using System;
using System.Collections.Generic;
using System.Text;
using System.Management;

namespace FDK
{
	public static class COS
	{
		/// <summary>
		/// OSがXP以前ならfalse, Vista以降ならtrueを返す
		/// </summary>
		/// <returns></returns>
		public static bool bIsVistaOrLater()
		{
			return bCheckOSVersion(6, 0);
		}
		/// <summary>
		/// OSがVista以前ならfalse, Win7以降ならtrueを返す
		/// </summary>
		/// <returns></returns>
		public static bool bIsWin7OrLater()
		{
			return bCheckOSVersion(6, 1);
		}
		/// <summary>
		/// OSがWin7以前ならfalse, Win8以降ならtrueを返す
		/// </summary>
		/// <returns></returns>
		public static bool bIsWin8OrLater()
		{
			return bCheckOSVersion(6, 2);
		}
		/// <summary>
		/// OSがWin10以前ならfalse, Win10以降ならtrueを返す
		/// </summary>
		/// <returns></returns>
		public static bool bIsWin10OrLater()
		{
			return bCheckOSVersion(10, 0);
		}
		/// <summary>
		/// OSがWin10以降、かつ指定build以降ならtrueを返す
		/// </summary>
		/// <returns></returns>
		public static bool bIsWin10OrLater(WIN10BUILD build)
		{
			if (bCheckOSVersion(10, 0))
			{
				if ( GetWin10BuildNumber() >= build )
				{
					return true;
				}
				else
				{
					return false;
				}
			}
			else
			{
				return false;
			};
		}


		/// <summary>
		/// 指定のOSバージョン以上であればtrueを返す
		/// </summary>
		private static bool bCheckOSVersion(int major, int minor)
		{
			//プラットフォームの取得
			//System.OperatingSystem os = System.Environment.OSVersion;
			//if (os.Platform != PlatformID.Win32NT)      // NT系でなければ、XP以前か、PC Windows系以外のOS。
			//{
			//	return false;
			//}
			//var mmb = tpGetOSVersion();
			int _major, _minor, _build;
			tpGetOSVersion(out _major, out _minor, out _build);

			//if (os.Version.Major >= major && os.Version.Minor >= minor)
			if (_major > major)
			{
				return true;
			}
			else if (_major == major && _minor >= minor)
			{
				return true;
			}
			else
			{
				return false;
			}
		}


		//public static (int major, int minor, int build) tpGetOSVersion()
		public static void tpGetOSVersion(out int major, out int minor, out int build)
		{
			//var result = (major: 0, minor: 0, build: 0);
			major = 0;
			minor = 0;
			build = 0;

			System.Management.ManagementClass mc =
				new System.Management.ManagementClass("Win32_OperatingSystem");
			System.Management.ManagementObjectCollection moc = mc.GetInstances();

			foreach (System.Management.ManagementObject mo in moc)
			{
				string ver = mo["Version"].ToString();
				string[] majorminor = ver.Split(new char[] { '.' }, StringSplitOptions.None);

				major = Convert.ToInt32(majorminor[0]);
				minor = Convert.ToInt32(majorminor[1]);
				build = Convert.ToInt32(mo["BuildNumber"]);

				break;  // 1回ループで終了(でいいよね)
			}
			moc.Dispose();
			mc.Dispose();

			//return result;
		}
		public enum WIN10BUILD : int
		{
			TH1 = 10240,	// 1507: 
			TH2 = 10586,	// 1511: November Update
			RS1 = 14393,	// 1607: Anniversary Update
			RS2 = 15063,	// 1703: Creators Update
			RS3 = 16299,	// 1709: Fall Creators Update
			RS4 = 17134,	// 1803: April 2018 Update
            RS5 = 17763,	// 1809: October 2018 Update
            _19H1 = 18362,  // 1903: May 2019 Update
			_19H2 = 18363,  // 1909: November 2019 Update
			UNKNOWN = -1,
			NOTWIN10 = 0
		}
		public static WIN10BUILD GetWin10BuildNumber()
		{
			WIN10BUILD ret = WIN10BUILD.UNKNOWN;

			//var mmb = tpGetOSVersion();
			int major, minor, build;
			tpGetOSVersion(out major, out minor, out build);

			if (major != 10)
			{
				ret = WIN10BUILD.NOTWIN10;
			}
			else
			{
				ret = (WIN10BUILD)build;
			}

			return ret;
		}
	}
}