using System.Runtime.InteropServices;

namespace MusicBridge.Agent;

// Obtain the current default output for each operation, including after device changes.
internal static class SystemVolume
{
    public static void Set(float level) => WithEndpoint(endpoint =>
    {
        if (!float.IsFinite(level) || level < 0 || level > 1)
            throw new ArgumentOutOfRangeException(nameof(level));
        var context = Guid.Empty;
        endpoint.SetMasterVolumeLevelScalar(level, ref context);
        return true;
    });

    public static (float Level, bool Muted) Read() => WithEndpoint(endpoint =>
    {
        endpoint.GetMasterVolumeLevelScalar(out var level);
        endpoint.GetMute(out var muted);
        return (level, muted);
    });

    public static void Change(float delta) => WithEndpoint(endpoint =>
    {
        endpoint.GetMasterVolumeLevelScalar(out var level);
        var context = Guid.Empty;
        endpoint.SetMasterVolumeLevelScalar(Math.Clamp(level + delta, 0f, 1f), ref context);
        return true;
    });

    public static void ToggleMute() => WithEndpoint(endpoint =>
    {
        endpoint.GetMute(out var muted);
        var context = Guid.Empty;
        endpoint.SetMute(!muted, ref context);
        return true;
    });

    private static T WithEndpoint<T>(Func<IAudioEndpointVolume, T> action)
    {
        var enumerator = (IMMDeviceEnumerator)new MMDeviceEnumerator();
        IMMDevice? device = null;
        object? volume = null;
        try
        {
            enumerator.GetDefaultAudioEndpoint(0, 1, out device); // Render, Multimedia
            var iid = typeof(IAudioEndpointVolume).GUID;
            device.Activate(ref iid, 23, IntPtr.Zero, out volume);
            return action((IAudioEndpointVolume)volume);
        }
        finally
        {
            if (volume is not null) Marshal.ReleaseComObject(volume);
            if (device is not null) Marshal.ReleaseComObject(device);
            Marshal.ReleaseComObject(enumerator);
        }
    }

    [ComImport, Guid("BCDE0395-E52F-467C-8E3D-C4579291692E")]
    private class MMDeviceEnumerator { }

    // COM declarations must preserve the native vtable order, including unused methods.
    // HRESULT failures are translated to exceptions by the COM interop runtime.
    [ComImport, Guid("A95664D2-9614-4F35-A746-DE8DB63617E6"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    private interface IMMDeviceEnumerator
    {
        void EnumAudioEndpoints(int flow, uint mask, out IntPtr devices);
        void GetDefaultAudioEndpoint(int flow, int role, out IMMDevice device);
    }

    [ComImport, Guid("D666063F-1587-4E43-81F1-B948E807363F"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    private interface IMMDevice
    {
        void Activate(ref Guid iid, uint context, IntPtr activation,
            [MarshalAs(UnmanagedType.IUnknown)] out object instance);
    }

    [ComImport, Guid("5CDF2C82-841E-4546-9722-0CF74078229A"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    private interface IAudioEndpointVolume
    {
        void RegisterControlChangeNotify(IntPtr callback);
        void UnregisterControlChangeNotify(IntPtr callback);
        void GetChannelCount(out uint count);
        void SetMasterVolumeLevel(float level, ref Guid context);
        void SetMasterVolumeLevelScalar(float level, ref Guid context);
        void GetMasterVolumeLevel(out float level);
        void GetMasterVolumeLevelScalar(out float level);
        void SetChannelVolumeLevel(uint channel, float level, ref Guid context);
        void SetChannelVolumeLevelScalar(uint channel, float level, ref Guid context);
        void GetChannelVolumeLevel(uint channel, out float level);
        void GetChannelVolumeLevelScalar(uint channel, out float level);
        void SetMute([MarshalAs(UnmanagedType.Bool)] bool muted, ref Guid context);
        void GetMute([MarshalAs(UnmanagedType.Bool)] out bool muted);
    }
}