Dashboard: Improve Progress bar implmentation with useTransition hook (#6769)

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## PR-Codex overview
This PR refines the `useDashboardRouter` functionality by implementing a progress bar during route transitions and removing the use of `LoadingRouteHref`. It introduces `RouteStartTransitionFn` for managing transition states and modifies the `DashboardRouterTopProgressBar` to reflect these changes.

### Detailed summary
- Removed `usePathname` and `useSearchParams` from `useRouterLoadingStatus`.
- Replaced `LoadingRouteHref` with `RouteStartTransitionFn` for managing transition states.
- Updated `replace` and `push` methods in `useDashboardRouter` to use `startTransition`.
- Refactored `DashboardRouterTopProgressBarInner` to use `isRouteLoading`.
- Adjusted progress bar visibility and state management based on `isRouteLoading`.

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Author: MananTank

apps/dashboard/src/@/lib/DashboardRouter.tsx

@@ -1,75 +1,64 @@
 "use client";
 
 // eslint-disable-next-line no-restricted-imports
-import { usePathname, useRouter, useSearchParams } from "next/navigation";
+import { useRouter } from "next/navigation";
 import {
-  Suspense,
+  type TransitionStartFunction,
   useEffect,
   useMemo,
   useRef,
   useState,
   useSyncExternalStore,
+  useTransition,
 } from "react";
 import { createStore } from "./reactive";
 
 // Using useDashboardRouter instead of useRouter gives us a nice progress bar on top of the page when navigating using router.push or router.replace
 
-// using a store instead of context to avoid triggering re-renders on root component
-const LoadingRouteHref = createStore<string | undefined>(undefined);
+const RouteStartTransitionFn = createStore<TransitionStartFunction>((fn) =>
+  fn(),
+);
 
 export function useDashboardRouter() {
+  const startTransition = useSyncExternalStore(
+    RouteStartTransitionFn.subscribe,
+    RouteStartTransitionFn.getValue,
+    RouteStartTransitionFn.getValue,
+  );
+
   const router = useRouter();
   return useMemo(() => {
     return {
       ...router,
       replace(href: string, options?: { scroll?: boolean }) {
-        LoadingRouteHref.setValue(href);
-        router.replace(href, options);
+        startTransition(() => {
+          router.replace(href, options);
+        });
       },
       push(href: string, options?: { scroll?: boolean }) {
-        LoadingRouteHref.setValue(href);
-        router.push(href, options);
+        startTransition(() => {
+          router.push(href, options);
+        });
       },
     };
-  }, [router]);
+  }, [router, startTransition]);
 }
 
-function useRouterLoadingStatus() {
-  const loadingHref = useSyncExternalStore(
-    LoadingRouteHref.subscribe,
-    LoadingRouteHref.getValue,
-    LoadingRouteHref.getValue,
-  );
-  const pathname = usePathname();
-  const searchParams = useSearchParams();
-  const searchParamsStr = searchParams?.toString();
-
-  const routerHref = pathname + (searchParamsStr ? `?${searchParamsStr}` : "");
-  const isLoading = loadingHref && loadingHref !== routerHref;
+const wait = (ms: number) => new Promise((resolve) => setTimeout(resolve, ms));
 
-  // reset loading on route load
+export function DashboardRouterTopProgressBar() {
+  const [isRouteLoading, startTransition] = useTransition();
   // eslint-disable-next-line no-restricted-syntax
   useEffect(() => {
-    if (!isLoading) {
-      LoadingRouteHref.setValue(undefined);
-    }
-  }, [isLoading]);
-
-  return isLoading;
-}
+    RouteStartTransitionFn.setValue(startTransition);
+  }, []);
 
-const wait = (ms: number) => new Promise((resolve) => setTimeout(resolve, ms));
-
-// Render this on root
-function DashboardRouterTopProgressBarInner() {
-  const isLoading = useRouterLoadingStatus();
   const [progress, setProgress] = useState(0);
-
   const progressStartedRef = useRef(false);
 
   // eslint-disable-next-line no-restricted-syntax
   useEffect(() => {
-    if (!isLoading) {
+    if (!isRouteLoading) {
       setProgress(0);
       progressStartedRef.current = false;
       return;
@@ -85,7 +74,7 @@ function DashboardRouterTopProgressBarInner() {
 
     async function updateProgressBar(progress: number, delay: number) {
       if (!isMounted) {
-        if (!isLoading) {
+        if (!isRouteLoading) {
           setProgress(100);
         }
         return;
@@ -112,14 +101,14 @@ function DashboardRouterTopProgressBarInner() {
     return () => {
       isMounted = false;
     };
-  }, [isLoading]);
+  }, [isRouteLoading]);
 
-  const width = isLoading ? progress : 100;
+  const width = isRouteLoading ? progress : 100;
   return (
     <span
       className="fixed top-0 block h-[3px] bg-foreground"
       style={{
-        opacity: isLoading ? "100" : "0",
+        opacity: isRouteLoading ? "100" : "0",
         width: `${width}%`,
         transition: width === 0 ? "none" : "width 0.2s ease, opacity 0.3s ease",
         zIndex: "100000000",
@@ -128,12 +117,3 @@ function DashboardRouterTopProgressBarInner() {
     />
   );
 }
-
-// need to wrap with suspense because of useSearchParams usage
-export function DashboardRouterTopProgressBar() {
-  return (
-    <Suspense fallback={null}>
-      <DashboardRouterTopProgressBarInner />
-    </Suspense>
-  );
-}