knowfoolery/frontend/apps/web/src/hooks/useTimer.ts

import { createSignal, onCleanup } from 'solid-js'

export function useTimer(durationMs: number) {
  const [remainingMs, setRemainingMs] = createSignal(durationMs)
  const [isExpired, setIsExpired] = createSignal(false)

  let t: number | undefined
  let startedAt: number | undefined

  const tick = () => {
    if (startedAt == null) return
    const elapsed = Date.now() - startedAt
    const remain = Math.max(0, durationMs - elapsed)
    setRemainingMs(remain)
    if (remain === 0) setIsExpired(true)
  }

  const start = () => {
    if (t != null) return
    startedAt = Date.now()
    tick()
    t = window.setInterval(tick, 250)
  }

  const stop = () => {
    if (t != null) {
      window.clearInterval(t)
      t = undefined
    }
  }

  onCleanup(() => stop())

  return { remainingMs, isExpired, start, stop }
}