Create link component with loader status

src/app/admin/photos/page.tsx

@@ -6,6 +6,7 @@ import AdminPhotosClient from '@/admin/AdminPhotosClient';
 import { revalidatePath } from 'next/cache';
 import { cookies } from 'next/headers';
 import { TIMEZONE_COOKIE_NAME } from '@/utility/timezone';
+import sleep from '@/utility/sleep';
 
 export const maxDuration = 60;
 
@@ -15,6 +16,8 @@ const INFINITE_SCROLL_INITIAL_ADMIN_PHOTOS = 25;
 const INFINITE_SCROLL_MULTIPLE_ADMIN_PHOTOS = 50;
 
 export default async function AdminPhotosPage() {
+  await sleep(3000);
+
   const timezone = (await cookies()).get(TIMEZONE_COOKIE_NAME)?.value;
 
   const [

src/components/LinkWithStatus.tsx

@@ -0,0 +1,111 @@
+'use client';
+
+import {
+  ComponentProps,
+  ReactNode,
+  useCallback,
+  useEffect,
+  useRef,
+  useState,
+} from 'react';
+import Link from 'next/link';
+import { usePathname } from 'next/navigation';
+import clsx from 'clsx/lite';
+
+// Avoid showing spinner for too short a time
+const FLICKER_THRESHOLD = 400;
+// Clear loading status after 10 seconds of inactivity
+const MAX_LOADING_DURATION = 10_000;
+
+export type LinkWithStatusProps = ComponentProps<typeof Link> & {
+  loader?: ReactNode
+}
+
+export default function LinkWithStatus({
+  loader,
+  href, 
+  className,
+  onClick,
+  children,
+  ...props
+}: LinkWithStatusProps) {
+  const path = usePathname();
+
+  const [isLoading, setIsLoading] = useState(false);
+  
+  const isLoadingStartTime = useRef<number | undefined>(undefined);
+
+  const startLoadingTimeout = useRef<NodeJS.Timeout | undefined>(undefined);
+  const stopLoadingTimeout = useRef<NodeJS.Timeout | undefined>(undefined);
+  const maxLoadingTimeout = useRef<NodeJS.Timeout | undefined>(undefined);
+
+  const clearTimeouts = useCallback(() =>
+    [startLoadingTimeout, stopLoadingTimeout, maxLoadingTimeout]
+      .forEach(timeout => {
+        if (timeout.current) { clearTimeout(timeout.current); }
+      }),
+  []);
+
+  const isVisitingLinkHref = path === href;
+
+  useEffect(() => {
+    if (isVisitingLinkHref) {
+      clearTimeouts();
+      const loadingDuration = isLoadingStartTime.current
+        ? Date.now() - isLoadingStartTime.current
+        : 0;
+      if (loadingDuration < FLICKER_THRESHOLD) {
+        stopLoadingTimeout.current = setTimeout(
+          () => { setIsLoading(false); },
+          FLICKER_THRESHOLD - loadingDuration,
+        );
+      } else {
+        setIsLoading(false);
+      }
+    }
+  }, [isVisitingLinkHref, clearTimeouts]);
+
+  // Clear timeouts when unmounting
+  useEffect(() => () => clearTimeouts(), [clearTimeouts]);
+
+  return <Link
+    {...props }
+    href={href}
+    className={clsx(
+      className,
+      'relative',
+    )}
+    onClick={e => {
+      const isOpeningNewTab = e.metaKey || e.ctrlKey;
+      if (!isVisitingLinkHref && !isOpeningNewTab) {
+        startLoadingTimeout.current = setTimeout(
+          () => {
+            isLoadingStartTime.current = Date.now();
+            setIsLoading(true);
+          },
+          FLICKER_THRESHOLD,
+        );
+        maxLoadingTimeout.current = setTimeout(
+          () => { setIsLoading(false); },
+          MAX_LOADING_DURATION,
+        );
+      }
+      onClick?.(e);
+    }}
+  >
+    <span className={clsx(
+      'flex transition-opacity',
+      loader
+        ? isLoading ? 'opacity-0' : 'opacity-100'
+        : isLoading ? 'opacity-50' : 'opacity-100',
+    )}>
+      {children}
+    </span>
+    {isLoading && loader && <span className={clsx(
+      'absolute inset-0',
+      'flex items-center justify-center',
+    )}>
+      {loader}
+    </span>}
+  </Link>;
+}

src/components/SwitcherItem.tsx

@@ -1,7 +1,8 @@
-import Link from 'next/link';
 import { clsx } from 'clsx/lite';
 import { SHOULD_PREFETCH_ALL_LINKS } from '@/site/config';
-import { JSX } from 'react';
+import { JSX, ReactNode } from 'react';
+import LinkWithStatus from './LinkWithStatus';
+import Spinner from './Spinner';
 
 export default function SwitcherItem({
   icon,
@@ -36,17 +37,23 @@ export default function SwitcherItem({
       : 'hover:text-gray-700 dark:hover:text-gray-400',
   );
 
-  const renderIcon = () => noPadding
-    ? icon
+  const renderContent = (content: ReactNode) => noPadding
+    ? content
     : <div className="w-[28px] h-[24px] flex items-center justify-center">
-      {icon}
+      {content}
     </div>;
 
   return (
     href
-      ? <Link {...{ title, href, className, prefetch }}>
-        {renderIcon()}
-      </Link>
-      : <div {...{ title, onClick, className }}>{renderIcon()}</div>
+      ? <LinkWithStatus {...{
+        title,
+        href,
+        className,
+        prefetch,
+        loader: <Spinner />,
+      }}>
+        {renderContent(icon)}
+      </LinkWithStatus>
+      : <div {...{ title, onClick, className }}>{renderContent(icon)}</div>
   );
 };

src/photo/PhotoEscapeHandler.tsx

@@ -19,7 +19,7 @@ export default function PhotoEscapeHandler() {
   useEffect(() => {
     if (shouldRespondToKeyboardCommands) {
       const onKeyUp = (e: KeyboardEvent) => {
-        if (e.key.toUpperCase() === 'ESCAPE' && escapePath) {
+        if (e.key?.toUpperCase() === 'ESCAPE' && escapePath) {
           router.push(escapePath, { scroll: false });
         };
       };