Oscilloscope

"use client"

import * as React from "react"
import { cn } from "@/lib/utils"
import { Toggle } from "@base-ui/react/toggle"
import { ToggleGroup } from "@base-ui/react/toggle-group"
import { Oscilloscope, OscilloscopeMode } from "@/components/ui/oscilloscope"

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

/**
 * Steps through `values` on a timer, so a 21st preview (and its cover video) shows every option
 * without a click. Picking a value stops the tour. Reduced motion never starts it.
 */
function useCycle<T>(values: readonly T[], ms: number) {
  const [index, setIndex] = React.useState(0)
  const [held, setHeld] = React.useState(false)
  React.useEffect(() => {
    if (held || reducedMotion()) return
    const id = window.setInterval(() => setIndex((n) => (n + 1) % values.length), ms)
    return () => window.clearInterval(id)
  }, [held, values.length, ms])
  const pick = React.useCallback(
    (value: T) => {
      setHeld(true)
      setIndex(Math.max(0, values.indexOf(value)))
    },
    [values],
  )
  return [values[index] as T, pick] as const
}

const MODES = [
  { value: "time", label: "Time" },
  { value: "xy", label: "XY" },
] as const satisfies readonly { value: OscilloscopeMode; label: string }[]

const MODE_VALUES = MODES.map((m) => m.value)

/**
 * A voice-like signal over time, then as an XY figure, in turn, its gain swelling like speech.
 * Pass an AnalyserNode to draw a real microphone or audio element instead.
 */
/** Syllables and pauses, like someone talking: the gain swells and falls a few times a second. */
function useSpeechGain() {
  const [gain, setGain] = React.useState(1)
  React.useEffect(() => {
    if (window.matchMedia("(prefers-reduced-motion: reduce)").matches) return
    const start = performance.now()
    const id = window.setInterval(() => {
      const t = (performance.now() - start) / 1000
      const syllable = Math.abs(Math.sin(t * Math.PI * 2.6))
      const phrase = 0.55 + 0.45 * Math.sin(t * Math.PI * 0.45)
      setGain(0.25 + 1.15 * syllable * phrase)
    }, 50)
    return () => window.clearInterval(id)
  }, [])
  return gain
}

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)
    window.addEventListener("resize", measure)
    return () => {
      observer.disconnect()
      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>
  )
}

/** A labeled segmented control on Base UI ToggleGroup. One value is always selected. */
function Segmented<T extends string>({
  label,
  value,
  onValueChange,
  options,
  className,
}: {
  label: string
  value: T
  onValueChange: (value: T) => void
  options: readonly { value: T; label: string }[]
  className?: string
}) {
  return (
    <div className={cn("flex max-w-full min-w-0 flex-col gap-1.5", className)}>
      <span className="text-[0.75rem]/[1rem] text-(color:--chatcn-fg-subtle) font-medium">{label}</span>
      <ToggleGroup
        value={[value]}
        onValueChange={(next) => {
          const picked = next[0] as T | undefined
          if (picked) onValueChange(picked)
        }}
        aria-label={label}
        className="bg-(color:--chatcn-fill) rounded-(--chatcn-radius-md) chatcn-scroll flex h-8 w-fit max-w-full items-center gap-0.5 overflow-x-auto p-0.5 pointer-coarse:h-11"
      >
        {options.map((option) => (
          <Toggle
            key={option.value}
            value={option.value}
            className={cn(
              "chatcn-focus rounded-(--chatcn-radius-sm) text-[0.8125rem]/[1.25rem] inline-flex h-full shrink-0 items-center px-2.5 font-medium whitespace-nowrap",
              "text-(color:--chatcn-fg-subtle) ease-(--chatcn-ease-standard) transition-[color,background-color,box-shadow] duration-150",
              "hover:text-(color:--chatcn-fg) data-[pressed]:bg-(color:--chatcn-card) data-[pressed]:text-(color:--chatcn-fg) data-[pressed]:shadow-(--chatcn-shadow-xs)",
            )}
          >
            {option.label}
          </Toggle>
        ))}
      </ToggleGroup>
    </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>
  )
}

export default function OscilloscopePreview() {
  const [mode, setMode] = useCycle<OscilloscopeMode>(MODE_VALUES, 1600)
  const gain = useSpeechGain()
  return (
    <FitFrame>
      <div className="flex w-full flex-col items-center justify-center gap-6 p-6">
        <div className="flex w-full max-w-xl flex-col gap-4">
          <Oscilloscope mode={mode} gain={gain} label="Voice signal" />
          <div data-fit-hide>
            <Segmented label="Mode" value={mode} onValueChange={setMode} options={MODES} />
          </div>
        </div>
        <MoreOn slug="oscilloscope">Plug in a microphone or any audio node. On</MoreOn>
      </div>
    </FitFrame>
  )
}