using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;

namespace FocusVolumeControl
{
    internal class Native
    {
        internal delegate void WinEventDelegate(IntPtr hWinEventHook, uint eventType, IntPtr hwnd, int idObject, int idChild, uint dwEventThread, uint dwmsEventTime);

        [DllImport("user32.dll")]
        static extern IntPtr SetWinEventHook(uint eventMin, uint eventMax, IntPtr hmodWinEventProc, WinEventDelegate lpfnWinEventProc, uint idProcess, uint idThread, uint dwFlags);

        [DllImport("user32.dll")]
        internal static extern bool UnhookWinEvent(IntPtr hWinEventHook);


        private const uint WINEVENT_OUTOFCONTEXT = 0;
        private const uint EVENT_SYSTEM_FOREGROUND = 3;

        internal static IntPtr RegisterForForegroundWindowChangedEvent(WinEventDelegate dele) => SetWinEventHook(EVENT_SYSTEM_FOREGROUND, EVENT_SYSTEM_FOREGROUND, IntPtr.Zero, dele, 0, 0, WINEVENT_OUTOFCONTEXT);


        [DllImport("user32.dll")]
        internal static extern IntPtr GetForegroundWindow();

        [DllImport("user32.dll", SetLastError = true)]
        internal static extern uint GetWindowThreadProcessId(IntPtr hWnd, out int processId);

    }
}