Skeleton

:root {
  --size-control-sm: 2rem;
  --size-control-md: 2.25rem;
  --size-control-lg: 2.5rem;
  --size-icon-sm: 0.875rem;
  --size-icon-md: 1rem;
  --size-icon-lg: 1.25rem;
  --size-roll-fade: 0.25em;
  --size-roll-fade-x: 0.5em;
  --duration-instant: 80ms;
  --duration-fast: 150ms;
  --duration-base: 220ms;
  --duration-slow: 350ms;
  --duration-slower: 500ms;
  --z-overlay: 1200;
  --z-modal: 1300;
  --z-popover: 1400;
  --z-toast: 1500;
  --z-tooltip: 1600;
  --focus-ring-width: 2px;
  --focus-ring-offset: 2px;
  --opacity-disabled: 0.5;
  --ease-spring: linear(0, 0.157, 0.48, 0.77, 0.97, 1.07, 1.1, 1.09, 1.05, 1.02, 1, 0.995, 1);
  --destructive-foreground: oklch(1 0 0);
  --overlay: color-mix(in oklch, oklch(0 0 0) 40%, transparent);
}

.dark {
  --destructive-foreground: oklch(1 0 0);
  --overlay: color-mix(in oklch, oklch(0 0 0) 60%, transparent);
}

@theme inline {
  --animate-popover-in: popover-in var(--duration-fast) cubic-bezier(0.22, 1, 0.36, 1) both;
  --animate-popover-out: popover-out var(--duration-instant) cubic-bezier(0.55, 0, 1, 0.45) both;
  --animate-collapsible-open: collapsible-open var(--duration-slow) cubic-bezier(0.22, 1, 0.36, 1);
  --animate-collapsible-close: collapsible-close var(--duration-base) cubic-bezier(0.55, 0, 1, 0.45) both;
  --color-destructive-foreground: var(--destructive-foreground);
  --color-overlay: var(--overlay);
  @keyframes popover-in {
    from {
      opacity: 0;
      filter: blur(6px);
      transform: scale(0.96);
    }
    to {
      opacity: 1;
      filter: blur(0);
      transform: scale(1);
    }
  }
  @keyframes popover-out {
    from {
      opacity: 1;
      filter: blur(0);
      transform: scale(1);
    }
    to {
      opacity: 0;
      filter: blur(6px);
      transform: scale(0.96);
    }
  }
  @keyframes collapsible-open {
    from {
      height: 0;
      opacity: 0;
      filter: blur(6px);
    }
    to {
      height: var(--collapsible-height);
      opacity: 1;
      filter: blur(0);
    }
  }
  @keyframes collapsible-close {
    from {
      height: var(--collapsible-height);
      opacity: 1;
      filter: blur(0);
    }
    to {
      height: 0;
      opacity: 0;
      filter: blur(6px);
    }
  }
}

@media (prefers-reduced-motion: reduce) {
  :root {
    --duration-instant: 1ms;
    --duration-fast: 1ms;
    --duration-base: 1ms;
    --duration-slow: 1ms;
    --duration-slower: 1ms;
  }
}

import type { Transition } from "motion/react";

/*
 * Motion tokens for JavaScript animations (motion/react).
 * Durations and easings mirror the CSS tokens in src/styles/tokens.css;
 * `pnpm check:tokens` fails if the two drift apart.
 */

/** Durations in seconds. Mirrors --duration-* in tokens.css. */
export const duration = {
  instant: 0.08,
  fast: 0.15,
  base: 0.22,
  slow: 0.35,
  slower: 0.5,
} as const;

/** Cubic-bezier easings. Mirrors --ease-* in tokens.css. */
export const ease = {
  out: [0.22, 1, 0.36, 1],
  in: [0.55, 0, 1, 0.45],
  inOut: [0.65, 0, 0.35, 1],
} as const;

/**
 * Named springs: the library's motion voice.
 * - snappy: quick, almost no overshoot. Toggles, tabs, small controls.
 * - smooth: slow and settled. Panels, sidebars, page sections.
 * - bouncy: playful overshoot. Rare, for moments of delight.
 */
export const spring = {
  snappy: { type: "spring", stiffness: 520, damping: 38, mass: 1 },
  smooth: { type: "spring", stiffness: 120, damping: 20, mass: 1 },
  bouncy: { type: "spring", stiffness: 300, damping: 15, mass: 1 },
} as const satisfies Record<string, Transition>;

export type SpringName = keyof typeof spring;

/**
 * The blur (owner, 2026-10-15): content that appears, leaves or swaps sharpens in from a 6px blur as it
 * fades, instead of only fading. Pair it with the movement the pattern already has. Not for fills,
 * highlights, hover or anything full-screen (those still fade), and with reduced motion it's opacity only.
 * The CSS keyframes in tokens.css use the same 6px (checked by `pnpm check:tokens`).
 */
export const blur = { hidden: "blur(6px)", shown: "blur(0px)" } as const;

/** Swapping content in place (Loading Button, Copy Button): the new rises 6px from blurred; the old lifts away blurring */
export const swap = {
  initial: { opacity: 0, filter: blur.hidden, y: 6 },
  animate: { opacity: 1, filter: blur.shown, y: 0 },
  exit: { opacity: 0, filter: blur.hidden, y: -6 },
} as const;

/**
 * The flow of a changing number (Number Ticker): a spring for the characters' moves, the width and the digits'
 * spin, sampled into CSS linear(), and a fade for characters coming and going. Web Animations timings, in
 * milliseconds. The curve is from number-flow, © 2024 Maxwell Barvian, MIT licence (its full notice is in
 * components/number-ticker/number-ticker.tsx).
 */
export const flow = {
  transform: {
    duration: 900,
    easing:
      "linear(0,.005,.019,.039,.066,.096,.129,.165,.202,.24,.278,.316,.354,.39,.426,.461,.494,.526,.557,.586,.614,.64,.665,.689,.711,.731,.751,.769,.786,.802,.817,.831,.844,.856,.867,.877,.887,.896,.904,.912,.919,.925,.931,.937,.942,.947,.951,.955,.959,.962,.965,.968,.971,.973,.976,.978,.98,.981,.983,.984,.986,.987,.988,.989,.99,.991,.992,.992,.993,.994,.994,.995,.995,.996,.996,.9963,.9967,.9969,.9972,.9975,.9977,.9979,.9981,.9982,.9984,.9985,.9987,.9988,.9989,1)",
  },
  opacity: { duration: 450, easing: "ease-out" },
} as const satisfies Record<string, EffectTiming>;

import { SkeletonSheen } from "@/components/ui/skeleton-sheen";
import { cn } from "@/lib/utils";
import type { ComponentProps } from "react";

/*
 * A placeholder block while content loads (owner's roadmap, 2026-10-16), with shadcn's API: one `div` you shape
 * with classes (`h-4 w-40`, `size-10 rounded-full`).
 * - A muted block with a calm sheen sweeping across it: one neutral hue, a step lighter, never a colour. The sheen
 *   lives in SkeletonSheen, a small client part, so Skeleton stays a server component, which is where loading
 *   states usually render (loading.tsx, Suspense fallbacks).
 * - Every skeleton on the page sweeps in step, however late it mounted (see skeleton-sheen.tsx).
 * - With reduced motion it's a still, muted block.
 * - Hidden from screen readers (aria-hidden): a grey block says nothing. Mark the region that's loading with
 *   aria-busy="true" and a visually hidden "Loading…" instead (the demos do).
 */

function Skeleton({ className, children, ...props }: ComponentProps<"div">) {
  return (
    <div
      data-slot="skeleton"
      aria-hidden
      className={cn("relative overflow-hidden rounded-md bg-muted", className)}
      {...props}
    >
      {children}
      <SkeletonSheen />
    </div>
  );
}

export { Skeleton };

"use client";

import { duration, ease } from "@/lib/motion";
import { useReducedMotion } from "motion/react";
import { useEffect, useRef } from "react";

/*
 * The light sweeping across a Skeleton. The only client part of Skeleton, so Skeleton stays server-safe.
 * - How: a band (a gradient one step lighter than the block, fading out at both sides) sits just outside the
 *   block and slides across it. Only `translate` moves, so the browser composites it on its own.
 * - In step: every sheen counts from the page's start (startTime 0 on the document timeline), so skeletons that
 *   mount at different moments still sweep together, as one loading surface.
 * - The pace: a 1.5s sweep, then a 0.5s rest, on ease.inOut. Calm, not a flicker.
 * - With reduced motion nothing moves: a still, muted block. Before hydration it's still too; the sweep starts
 *   once React runs.
 * - The Web Animations API directly, rather than motion: motion doesn't expose an animation's start time, and
 *   that's what keeps every sheen in step.
 */

const period = duration.slower * 4 * 1000;
/** The share of each period spent sweeping; the rest is a pause */
const sweep = 0.75;

function SkeletonSheen() {
  const reduce = useReducedMotion() ?? false;
  const ref = useRef<HTMLSpanElement>(null);

  useEffect(() => {
    const node = ref.current;
    if (!node || reduce || typeof node.animate !== "function") return;
    // From the start of the line in either writing direction
    const [from, to] = getComputedStyle(node).direction === "rtl" ? ["100%", "-100%"] : ["-100%", "100%"];
    const animation = node.animate(
      [
        { translate: from, easing: `cubic-bezier(${ease.inOut.join(", ")})` },
        { translate: to, offset: sweep },
        { translate: to },
      ],
      { duration: period, iterations: Number.POSITIVE_INFINITY },
    );
    animation.startTime = 0;
    return () => animation.cancel();
  }, [reduce]);

  return (
    <span
      ref={ref}
      aria-hidden
      data-slot="skeleton-sheen"
      className="pointer-events-none absolute inset-0 -translate-x-full bg-linear-to-r from-transparent via-background/60 to-transparent rtl:translate-x-full dark:via-foreground/5"
    />
  );
}

export { SkeletonSheen };