import * as React from "react"

/**
 * When Leo greets, measured from the arrival starting.
 *
 * Not at mount, which is where the greeting used to fire and where it could not
 * be seen. Two reasons, and both of them are about what else is happening in
 * that first frame. The gesture is a ~420ms keyframe on SVG transforms driven
 * from JavaScript, so at mount it competes with the page's own first layout and
 * the frames that carry it are the frames most likely to be dropped. And the
 * launcher arrives icon-only with its wash still 150ms out, so a greeting there
 * lands before there is anything to greet from: the star had finished moving
 * before the chip started opening, which reads as the star not animating at all.
 *
 * This puts the flick inside the opening beat instead
 * (`--ask-leo-label-open-*` in `globals.css`: 140ms in, 380ms long), so the star
 * and the box move together and the label's ink and shimmer follow it.
 */
const GREETING_DELAY_MS = 160

/**
 * How long the greeting is held — the gesture plus its sparkle stagger, with a
 * frame in hand.
 *
 * Released rather than left on for the rest of the arrival, because the state it
 * drives (`LeoIcon`'s `invited`) is a one-shot: while it stays set, a hover is
 * not a state change, so Leo would ignore the pointer for as long as the
 * arrival claims to be running.
 */
const GREETING_HOLD_MS = 600

/**
 * True for the stretch of an arrival where Leo should be mid-gesture.
 *
 * `active` is the arrival itself (`useOneShotIntro`). This delays the greeting
 * into it and then lets go, so the caller can hand the result straight to
 * `LeoIcon`'s `motionActive` beside its own hover state.
 */
export function useStagedGreeting(active: boolean): boolean {
  const [greeting, setGreeting] = React.useState(false)

  React.useEffect(() => {
    if (!active) return
    let release = 0
    const start = window.setTimeout(() => {
      setGreeting(true)
      release = window.setTimeout(() => setGreeting(false), GREETING_HOLD_MS)
    }, GREETING_DELAY_MS)
    return () => {
      window.clearTimeout(start)
      window.clearTimeout(release)
    }
  }, [active])

  return greeting
}