Implement desktop sync protocol handling

WirelessTextSyncer.Desktop.sln

@@ -5,6 +5,8 @@ VisualStudioVersion = 17.0.31903.59
 MinimumVisualStudioVersion = 10.0.40219.1
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "WirelessTextSyncer.Windows", "WirelessTextSyncer.Windows\WirelessTextSyncer.Windows.csproj", "{7AD6081A-F4EB-45AA-917B-2CCFA54E0A67}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "WirelessTextSyncer.Windows.Tests", "WirelessTextSyncer.Windows.Tests\WirelessTextSyncer.Windows.Tests.csproj", "{FD53F0F1-EAE0-4CB2-9AC8-57797F0B95D1}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -18,5 +20,9 @@ Global
 		{7AD6081A-F4EB-45AA-917B-2CCFA54E0A67}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{7AD6081A-F4EB-45AA-917B-2CCFA54E0A67}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{7AD6081A-F4EB-45AA-917B-2CCFA54E0A67}.Release|Any CPU.Build.0 = Release|Any CPU
+		{FD53F0F1-EAE0-4CB2-9AC8-57797F0B95D1}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{FD53F0F1-EAE0-4CB2-9AC8-57797F0B95D1}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{FD53F0F1-EAE0-4CB2-9AC8-57797F0B95D1}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{FD53F0F1-EAE0-4CB2-9AC8-57797F0B95D1}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 EndGlobal

WirelessTextSyncer.Windows.Tests/SyncMessageTests.cs

@@ -0,0 +1,31 @@
+using System.Text.Json;
+using WirelessTextSyncer.Windows.Models;
+
+namespace WirelessTextSyncer.Windows.Tests;
+
+[TestClass]
+public sealed class SyncMessageTests
+{
+    [TestMethod]
+    public void DeserializeAndroidInsertTextMessage()
+    {
+        var message = JsonSerializer.Deserialize<SyncMessage>(
+            """{"action":"insertText","text":"hello"}""",
+            new JsonSerializerOptions(JsonSerializerDefaults.Web));
+
+        Assert.IsNotNull(message);
+        Assert.AreEqual(SyncAction.InsertText, message.Action);
+        Assert.AreEqual("hello", message.Text);
+    }
+
+    [TestMethod]
+    public void DeserializeAndroidBackspaceMessage()
+    {
+        var message = JsonSerializer.Deserialize<SyncMessage>(
+            """{"action":"backspace"}""",
+            new JsonSerializerOptions(JsonSerializerDefaults.Web));
+
+        Assert.IsNotNull(message);
+        Assert.AreEqual(SyncAction.Backspace, message.Action);
+    }
+}

WirelessTextSyncer.Windows.Tests/WirelessTextSyncer.Windows.Tests.csproj

@@ -0,0 +1,27 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0-windows</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+
+    <IsPackable>false</IsPackable>
+    <IsTestProject>true</IsTestProject>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="coverlet.collector" Version="6.0.0" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
+    <PackageReference Include="MSTest.TestAdapter" Version="3.1.1" />
+    <PackageReference Include="MSTest.TestFramework" Version="3.1.1" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <Using Include="Microsoft.VisualStudio.TestTools.UnitTesting" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\WirelessTextSyncer.Windows\WirelessTextSyncer.Windows.csproj" />
+  </ItemGroup>
+
+</Project>

WirelessTextSyncer.Windows/Models/SyncAction.cs

@@ -1,5 +1,8 @@
 namespace WirelessTextSyncer.Windows.Models;
 
+using System.Text.Json.Serialization;
+
+[JsonConverter(typeof(SyncActionJsonConverter))]
 public enum SyncAction
 {
     InsertText,

WirelessTextSyncer.Windows/Models/SyncActionJsonConverter.cs

@@ -0,0 +1,41 @@
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace WirelessTextSyncer.Windows.Models;
+
+public sealed class SyncActionJsonConverter : JsonConverter<SyncAction>
+{
+    public override SyncAction Read(
+        ref Utf8JsonReader reader,
+        Type typeToConvert,
+        JsonSerializerOptions options)
+    {
+        var value = reader.GetString();
+
+        return value switch
+        {
+            "insertText" => SyncAction.InsertText,
+            "backspace" => SyncAction.Backspace,
+            "enter" => SyncAction.Enter,
+            "ping" => SyncAction.Ping,
+            _ => throw new JsonException($"Unsupported sync action: {value}")
+        };
+    }
+
+    public override void Write(
+        Utf8JsonWriter writer,
+        SyncAction value,
+        JsonSerializerOptions options)
+    {
+        var action = value switch
+        {
+            SyncAction.InsertText => "insertText",
+            SyncAction.Backspace => "backspace",
+            SyncAction.Enter => "enter",
+            SyncAction.Ping => "ping",
+            _ => throw new JsonException($"Unsupported sync action: {value}")
+        };
+
+        writer.WriteStringValue(action);
+    }
+}

WirelessTextSyncer.Windows/Services/KeyboardInjectionService.cs

@@ -1,7 +1,15 @@
 namespace WirelessTextSyncer.Windows.Services;
 
+using System.Runtime.InteropServices;
+
 public sealed class KeyboardInjectionService : IKeyboardInjectionService
 {
+    private const uint InputKeyboard = 1;
+    private const uint KeyEventFKeyUp = 0x0002;
+    private const uint KeyEventFUnicode = 0x0004;
+    private const ushort VirtualKeyBack = 0x08;
+    private const ushort VirtualKeyReturn = 0x0D;
+
     public void InsertText(string text)
     {
         if (string.IsNullOrEmpty(text))
@@ -9,16 +17,103 @@ public sealed class KeyboardInjectionService : IKeyboardInjectionService
             return;
         }
 
-        SendKeys.SendWait(text);
+        foreach (var character in text)
+        {
+            SendUnicode(character);
+        }
     }
 
     public void Backspace()
     {
-        SendKeys.SendWait("{BACKSPACE}");
+        SendVirtualKey(VirtualKeyBack);
     }
 
     public void Enter()
     {
-        SendKeys.SendWait("{ENTER}");
+        SendVirtualKey(VirtualKeyReturn);
+    }
+
+    private static void SendUnicode(char character)
+    {
+        Send([
+            CreateUnicodeInput(character, 0),
+            CreateUnicodeInput(character, KeyEventFKeyUp)
+        ]);
+    }
+
+    private static void SendVirtualKey(ushort virtualKey)
+    {
+        Send([
+            CreateVirtualKeyInput(virtualKey, 0),
+            CreateVirtualKeyInput(virtualKey, KeyEventFKeyUp)
+        ]);
+    }
+
+    private static void Send(INPUT[] inputs)
+    {
+        var sent = SendInput((uint)inputs.Length, inputs, Marshal.SizeOf<INPUT>());
+        if (sent != inputs.Length)
+        {
+            throw new InvalidOperationException("Windows did not accept all keyboard input events.");
+        }
+    }
+
+    private static INPUT CreateUnicodeInput(char character, uint flags)
+    {
+        return new INPUT
+        {
+            type = InputKeyboard,
+            U = new InputUnion
+            {
+                ki = new KEYBDINPUT
+                {
+                    wScan = character,
+                    dwFlags = KeyEventFUnicode | flags
+                }
+            }
+        };
+    }
+
+    private static INPUT CreateVirtualKeyInput(ushort virtualKey, uint flags)
+    {
+        return new INPUT
+        {
+            type = InputKeyboard,
+            U = new InputUnion
+            {
+                ki = new KEYBDINPUT
+                {
+                    wVk = virtualKey,
+                    dwFlags = flags
+                }
+            }
+        };
+    }
+
+    [DllImport("user32.dll", SetLastError = true)]
+    private static extern uint SendInput(uint numberOfInputs, INPUT[] inputs, int sizeOfInputStructure);
+
+    [StructLayout(LayoutKind.Sequential)]
+    private struct INPUT
+    {
+        public uint type;
+        public InputUnion U;
+    }
+
+    [StructLayout(LayoutKind.Explicit)]
+    private struct InputUnion
+    {
+        [FieldOffset(0)]
+        public KEYBDINPUT ki;
+    }
+
+    [StructLayout(LayoutKind.Sequential)]
+    private struct KEYBDINPUT
+    {
+        public ushort wVk;
+        public ushort wScan;
+        public uint dwFlags;
+        public uint time;
+        public UIntPtr dwExtraInfo;
     }
 }

WirelessTextSyncer.Windows/Services/WebSocketServerService.cs

@@ -8,8 +8,14 @@ namespace WirelessTextSyncer.Windows.Services;
 
 public sealed class WebSocketServerService : IDisposable
 {
+    private static readonly JsonSerializerOptions JsonOptions = new(JsonSerializerDefaults.Web)
+    {
+        PropertyNameCaseInsensitive = true
+    };
+
     private readonly SyncMessageHandler messageHandler;
     private readonly List<IWebSocketConnection> clients = [];
+    private readonly object clientsLock = new();
     private WebSocketServer? server;
 
     public WebSocketServerService(SyncMessageHandler messageHandler)
@@ -21,7 +27,16 @@ public sealed class WebSocketServerService : IDisposable
 
     public string LocalIpAddress { get; private set; } = "127.0.0.1";
 
-    public bool HasClient => clients.Count > 0;
+    public bool HasClient
+    {
+        get
+        {
+            lock (clientsLock)
+            {
+                return clients.Count > 0;
+            }
+        }
+    }
 
     public event EventHandler? StatusChanged;
 
@@ -34,13 +49,21 @@ public sealed class WebSocketServerService : IDisposable
         server.Start(socket =>
         {
             socket.OnOpen = () =>
+            {
+                lock (clientsLock)
                 {
                     clients.Add(socket);
+                }
+
                 StatusChanged?.Invoke(this, EventArgs.Empty);
             };
             socket.OnClose = () =>
+            {
+                lock (clientsLock)
                 {
                     clients.Remove(socket);
+                }
+
                 StatusChanged?.Invoke(this, EventArgs.Empty);
             };
             socket.OnMessage = HandleRawMessage;
@@ -49,18 +72,26 @@ public sealed class WebSocketServerService : IDisposable
 
     public void Dispose()
     {
-        foreach (var client in clients.ToArray())
+        IWebSocketConnection[] currentClients;
+        lock (clientsLock)
+        {
+            currentClients = clients.ToArray();
+            clients.Clear();
+        }
+
+        foreach (var client in currentClients)
         {
             client.Close();
         }
 
-        clients.Clear();
         server?.Dispose();
     }
 
     private void HandleRawMessage(string rawMessage)
     {
-        var message = JsonSerializer.Deserialize<SyncMessage>(rawMessage);
+        try
+        {
+            var message = JsonSerializer.Deserialize<SyncMessage>(rawMessage, JsonOptions);
             if (message is null)
             {
                 return;
@@ -68,6 +99,11 @@ public sealed class WebSocketServerService : IDisposable
 
             messageHandler.Handle(message);
         }
+        catch (JsonException)
+        {
+            return;
+        }
+    }
 
     private static string ResolveLocalIpAddress()
     {

WirelessTextSyncer.Windows/Tray/TrayApplicationContext.cs

@@ -75,6 +75,7 @@ public sealed class TrayApplicationContext : ApplicationContext
     private void UpdateTrayText()
     {
         var status = server.HasClient ? "connected" : "waiting";
-        notifyIcon.Text = $"WirelessTextSyncer {server.LocalIpAddress}:{server.Port} ({status})";
+        var text = $"WirelessTextSyncer {server.LocalIpAddress}:{server.Port} ({status})";
+        notifyIcon.Text = text.Length > 63 ? text[..63] : text;
     }
 }

WirelessTextSyncer.Windows/WirelessTextSyncer.Windows.csproj

@@ -10,7 +10,6 @@
 
   <ItemGroup>
     <PackageReference Include="Fleck" Version="1.2.0" />
-    <PackageReference Include="InputSimulatorPlus" Version="1.0.7" />
     <PackageReference Include="Microsoft.Extensions.Configuration.Json" Version="10.0.8" />
   </ItemGroup>