using System.Runtime.InteropServices;

namespace RTCSync.Utils;

public abstract class WindowsTimeUtils
{
    // c# datetime set
    [DllImport("kernel32.dll")]
    public static extern bool SetSystemTime(ref SystemTime time);

    [DllImport("kernel32.dll")]
    public static extern void GetSystemTime(ref SystemTime time);

    [StructLayout(LayoutKind.Sequential)]
    public struct SystemTime
    {
        public ushort Year, Month, DayOfWeek, Day;
        public ushort Hour, Minute, Second, Milliseconds;

        public SystemTime() { }

        public SystemTime(DateTime dt)
        {
            Year = (ushort)dt.Year;
            Month = (ushort)dt.Month;
            DayOfWeek = (ushort)dt.DayOfWeek;
            Day = (ushort)dt.Day;
            Hour = (ushort)dt.Hour;
            Minute = (ushort)dt.Minute;
            Second = (ushort)dt.Second;
            Milliseconds = (ushort)dt.Millisecond;
        }
    }

    // Фикс для Windows 7 SP1 без обновлений
    // DataTime.Now использует слишком новый API
    public static DateTime Now()
    {
        var st = new SystemTime();
        GetSystemTime(ref st);
        return new DateTime(st.Year, st.Month, st.Day,
            st.Hour, st.Minute, st.Second, st.Milliseconds,
            DateTimeKind.Utc).ToLocalTime();
    }
}