1 files changed, 71 insertions, 23 deletions

diff --git a/packages/frontend/src/scripts/focus.ts b/packages/frontend/src/scripts/focus.ts
index ea6ee61c88..eb2da5ad86 100644
--- a/packages/frontend/src/scripts/focus.ts
+++ b/packages/frontend/src/scripts/focus.ts
@@ -3,30 +3,78 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-export function focusPrev(el: Element | null, self = false, scroll = true) {
-	if (el == null) return;
-	if (!self) el = el.previousElementSibling;
-	if (el) {
-		if (el.hasAttribute('tabindex')) {
-			(el as HTMLElement).focus({
-				preventScroll: !scroll,
-			});
-		} else {
-			focusPrev(el.previousElementSibling, true);
-		}
+import { getScrollPosition, getScrollContainer, getStickyBottom, getStickyTop } from '@/scripts/scroll.js';
+import { getElementOrNull, getNodeOrNull } from '@/scripts/get-dom-node-or-null.js';
+
+type MaybeHTMLElement = EventTarget | Node | Element | HTMLElement;
+
+export const isFocusable = (input: MaybeHTMLElement | null | undefined): input is HTMLElement => {
+	if (input == null || !(input instanceof HTMLElement)) return false;
+
+	if (input.tabIndex < 0) return false;
+	if ('disabled' in input && input.disabled === true) return false;
+	if ('readonly' in input && input.readonly === true) return false;
+
+	if (!input.ownerDocument.contains(input)) return false;
+
+	const style = window.getComputedStyle(input);
+	if (style.display === 'none') return false;
+	if (style.visibility === 'hidden') return false;
+	if (style.opacity === '0') return false;
+	if (style.pointerEvents === 'none') return false;
+
+	return true;
+};
+
+export const focusPrev = (input: MaybeHTMLElement | null | undefined, self = false, scroll = true) => {
+	const element = self ? input : getElementOrNull(input)?.previousElementSibling;
+	if (element == null) return;
+	if (isFocusable(element)) {
+		focusOrScroll(element, scroll);
+	} else {
+		focusPrev(element, false, scroll);
 	}
-}
+};
 
-export function focusNext(el: Element | null, self = false, scroll = true) {
-	if (el == null) return;
-	if (!self) el = el.nextElementSibling;
-	if (el) {
-		if (el.hasAttribute('tabindex')) {
-			(el as HTMLElement).focus({
-				preventScroll: !scroll,
-			});
-		} else {
-			focusPrev(el.nextElementSibling, true);
+export const focusNext = (input: MaybeHTMLElement | null | undefined, self = false, scroll = true) => {
+	const element = self ? input : getElementOrNull(input)?.nextElementSibling;
+	if (element == null) return;
+	if (isFocusable(element)) {
+		focusOrScroll(element, scroll);
+	} else {
+		focusNext(element, false, scroll);
+	}
+};
+
+export const focusParent = (input: MaybeHTMLElement | null | undefined, self = false, scroll = true) => {
+	const element = self ? input : getNodeOrNull(input)?.parentElement;
+	if (element == null) return;
+	if (isFocusable(element)) {
+		focusOrScroll(element, scroll);
+	} else {
+		focusParent(element, false, scroll);
+	}
+};
+
+const focusOrScroll = (element: HTMLElement, scroll: boolean) => {
+	if (scroll) {
+		const scrollContainer = getScrollContainer(element) ?? document.documentElement;
+		const scrollContainerTop = getScrollPosition(scrollContainer);
+		const stickyTop = getStickyTop(element, scrollContainer);
+		const stickyBottom = getStickyBottom(element, scrollContainer);
+		const top = element.getBoundingClientRect().top;
+		const bottom = element.getBoundingClientRect().bottom;
+
+		let scrollTo = scrollContainerTop;
+		if (top < stickyTop) {
+			scrollTo += top - stickyTop;
+		} else if (bottom > window.innerHeight - stickyBottom) {
+			scrollTo += bottom - window.innerHeight + stickyBottom;
 		}
+		scrollContainer.scrollTo({ top: scrollTo, behavior: 'instant' });
+	}
+
+	if (document.activeElement !== element) {
+		element.focus({ preventScroll: true });
 	}
-}
+};