Determine state of Quiet Hours/Focus Assist with WNF

focus_assist.cpp

//
// Not to be used in any serious manner
//

#include <Windows.h>
#include <iostream>
#define NT_SUCCESS(Status) (((NTSTATUS)(Status)) >= 0)

typedef struct _WNF_STATE_NAME
{
    ULONG Data[2];
} WNF_STATE_NAME, *PWNF_STATE_NAME;

typedef struct _WNF_TYPE_ID
{
    GUID TypeId;
} WNF_TYPE_ID, *PWNF_TYPE_ID;

typedef const WNF_TYPE_ID *PCWNF_TYPE_ID;
typedef ULONG WNF_CHANGE_STAMP, *PWNF_CHANGE_STAMP;

extern "C"
NTSTATUS
NTAPI
NtQueryWnfStateData(
    _In_ PWNF_STATE_NAME StateName,
    _In_opt_ PWNF_TYPE_ID TypeId,
    _In_opt_ const VOID* ExplicitScope,
    _Out_ PWNF_CHANGE_STAMP ChangeStamp,
    _Out_writes_bytes_to_opt_(*BufferSize, *BufferSize) PVOID Buffer,
    _Inout_ PULONG BufferSize);

#pragma comment(lib, "ntdll.lib")

int wmain()
{
    // WNF_SHEL_QUIETHOURS_ACTIVE_PROFILE_CHANGED
    // This wnf is signaled whenever active quiet hours profile / mode changes.
    // The value is the restrictive level of an active profile and the restrictive level is unique per profile
    //
    WNF_STATE_NAME WNF_SHEL_QUIETHOURS_ACTIVE_PROFILE_CHANGED{ 0xA3BF1C75, 0xD83063E };

    WNF_CHANGE_STAMP unused_change_stamp{};
    DWORD buffer = 0;
    ULONG buffer_size = sizeof(buffer);

    if (NT_SUCCESS(::NtQueryWnfStateData(&WNF_SHEL_QUIETHOURS_ACTIVE_PROFILE_CHANGED, nullptr, nullptr, &unused_change_stamp, &buffer, &buffer_size)))
    {
        std::cout << "Focus Assist status: ";
        switch (buffer)
        {
        case 0:
            std::cout << "Off";
            break;
        case 1:
            std::cout << "On (Priority only)";
            break;
        case 2:
            std::cout << "On (Alarms only)";
            break;
        default:
            std::cout << "???";
            break;
        }
    }
}