Sync status

// Copyright (c) 2026 Bruno Delorence. MIT License.'use client';import { useEffect, useId, useLayoutEffect, useRef, useState, type CSSProperties } from 'react';import { bridge } from './goo';import { GhostPointer, runDemo } from './ghost-pointer';import { useAutoplay } from './use-autoplay';import styles from './sync-status.module.css';/* * Sync status: a pill that says how the sync is going. "Syncing", with a spinner, settles on * "Synced" with a check; when a sync fails the pill turns red, "Sync failed", and a round black * retry button buds off its end and pulls away, like a drop of liquid splitting in two. Retry * and the button flows back into the pill, which syncs again. * * - At rest, everything is plain HTML and CSS: the pill and the button, side by side, centred. * - Between states, the shapes are drawn in one SVG layer for the length of the move: the pill, *   the button and the goo between them (goo.ts), all driven by springs in a requestAnimationFrame *   loop that stops when they settle. The pill's width and place come from the layouts before and *   after the change (FLIP); the button leaves from inside the pill's round end, in the pill's *   colour, and takes its own as it gets away. * - The words cross-fade with a touch of blur; only the end changes ("Sync|ing", "Sync|ed", *   "Sync| failed").

/* Sync status (sync-status.tsx). Sizes are in em: the stage sets the font-size from its own width   (a container query), so the pill grows with the room it has. The group's state (syncing,   synced, failed) is a data attribute; while the shapes move, the group also has data-goo, and   the SVG layer draws them in place of the HTML backgrounds.   Colours are the tokens below, light-dark(light, dark) where the two differ: the component takes   the color-scheme it inherits from the page (light unless the page says otherwise), or the one   its colorScheme prop sets (data-color-scheme). */.root {  /* The stage, and what is raised on it: the pill, Sync now and Offline. */  --surface: #efeff3;  --surface-2: #fff;  /* The words, the spinner and Sync now's arrow; Sync now while a sync runs. */  --ink: #1c1c1e;  --ink-muted: #8e8e93;  /* The spinner as it leaves: SVG's default black on light, as it always was; the ink on dark,     where black would vanish into the pill. */  --spinner-out: #000;  /* The stage's edge, and the hairlines round the pill and button, and round the controls. */  --line: rgb(0 0 0 / 0.05);  --edge: rgb(0 0 0 / 0.14);  --control-edge: rgb(0 0 0 / 0.08);  /* The lift under the pill and button, under the controls, and under the switch's knob. */

/* * The goo between two circles: the curved bridge that joins them while they are close, narrows * as they draw apart, and snaps. Drawn in the same colour as the shapes it joins, it makes them * read as one drop of liquid splitting in two, or two drops merging. * * The curve is the classic metaball construction: two points on each circle, where the bridge * leaves it, and cubic curves between them whose handles follow the circles' tangents. */export type Circle = { x: number; y: number; r: number };type Point = { x: number; y: number };const towards = (from: Point, angle: number, length: number): Point => ({  x: from.x + Math.cos(angle) * length,  y: from.y + Math.sin(angle) * length,});const write = ({ x, y }: Point) => `${x.toFixed(2)} ${y.toFixed(2)}`;/** * The bridge from `a` to `b`, as an SVG path, or '' when there is none. It spreads widest while * the circles overlap, and narrows to nothing as the distance between their centres reaches * `reach` (px).

'use client';import type { CSSProperties, Ref } from 'react';/* * The demo's ghost pointer, and the timeline that moves it. A demo is a script of awaited steps: * wait, glide the pointer onto a control, press it and call the component's own handler, as a * click would. Stopping the demo (the reader takes over, or it scrolls away) ends the step in * progress at once: its promise rejects, which ends the script right there, and the pointer * fades out. */export type Demo = {  /** Resolves after `ms`. */  wait: (ms: number) => Promise<void>;  /** Glides the pointer onto `target`: its middle, or a point given as shares of its size. */  moveTo: (target: Element | null | undefined, at?: { x: number; y: number }) => Promise<void>;  /** Presses and lets go; `action` runs as the pointer goes down. */  press: (action: () => void) => Promise<void>;};/** What a stopped demo's pending step rejects with. */class Stopped extends Error {}

'use client';import { useCallback, useEffect, useRef, useState } from 'react';/* * When a demo may play on its own: while part of it is on screen and the tab is visible, never * under reduced motion, and not while the reader is using it. `take()` hands it to the reader; it * takes back over `idle` ms after their last input. */export function useAutoplay<T extends HTMLElement>(idle = 6000) {  const ref = useRef<T>(null);  const [visible, setVisible] = useState(false);  const [reduced, setReduced] = useState(true);  const [taken, setTaken] = useState(false);  const timer = useRef(0);  useEffect(() => {    const element = ref.current;    if (!element) return;    let onScreen = false;    const update = () => setVisible(onScreen && !document.hidden);    const observer = new IntersectionObserver(      ([entry]) => {        onScreen = entry.isIntersecting;