Calculator Widget

"use client"

import * as React from "react"
import { CalculatorWidget } from "@/components/ui/calculator-widget"

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>
  )
}

function CalculatorWidgetDemo() {
  return (
    <div className="w-full max-w-2xl">
      <CalculatorWidget
        title="Monthly inference cost"
        description="Move the sliders to see how traffic and caching change the bill."
        inputs={[
          {
            name: "requests",
            label: "Requests per day",
            min: 1000,
            max: 200000,
            step: 1000,
            defaultValue: 8000,
            format: "integer",
          },
          {
            name: "tokens",
            label: "Input tokens per request",
            min: 500,
            max: 20000,
            step: 100,
            defaultValue: 6000,
            format: "integer",
          },
          {
            name: "output",
            label: "Output tokens per request",
            min: 50,
            max: 4000,
            step: 50,
            defaultValue: 600,
            format: "integer",
          },
          {
            name: "cache",
            label: "Cache hit rate",
            min: 0,
            max: 90,
            step: 5,
            defaultValue: 60,
            format: "percent",
          },
        ]}
        outputs={[
          {
            name: "total",
            label: "Per month",
            primary: true,
            format: "currency",
            formula: "inputCost + cachedCost + outputCost",
            hint: "30 days at $3 per 1M input, $0.30 cached, $15 output",
          },
          {
            name: "inputCost",
            hidden: true,
            label: "Uncached input",
            format: "currency",
            formula: "requests * 30 * tokens * (1 - cache / 100) / 1000000 * 3",
          },
          {
            name: "cachedCost",
            hidden: true,
            label: "Cached input",
            format: "currency",
            formula: "requests * 30 * tokens * cache / 100 / 1000000 * 0.3",
          },
          {
            name: "outputCost",
            hidden: true,
            label: "Output",
            format: "currency",
            formula: "requests * 30 * output / 1000000 * 15",
          },
          {
            name: "perThousand",
            label: "Per 1,000 requests",
            format: "currency",
            formula: "total / (requests * 30) * 1000",
          },
        ]}
        breakdown={[
          { label: "Uncached input", formula: "inputCost" },
          { label: "Cached input", formula: "cachedCost" },
          { label: "Output", formula: "outputCost" },
        ]}
        onSubmit={() => {}}
        submitLabel="Use these numbers"
      />
    </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>
  )
}

/** The kit's own example, framed for the 21st preview. */
export default function CalculatorWidgetPreview() {
  return (
    <FitFrame minWidth="36rem">
      <div className="flex w-full flex-col items-center justify-center gap-4 p-6">
        <div className="flex w-full max-w-2xl justify-center">
          <CalculatorWidgetDemo />
        </div>
        <MoreOn slug="calculator-widget">A calculator an assistant fills in, with a breakdown. On</MoreOn>
      </div>
    </FitFrame>
  )
}