From 272088208630c094b0cee1086a664c533b8d342e Mon Sep 17 00:00:00 2001
From: Alexander Harding <noreply@harding.dev>
Date: Wed, 29 Jan 2025 23:00:34 -0600
Subject: [PATCH] fix: deeplink can be flakey (#1831)

---
 .../java/app/vger/voyager/MainActivity.java   |  8 ++-
 .../ActionRequestHandler.swift                |  4 ++
 src/core/listeners/AppUrlListener.tsx         | 54 ++++++++++++++-----
 3 files changed, 51 insertions(+), 15 deletions(-)

diff --git a/android/app/src/main/java/app/vger/voyager/MainActivity.java b/android/app/src/main/java/app/vger/voyager/MainActivity.java
index 72966b9762..bc1ad25792 100644
--- a/android/app/src/main/java/app/vger/voyager/MainActivity.java
+++ b/android/app/src/main/java/app/vger/voyager/MainActivity.java
@@ -59,7 +59,13 @@ protected void onNewIntent(Intent intent) {
                 return;
             }
 
-            newIntent.setData(Uri.parse(potentialUrl));
+            Uri uri = Uri.parse(potentialUrl);
+
+            // Add a timestamp to the URL to let app know it is not stale
+            Uri.Builder uriBuilder = uri.buildUpon();
+            long currentTime = System.currentTimeMillis() / 1000L;
+            uriBuilder.appendQueryParameter("t", String.valueOf(currentTime));
+            newIntent.setData(uriBuilder.build());
 
             bridge.onNewIntent(newIntent);
         }
diff --git a/ios/App/VoyagerActionExtension/ActionRequestHandler.swift b/ios/App/VoyagerActionExtension/ActionRequestHandler.swift
index 1b42aa0b39..c6a79253a2 100644
--- a/ios/App/VoyagerActionExtension/ActionRequestHandler.swift
+++ b/ios/App/VoyagerActionExtension/ActionRequestHandler.swift
@@ -62,6 +62,10 @@ extension URL {
   var iceCubesAppDeepLink: URL {
     var components = URLComponents(url: self, resolvingAgainstBaseURL: false)!
     components.scheme = "vger"
+
+    // Add a timestamp so the app can check if the deep link is stale or not
+    components.queryItems = (components.queryItems ?? []) + [URLQueryItem(name: "t", value: String(Int(Date().timeIntervalSince1970)))]
+
     return components.url!
   }
 }
diff --git a/src/core/listeners/AppUrlListener.tsx b/src/core/listeners/AppUrlListener.tsx
index 468132d5b0..0f4e61259f 100644
--- a/src/core/listeners/AppUrlListener.tsx
+++ b/src/core/listeners/AppUrlListener.tsx
@@ -11,7 +11,17 @@ import { deepLinkFailed } from "#/helpers/toastMessages";
 import useAppToast from "#/helpers/useAppToast";
 import { useAppSelector } from "#/store";
 
+const PREVIOUS_APP_URL_STORAGE_KEY = "previous-app-url";
+
+(async () => {
+  const response = await App.getLaunchUrl();
+
+  // If normal startup, remove previous app url
+  if (!response?.url) localStorage.removeItem(PREVIOUS_APP_URL_STORAGE_KEY);
+})();
+
 export default function AppUrlListener() {
+  const presentToast = useAppToast();
   const { redirectToLemmyObjectIfNeeded } = useLemmyUrlHandler();
   const knownInstances = useAppSelector(
     (state) => state.instances.knownInstances,
@@ -21,8 +31,7 @@ export default function AppUrlListener() {
   );
   const deepLinkReady = useAppSelector((state) => state.deepLinkReady.ready);
 
-  const appUrlToOpen = useRef<string | undefined>();
-  const presentToast = useAppToast();
+  const appUrlFromEventRef = useRef<string>();
 
   const notReady =
     !knownInstances ||
@@ -30,24 +39,43 @@ export default function AppUrlListener() {
     !connectedInstance ||
     !deepLinkReady;
 
-  const onAppUrl = async (url: string) => {
-    if (notReady) {
-      appUrlToOpen.current = url;
+  const onAppUrlIfNeeded = async () => {
+    // wait for router to get into a good state before pushing
+    // (needed for pushing user profiles from app startup)
+    if (notReady) return;
+
+    // If appUrl received from explicit event, redirect to it
+    if (appUrlFromEventRef.current) {
+      redirectTo(appUrlFromEventRef.current);
+      appUrlFromEventRef.current = undefined;
       return;
     }
 
-    // wait for router to get into a good state before pushing
-    // (needed for pushing user profiles from app startup)
-    const result = await redirectToLemmyObjectIfNeeded(url);
+    const url = (await App.getLaunchUrl())?.url;
 
-    if (result === "not-found") presentToast(deepLinkFailed);
+    if (!url) return;
+
+    // If appUrl received from launch, redirect to it if it's not stale
+    // (the appUrl could be stale if web process was killed, but native wrapper wasn't)
+    if (url === localStorage.getItem(PREVIOUS_APP_URL_STORAGE_KEY)) return;
+
+    redirectTo(url);
   };
 
-  const onAppUrlEvent = useEffectEvent(onAppUrl);
+  async function redirectTo(url: string) {
+    const result = await redirectToLemmyObjectIfNeeded(normalizeObjectUrl(url));
+
+    if (result === "not-found") presentToast(deepLinkFailed);
+
+    localStorage.setItem(PREVIOUS_APP_URL_STORAGE_KEY, url);
+  }
+
+  const onAppUrlIfNeededEvent = useEffectEvent(onAppUrlIfNeeded);
 
   useEffect(() => {
     const listener = App.addListener("appUrlOpen", (event) => {
-      onAppUrlEvent(normalizeObjectUrl(event.url));
+      appUrlFromEventRef.current = event.url;
+      onAppUrlIfNeededEvent();
     });
 
     return () => {
@@ -57,10 +85,8 @@ export default function AppUrlListener() {
 
   useEffect(() => {
     if (notReady) return;
-    if (!appUrlToOpen.current) return;
 
-    onAppUrlEvent(appUrlToOpen.current);
-    appUrlToOpen.current = undefined;
+    onAppUrlIfNeededEvent();
   }, [notReady]);
 
   return null;