using System.Runtime.InteropServices;
using System.Text;

namespace WindowWatcher;

internal static partial class NativeMethods
{
    [LibraryImport("user32.dll")]
    internal static partial IntPtr GetForegroundWindow();

    [DllImport("user32.dll", CharSet = CharSet.Unicode)]
    internal static extern int GetWindowText(IntPtr hWnd, StringBuilder text, int count);

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

    [StructLayout(LayoutKind.Sequential)]
    internal struct LASTINPUTINFO
    {
        public uint cbSize;
        public uint dwTime;
    }

    [DllImport("user32.dll")]
    internal static extern bool GetLastInputInfo(ref LASTINPUTINFO plii);

    internal static TimeSpan GetIdleTime()
    {
        var info = new LASTINPUTINFO { cbSize = (uint)Marshal.SizeOf<LASTINPUTINFO>() };
        if (!GetLastInputInfo(ref info))
            return TimeSpan.Zero;
        return TimeSpan.FromMilliseconds(Environment.TickCount64 - info.dwTime);
    }
}