Use cases explorer

"use client";import * as React from "react";import { CodeBlock, CodeWindow, WindowCopyButton } from "@/components/site/code-window";import { Tabs, TabsContent, TabsList, TabsTrigger } from "@/components/ui/tabs";import { cn } from "@/lib/utils";// The home page's use case explorer: one card in the soft blue ring, the use cases down the left (a row that scrolls on// phones), each with its icon, title and a line of description. One pale brand-tint card (the tabs' own pill) glides between// them on a spring to mark the picked one. The right side shows that use case's code in the code window, over an optional backdrop (the site// uses its ring pattern). Every window shares one grid cell, so switching never resizes the card. While on screen it// steps through the use cases every six seconds, a small donut on the picked one counting down; it holds while the// pointer or keyboard focus is inside, and never steps under reduced motion.export type UseCaseItem = {  id: string;  title: string;  description: string;  icon?: React.ReactNode;  code: string;  /** Extra buttons in the window's chrome bar beside copy (try in an agent, docs). */  actions?: React.ReactNode;};const CYCLE_MS = 6000;function CycleDonut({ restartKey, running }: { restartKey: string; running: boolean }) {  const ref = React.useRef<SVGCircleElement>(null);  const animation = React.useRef<Animation | null>(null);  React.useEffect(() => {    const circle = ref.current;    if (!circle?.animate) return;    animation.current = circle.animate([{ strokeDashoffset: 1 }, { strokeDashoffset: 0 }], { duration: CYCLE_MS, easing: "linear", fill: "forwards" });    return () => animation.current?.cancel();  }, [restartKey]);  React.useEffect(() => {    if (running) animation.current?.play();    else animation.current?.pause();  }, [running, restartKey]);  return (    <svg aria-hidden="true" viewBox="0 0 16 16" className="absolute top-3 right-3 size-3.5 -rotate-90">      <circle cx="8" cy="8" r="6" fill="none" strokeWidth="2.5" className="stroke-neutral-70/15" />      <circle ref={ref} cx="8" cy="8" r="6" fill="none" strokeWidth="2.5" pathLength={1} strokeDasharray="1" strokeDashoffset="1" className="stroke-neutral-70" />    </svg>  );}/** The "Try in" group for the window's chrome bar: a label and small agent buttons on one dark chip. */function UseCaseTryIn({ label = "Try in", children, className }: { label?: string; children: React.ReactNode; className?: string }) {  return (    <div className={cn("flex shrink-0 items-center gap-0.5 overflow-hidden rounded-card border border-white/10 bg-dark p-0.5 transition-[border-color] duration-150 ease-out hover:border-white/20 motion-reduce:transition-none", className)}>      <span className="pr-1 pl-2 text-caption font-medium text-white">{label}</span>      {children}    </div>  );}function useReducedMotion() {  const [reduced, setReduced] = React.useState(false);  React.useEffect(() => {    const query = window.matchMedia("(prefers-reduced-motion: reduce)");    const sync = () => setReduced(query.matches);    sync();    query.addEventListener("change", sync);    return () => query.removeEventListener("change", sync);  }, []);  return reduced;}function UseCases({ items, defaultValue, backdrop, className }: { items: UseCaseItem[]; defaultValue?: string; backdrop?: React.ReactNode; className?: string }) {  const [value, setValue] = React.useState(defaultValue ?? items[0]?.id ?? "");  const index = Math.max(0, items.findIndex((item) => item.id === value));  const reduced = useReducedMotion();  // The cycle runs while 40 percent of the card is on screen and nothing inside holds it. Focus from a click is ignored:  // it lingers after the pointer leaves (the code is focusable), which would otherwise hold the cycle indefinitely.  const rootRef = React.useRef<HTMLDivElement>(null);  const [inView, setInView] = React.useState(false);  const [hovered, setHovered] = React.useState(false);  const [focused, setFocused] = React.useState(false);  const running = inView && !hovered && !focused && !reduced && items.length > 1;  // Bumped on every pick, even of the one already showing, so the timer and the donut start over.  const [pick, setPick] = React.useState(0);  const shown = React.useRef({ index, pick: 0, ms: 0 });  React.useEffect(() => {    const root = rootRef.current;    if (!root) return;    const observer = new IntersectionObserver(([entry]) => setInView(entry.isIntersecting), { threshold: 0.4 });    observer.observe(root);    return () => observer.disconnect();  }, []);  React.useEffect(() => {    if (!running) return;    if (shown.current.index !== index || shown.current.pick !== pick) shown.current = { index, pick, ms: 0 };    const current = shown.current;    const startedAt = performance.now();    const timer = window.setTimeout(() => setValue(items[(index + 1) % items.length].id), CYCLE_MS - current.ms);    return () => {      window.clearTimeout(timer);      current.ms += performance.now() - startedAt;    };  }, [index, running, pick, items]);  return (    <div      ref={rootRef}      data-slot="use-cases"      onPointerEnter={() => setHovered(true)}      onPointerLeave={() => setHovered(false)}      onFocus={(event) => setFocused(event.target.matches(":focus-visible"))}      onBlur={(event) => {        if (!event.currentTarget.contains(event.relatedTarget as Node | null)) setFocused(false);      }}      className={cn("rounded-card bg-ring-tint p-2", className)}    >      <Tabs        value={value}        onValueChange={(next) => {          setValue(next);          setPick((count) => count + 1);        }}        orientation="vertical"        className="gap-0 overflow-hidden rounded-card bg-surface ring-1 ring-hairline md:flex-row"      >        <div className="w-full shrink-0 snap-x snap-mandatory scroll-pl-2.5 overflow-x-auto border-b border-line-subtle bg-surface md:w-auto md:min-w-80 md:scroll-pl-0 md:overflow-visible md:border-r md:border-b-0">          {/* The list's own pill, restyled as the pale brand-tint card, glides to the picked tab on a spring. */}          <TabsList aria-label="Code examples" pillClassName="rounded-card bg-tint" className="w-max flex-row items-stretch gap-0.5 p-2.5 md:grid md:w-auto md:auto-rows-fr md:p-2">            {items.map((item, i) => {              const active = item.id === value;              return (                <TabsTrigger                  key={item.id}                  value={item.id}                  className={cn(                    "relative h-auto w-70 shrink-0 snap-start flex-col items-start justify-start gap-1 rounded-card px-4 py-3 text-left whitespace-normal text-fg transition-[background-color,opacity] duration-200 ease-out motion-reduce:transition-none md:w-auto md:max-w-80",                    active ? "opacity-100" : "bg-transparent opacity-70 hover:bg-tint/60 hover:opacity-100",                  )}                >                  {active && !reduced && items.length > 1 && <CycleDonut restartKey={`${i}-${pick}`} running={running} />}                  <span className="flex items-center gap-3">                    {item.icon && <span className="grid size-7 shrink-0 place-items-center rounded-control bg-brand p-1.5 text-white [&_svg]:size-4">{item.icon}</span>}                    <span className="text-body leading-snug font-normal whitespace-nowrap text-fg">{item.title}</span>                  </span>                  <span className={cn("text-body-sm leading-snug whitespace-normal text-fg-muted", item.icon && "pl-10")}>{item.description}</span>                </TabsTrigger>              );            })}          </TabsList>        </div>        <div className="relative isolate flex min-w-0 flex-1 items-center justify-center overflow-hidden px-4 py-12 md:px-6 md:py-16">          {backdrop && (            <div aria-hidden="true" className="pointer-events-none absolute inset-0 -z-10">              {backdrop}            </div>          )}          <div className="grid w-full max-w-3xl grid-cols-[minmax(0,1fr)]">            {items.map((item) => (              <TabsContent key={item.id} value={item.id} forceMount className="col-start-1 row-start-1 data-[state=inactive]:invisible">                <CodeWindow                  label={item.title}                  actions={                    <>                      {item.actions}                      <WindowCopyButton value={item.code} label={`Copy the ${item.title.toLowerCase()} example`} />                    </>                  }                >                  <div className="overflow-auto">                    <CodeBlock code={item.code} className="p-4" />                  </div>                </CodeWindow>              </TabsContent>            ))}          </div>        </div>      </Tabs>    </div>  );}export { UseCases, UseCaseTryIn };