app: Keep GlobalStore.lastVisitedAccountId updated

Author: sm-sayedi

lib/model/actions.dart

@@ -21,6 +21,16 @@ Future<void> logOutAccount(GlobalStore globalStore, int accountId) async {
   await globalStore.removeAccount(accountId);
 }
 
+Future<void> removeLastVisitedAccountIfNecessary(GlobalStore store, int loggedOutAccountId) async {
+  // If account is not logged out yet, do nothing.
+  if (store.getAccount(loggedOutAccountId) != null) return;
+
+  // If the logged-out account is different than the last visited one, do nothing.
+  if (loggedOutAccountId != store.lastVisitedAccountId) return;
+
+  await store.deleteLastVisitedAccount();
+}
+
 Future<void> unregisterToken(GlobalStore globalStore, int accountId) async {
   final account = globalStore.getAccount(accountId);
   if (account == null) return; // TODO(log)

lib/widgets/app.dart

@@ -254,6 +254,7 @@ class _ZulipAppState extends State<ZulipApp> with WidgetsBindingObserver {
             if (widget.navigatorObservers != null)
               ...widget.navigatorObservers!,
             _PreventEmptyStack(),
+            _UpdateLastVisitedAccount(GlobalStoreWidget.of(context)),
           ],
           builder: (BuildContext context, Widget? child) {
             if (!ZulipApp.ready.value) {
@@ -305,6 +306,44 @@ class _PreventEmptyStack extends NavigatorObserver {
   }
 }
 
+class _UpdateLastVisitedAccount extends NavigatorObserver {
+  _UpdateLastVisitedAccount(this.globalStore);
+
+  final GlobalStore globalStore;
+
+  void _changeLastVisitedAccountIfNecessary(Route<dynamic>? route) {
+    if (route case AccountPageRouteMixin(accountId: var new_)) {
+      final old = globalStore.lastVisitedAccountId;
+      switch ((old, new_)) {
+        case (null, int _):
+          globalStore.insertLastVisitedAccount(new_);
+        case (int _, int _) when old != new_:
+          globalStore.updateLastVisitedAccount(new_);
+      }
+    }
+  }
+
+  @override
+  void didPush(Route<void> route, Route<void>? previousRoute) {
+    _changeLastVisitedAccountIfNecessary(route);
+  }
+
+  @override
+  void didPop(Route<void> route, Route<void>? previousRoute) {
+    _changeLastVisitedAccountIfNecessary(previousRoute);
+  }
+
+  @override
+  void didRemove(Route<void> route, Route<void>? previousRoute) {
+    _changeLastVisitedAccountIfNecessary(previousRoute);
+  }
+
+  @override
+  void didReplace({Route<void>? newRoute, Route<void>? oldRoute}) {
+    _changeLastVisitedAccountIfNecessary(newRoute);
+  }
+}
+
 class ChooseAccountPage extends StatelessWidget {
   const ChooseAccountPage({super.key});
 
@@ -337,7 +376,12 @@ class ChooseAccountPage extends StatelessWidget {
                 if (await dialog.result == true) {
                   if (!context.mounted) return;
                   // TODO error handling if db write fails?
-                  unawaited(logOutAccount(GlobalStoreWidget.of(context), accountId));
+                  unawaited(Future(() async {
+                    if (!context.mounted) return;
+                    await logOutAccount(GlobalStoreWidget.of(context), accountId);
+                    if (!context.mounted) return;
+                    await removeLastVisitedAccountIfNecessary(GlobalStoreWidget.of(context), accountId);
+                  }));
                 }
               },
               child: Text(zulipLocalizations.chooseAccountPageLogOutButton)),