lightweight variant (#1)

Reviewed-on: #1
Co-authored-by: Aleksandr Neychev <alexnejchev73@gmail.com>

CursorLang.Agent/Agent.cs

@@ -0,0 +1,129 @@
+using System.ComponentModel;
+using CursorLang.Agent.Services;
+using CursorLang.Agent.Windows;
+using CursorLang.Core.Models;
+using CursorLang.Core.Services;
+using CursorLang.Core.Threading;
+
+namespace CursorLang.Agent;
+
+/// <summary>
+/// The background half of CursorLang: the hook, the layout polling, the popup and the
+/// tray icon, with a Win32 message loop underneath and no WPF anywhere.
+/// </summary>
+/// <remarks>
+/// The services are wired by hand rather than through a container, and that is a
+/// decision rather than an omission: the whole point of this process is how little it
+/// weighs, and a container is a megabyte of assembly and a graph of reflection on the
+/// way to the same object. There are ten of them and they are all listed here.
+/// </remarks>
+internal sealed class Agent : IDisposable
+{
+    private readonly SingleInstanceGate _gate;
+    private readonly AgentWindow _window;
+    private readonly SettingsService _settingsService;
+    private readonly AppSettings _settings;
+    private readonly LocalizationService _localization;
+    private readonly NativePopupWindow _popupWindow;
+    private readonly LayoutPopupService _popupService;
+    private readonly KeyboardLayoutService _layoutService;
+    private readonly CapsLockHotkeyService _hotkeyService;
+    private readonly LayoutNotificationCoordinator _notifications;
+    private readonly CapsLockSwitchCoordinator _capsLock;
+    private readonly NativeTrayIcon _tray;
+
+    internal Agent(SingleInstanceGate gate)
+    {
+        _gate = gate;
+
+        _window = new AgentWindow();
+        _window.AddFilter(OnWindowMessage);
+
+        _settingsService = new SettingsService();
+        _settings = _settingsService.Load();
+
+        _localization = new LocalizationService { CurrentLanguage = _settings.Language };
+        _settings.PropertyChanged += OnSettingsChanged;
+
+        _popupWindow = new NativePopupWindow(_settings);
+        _popupService = new LayoutPopupService(_popupWindow, _settings);
+
+        _layoutService = new KeyboardLayoutService(new KeyboardLayoutOptions());
+        _hotkeyService = new CapsLockHotkeyService(_settings, _window.Post);
+
+        _notifications = new LayoutNotificationCoordinator(_layoutService, _popupService);
+        _capsLock = new CapsLockSwitchCoordinator(_hotkeyService, _layoutService, _popupService, _settings);
+
+        _tray = new NativeTrayIcon(_window, _localization);
+    }
+
+    /// <summary>Starts everything and pumps messages until the user asks to quit.</summary>
+    internal int Run(bool automatic)
+    {
+        _gate.ActivationRequested += OnActivationRequested;
+
+        _tray.OpenRequested += OnOpenRequested;
+        _tray.ExitRequested += OnExitRequested;
+
+        bool hasTray = _tray.Install();
+
+        _notifications.Start();
+        _capsLock.Start();
+
+        if (!automatic || !hasTray)
+        {
+            SettingsLauncher.Open();
+        }
+
+        return MessageLoop.Run();
+    }
+
+    public void Dispose()
+    {
+        _gate.ActivationRequested -= OnActivationRequested;
+
+        _tray.OpenRequested -= OnOpenRequested;
+        _tray.ExitRequested -= OnExitRequested;
+
+        _settings.PropertyChanged -= OnSettingsChanged;
+
+        _capsLock.Dispose();
+        _notifications.Dispose();
+        _hotkeyService.Dispose();
+        _layoutService.Dispose();
+        _popupService.Dispose();
+        _settingsService.Dispose();
+        _tray.Dispose();
+        _window.Dispose();
+    }
+
+    // The settings window has written the file and says so. The write was a single
+    // atomic move, so there is nothing to wait for and nothing half-written to read
+    private bool OnWindowMessage(uint message, IntPtr wParam, IntPtr lParam)
+    {
+        if (message != SettingsSignal.Message)
+        {
+            return false;
+        }
+
+        _settingsService.Reload();
+        return true;
+    }
+
+    private void OnSettingsChanged(object? sender, PropertyChangedEventArgs e)
+    {
+        if (e.PropertyName == nameof(AppSettings.Language))
+        {
+            _localization.CurrentLanguage = _settings.Language;
+        }
+    }
+
+    // A second launch of the agent, from the Start menu for instance. The one already
+    // running answers the way the user expects a second launch to be answered
+    private void OnActivationRequested(object? sender, EventArgs e) =>
+        _window.Post(() => SettingsLauncher.Open());
+
+    private void OnOpenRequested(object? sender, EventArgs e) => SettingsLauncher.Open();
+
+    private void OnExitRequested(object? sender, EventArgs e) => _window.Quit();
+}