[PM-6655] Add username empty fallback on passkey (#3101)

* PM-6655 Added fallback "Unknown account" to passkey username and moved it so it can be shared with Android

* PM-6655 Improved code lines formatting

src/Core/Models/View/LoginView.cs

@@ -1,8 +1,7 @@
-using System;
+using Bit.Core.Enums;
-using System.Collections.Generic;
-using System.Linq;
-using Bit.Core.Enums;
 using Bit.Core.Models.Domain;
+using Bit.Core.Resources.Localization;
+using Bit.Core.Utilities;
 
 namespace Bit.Core.Models.View
 {
@@ -40,4 +39,15 @@ namespace Bit.Core.Models.View
             };
         }
     }
+
+    public static class LoginViewExtensions
+    {
+        public static string GetMainFido2CredentialUsername(this LoginView loginView)
+        {
+            return loginView.MainFido2Credential.UserName
+                    .FallbackOnNullOrWhiteSpace(loginView.MainFido2Credential.UserDisplayName)
+                    .FallbackOnNullOrWhiteSpace(loginView.Username)
+                    .FallbackOnNullOrWhiteSpace(AppResources.UnknownAccount);
+        }
+    }
 }

src/Core/Resources/Localization/AppResources.Designer.cs

@@ -7208,6 +7208,15 @@ namespace Bit.Core.Resources.Localization {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Unknown account.
+        /// </summary>
+        public static string UnknownAccount {
+            get {
+                return ResourceManager.GetString("UnknownAccount", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Unknown {0} error occurred..
         /// </summary>

src/Core/Resources/Localization/AppResources.resx

@@ -2942,6 +2942,9 @@ Do you want to switch to this account?</value>
   <data name="Passwords" xml:space="preserve">
     <value>Passwords</value>
   </data>
+  <data name="UnknownAccount" xml:space="preserve">
+    <value>Unknown account</value>
+  </data>
   <data name="SetUpAutofill" xml:space="preserve">
     <value>Set up auto-fill</value>
   </data>

src/Core/Utilities/StringExtensions.cs

@@ -1,5 +1,4 @@
-using System;
+using System.Globalization;
-using System.Globalization;
 using System.Text;
 
 namespace Bit.Core.Utilities
@@ -30,5 +29,7 @@ namespace Bit.Core.Utilities
                 .ToString()
                 .Normalize(NormalizationForm.FormC);
         }
+
+        public static string FallbackOnNullOrWhiteSpace(this string s, string fallback) => string.IsNullOrWhiteSpace(s) ? fallback : s;
     }
 }

src/iOS.Core/Utilities/ASHelpers.cs

@@ -2,6 +2,7 @@
 using Bit.Core.Abstractions;
 using Bit.Core.Enums;
 using Bit.Core.Models.View;
+using Bit.Core.Resources.Localization;
 using Bit.Core.Services;
 using Bit.Core.Utilities;
 using Foundation;
@@ -148,19 +149,8 @@ namespace Bit.iOS.Core.Utilities
                     return null;
                 }
 
-                var userName = cipher.Login.MainFido2Credential.UserName;
-                if (string.IsNullOrWhiteSpace(userName))
-                {
-                    userName = cipher.Login.MainFido2Credential.UserDisplayName;
-
-                    if (string.IsNullOrWhiteSpace(userName))
-                    {
-                        userName = cipher.Login.Username;
-                    }
-                }
-
                 return new ASPasskeyCredentialIdentity(cipher.Login.MainFido2Credential.RpId,
-                    userName,
+                    cipher.Login.GetMainFido2CredentialUsername(),
                     NSData.FromArray(cipher.Login.MainFido2Credential.CredentialId.GuidToRawFormat()),
                     cipher.Login.MainFido2Credential.UserHandle,
                     cipher.Id);