meeting-assistant/MeetingAssistant/Taskbar/WindowsTaskbarIconService.cs

using System.Drawing;
using System.Runtime.InteropServices;
using System.Windows.Forms;
using MeetingAssistant.LaunchProfiles;
using MeetingAssistant.Recording;

namespace MeetingAssistant.Taskbar;

public sealed class WindowsTaskbarIconService : IHostedService, IDisposable
{
    private readonly MeetingRecordingCoordinator coordinator;
    private readonly ILaunchProfileOptionsProvider launchProfiles;
    private readonly ILogger<WindowsTaskbarIconService> logger;
    private readonly TaskCompletionSource started = new(TaskCreationOptions.RunContinuationsAsynchronously);
    private Thread? uiThread;
    private SynchronizationContext? uiContext;
    private NotifyIcon? notifyIcon;
    private ContextMenuStrip? contextMenu;
    private System.Windows.Forms.Timer? refreshTimer;
    private Icon? currentIcon;
    private RecordingProcessState? currentState;

    public WindowsTaskbarIconService(
        MeetingRecordingCoordinator coordinator,
        ILaunchProfileOptionsProvider launchProfiles,
        ILogger<WindowsTaskbarIconService> logger)
    {
        this.coordinator = coordinator;
        this.launchProfiles = launchProfiles;
        this.logger = logger;
    }

    public Task StartAsync(CancellationToken cancellationToken)
    {
        if (!OperatingSystem.IsWindows())
        {
            logger.LogInformation("Taskbar icon is only supported on Windows");
            return Task.CompletedTask;
        }

        uiThread = new Thread(RunMessageLoop)
        {
            IsBackground = true,
            Name = "Meeting Assistant Taskbar Icon"
        };
        uiThread.SetApartmentState(ApartmentState.STA);
        uiThread.Start();

        return started.Task.WaitAsync(cancellationToken);
    }

    public async Task StopAsync(CancellationToken cancellationToken)
    {
        var context = uiContext;
        if (context is not null)
        {
            context.Post(_ => Application.ExitThread(), null);
        }

        if (uiThread is not null)
        {
            while (uiThread.IsAlive && !cancellationToken.IsCancellationRequested)
            {
                await Task.Delay(50, cancellationToken);
            }
        }
    }

    public void Dispose()
    {
        currentIcon?.Dispose();
        contextMenu?.Dispose();
        notifyIcon?.Dispose();
        refreshTimer?.Dispose();
    }

    private void RunMessageLoop()
    {
        try
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            uiContext = SynchronizationContext.Current ?? new WindowsFormsSynchronizationContext();
            SynchronizationContext.SetSynchronizationContext(uiContext);

            contextMenu = new ContextMenuStrip();
            contextMenu.Opening += (_, _) => RebuildMenu();
            notifyIcon = new NotifyIcon
            {
                ContextMenuStrip = contextMenu,
                Visible = true
            };
            refreshTimer = new System.Windows.Forms.Timer
            {
                Interval = 1000
            };
            refreshTimer.Tick += (_, _) => RefreshVisualState();
            refreshTimer.Start();
            RefreshVisualState();
            started.TrySetResult();

            Application.Run();
        }
        catch (Exception exception)
        {
            started.TrySetException(exception);
            logger.LogError(exception, "Taskbar icon service failed");
        }
        finally
        {
            refreshTimer?.Stop();
            if (notifyIcon is not null)
            {
                notifyIcon.Visible = false;
            }

            Dispose();
        }
    }

    private void RefreshVisualState()
    {
        if (notifyIcon is null)
        {
            return;
        }

        var menu = BuildMenu();
        if (currentState != menu.State)
        {
            var nextIcon = CreateIcon(menu.State);
            notifyIcon.Icon = nextIcon;
            currentIcon?.Dispose();
            currentIcon = nextIcon;
            currentState = menu.State;
        }

        notifyIcon.Text = TruncateTooltip(menu.Tooltip);
    }

    private void RebuildMenu()
    {
        if (contextMenu is null)
        {
            return;
        }

        var menu = BuildMenu();
        contextMenu.Items.Clear();
        foreach (var menuItem in menu.Items)
        {
            var item = new ToolStripMenuItem(menuItem.Text)
            {
                Tag = menuItem
            };
            item.Click += (_, _) => _ = ExecuteMenuItemAsync(menuItem);
            contextMenu.Items.Add(item);
        }
    }

    private MeetingTaskbarMenu BuildMenu()
    {
        return MeetingTaskbarMenuBuilder.Build(
            coordinator.CurrentStatus,
            launchProfiles.GetProfiles());
    }

    private async Task ExecuteMenuItemAsync(MeetingTaskbarMenuItem item)
    {
        try
        {
            switch (item.Action)
            {
                case MeetingTaskbarAction.StartRecording:
                    await coordinator.StartAsync(item.ProfileName, CancellationToken.None);
                    break;
                case MeetingTaskbarAction.StopRecording:
                    await coordinator.StopAsync(CancellationToken.None);
                    break;
                case MeetingTaskbarAction.AbortRecording:
                    await coordinator.AbortAsync(CancellationToken.None);
                    break;
                case MeetingTaskbarAction.SwitchProfile:
                    await coordinator.ToggleAsync(item.ProfileName, CancellationToken.None);
                    break;
            }
        }
        catch (Exception exception)
        {
            logger.LogError(
                exception,
                "Taskbar menu action {Action} failed for launch profile {LaunchProfile}",
                item.Action,
                item.ProfileName);
        }
    }

    private static string TruncateTooltip(string tooltip)
    {
        return tooltip.Length <= 63 ? tooltip : tooltip[..63];
    }

    private static Icon CreateIcon(RecordingProcessState state)
    {
        var (color, text) = state switch
        {
            RecordingProcessState.Recording => (Color.FromArgb(220, 38, 38), "R"),
            RecordingProcessState.Summarizing => (Color.FromArgb(37, 99, 235), "S"),
            _ => (Color.FromArgb(75, 85, 99), "I")
        };

        using var bitmap = new Bitmap(16, 16);
        using (var graphics = Graphics.FromImage(bitmap))
        {
            graphics.Clear(Color.Transparent);
            graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
            using var brush = new SolidBrush(color);
            graphics.FillEllipse(brush, 1, 1, 14, 14);
            using var font = new Font(FontFamily.GenericSansSerif, 8, FontStyle.Bold, GraphicsUnit.Pixel);
            using var textBrush = new SolidBrush(Color.White);
            var size = graphics.MeasureString(text, font);
            graphics.DrawString(
                text,
                font,
                textBrush,
                (16 - size.Width) / 2,
                (16 - size.Height) / 2);
        }

        var handle = bitmap.GetHicon();
        try
        {
            return (Icon)Icon.FromHandle(handle).Clone();
        }
        finally
        {
            DestroyIcon(handle);
        }
    }

    [DllImport("user32.dll", SetLastError = true)]
    private static extern bool DestroyIcon(IntPtr hIcon);
}