param(
    [Parameter(Mandatory=$true)]
    [ValidateSet("list","set","next","current")]
    [string]$Action,

    [int]$Index = -1
)

$ErrorActionPreference = 'Stop'

Add-Type -TypeDefinition @'
using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;

namespace JarvisAudio
{
    [Guid("A95664D2-9614-4F35-A746-DE8DB63617E6"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    public interface IMMDeviceEnumerator
    {
        [PreserveSig] int EnumAudioEndpoints(int dataFlow, int stateMask, out IMMDeviceCollection devices);
        [PreserveSig] int GetDefaultAudioEndpoint(int dataFlow, int role, out IMMDevice device);
        [PreserveSig] int GetDevice([MarshalAs(UnmanagedType.LPWStr)] string id, out IMMDevice device);
    }

    [Guid("0BD7A1BE-7A1A-44DB-8397-CC5392387B5E"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    public interface IMMDeviceCollection
    {
        [PreserveSig] int GetCount(out int count);
        [PreserveSig] int Item(int idx, out IMMDevice device);
    }

    [Guid("D666063F-1587-4E43-81F1-B948E807363F"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    public interface IMMDevice
    {
        [PreserveSig] int Activate(ref Guid iid, int clsCtx, IntPtr activationParams, [MarshalAs(UnmanagedType.IUnknown)] out object iface);
        [PreserveSig] int OpenPropertyStore(int access, out IPropertyStore store);
        [PreserveSig] int GetId([MarshalAs(UnmanagedType.LPWStr)] out string id);
        [PreserveSig] int GetState(out int state);
    }

    [Guid("886D8EEB-8CF2-4446-8D02-CDBA1DBDCF99"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    public interface IPropertyStore
    {
        [PreserveSig] int GetCount(out int count);
        [PreserveSig] int GetAt(int idx, out PROPERTYKEY key);
        [PreserveSig] int GetValue(ref PROPERTYKEY key, out PROPVARIANT value);
    }

    [StructLayout(LayoutKind.Sequential)]
    public struct PROPERTYKEY
    {
        public Guid formatId;
        public int propertyId;
    }

    [StructLayout(LayoutKind.Sequential)]
    public struct PROPVARIANT
    {
        public ushort vt;
        public ushort r1;
        public ushort r2;
        public ushort r3;
        public IntPtr p;
        public IntPtr p2;
    }

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

    [Guid("F8679F50-850A-41CF-9C72-430F290290C8"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    public interface IPolicyConfig
    {
        [PreserveSig] int GetMixFormat();
        [PreserveSig] int GetDeviceFormat();
        [PreserveSig] int ResetDeviceFormat();
        [PreserveSig] int SetDeviceFormat();
        [PreserveSig] int GetProcessingPeriod();
        [PreserveSig] int SetProcessingPeriod();
        [PreserveSig] int GetShareMode();
        [PreserveSig] int SetShareMode();
        [PreserveSig] int GetPropertyValue();
        [PreserveSig] int SetPropertyValue();
        [PreserveSig] int SetDefaultEndpoint([MarshalAs(UnmanagedType.LPWStr)] string deviceId, uint role);
        [PreserveSig] int SetEndpointVisibility();
    }

    [ComImport, Guid("870AF99C-171D-4F9E-AF0D-E63DF40C2BC9")]
    public class PolicyConfigClient {}

    public class Device
    {
        public string Id { get; set; }
        public string Name { get; set; }
    }

    public static class Manager
    {
        const int eRender = 0;
        const int DEVICE_STATE_ACTIVE = 1;

        static PROPERTYKEY PKEY_Device_FriendlyName = new PROPERTYKEY {
            formatId = new Guid("a45c254e-df1c-4efd-8020-67d146a850e0"),
            propertyId = 14
        };

        public static List<Device> ListRender()
        {
            var enumr = (IMMDeviceEnumerator)new MMDeviceEnumerator();
            IMMDeviceCollection coll;
            int hr = enumr.EnumAudioEndpoints(eRender, DEVICE_STATE_ACTIVE, out coll);
            if (hr != 0) throw new Exception("EnumAudioEndpoints failed: 0x" + hr.ToString("X"));

            int count;
            coll.GetCount(out count);

            var result = new List<Device>();
            for (int i = 0; i < count; i++)
            {
                IMMDevice dev;
                coll.Item(i, out dev);
                string id;
                dev.GetId(out id);

                IPropertyStore store;
                dev.OpenPropertyStore(0, out store);

                PROPVARIANT v;
                store.GetValue(ref PKEY_Device_FriendlyName, out v);
                string name = v.p != IntPtr.Zero ? Marshal.PtrToStringUni(v.p) : "(unknown)";

                result.Add(new Device { Id = id, Name = name });
            }
            return result;
        }

        public static string GetDefaultRenderId()
        {
            var enumr = (IMMDeviceEnumerator)new MMDeviceEnumerator();
            IMMDevice dev;
            int hr = enumr.GetDefaultAudioEndpoint(eRender, 0, out dev); // eConsole = 0
            if (hr != 0) return null;
            string id;
            dev.GetId(out id);
            return id;
        }

        public static void SetDefault(string deviceId)
        {
            var cfg = (IPolicyConfig)new PolicyConfigClient();
            cfg.SetDefaultEndpoint(deviceId, 0); // eConsole
            cfg.SetDefaultEndpoint(deviceId, 1); // eMultimedia
            cfg.SetDefaultEndpoint(deviceId, 2); // eCommunications
        }
    }
}
'@ -Language CSharp

$devs = [JarvisAudio.Manager]::ListRender()

switch ($Action) {
    "list" {
        for ($i = 0; $i -lt $devs.Count; $i++) {
            Write-Output ("{0}`t{1}" -f $i, $devs[$i].Name)
        }
    }
    "current" {
        $cur = [JarvisAudio.Manager]::GetDefaultRenderId()
        for ($i = 0; $i -lt $devs.Count; $i++) {
            if ($devs[$i].Id -eq $cur) {
                Write-Output ("{0}`t{1}" -f $i, $devs[$i].Name)
                return
            }
        }
        Write-Output "-1`t(unknown)"
    }
    "set" {
        if ($Index -lt 0 -or $Index -ge $devs.Count) {
            Write-Error "Index out of range: $Index (have $($devs.Count) devices)"
            exit 2
        }
        [JarvisAudio.Manager]::SetDefault($devs[$Index].Id)
        Write-Output ("OK`t{0}" -f $devs[$Index].Name)
    }
    "next" {
        $cur = [JarvisAudio.Manager]::GetDefaultRenderId()
        $curIdx = -1
        for ($i = 0; $i -lt $devs.Count; $i++) {
            if ($devs[$i].Id -eq $cur) { $curIdx = $i; break }
        }
        $nextIdx = ($curIdx + 1) % $devs.Count
        [JarvisAudio.Manager]::SetDefault($devs[$nextIdx].Id)
        Write-Output ("OK`t{0}" -f $devs[$nextIdx].Name)
    }
}