ColorControl/Shared/EventDispatcher/PowerEventDispatcher.cs

using Microsoft.Win32;
using NWin32;

namespace ColorControl.Shared.EventDispatcher;

public enum PowerOnOffState
{
    None = 0,
    StartUp = 1,
    Resume = 2,
    ScreenSaver = 3,
    ShutDown = 4,
    StandBy = 5,
    MonitorOff = 6,
    MonitorOn = 7
}

public enum WindowsMonitorPowerSetting
{
    Off = 0,
    On = 1,
    Dimmed = 2
}

public class PowerStateChangedEventArgs : EventArgs
{
    public PowerOnOffState State { get; private set; }

    public PowerStateChangedEventArgs(PowerOnOffState state)
    {
        State = state;
    }
}

public class PowerEventDispatcher : EventDispatcher<PowerStateChangedEventArgs>
{
    public const string Event_Suspend = "Suspend";
    public const string Event_Resume = "Resume";
    public const string Event_Startup = "Startup";
    public const string Event_Shutdown = "Shutdown";
    public const string Event_MonitorOff = "MonitorOff";
    public const string Event_MonitorOn = "MonitorOn";

    private static readonly NLog.Logger Logger = NLog.LogManager.GetCurrentClassLogger();

    public PowerEventDispatcher()
    {
        SystemEvents.PowerModeChanged += OnPowerModeChanged;
    }

    public void SendEvent(string eventName)
    {
        var state = eventName switch
        {
            Event_Shutdown => PowerOnOffState.ShutDown,
            Event_Startup => PowerOnOffState.StartUp,
            Event_MonitorOff => PowerOnOffState.MonitorOff,
            Event_MonitorOn => PowerOnOffState.MonitorOn,
            _ => PowerOnOffState.None
        };

        if (state == PowerOnOffState.None)
        {
            return;
        }

        if (state == PowerOnOffState.ShutDown)
        {
            DispatchEventWithExecutionState(Event_Shutdown, PowerOnOffState.ShutDown);
            return;
        }

        DispatchEvent(eventName, new PowerStateChangedEventArgs(state));
    }

    public async Task SendEventAsync(string eventName)
    {
        var state = eventName switch
        {
            Event_Startup => PowerOnOffState.StartUp,
            _ => PowerOnOffState.None
        };

        await DispatchEventAsync(eventName, new PowerStateChangedEventArgs(state));
    }

    private async void OnPowerModeChanged(object sender, PowerModeChangedEventArgs e)
    {
        if (e.Mode == PowerModes.Suspend)
        {
            DispatchEventWithExecutionState(Event_Suspend, PowerOnOffState.StandBy);
        }
        else if (e.Mode == PowerModes.Resume)
        {
            await DispatchEventAsync(Event_Resume, new PowerStateChangedEventArgs(PowerOnOffState.Resume));
            DispatchEvent(Event_Resume, new PowerStateChangedEventArgs(PowerOnOffState.Resume));
        }
    }

    private void DispatchEventWithExecutionState(string eventName, PowerOnOffState powerState)
    {
        var error = NativeMethods.SetThreadExecutionState(NativeConstants.ES_CONTINUOUS | NativeConstants.ES_SYSTEM_REQUIRED | NativeConstants.ES_AWAYMODE_REQUIRED);
        try
        {
            Logger.Debug($"SetThreadExecutionState: {error}, Thread#: {Environment.CurrentManagedThreadId}");
            DispatchEvent(eventName, new PowerStateChangedEventArgs(powerState));
        }
        finally
        {
            var error2 = NativeMethods.SetThreadExecutionState(NativeConstants.ES_CONTINUOUS);
            Logger.Debug($"SetThreadExecutionState (reset): {error2}, Thread#: {Environment.CurrentManagedThreadId}");
        }
    }
}