Sparkle burst

/**
 * @title Sparkle Burst
 * @category overlays
 * @description A ring of four-point star sparkles that pops out from a point, spins and fades, over a soft pulse ring.
 * @duration 27
 * @use Drawing the eye to a button, price or word the moment it appears
 * @use A small "done" or "new" accent on a card
 * @avoid Full-screen celebrations. Use `confetti`
 * @tags sparkle, star, twinkle, emphasis, accent
 * @example
 * <Sequence from={20} durationInFrames={40}>
 *   <SparkleBurst origin={{ x: 72, y: 64 }} count={8} />
 * </Sequence>
 */
import type React from "react";
import { AbsoluteFill, random } from "remotion";
import { type MotionProps, tween, useMotion, useTheme, useViewport } from "./core";

export type SparkleBurstProps = MotionProps & {
  /** Center of the burst in % of the canvas (0-100 on each axis). */
  origin?: { x: number; y: number };
  /** Number of sparkles. 6-12 reads best. */
  count?: number;
  /** How far the sparkles travel, in design units. */
  radius?: number;
  /** Largest sparkle size in design units. */
  size?: number;
  /** Sparkle color. Defaults to the theme highlight. */
  color?: string;
  /** Every other sparkle, and the pulse ring. Defaults to the theme accent. */
  secondaryColor?: string;
  /** Show the expanding ring behind the sparkles. */
  ring?: boolean;
  seed?: string | number;
  style?: React.CSSProperties;
  className?: string;
};

/** Four-point star in a 100 × 100 box: concave sides meeting in sharp tips. */
const STAR = "M50 0C53 35 65 47 100 50C65 53 53 65 50 100C47 65 35 53 0 50C35 47 47 35 50 0Z";

export function SparkleBurst({
  origin = { x: 50, y: 50 },
  count = 8,
  radius = 150,
  size = 44,
  color,
  secondaryColor,
  ring = true,
  seed = "sparkle",
  style,
  className,
  ...motion
}: SparkleBurstProps) {
  const theme = useTheme();
  const { u, width, height } = useViewport();
  const m = useMotion(motion);
  const primary = color ?? theme.colors.highlight;
  const secondary = secondaryColor ?? theme.colors.accent;
  const lifeFrames = Math.round(m.enterFrames * 1.5);
  const x0 = (origin.x / 100) * width;
  const y0 = (origin.y / 100) * height;
  const pulse = tween(m.frame, m.fps, { from: m.delay, duration: m.enterFrames, motion: "smooth" });
  const pulseSize = u(radius) * 1.3 * pulse;

  const sparkles = Array.from({ length: count }, (_, i) => {
    const r = (key: string) => random(`${seed}-${i}-${key}`);
    const start = m.delay + Math.floor(r("delay") * 4);
    const life = (m.frame - start) / lifeFrames;
    if (life <= 0 || life >= 1) return null;
    const out = Math.min(tween(m.frame, m.fps, { from: start, duration: m.enterFrames, motion: m.preset }), 1.15);
    const theta = ((i + (r("angle") - 0.5) * 0.7) / count) * Math.PI * 2 - Math.PI / 2;
    const distance = u(radius) * (0.55 + 0.45 * r("distance")) * out;
    // Pops to full size early in its life, then shrinks away.
    const s = u(size) * (0.45 + 0.55 * r("size")) * Math.sin(Math.PI * life ** 0.6);
    const turn = (i % 2 === 0 ? 1 : -1) * (30 + 60 * life) + (r("spin") - 0.5) * 40;
    return (
      <svg
        key={i}
        aria-hidden="true"
        viewBox="0 0 100 100"
        width={s}
        height={s}
        style={{
          position: "absolute",
          left: x0 + Math.cos(theta) * distance - s / 2,
          top: y0 + Math.sin(theta) * distance - s / 2,
          rotate: `${turn}deg`,
          overflow: "visible",
        }}
      >
        <path d={STAR} fill={i % 2 === 0 ? primary : secondary} />
      </svg>
    );
  });

  return (
    <AbsoluteFill className={className} style={{ pointerEvents: "none", opacity: 1 - m.exit, ...style }}>
      {ring && pulse > 0 && pulse < 1 && (
        <div
          style={{
            position: "absolute",
            left: x0 - pulseSize / 2,
            top: y0 - pulseSize / 2,
            width: pulseSize,
            height: pulseSize,
            borderRadius: "50%",
            border: `${u(3)}px solid ${secondary}`,
            opacity: (1 - pulse) * 0.7,
          }}
        />
      )}
      {sparkles}
    </AbsoluteFill>
  );
}