Import AITURK IDE 1.0.0-beta.1 from Hermes 63279301; preserve MIT license

ui-tui/src/lib/viewportStore.ts

@@ -0,0 +1,136 @@
+import type { ScrollBoxHandle } from '@hermes/ink'
+import type { RefObject } from 'react'
+import { useCallback, useMemo, useSyncExternalStore } from 'react'
+
+export interface ViewportSnapshot {
+  atBottom: boolean
+  bottom: number
+  pending: number
+  scrollHeight: number
+  top: number
+  viewportHeight: number
+}
+
+export interface ScrollbarSnapshot {
+  scrollHeight: number
+  top: number
+  viewportHeight: number
+}
+
+const EMPTY: ViewportSnapshot = {
+  atBottom: true,
+  bottom: 0,
+  pending: 0,
+  scrollHeight: 0,
+  top: 0,
+  viewportHeight: 0
+}
+
+const EMPTY_SCROLLBAR: ScrollbarSnapshot = {
+  scrollHeight: 0,
+  top: 0,
+  viewportHeight: 0
+}
+
+export function getViewportSnapshot(s?: ScrollBoxHandle | null): ViewportSnapshot {
+  if (!s) {
+    return EMPTY
+  }
+
+  const pending = s.getPendingDelta()
+  const top = Math.max(0, s.getScrollTop() + pending)
+  const viewportHeight = Math.max(0, s.getViewportHeight())
+  const cachedScrollHeight = Math.max(viewportHeight, s.getScrollHeight())
+  let scrollHeight = cachedScrollHeight
+  const bottom = top + viewportHeight
+  let atBottom = s.isSticky() || bottom >= scrollHeight - 2
+
+  if (!atBottom) {
+    scrollHeight = Math.max(viewportHeight, s.getFreshScrollHeight?.() ?? cachedScrollHeight)
+    atBottom = s.isSticky() || bottom >= scrollHeight - 2
+  }
+
+  return {
+    atBottom,
+    bottom,
+    pending,
+    scrollHeight,
+    top,
+    viewportHeight
+  }
+}
+
+export function viewportSnapshotKey(v: ViewportSnapshot) {
+  return `${v.atBottom ? 1 : 0}:${Math.ceil(v.top / 8) * 8}:${v.viewportHeight}:${Math.ceil(v.scrollHeight / 8) * 8}:${v.pending}`
+}
+
+export function getScrollbarSnapshot(s?: ScrollBoxHandle | null): ScrollbarSnapshot {
+  if (!s) {
+    return EMPTY_SCROLLBAR
+  }
+
+  const viewportHeight = Math.max(0, s.getViewportHeight())
+  const top = Math.max(0, s.getScrollTop())
+  const cachedScrollHeight = Math.max(viewportHeight, s.getScrollHeight())
+  let scrollHeight = cachedScrollHeight
+  let maxTop = Math.max(0, scrollHeight - viewportHeight)
+
+  if (top < maxTop) {
+    const freshScrollHeight = Math.max(viewportHeight, s.getFreshScrollHeight?.() ?? cachedScrollHeight)
+    const freshMaxTop = Math.max(0, freshScrollHeight - viewportHeight)
+
+    if (top >= freshMaxTop) {
+      scrollHeight = freshScrollHeight
+      maxTop = freshMaxTop
+    }
+  }
+
+  return {
+    scrollHeight,
+    top: Math.max(0, Math.min(maxTop, top)),
+    viewportHeight
+  }
+}
+
+export function scrollbarSnapshotKey(v: ScrollbarSnapshot) {
+  return `${v.top}:${v.viewportHeight}:${v.scrollHeight}`
+}
+
+export function useViewportSnapshot(scrollRef: RefObject<ScrollBoxHandle | null>): ViewportSnapshot {
+  const key = useSyncExternalStore(
+    useCallback((cb: () => void) => scrollRef.current?.subscribe(cb) ?? (() => {}), [scrollRef]),
+    () => viewportSnapshotKey(getViewportSnapshot(scrollRef.current)),
+    () => viewportSnapshotKey(EMPTY)
+  )
+
+  return useMemo(() => {
+    const [atBottom = '1', top = '0', viewportHeight = '0', scrollHeight = '0', pending = '0'] = key.split(':')
+
+    return {
+      atBottom: atBottom === '1',
+      bottom: Number(top) + Number(viewportHeight),
+      pending: Number(pending),
+      scrollHeight: Number(scrollHeight),
+      top: Number(top),
+      viewportHeight: Number(viewportHeight)
+    }
+  }, [key])
+}
+
+export function useScrollbarSnapshot(scrollRef: RefObject<ScrollBoxHandle | null>): ScrollbarSnapshot {
+  const key = useSyncExternalStore(
+    useCallback((cb: () => void) => scrollRef.current?.subscribe(cb) ?? (() => {}), [scrollRef]),
+    () => scrollbarSnapshotKey(getScrollbarSnapshot(scrollRef.current)),
+    () => scrollbarSnapshotKey(EMPTY_SCROLLBAR)
+  )
+
+  return useMemo(() => {
+    const [top = '0', viewportHeight = '0', scrollHeight = '0'] = key.split(':')
+
+    return {
+      scrollHeight: Number(scrollHeight),
+      top: Number(top),
+      viewportHeight: Number(viewportHeight)
+    }
+  }, [key])
+}