Clarification on Default Value for Start Date in Door Lock Online Tile Limited Password repeat section (#331)

…t with dialog information showing the error and if the init start date
is null fill it with the needed value

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## Jira Ticket
[SP-368](https://syncrow.atlassian.net/browse/SP-368)

## Description

now if user change end time into value before start time it prevent it
and give init start date value to start date

## Type of Change

<!--- Put an `x` in all the boxes that apply: -->

- [ ] ✨ New feature (non-breaking change which adds functionality)
- [x] 🛠️ Bug fix (non-breaking change which fixes an issue)
- [ ] ❌ Breaking change (fix or feature that would cause existing
functionality to change)
- [ ] 🧹 Code refactor
- [ ] ✅ Build configuration change
- [ ] 📝 Documentation
- [ ] 🗑️ Chore 


[SP-368]:
https://syncrow.atlassian.net/browse/SP-368?atlOrigin=eyJpIjoiNWRkNTljNzYxNjVmNDY3MDlhMDU5Y2ZhYzA5YTRkZjUiLCJwIjoiZ2l0aHViLWNvbS1KU1cifQ

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(),
@@ -94,7 +96,8 @@ 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,
       initialTime: TimeOfDay.now(),
@@ -105,18 +108,14 @@ class VisitorPasswordBloc
               primary: ColorsManager.primaryColor,
               onSurface: Colors.black,
             ),
-              buttonTheme: const ButtonThemeData(
-                colorScheme: ColorScheme.light(
-                  primary: Colors.green,
-                ),
-              ),
           ),
           child: child!,
         );
       },
     );
 
-      if (timePicked != null) {
+    if (timePicked == null) return;
+
     final selectedDateTime = DateTime(
       picked.year,
       picked.month,
@@ -124,57 +123,98 @@ class VisitorPasswordBloc
       timePicked.hour,
       timePicked.minute,
     );
-
+    final selectedTimestamp = selectedDateTime.millisecondsSinceEpoch ~/ 1000;
-        final selectedTimestamp =
+    final currentTimestamp = DateTime.now().millisecondsSinceEpoch ~/ 1000;
-            selectedDateTime.millisecondsSinceEpoch ~/ 1000;
 
     if (event.isStart) {
+      // START TIME VALIDATION
       if (expirationTimeTimeStamp != null &&
           selectedTimestamp > expirationTimeTimeStamp!) {
-            CustomSnackBar.displaySnackBar(
-              'Effective Time cannot be later than Expiration Time.',
-            );
-            return;
-          }
-          if(selectedTimestamp < DateTime.now().millisecondsSinceEpoch ~/ 1000) {
-            if(selectedTimestamp < DateTime.now().millisecondsSinceEpoch ~/ 1000) {
         await showDialog<void>(
           context: event.context,
           builder: (context) => AlertDialog(
-                  title: const Text('Effective Time cannot be earlier than current time.'),
+            title: const Text(
+              'Effective Time cannot be later than Expiration Time.',
+            ),
             actionsAlignment: MainAxisAlignment.center,
-                  content: 
+            content: FilledButton(
-                    FilledButton(
               onPressed: () {
                 Navigator.of(event.context).pop();
-                        add(SelectTimeVisitorPassword(context: event.context, isStart: true, isRepeat: false));
+                add(SelectTimeVisitorPassword(
+                  context: event.context,
+                  isStart: true,
+                  isRepeat: false,
+                ));
               },
               child: const Text('OK'),
             ),
-                  
           ),
         );
-            }
         return;
       }
+
+      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!) {
-            CustomSnackBar.displaySnackBar(
+        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(
       ToggleRepeatEvent event, Emitter<VisitorPasswordState> emit) {