Function createScrollPersistence

packages/app/src/context/layout-scroll.ts:16–126

(opts: Options)

}

export function createScrollPersistence(opts: Options) {
  const wait = opts.debounceMs ?? 200
  const [cache, setCache] = createStore<Record<string, ScrollMap>>({})
  const dirty = new Set<string>()
  const timers = new Map<string, ReturnType<typeof setTimeout>>()

  function clone(input?: ScrollMap) {
    const out: ScrollMap = {}
    if (!input) return out

    for (const key of Object.keys(input)) {
      const pos = input[key]
      if (!pos) continue
      out[key] = { x: pos.x, y: pos.y }
    }

    return out
  }

  function seed(sessionKey: string) {
    const next = clone(opts.getSnapshot(sessionKey))
    const current = cache[sessionKey]
    if (!current) {
      setCache(sessionKey, next)
      return
    }

    if (Object.keys(current).length > 0) return
    if (Object.keys(next).length === 0) return
    setCache(sessionKey, next)
  }

  function scroll(sessionKey: string, tab: string) {
    seed(sessionKey)
    return cache[sessionKey]?.[tab] ?? opts.getSnapshot(sessionKey)?.[tab]
  }

  function schedule(sessionKey: string) {
    const prev = timers.get(sessionKey)
    if (prev) clearTimeout(prev)
    timers.set(
      sessionKey,
      setTimeout(() => flush(sessionKey), wait),
    )
  }

  function setScroll(sessionKey: string, tab: string, pos: SessionScroll) {
    seed(sessionKey)

    const prev = cache[sessionKey]?.[tab]
    if (prev?.x === pos.x && prev?.y === pos.y) return

    setCache(sessionKey, tab, { x: pos.x, y: pos.y })
    dirty.add(sessionKey)
    schedule(sessionKey)
  }

  function flush(sessionKey: string) {