Stat Card

"use client"

import * as React from "react"
import { StatCard, StatCardGroup } from "@/components/ui/stat-card"

const reducedMotion = () => window.matchMedia("(prefers-reduced-motion: reduce)").matches

const TICK_MS = 1100

const POINTS = 12

/** An incident around tick 14: latency and errors spike, requests dip, then everything recovers. */
const spike = (i: number) => Math.exp(-((i - 14) ** 2) / 10)

/** A deterministic wobble, so every load plays the same morning. */
const wobble = (n: number, seed: number) => {
  const x = Math.sin(n * 12.9898 + seed * 78.233) * 43758.5453
  return x - Math.floor(x) - 0.5
}

/** Each card's last twelve points at tick `t`. */
function seriesAt(t: number) {
  const make = (f: (i: number) => number) => Array.from({ length: POINTS }, (_, k) => f(t + k - POINTS))
  return {
    requests: make((i) => 1_240_000 + i * 9_000 - spike(i) * 420_000 + wobble(i, 1) * 30_000),
    latency: make((i) => 128 + spike(i) * 340 + wobble(i, 2) * 14),
    errors: make((i) => 0.0031 + spike(i) * 0.021 + wobble(i, 3) * 0.0008),
  }
}

const FIT_CSS = "html,body{overflow:hidden}[data-fit-small] [data-fit-hide]{display:none!important}"

/**
 * 21st shows a demo in a small frame: about 674 by 421 on a component page, 358 by 224 on a
 * phone and 245 by 139 on a profile card. A demo taller than its frame gets scrollbars, which
 * render white on dark pages. FitFrame fills the frame exactly instead.
 *
 * - "scale": the content shrinks until it fits, centered. For visuals such as orbs.
 * - "crop": the content stays at full size from the top and fades out at the bottom. For text
 *   that streams in, where a changing scale would make the page breathe.
 *
 * `minWidth` lays out a wide demo (a table, a two column panel) at that width and scales it down
 * to the frame, instead of letting it collapse to a narrow layout. The frame centers it, so it
 * shrinks evenly on both sides.
 *
 * Anything marked `data-fit-hide` (state buttons, the chatcn.dev line) drops out in frames
 * shorter than `hideBelow`, so a profile card shows the visual alone.
 */
function FitFrame({
  children,
  mode = "scale",
  hideBelow = 360,
  minWidth,
}: {
  children: React.ReactNode
  mode?: "scale" | "crop"
  hideBelow?: number
  minWidth?: string
}) {
  const content = React.useRef<HTMLDivElement>(null)
  const [cropped, setCropped] = React.useState(false)

  React.useLayoutEffect(() => {
    const el = content.current
    if (!el) return
    const measure = () => {
      const vw = window.innerWidth
      const vh = window.innerHeight
      el.toggleAttribute("data-fit-small", vh < hideBelow)
      // Layout sizes ignore the transform, so measuring never feeds back.
      const w = Math.max(el.offsetWidth, el.scrollWidth)
      const h = Math.max(el.offsetHeight, el.scrollHeight)
      const scale = mode === "scale" ? Math.min(1, vw / w, vh / h) : 1
      el.style.transform = scale < 1 ? `scale(${scale})` : ""
      setCropped(mode === "crop" && h > vh + 1)
    }
    measure()
    const observer = new ResizeObserver(measure)
    observer.observe(el)
    // Content that changes inside a fixed width box (a headline that cycles words) never resizes
    // the box itself, so changes below it measure again on the next frame.
    let frame = 0
    const mutations = new MutationObserver(() => {
      cancelAnimationFrame(frame)
      frame = requestAnimationFrame(measure)
    })
    mutations.observe(el, { subtree: true, childList: true, characterData: true })
    window.addEventListener("resize", measure)
    return () => {
      observer.disconnect()
      mutations.disconnect()
      cancelAnimationFrame(frame)
      window.removeEventListener("resize", measure)
    }
  }, [mode, hideBelow])

  const fade = "linear-gradient(to bottom, #000 calc(100% - 40px), transparent)"
  return (
    <div
      className="flex w-full justify-center overflow-hidden"
      style={{
        height: "100dvh",
        alignItems: mode === "crop" ? "flex-start" : "center",
        maskImage: cropped ? fade : undefined,
        WebkitMaskImage: cropped ? fade : undefined,
      }}
    >
      <style>{FIT_CSS}</style>
      <div
        ref={content}
        className="w-full shrink-0"
        style={{ transformOrigin: mode === "crop" ? "top center" : "center", minWidth }}
      >
        {children}
      </div>
    </div>
  )
}

/** The line under each 21st demo that points back to the kit. */
function MoreOn({ slug, children }: { slug: string; children: React.ReactNode }) {
  return (
    <p data-fit-hide className="text-[0.75rem]/[1rem] text-(color:--chatcn-fg-faint) text-center text-balance">
      {children}{" "}
      <a
        href={`https://chatcn.dev/docs/components/${slug}`}
        target="_blank"
        rel="noopener"
        className="text-(color:--chatcn-fg-subtle) hover:text-(color:--chatcn-fg) underline underline-offset-2"
      >
        chatcn.dev
      </a>
    </p>
  )
}

/**
 * A live dashboard through an incident: p95 latency and errors spike while requests dip, then
 * everything recovers. Values and sparklines tick every second, and each delta turns red or green
 * by which direction is good news for that figure. Loops.
 */
export default function StatCardPreview() {
  const [tick, setTick] = React.useState(10)

  React.useEffect(() => {
    if (reducedMotion()) return
    const id = window.setInterval(() => setTick((n) => (n >= 30 ? 4 : n + 1)), TICK_MS)
    return () => window.clearInterval(id)
  }, [])

  const s = seriesAt(tick)
  const last = (a: number[]) => a[a.length - 1]!
  const change = (a: number[]) => (last(a) - a[0]!) / a[0]!

  return (
    <FitFrame minWidth="34rem">
      <div className="flex w-full flex-col items-center justify-center gap-5 p-6">
        <div className="w-full max-w-xl">
          <StatCardGroup>
            <StatCard
              size="lg"
              label="Requests"
              value={Math.round(last(s.requests))}
              format="compact"
              delta={{ value: change(s.requests), label: "in 12 min" }}
              trend={s.requests}
            />
            <StatCard
              size="lg"
              label="p95 latency"
              value={Math.round(last(s.latency))}
              unit="ms"
              delta={{ value: change(s.latency), label: "in 12 min" }}
              goodDirection="down"
              trend={s.latency}
            />
            <StatCard
              size="lg"
              label="Error rate"
              value={last(s.errors)}
              format="percent"
              delta={{ value: last(s.errors) - s.errors[0]!, format: "percent", label: "pts" }}
              goodDirection="down"
              trend={s.errors}
            />
          </StatCardGroup>
        </div>
        <MoreOn slug="stat-card">Figures with deltas, sparklines and good or bad tone. On</MoreOn>
      </div>
    </FitFrame>
  )
}