1400, gravity: (opts.origin ? o.h : H) * 0.9 * power, drag: 1 });
      }
    } else if (kind === 'cannons') {
      const n = cap(60);
      for (const side of [-1, 1]) {
        const x = side < 0 ? 0 : window.innerWidth;
        for (let i = 0; i < n; i++) {
          const a = -Math.PI / 2 + side * -(0.35 + r() * 0.5);
          const v = 900 * power * (0.55 + r() * 0.6);
          pieces.push({ x, y: H, vx: Math.cos(a) * v, vy: Math.sin(a) * v, spin: (r() - 0.5) * 4, size: 7 + r() * 6, shape: shape(), color: pick(), life: 2400 + r() * 900, delay: r() * 120, gravity: 1300, drag: 1.8 });
        }
      }
    } else if (kind === 'fireworks') {
      const shells = 3;
      for (let s = 0; s < shells; s++) {
        const cx = o.x + (s - 1) * Math.min(220, window.innerWidth * 0.22) + (r() - 0.5) * 40;
        const cy = o.y - 40 - r() * 60;
        const color = colors[s % colors.length];
        const n = cap(36);
        for (let i = 0; i < n; i++) {
          const a = (i / n) * Math.PI * 2 + r() * 0.2;
          const v = 230 * power * (0.8 + r() * 0.3);
          pieces.push({ x: cx, y: cy, vx: Math.cos(a) * v, vy: Math.sin(a) * v, spin: 0, size: 5 + r() * 3, shape: 'spark', color, life: 1300 + r() * 300, delay: s * 380, gravity: 160, drag: 2.6 });
        }
      }
    }
    launch(pieces);
  }, []);
}

/* ------------------------------------------------------------------ */

export interface CelebrateProps {
  kind?: CelebrateKind;
  /** click: on every click inside. view: once when it scrolls into view. manual: only when `fire` changes. */
  trigger?: 'click' | 'view' | 'manual';
  /** With trigger manual: change this number to fire again */
  fire?: number;
  count?: number;
  power?: number;
  colors?: string[];
  /** Milliseconds after the trigger */
  delay?: number;
  className?: string;
  children?: React.ReactNode;
}

/**
 * Fires a celebration from its own box.
 *   <Celebrate kind="burst" trigger="click"><Button>Publish</Button></Celebrate>
 */
export function Celebrate({ kind = 'burst', trigger = 'click', fire: fireKey, count, power, colors, delay = 0, className, children }: CelebrateProps) {
  const fire = useCelebrate();
  const [ref, inView] = useInView<HTMLDivElement>('0px 0px -20% 0px');
  const done = useRef(false);
  const go = useCallback(() => {
    const id = window.setTimeout(() => fire(kind, { origin: ref.current, count, power, colors }), delay);
    return () => window.clearTimeout(id);
  }, [fire, kind, count, power, colors, delay, ref]);
  useEffect(() => {
    if (trigger !== 'view' || !inView || done.current) return;
    done.current = true;
    return go();
  }, [trigger, inView, go]);
  const first = useRef(true);
  useEffect(() => {
    if (trigger !== 'manual') return;
    if (first.current) {
      first.current = false;
      return;
    }
    return go();
  }, [fireKey, trigger, go]);
  return (
    <div ref={ref} className={cn('relative', className)} onClickCapture={trigger === 'click' ? () => go() : undefined}>
      {children}
    </div>
  );
}

/* ------------------------------------------------------------------ */
/* Sparkles                                                            */
/* ------------------------------------------------------------------ */

const SPARKLE_SPOTS: [number, number, number, number][] = [
  // x %, y %, size px, delay ms
  [-6, 12, 14, 0],
  [104, 4, 11, 260],
  [96, 92, 16, 520],
  [10, 100, 10, 780],
  [52, -14, 12, 1040],
  [-10, 70, 9, 1300],
];

/**
 * Small four-pointed stars that twinkle around its children, in view and
 * brighter on hover. Placed on fixed spots, so server and browser agree.
 *   <Sparkles><span>new</span></Sparkles>
 */
export function Sparkles({ children, tone = 'accent', className }: { children: React.ReactNode; tone?: 'accent' | 'warning' | 'foreground'; className?: string }) {
  const color = tone === 'accent' ? 'var(--primary)' : tone === 'warning' ? 'var(--warning)' : 'var(--foreground)';
  return (
    <span className={cn('group/sparkle relative inline-block', className)}>
      <style href="kit-sparkles" precedence="default">{`@keyframes ksk-twinkle{0%,100%{transform:scale(0) rotate(0deg);opacity:0}40%{transform:scale(1) rotate(45deg);opacity:1}70%{transform:scale(.6) rotate(90deg);opacity:.6}}.ksk-star{animation:ksk-twinkle 2.6s var(--ease-kit) infinite both}.group\\/sparkle:hover .ksk-star{animation-duration:1.3s}@media (prefers-reduced-motion:reduce){.ksk-star{animation:none;transform:scale(.8);opacity:.8}}`}</style>
      {SPARKLE_SPOTS.map(([x, y, s, d], i) => (
        <svg key={i} aria-hidden viewBox="0 0 24 24" className="ksk-star pointer-events-none absolute" style={{ left: `${x}%`, top: `${y}%`, width: s, height: s, marginLeft: -s / 2, marginTop: -s / 2, animationDelay: `${d}ms`, color }}>
          <path d="M12 0c.8 6.4 5.6 11.2 12 12-6.4.8-11.2 5.6-12 12-.8-6.4-5.6-11.2-12-12C6.4 11.2 11.2 6.4 12 0Z" fill="currentColor" />
        </svg>
      ))}
      <span className="relative">{children}</span>
    </span>
  );
}