refactored a bit to use the Maybe pattern

implemented via ienumerable<t> so we can make use of the existing ienum monads

mRemoteNGTests/Config/Serializers/ConnectionSerializers/XmlConnectionNodeSerializer27Tests.cs

@@ -7,6 +7,7 @@
 using mRemoteNG.Credential;
 using mRemoteNG.Security;
 using mRemoteNG.Security.Factories;
+using mRemoteNG.Tools;
 using NSubstitute;
 using NUnit.Framework;
 
@@ -79,7 +80,7 @@ private class TestCaseDataSource
                 Username = "myuser",
                 Domain = "superdomain",
                 Password = "pass",
-                CredentialRecordId = Guid.Empty,
+                CredentialRecordId = Guid.Empty.Maybe(),
                 Hostname = "somehost",
                 ExtApp = "myextapp",
                 PreExtApp = "preext1",

mRemoteNGTests/Config/Serializers/MiscSerializers/CsvConnectionsSerializerMremotengFormatTests.cs

@@ -3,6 +3,7 @@
 using mRemoteNG.Connection;
 using mRemoteNG.Credential;
 using mRemoteNG.Security;
+using mRemoteNG.Tools;
 using mRemoteNG.Tree;
 using NSubstitute;
 using NUnit.Framework;
@@ -87,7 +88,7 @@ private ConnectionInfo BuildConnectionInfo()
             return new ConnectionInfo
             {
                 Name = ConnectionName,
-                CredentialRecordId = Guid.NewGuid(),
+                CredentialRecordId = Guid.NewGuid().Maybe(),
                 Inheritance = {Colors = true}
             };
         }

mRemoteNGTests/Tools/MaybeTests.cs

@@ -0,0 +1,23 @@
+using mRemoteNG.Tools;
+using NUnit.Framework;
+
+namespace mRemoteNGTests.Tools
+{
+	public class MaybeTests
+	{
+		[Test]
+		public void MaybeReturnsEmptyListWhenGivenNullValue()
+		{
+			var sut = new Maybe<object>(null);
+			Assert.That(sut, Is.Empty);
+		}
+
+		[Test]
+		public void MaybeReturnsValueIfNotNull()
+		{
+			var expected = new object();
+			var sut = new Maybe<object>(expected);
+			Assert.That(sut, Has.Member(expected));
+		}
+	}
+}

mRemoteNGTests/mRemoteNGTests.csproj

@@ -172,6 +172,7 @@
     <Compile Include="TestHelpers\FileTestHelpers.cs" />
     <Compile Include="Tools\ExternalToolsArgumentParserTests.cs" />
     <Compile Include="Tools\FullyObservableCollectionTests.cs" />
+    <Compile Include="Tools\MaybeTests.cs" />
     <Compile Include="Tree\ClickHandlers\TreeNodeCompositeClickHandlerTests.cs" />
     <Compile Include="Tree\ConnectionTreeDragAndDropHandlerTests.cs" />
     <Compile Include="Tree\ConnectionTreeModelTests.cs" />

mRemoteV1/App/Initialization/CredsAndConsSetup.cs

@@ -3,6 +3,7 @@
 using System.Linq;
 using mRemoteNG.Connection;
 using mRemoteNG.Credential;
+using mRemoteNG.Tools;
 
 namespace mRemoteNG.App.Initialization
 {
@@ -37,7 +38,7 @@ private void LoadDefaultConnectionCredentials()
         {
             var defaultCredId = Settings.Default.ConDefaultCredentialRecord;
             var matchedCredentials = _credentialsService.GetCredentialRecords().Where(record => record.Id.Equals(defaultCredId)).ToArray();
-            DefaultConnectionInfo.Instance.CredentialRecordId = matchedCredentials.Any() ? matchedCredentials.First().Id : default(Guid?);
+            DefaultConnectionInfo.Instance.CredentialRecordId = matchedCredentials.FirstOrDefault()?.Id.Maybe();
         }
     }
 }

mRemoteV1/Config/Serializers/ConnectionSerializers/XmlConnectionsDeserializer.cs

@@ -16,6 +16,7 @@
 using mRemoteNG.Credential;
 using mRemoteNG.Messages;
 using mRemoteNG.Security;
+using mRemoteNG.Tools;
 using mRemoteNG.Tree;
 using mRemoteNG.Tree.Root;
 using mRemoteNG.UI.Forms;
@@ -508,7 +509,7 @@ private ConnectionInfo GetConnectionInfoFromXml(XmlNode xmlnode)
                 if (_confVersion >= 2.7)
                 {
                     connectionInfo.Inheritance.CredentialRecord = bool.Parse(xmlnode.Attributes["InheritCredentialRecord"]?.Value ?? "False");
-                    connectionInfo.CredentialRecordId = Guid.Parse(xmlnode.Attributes["CredentialId"]?.Value ?? "");
+                    connectionInfo.CredentialRecordId = Guid.Parse(xmlnode.Attributes["CredentialId"]?.Value ?? "").Maybe();
                 }
             }
             catch (Exception ex)

mRemoteV1/Config/Serializers/MiscSerializers/CsvConnectionsSerializerMremotengFormat.cs

@@ -90,10 +90,10 @@ private void SerializeConnectionInfo(ConnectionInfo con)
 
             csvLine += con.Name + ";" + GetNodePath(con) + ";" + con.Description + ";" + con.Icon + ";" + con.Panel + ";";
 
-            if (con.CredentialRecordId.HasValue)
+            if (con.CredentialRecordId.Any())
             {
                 var credentialRecord =
-                    _credentialRepositoryList.GetCredentialRecord(con.CredentialRecordId.Value);
+                    _credentialRepositoryList.GetCredentialRecord(con.CredentialRecordId.Single());
 
                 if (_saveFilter.SaveUsername)
                     csvLine += credentialRecord?.Username + ";";

mRemoteV1/Config/Serializers/Versioning/XmlCredentialManagerUpgrader.cs

@@ -131,7 +131,7 @@ public void ApplyCredentialMapping(IDictionary<Guid, ICredentialRecord> map, IEn
                 Guid id;
                 Guid.TryParse(connectionInfo.ConstantID, out id);
                 if (map.ContainsKey(id))
-                    connectionInfo.CredentialRecordId = map[id].Id;
+                    connectionInfo.CredentialRecordId = map[id].Id.Maybe();
             }
         }
     }

mRemoteV1/Connection/AbstractConnectionRecord.cs

@@ -7,7 +7,6 @@
 using mRemoteNG.Connection.Protocol.ICA;
 using mRemoteNG.Connection.Protocol.RDP;
 using mRemoteNG.Connection.Protocol.VNC;
-using mRemoteNG.Credential;
 using mRemoteNG.Tools;
 using mRemoteNG.UI.Controls;
 // ReSharper disable ArrangeAccessorOwnerBody
@@ -24,7 +23,7 @@ public abstract class AbstractConnectionRecord : INotifyPropertyChanged
         private string _panel = "";
 
         private string _hostname = "";
-        private Guid? _credentialRecordId;
+        private Maybe<Guid> _credentialRecordId = new Maybe<Guid>();
 
         private ProtocolType _protocol;
         private string _extApp = "";
@@ -137,7 +136,7 @@ public virtual string Hostname
             LocalizedAttributes.LocalizedDescription(nameof(Language.strPropertyDescriptionCredential))]
         [Editor(typeof(CredentialRecordListAdaptor), typeof(UITypeEditor))]
         [TypeConverter(typeof(ExpandableObjectConverter))]
-        public virtual Guid? CredentialRecordId
+        public virtual Maybe<Guid> CredentialRecordId
         {
             get { return GetPropertyValue(nameof(CredentialRecordId), _credentialRecordId); }
             set { SetField(ref _credentialRecordId, value, nameof(CredentialRecordId)); }

mRemoteV1/Connection/Protocol/ICA/IcaProtocol.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Linq;
 using System.Security;
 using AxWFICALib;
 using System.Windows.Forms;
@@ -123,9 +124,9 @@ private void SetCredentials()
                 var pass = new SecureString();
                 var dom = "";
 
-			    if (_info.CredentialRecordId.HasValue)
+			    if (_info.CredentialRecordId.Any())
 			    {
-			        var credentialRecord = Runtime.CredentialProviderCatalog.GetCredentialRecord(_info.CredentialRecordId.Value);
+			        var credentialRecord = Runtime.CredentialProviderCatalog.GetCredentialRecord(_info.CredentialRecordId.Single());
 			        user = credentialRecord?.Username ?? "";
 			        pass = credentialRecord?.Password ?? "".ConvertToSecureString();
 			        dom = credentialRecord?.Domain ?? "";

mRemoteV1/Connection/Protocol/PuttyBase.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Diagnostics;
 using System.Drawing;
+using System.Linq;
 using System.Threading;
 using System.Windows.Forms;
 using mRemoteNG.Credential;
@@ -75,9 +76,9 @@ public override bool Connect()
 						var password = "";
 					    var credentialRecord = default(ICredentialRecord);
 
-					    if (InterfaceControl.Info.CredentialRecordId.HasValue)
+					    if (InterfaceControl.Info.CredentialRecordId.Any())
 					    {
-					        credentialRecord = Runtime.CredentialProviderCatalog.GetCredentialRecord(InterfaceControl.Info.CredentialRecordId.Value);
+					        credentialRecord = Runtime.CredentialProviderCatalog.GetCredentialRecord(InterfaceControl.Info.CredentialRecordId.Single());
 					    }
 
 						if (!string.IsNullOrEmpty(credentialRecord?.Username))

mRemoteV1/Connection/Protocol/RDP/RdpProtocol.cs

@@ -6,6 +6,7 @@
 using System.Windows.Forms;
 using System.Threading;
 using System.ComponentModel;
+using System.Linq;
 using System.Security;
 using mRemoteNG.Messages;
 using mRemoteNG.App;
@@ -346,9 +347,9 @@ private void SetRdGateway()
 					{
 						if (_connectionInfo.RDGatewayUseConnectionCredentials == RDGatewayUseConnectionCredentials.Yes)
 						{
-						    if (!_connectionInfo.CredentialRecordId.HasValue) return;
+						    if (!_connectionInfo.CredentialRecordId.Any()) return;
 						    var credentialRecord =
-						        Runtime.CredentialProviderCatalog.GetCredentialRecord(_connectionInfo.CredentialRecordId.Value);
+						        Runtime.CredentialProviderCatalog.GetCredentialRecord(_connectionInfo.CredentialRecordId.Single());
 						    _rdpClient.TransportSettings2.GatewayUsername = credentialRecord?.Username;
 						    _rdpClient.TransportSettings2.GatewayPassword = credentialRecord?.Password.ConvertToUnsecureString();
 						    _rdpClient.TransportSettings2.GatewayDomain = credentialRecord?.Domain;
@@ -424,9 +425,9 @@ private void SetCredentials()
 				var password = new SecureString();
 				var domain = "";
 
-			    if (_connectionInfo.CredentialRecordId.HasValue)
+			    if (_connectionInfo.CredentialRecordId.Any())
 			    {
-			        var credentialRecord = Runtime.CredentialProviderCatalog.GetCredentialRecord(_connectionInfo.CredentialRecordId.Value);
+			        var credentialRecord = Runtime.CredentialProviderCatalog.GetCredentialRecord(_connectionInfo.CredentialRecordId.Single());
 			        userName = credentialRecord?.Username ?? "";
 			        password = credentialRecord?.Password ?? new SecureString();
 			        domain = credentialRecord?.Domain ?? "";

mRemoteV1/Connection/Protocol/VNC/Connection.Protocol.VNC.cs

@@ -1,6 +1,7 @@
 using System;
 using mRemoteNG.App;
 using System.ComponentModel;
+using System.Linq;
 using mRemoteNG.Security;
 using mRemoteNG.Tools;
 using mRemoteNG.UI.Forms;
@@ -165,9 +166,9 @@ private void SetEventHandlers()
 				_VNC.ConnectComplete += VNCEvent_Connected;
 				_VNC.ConnectionLost += VNCEvent_Disconnected;
 				FrmMain.ClipboardChanged += VNCEvent_ClipboardChanged;
-                if (!Info.CredentialRecordId.HasValue)
+                if (!Info.CredentialRecordId.Any())
                     return;
-			    var credentialRecord = Runtime.CredentialProviderCatalog.GetCredentialRecord(Info.CredentialRecordId.Value);
+			    var credentialRecord = Runtime.CredentialProviderCatalog.GetCredentialRecord(Info.CredentialRecordId.Single());
                 if (((int)Force & (int)ConnectionInfo.Force.NoCredentials) != (int)ConnectionInfo.Force.NoCredentials 
                     && credentialRecord?.Password?.Length > 0)
 				{
@@ -202,8 +203,8 @@ private void VNCEvent_ClipboardChanged()
 
 		private string VNCEvent_Authenticate()
 		{
-		    return Info.CredentialRecordId.HasValue 
-                ? Runtime.CredentialProviderCatalog.GetCredentialRecord(Info.CredentialRecordId.Value).Password.ConvertToUnsecureString() 
+		    return Info.CredentialRecordId.Any()
+                ? Runtime.CredentialProviderCatalog.GetCredentialRecord(Info.CredentialRecordId.Single())?.Password?.ConvertToUnsecureString() 
                 : "";
 		}
 

mRemoteV1/Tools/Extensions.cs

@@ -0,0 +1,11 @@
+
+namespace mRemoteNG.Tools
+{
+	public static class Extensions
+	{
+		public static Maybe<T> Maybe<T>(this T value)
+		{
+			return new Maybe<T>(value);
+		}
+	}
+}

mRemoteV1/Tools/Maybe.cs

@@ -0,0 +1,32 @@
+using System.Collections;
+using System.Collections.Generic;
+
+namespace mRemoteNG.Tools
+{
+	public class Maybe<T> : IEnumerable<T>
+	{
+		private readonly T[] _maybe;
+
+		public Maybe()
+		{
+			_maybe = new T[0];
+		}
+
+		public Maybe(T value)
+		{
+			_maybe = value != null 
+				? new[] {value} 
+				: new T[0];
+		}
+
+		IEnumerator IEnumerable.GetEnumerator()
+		{
+			return GetEnumerator();
+		}
+
+		public IEnumerator<T> GetEnumerator()
+		{
+			return ((IEnumerable<T>)_maybe).GetEnumerator();
+		}
+	}
+}

mRemoteV1/mRemoteV1.csproj

@@ -295,12 +295,14 @@
     <Compile Include="Security\Factories\CryptoProviderFactoryFromXml.cs" />
     <Compile Include="Tools\Cmdline\StartupArgumentsInterpreter.cs" />
     <Compile Include="Tools\CustomCollections\CollectionUpdatedEventArgs.cs" />
+    <Compile Include="Tools\Extensions.cs" />
     <Compile Include="Tools\ExternalToolArgumentParser.cs" />
     <Compile Include="Tools\Cmdline\CmdArgumentsInterpreter.cs" />
     <Compile Include="Tools\ConnectionsTreeToMenuItemsConverter.cs" />
     <Compile Include="Tools\ExternalToolsService.cs" />
     <Compile Include="Tools\ExternalToolsTypeConverter.cs" />
     <Compile Include="Tools\CustomCollections\INotifyCollectionUpdated.cs" />
+    <Compile Include="Tools\Maybe.cs" />
     <Compile Include="Tools\MouseClickSimulator.cs" />
     <Compile Include="Tools\NotificationAreaIcon.cs" />
     <Compile Include="Tools\ScanHost.cs" />