now if user change end time into value before start time it prevent it with dialog information showing the error and if the init start date is null fill it with the needed value

lib/pages/visitor_password/bloc/visitor_password_bloc.dart

@@ -21,7 +21,6 @@ import 'package:syncrow_web/utils/snack_bar.dart';
 
 class VisitorPasswordBloc
     extends Bloc<VisitorPasswordEvent, VisitorPasswordState> {
-
   VisitorPasswordBloc() : super(VisitorPasswordInitial()) {
     on<SelectUsageFrequency>(selectUsageFrequency);
     on<FetchDevice>(_onFetchDevice);
@@ -87,6 +86,9 @@ class VisitorPasswordBloc
     SelectTimeVisitorPassword event,
     Emitter<VisitorPasswordState> emit,
   ) async {
+    // Ensure expirationTimeTimeStamp has a value
+    effectiveTimeTimeStamp ??= DateTime.now().millisecondsSinceEpoch ~/ 1000;
+
     final DateTime? picked = await showDatePicker(
       context: event.context,
       initialDate: DateTime.now(),
@@ -94,86 +96,124 @@ class VisitorPasswordBloc
       lastDate: DateTime.now().add(const Duration(days: 5095)),
     );
 
-    if (picked != null) {
+    if (picked == null) return;
-      final TimeOfDay? timePicked = await showTimePicker(
+
-        context: event.context,
+    final TimeOfDay? timePicked = await showTimePicker(
-        initialTime: TimeOfDay.now(),
+      context: event.context,
-        builder: (context, child) {
+      initialTime: TimeOfDay.now(),
-          return Theme(
+      builder: (context, child) {
-            data: ThemeData.light().copyWith(
+        return Theme(
-              colorScheme: const ColorScheme.light(
+          data: ThemeData.light().copyWith(
-                primary: ColorsManager.primaryColor,
+            colorScheme: const ColorScheme.light(
-                onSurface: Colors.black,
+              primary: ColorsManager.primaryColor,
-              ),
+              onSurface: Colors.black,
-              buttonTheme: const ButtonThemeData(
-                colorScheme: ColorScheme.light(
-                  primary: Colors.green,
-                ),
-              ),
             ),
-            child: child!,
+          ),
-          );
+          child: child!,
-        },
-      );
-
-      if (timePicked != null) {
-        final selectedDateTime = DateTime(
-          picked.year,
-          picked.month,
-          picked.day,
-          timePicked.hour,
-          timePicked.minute,
         );
+      },
+    );
 
-        final selectedTimestamp =
+    if (timePicked == null) return;
-            selectedDateTime.millisecondsSinceEpoch ~/ 1000;
 
-        if (event.isStart) {
+    final selectedDateTime = DateTime(
-          if (expirationTimeTimeStamp != null &&
+      picked.year,
-              selectedTimestamp > expirationTimeTimeStamp!) {
+      picked.month,
-            CustomSnackBar.displaySnackBar(
+      picked.day,
+      timePicked.hour,
+      timePicked.minute,
+    );
+    final selectedTimestamp = selectedDateTime.millisecondsSinceEpoch ~/ 1000;
+    final currentTimestamp = DateTime.now().millisecondsSinceEpoch ~/ 1000;
+
+    if (event.isStart) {
+      // START TIME VALIDATION
+      if (expirationTimeTimeStamp != null &&
+          selectedTimestamp > expirationTimeTimeStamp!) {
+        await showDialog<void>(
+          context: event.context,
+          builder: (context) => AlertDialog(
+            title: const Text(
               'Effective Time cannot be later than Expiration Time.',
-            );
+            ),
-            return;
+            actionsAlignment: MainAxisAlignment.center,
-          }
+            content: FilledButton(
-          if(selectedTimestamp < DateTime.now().millisecondsSinceEpoch ~/ 1000) {
+              onPressed: () {
-            if(selectedTimestamp < DateTime.now().millisecondsSinceEpoch ~/ 1000) {
+                Navigator.of(event.context).pop();
-              await showDialog<void>(
+                add(SelectTimeVisitorPassword(
-                context: event.context,
+                  context: event.context,
-                builder: (context) => AlertDialog(
+                  isStart: true,
-                  title: const Text('Effective Time cannot be earlier than current time.'),
+                  isRepeat: false,
-                  actionsAlignment: MainAxisAlignment.center,
+                ));
-                  content: 
+              },
-                    FilledButton(
+              child: const Text('OK'),
-                      onPressed: () {
+            ),
-                        Navigator.of(event.context).pop();
+          ),
-                        add(SelectTimeVisitorPassword(context: event.context, isStart: true, isRepeat: false));
+        );
-                      },
+        return;
-                      child: const Text('OK'),
-                    ),
-                  
-                ),
-              );
-            }
-            return;
-          }
-          effectiveTimeTimeStamp = selectedTimestamp;
-          startTimeAccess = selectedDateTime.toString().split('.').first;
-        } else {
-          if (effectiveTimeTimeStamp != null &&
-              selectedTimestamp < effectiveTimeTimeStamp!) {
-            CustomSnackBar.displaySnackBar(
-              'Expiration Time cannot be earlier than Effective Time.',
-            );
-            return;
-          }
-          expirationTimeTimeStamp = selectedTimestamp;
-          endTimeAccess = selectedDateTime.toString().split('.').first;
-        }
-        emit(ChangeTimeState());
-        emit(VisitorPasswordInitial());
       }
+
+      if (selectedTimestamp < currentTimestamp) {
+        await showDialog<void>(
+          context: event.context,
+          builder: (context) => AlertDialog(
+            title: const Text(
+              'Effective Time cannot be earlier than current time.',
+            ),
+            actionsAlignment: MainAxisAlignment.center,
+            content: FilledButton(
+              onPressed: () {
+                Navigator.of(event.context).pop();
+                add(SelectTimeVisitorPassword(
+                  context: event.context,
+                  isStart: true,
+                  isRepeat: false,
+                ));
+              },
+              child: const Text('OK'),
+            ),
+          ),
+        );
+        return;
+      }
+
+      // Save effective time
+      effectiveTimeTimeStamp = selectedTimestamp;
+      startTimeAccess = selectedDateTime.toString().split('.').first;
+    } else {
+      // END TIME VALIDATION
+      if (effectiveTimeTimeStamp != null &&
+          selectedTimestamp < effectiveTimeTimeStamp!) {
+        await showDialog<void>(
+          context: event.context,
+          builder: (context) => AlertDialog(
+            title: const Text(
+              'Expiration Time cannot be earlier than Effective Time.',
+            ),
+            actionsAlignment: MainAxisAlignment.center,
+            content: FilledButton(
+              onPressed: () {
+                Navigator.of(event.context).pop();
+                add(SelectTimeVisitorPassword(
+                  context: event.context,
+                  isStart: false,
+                  isRepeat: false,
+                ));
+              },
+              child: const Text('OK'),
+            ),
+          ),
+        );
+        return;
+      }
+
+      // Save expiration time
+      expirationTimeTimeStamp = selectedTimestamp;
+      endTimeAccess = selectedDateTime.toString().split('.').first;
     }
+
+    emit(ChangeTimeState());
+    emit(VisitorPasswordInitial());
   }
 
   bool toggleRepeat(
@@ -213,7 +253,7 @@ class VisitorPasswordBloc
       FetchDevice event, Emitter<VisitorPasswordState> emit) async {
     try {
       emit(DeviceLoaded());
-         final projectUuid = await ProjectManager.getProjectUUID() ?? '';
+      final projectUuid = await ProjectManager.getProjectUUID() ?? '';
 
       data = await AccessMangApi().fetchDoorLockDeviceList(projectUuid);
       emit(TableLoaded(data));