[Hosts] Improved duplicate hosts finding (#24294)

* improved duplicate hosts finding

* improved filters with AdvancedCollectionView

* cancel FindDuplicates when file is reloaded

src/modules/Hosts/Hosts.Tests/EntryTest.cs

@@ -28,7 +28,7 @@ public class EntryTest
         [DataRow("# # \t10.1.1.1 host#comment", "10.1.1.1", "host", "comment", false)]
         public void Valid_Entry_SingleHost(string line, string address, string host, string comment, bool active)
         {
-            var entry = new Entry(line);
+            var entry = new Entry(0, line);
 
             Assert.AreEqual(entry.Address, address);
             Assert.AreEqual(entry.Hosts, host);
@@ -52,7 +52,7 @@ public void Valid_Entry_SingleHost(string line, string address, string host, str
         [DataRow("#10.1.1.1 host host.local#comment", "10.1.1.1", "host host.local", "comment", false)]
         public void Valid_Entry_MultipleHosts(string line, string address, string host, string comment, bool active)
         {
-            var entry = new Entry(line);
+            var entry = new Entry(0, line);
 
             Assert.AreEqual(entry.Address, address);
             Assert.AreEqual(entry.Hosts, host);
@@ -76,7 +76,7 @@ public void Valid_Entry_MultipleHosts(string line, string address, string host,
         [DataRow("host 10.1.1.1")]
         public void Not_Valid_Entry(string line)
         {
-            var entry = new Entry(line);
+            var entry = new Entry(0, line);
             Assert.IsFalse(entry.Valid);
         }
     }

src/modules/Hosts/Hosts.Tests/HostsServiceTest.cs

@@ -70,7 +70,7 @@ public async Task Host_Added()
             fileSystem.AddFile(service.HostsFilePath, new MockFileData(content));
 
             var (_, entries) = await service.ReadAsync();
-            entries.Add(new Entry("10.1.1.30", "host30 host30.local", "new entry", false));
+            entries.Add(new Entry(0, "10.1.1.30", "host30 host30.local", "new entry", false));
             await service.WriteAsync(string.Empty, entries);
 
             var result = fileSystem.GetFile(service.HostsFilePath);

src/modules/Hosts/Hosts/Helpers/ExpressionExtensions.cs

@@ -0,0 +1,43 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
+using System.Linq.Expressions;
+
+namespace Hosts.Helpers
+{
+    // https://stackoverflow.com/a/22569086
+    public static class ExpressionExtensions
+    {
+        public static Expression<Func<T, bool>> And<T>(
+            this Expression<Func<T, bool>> expr1,
+            Expression<Func<T, bool>> expr2)
+        {
+            var secondBody = expr2.Body.Replace(expr2.Parameters[0], expr1.Parameters[0]);
+            return Expression.Lambda<Func<T, bool>>(Expression.AndAlso(expr1.Body, secondBody), expr1.Parameters);
+        }
+
+        public static Expression Replace(this Expression expression, Expression searchEx, Expression replaceEx)
+        {
+            return new ReplaceVisitor(searchEx, replaceEx).Visit(expression);
+        }
+
+        internal class ReplaceVisitor : ExpressionVisitor
+        {
+            private readonly Expression _from;
+            private readonly Expression _to;
+
+            public ReplaceVisitor(Expression from, Expression to)
+            {
+                _from = from;
+                _to = to;
+            }
+
+            public override Expression Visit(Expression node)
+            {
+                return node == _from ? _to : base.Visit(node);
+            }
+        }
+    }
+}

src/modules/Hosts/Hosts/Helpers/HostsService.cs

@@ -82,7 +82,7 @@ public async Task<(string Unparsed, List<Entry> Entries)> ReadAsync()
                     continue;
                 }
 
-                var entry = new Entry(line);
+                var entry = new Entry(i, line);
 
                 if (entry.Valid)
                 {

src/modules/Hosts/Hosts/Models/AddressType.cs

@@ -0,0 +1,13 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace Hosts.Models
+{
+    public enum AddressType
+    {
+        Invalid = 0,
+        IPv4 = 1,
+        IPv6 = 2,
+    }
+}

src/modules/Hosts/Hosts/Models/Entry.cs

@@ -22,6 +22,7 @@ public string Address
             set
             {
                 SetProperty(ref _address, value);
+                SetAddressType();
                 OnPropertyChanged(nameof(Valid));
             }
         }
@@ -54,22 +55,28 @@ public string Hosts
         [ObservableProperty]
         private bool _duplicate;
 
-        public bool Valid => ValidationHelper.ValidHosts(_hosts) && (ValidationHelper.ValidIPv4(_address) || ValidationHelper.ValidIPv6(_address));
+        public bool Valid => ValidationHelper.ValidHosts(_hosts) && Type != AddressType.Invalid;
+
+        public AddressType Type { get; private set; }
 
         public string[] SplittedHosts { get; private set; }
 
+        public int Id { get; set; }
+
         public Entry()
         {
         }
 
-        public Entry(string line)
+        public Entry(int id, string line)
         {
+            Id = id;
             _line = line.Trim();
             Parse();
         }
 
-        public Entry(string address, string hosts, string comment, bool active)
+        public Entry(int id, string address, string hosts, string comment, bool active)
         {
+            Id = id;
             Address = address.Trim();
             Hosts = hosts.Trim();
             Comment = comment.Trim();
@@ -151,5 +158,21 @@ public string GetLine()
         {
             return _line;
         }
+
+        private void SetAddressType()
+        {
+            if (ValidationHelper.ValidIPv4(_address))
+            {
+                Type = AddressType.IPv4;
+            }
+            else if (ValidationHelper.ValidIPv6(_address))
+            {
+                Type = AddressType.IPv6;
+            }
+            else
+            {
+                Type = AddressType.Invalid;
+            }
+        }
     }
 }

src/modules/Hosts/Hosts/Settings/IUserSettings.cs

@@ -2,6 +2,7 @@
 // The Microsoft Corporation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System;
 using Settings.UI.Library.Enumerations;
 
 namespace Hosts.Settings
@@ -10,6 +11,10 @@ public interface IUserSettings
     {
         public bool ShowStartupWarning { get; }
 
+        public bool LoopbackDuplicates { get; }
+
         public AdditionalLinesPosition AdditionalLinesPosition { get; }
+
+        event EventHandler LoopbackDuplicatesChanged;
     }
 }

src/modules/Hosts/Hosts/Settings/UserSettings.cs

@@ -22,19 +22,37 @@ public class UserSettings : IUserSettings
 
         public bool ShowStartupWarning { get; private set; }
 
+        private bool _loopbackDuplicates;
+
+        public bool LoopbackDuplicates
+        {
+            get => _loopbackDuplicates;
+            set
+            {
+                if (_loopbackDuplicates != value)
+                {
+                    _loopbackDuplicates = value;
+                    LoopbackDuplicatesChanged?.Invoke(this, EventArgs.Empty);
+                }
+            }
+        }
+
         public AdditionalLinesPosition AdditionalLinesPosition { get; private set; }
 
         public UserSettings()
         {
             _settingsUtils = new SettingsUtils();
             ShowStartupWarning = true;
+            LoopbackDuplicates = false;
             AdditionalLinesPosition = AdditionalLinesPosition.Top;
 
             LoadSettingsFromJson();
 
             _watcher = Helper.GetFileWatcher(HostsModuleName, "settings.json", () => LoadSettingsFromJson());
         }
 
+        public event EventHandler LoopbackDuplicatesChanged;
+
         private void LoadSettingsFromJson()
         {
             lock (_loadingSettingsLock)
@@ -60,6 +78,7 @@ private void LoadSettingsFromJson()
                         {
                             ShowStartupWarning = settings.Properties.ShowStartupWarning;
                             AdditionalLinesPosition = settings.Properties.AdditionalLinesPosition;
+                            LoopbackDuplicates = settings.Properties.LoopbackDuplicates;
                         }
 
                         retry = false;