Couple fixes for beta.

Wino.Mail.ViewModels/AccountSetupProgressPageViewModel.cs

@@ -220,7 +220,12 @@ public partial class AccountSetupProgressPageViewModel : MailBaseViewModel
                     _createdAccount.Base64ProfilePictureData = profileResult.ProfileInformation.Base64ProfilePictureData;
 
                     if (!string.IsNullOrEmpty(profileResult.ProfileInformation.AccountAddress))
+                    {
+                        if (await _accountService.AccountAddressExistsAsync(profileResult.ProfileInformation.AccountAddress, _createdAccount.Id).ConfigureAwait(false))
+                            throw new InvalidOperationException(Translator.DialogMessage_AccountAddressExistsMessage);
+
                         _createdAccount.Address = profileResult.ProfileInformation.AccountAddress;
+                    }
 
                     await _accountService.UpdateProfileInformationAsync(_createdAccount.Id, profileResult.ProfileInformation);
                 }

Wino.Mail.ViewModels/ImapCalDavSettingsPageViewModel.cs

@@ -34,6 +34,7 @@ public partial class ImapCalDavSettingsPageViewModel : MailBaseViewModel
     private Guid _editingAccountId;
     private SpecialImapProvider _editingSpecialImapProvider;
     private TaskCompletionSource<ImapCalDavSetupResult> _completionSource;
+    private AccountCreationDialogResult _accountCreationContext;
     private bool _isCompletionFinalized;
     private bool _localOnlyInfoShown;
 
@@ -283,6 +284,7 @@ public partial class ImapCalDavSettingsPageViewModel : MailBaseViewModel
         _pageMode = context.Mode;
         _editingAccountId = context.AccountId;
         _completionSource = context.CompletionSource;
+        _accountCreationContext = context.AccountCreationDialogResult;
         _isCompletionFinalized = false;
         _localOnlyInfoShown = false;
         SelectedSetupTabIndex = 0;
@@ -406,6 +408,13 @@ public partial class ImapCalDavSettingsPageViewModel : MailBaseViewModel
             ValidateImapSettings(serverInformation);
             ValidateCalendarModeSpecificSettings(serverInformation);
 
+            var excludedAccountId = _pageMode == ImapCalDavSettingsPageMode.Edit
+                ? _editingAccountId
+                : (Guid?)null;
+
+            if (!await ValidateAccountUniquenessAsync(excludedAccountId).ConfigureAwait(false))
+                return;
+
             await ValidateImapConnectivityAsync(serverInformation);
             IsImapValidationSucceeded = true;
 
@@ -770,6 +779,34 @@ public partial class ImapCalDavSettingsPageViewModel : MailBaseViewModel
         Messenger.Send(new BackBreadcrumNavigationRequested());
     }
 
+    private async Task<bool> ValidateAccountUniquenessAsync(Guid? excludedAccountId)
+    {
+        var accountName = (_pageMode == ImapCalDavSettingsPageMode.Create || _pageMode == ImapCalDavSettingsPageMode.Wizard)
+            ? _accountCreationContext?.AccountName
+            : null;
+
+        if (!string.IsNullOrWhiteSpace(accountName) &&
+            await _accountService.AccountNameExistsAsync(accountName, excludedAccountId).ConfigureAwait(false))
+        {
+            _mailDialogService.InfoBarMessage(
+                Translator.DialogMessage_AccountExistsTitle,
+                Translator.DialogMessage_AccountNameExistsMessage,
+                InfoBarMessageType.Error);
+            return false;
+        }
+
+        if (await _accountService.AccountAddressExistsAsync(EmailAddress, excludedAccountId).ConfigureAwait(false))
+        {
+            _mailDialogService.InfoBarMessage(
+                Translator.DialogMessage_AccountExistsTitle,
+                Translator.DialogMessage_AccountAddressExistsMessage,
+                InfoBarMessageType.Error);
+            return false;
+        }
+
+        return true;
+    }
+
     private async Task SaveEditFlowAsync(CustomServerInformation serverInformation)
     {
         var account = await _accountService.GetAccountAsync(_editingAccountId).ConfigureAwait(false);

Wino.Mail.ViewModels/ProviderSelectionPageViewModel.cs

@@ -1,5 +1,6 @@
 using System.Collections.Generic;
 using System.Linq;
+using System.Threading.Tasks;
 using CommunityToolkit.Mvvm.ComponentModel;
 using CommunityToolkit.Mvvm.Input;
 using CommunityToolkit.Mvvm.Messaging;
@@ -16,6 +17,8 @@ namespace Wino.Mail.ViewModels;
 
 public partial class ProviderSelectionPageViewModel : MailBaseViewModel
 {
+    private readonly IAccountService _accountService;
+    private readonly IDialogServiceBase _dialogService;
     private readonly IProviderService _providerService;
     private readonly INewThemeService _themeService;
 
@@ -53,10 +56,14 @@ public partial class ProviderSelectionPageViewModel : MailBaseViewModel
     public bool IsInitialSynchronizationWarningVisible => SelectedInitialSynchronizationRange?.IsEverything == true;
 
     public ProviderSelectionPageViewModel(
+        IAccountService accountService,
+        IDialogServiceBase dialogService,
         IProviderService providerService,
         INewThemeService themeService,
         WelcomeWizardContext wizardContext)
     {
+        _accountService = accountService;
+        _dialogService = dialogService;
         _providerService = providerService;
         _themeService = themeService;
         WizardContext = wizardContext;
@@ -107,10 +114,19 @@ public partial class ProviderSelectionPageViewModel : MailBaseViewModel
     }
 
     [RelayCommand]
-    private void Proceed()
+    private async Task ProceedAsync()
     {
         if (!CanProceed) return;
 
+        if (await _accountService.AccountNameExistsAsync(AccountName).ConfigureAwait(false))
+        {
+            await _dialogService.ShowMessageAsync(
+                Translator.DialogMessage_AccountNameExistsMessage,
+                Translator.DialogMessage_AccountExistsTitle,
+                WinoCustomMessageDialogIcon.Warning);
+            return;
+        }
+
         // Persist to wizard context
         WizardContext.SelectedProvider = SelectedProvider;
         WizardContext.AccountName = AccountName?.Trim();

Wino.Mail.ViewModels/SpecialImapCredentialsPageViewModel.cs

@@ -15,6 +15,8 @@ namespace Wino.Mail.ViewModels;
 
 public partial class SpecialImapCredentialsPageViewModel : MailBaseViewModel
 {
+    private readonly IAccountService _accountService;
+    private readonly IDialogServiceBase _dialogService;
     private static readonly Dictionary<SpecialImapProvider, string> AppPasswordHelpLinks = new()
     {
         { SpecialImapProvider.iCloud, "https://support.apple.com/en-us/102654" },
@@ -56,9 +58,13 @@ public partial class SpecialImapCredentialsPageViewModel : MailBaseViewModel
             : Translator.ProviderSelection_CalendarMode_CalDavDescription_Yahoo;
 
     public SpecialImapCredentialsPageViewModel(
+        IAccountService accountService,
+        IDialogServiceBase dialogService,
         INativeAppService nativeAppService,
         WelcomeWizardContext wizardContext)
     {
+        _accountService = accountService;
+        _dialogService = dialogService;
         _nativeAppService = nativeAppService;
         WizardContext = wizardContext;
     }
@@ -98,10 +104,19 @@ public partial class SpecialImapCredentialsPageViewModel : MailBaseViewModel
     }
 
     [RelayCommand]
-    private void Proceed()
+    private async Task ProceedAsync()
     {
         if (!CanProceed) return;
 
+        if (await _accountService.AccountAddressExistsAsync(EmailAddress).ConfigureAwait(false))
+        {
+            await _dialogService.ShowMessageAsync(
+                Translator.DialogMessage_AccountAddressExistsMessage,
+                Translator.DialogMessage_AccountExistsTitle,
+                WinoCustomMessageDialogIcon.Warning);
+            return;
+        }
+
         WizardContext.DisplayName = DisplayName?.Trim();
         WizardContext.EmailAddress = EmailAddress?.Trim();
         WizardContext.AppSpecificPassword = AppSpecificPassword?.Trim();