| 1 | import { useEffect, useRef } from "react"; |
| 2 | import gsap from "gsap"; |
| 3 | import { DUR_SLOW, EASE_OUT, prefersReducedMotion } from "./gsapAnimations"; |
| 4 | |
| 5 | // Animates each data-entrance element in once. First mount (and every |
| 6 | // resetKey change) pre-seeds the seen set so restored history never animates; |
| 7 | // the scan only runs when deps changes, skipping streaming token updates. |
| 8 | export function useEntranceAnimation<T extends HTMLElement>( |
| 9 | resetKey?: unknown, |
| 10 | deps?: unknown, |
| 11 | selector = "[data-entrance]", |
| 12 | ) { |
| 13 | const ref = useRef<T | null>(null); |
| 14 | const seen = useRef(new Set<string>()); |
| 15 | const timerRef = useRef<number | null>(null); |
| 16 | const firstRun = useRef(true); |
| 17 | const prevResetKey = useRef(resetKey); |
| 18 | |
| 19 | // Reset on session switch. |
| 20 | if (prevResetKey.current !== resetKey) { |
| 21 | prevResetKey.current = resetKey; |
| 22 | seen.current = new Set(); |
| 23 | firstRun.current = true; |
| 24 | if (timerRef.current !== null) { |
| 25 | clearTimeout(timerRef.current); |
| 26 | timerRef.current = null; |
| 27 | } |
| 28 | } |
| 29 | |
| 30 | // Single effect: on first mount, pre-seed the seen set (no animation). |
| 31 | // On subsequent deps changes, animate only newly-added elements. |
| 32 | // This avoids the double querySelectorAll that two separate effects cause. |
| 33 | useEffect(() => { |
| 34 | const container = ref.current; |
| 35 | if (!container) return; |
| 36 | |
| 37 | const entries: HTMLElement[] = []; |
| 38 | container.querySelectorAll(selector).forEach((el) => { |
| 39 | const id = el.getAttribute("data-entrance"); |
| 40 | if (id && !seen.current.has(id)) { |
| 41 | seen.current.add(id); |
| 42 | // First run: just record IDs, don't animate history items. |
| 43 | if (firstRun.current) return; |
| 44 | entries.push(el as HTMLElement); |
| 45 | } |
| 46 | }); |
| 47 | |
| 48 | if (firstRun.current) { |
| 49 | firstRun.current = false; |
| 50 | return; // Pre-seeded — no entrance animation for history items. |
| 51 | } |
| 52 | |
| 53 | if (entries.length === 0) return; |
| 54 | |
| 55 | const reduced = prefersReducedMotion(); |
| 56 | if (reduced) { |
| 57 | gsap.set(entries, { opacity: 1, clearProps: "transform" }); |
| 58 | return; |
| 59 | } |
| 60 | |
| 61 | // Batch: if multiple items arrive in the same tick, animate together. |
| 62 | if (timerRef.current !== null) clearTimeout(timerRef.current); |
| 63 | timerRef.current = window.setTimeout(() => { |
| 64 | timerRef.current = null; |
| 65 | gsap.fromTo( |
| 66 | entries, |
| 67 | { opacity: 0, y: 12 }, |
| 68 | { |
| 69 | opacity: 1, |
| 70 | y: 0, |
| 71 | duration: DUR_SLOW, |
| 72 | ease: EASE_OUT, |
| 73 | stagger: itemsStagger(entries.length), |
| 74 | clearProps: "transform", |
| 75 | }, |
| 76 | ); |
| 77 | }, 16); |
| 78 | |
| 79 | return () => { |
| 80 | if (timerRef.current !== null) clearTimeout(timerRef.current); |
| 81 | }; |
| 82 | // Only re-scan when deps change — NOT on every render. |
| 83 | }, [deps]); // eslint-disable-line react-hooks/exhaustive-deps |
| 84 | |
| 85 | return ref; |
| 86 | } |
| 87 | |
| 88 | function itemsStagger(count: number): number { |
| 89 | if (count <= 1) return 0; |
| 90 | if (count <= 3) return 0.06; |
| 91 | return 0.04; |
| 92 | } |
| 93 |