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

namespace NX_Installation
{
    class GetWindowsMainVersionInfo
    {
        /* API-Deklarationen */
        [StructLayout(LayoutKind.Sequential)]

        private struct OSVERSIONINFOEX
        {
            public int dwOSVersionInfoSize;
            public int dwMajorVersion;
            public int dwMinorVersion;
            public int dwBuildNumber;
            public int dwPlatformId;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 128)]
            public string szCSDVersion;
            public Int16 wServicePackMajor;
            public Int16 wServicePackMinor;
            public Int16 wSuiteMask;
            public Byte wProductType;
            public Byte wReserved;
        }

        [DllImport("kernel32")]
        static extern bool GetVersionEx(ref OSVERSIONINFOEX osvi);
        private const int VER_NT_WORKSTATION = 0x0000001;

        /* Aufzählung für die Windows-Hauptversion */
        public enum WindowsMainVersion
        {
            WindowsXP,
            WindowsServer2003,
            WindowsXP_64,
            WindowsVista,
            WindowsVista_64,
            WindowsServer2008,
            Windows7,
            Windows7_64,
            WindowsServer2008R2,
            Windows8,
            Windows8_64,
            Windows10,
            Windows10_64,
            WindowsServer2012,
            Unknown
        }

        /* Ermittelt die Windows-Hauptversion */
        /// <summary>
        /// Returns the Windows Main Version
        /// </summary>
        /// <returns></returns>
        public WindowsMainVersion GetWindowsMainVersion()
        {
            OSVERSIONINFOEX osVersionInfo = new OSVERSIONINFOEX();
            osVersionInfo.dwOSVersionInfoSize = Marshal.SizeOf(osVersionInfo);
            if (GetVersionEx(ref osVersionInfo))
            {
                switch (osVersionInfo.dwMajorVersion)
                {
                    case 5:
                        if (Environment.OSVersion.Version.Minor == 1)
                        {
                            return WindowsMainVersion.WindowsXP;
                        }
                        else if (Environment.OSVersion.Version.Minor == 2)
                        {
                            if (osVersionInfo.wProductType == VER_NT_WORKSTATION)
                            {
                                return WindowsMainVersion.WindowsXP_64;
                            }
                            else
                            {
                                return WindowsMainVersion.WindowsServer2003;
                            }
                        }
                        else
                        {
                            return WindowsMainVersion.Unknown;
                        }
                    case 6:
                        if (Environment.OSVersion.Version.Minor == 0)
                        {
                            if (osVersionInfo.wProductType == VER_NT_WORKSTATION)
                            {
                                if (Convert.ToString(GetPlatform()) == "X86")
                                {
                                    return WindowsMainVersion.WindowsVista;
                                }
                                if (Convert.ToString(GetPlatform()) == "X64")
                                {
                                    return WindowsMainVersion.WindowsVista_64;
                                }
                                else
                                {
                                    throw new Exception("GetPlatform has no valid value");
                                }
                            }
                            else
                            {
                                return WindowsMainVersion.WindowsServer2008;
                            }
                        }
                        else if (Environment.OSVersion.Version.Minor == 1)
                        {
                            if (osVersionInfo.wProductType == VER_NT_WORKSTATION)
                            {
                                if (Convert.ToString(GetPlatform()) == "X86")
                                {
                                    return WindowsMainVersion.Windows7;
                                }
                                if (Convert.ToString(GetPlatform()) == "X64")
                                {
                                    return WindowsMainVersion.Windows7_64;
                                }
                                else
                                {
                                    throw new Exception("GetPlatform has no valid value");
                                }
                            }
                            else
                            {
                                return WindowsMainVersion.WindowsServer2008R2;
                            }
                        }
                        else if (Environment.OSVersion.Version.Minor == 2)
                        {
                            if (osVersionInfo.wProductType == VER_NT_WORKSTATION)
                            {
                                if (Convert.ToString(GetPlatform()) == "X86")
                                {
                                    return WindowsMainVersion.Windows8;
                                }
                                if (Convert.ToString(GetPlatform()) == "X64")
                                {
                                    return WindowsMainVersion.Windows8_64;
                                }
                                else
                                {
                                    throw new Exception("GetPlatform has no valid value");
                                }
                            }
                            else
                            {
                                return WindowsMainVersion.WindowsServer2012;
                            }
                        }
                        return WindowsMainVersion.Unknown;
                    case 10:
                        if (Environment.OSVersion.Version.Minor == 0)
                        {
                            //return WindowsMainVersion.Windows10_64;
                            if (osVersionInfo.wProductType == VER_NT_WORKSTATION)
                            {
                                if (Convert.ToString(GetPlatform()) == "X86")
                                {
                                    return WindowsMainVersion.Windows10;
                                }
                                if (Convert.ToString(GetPlatform()) == "X64")
                                {
                                    return WindowsMainVersion.Windows10_64;
                                }
                                else
                                {
                                    throw new Exception("GetPlatform has no valid value");
                                }
                            }
                            else
                            {
                                return WindowsMainVersion.WindowsServer2012;
                            }
                        }
                        else
                        {
                            return WindowsMainVersion.Unknown;
                        }
                    default:
                        return WindowsMainVersion.Unknown;
                }
            }
            else
            {
                throw new Exception("GetVersionEx provides false back");
            }
        }

        public enum Platform
        {
            X86,
            X64,
            Unknown
        }

        internal const ushort PROCESSOR_ARCHITECTURE_INTEL = 0;
        internal const ushort PROCESSOR_ARCHITECTURE_IA64 = 6;
        internal const ushort PROCESSOR_ARCHITECTURE_AMD64 = 9;
        internal const ushort PROCESSOR_ARCHITECTURE_UNKNOWN = 0xFFFF;

        [StructLayout(LayoutKind.Sequential)]
        internal struct SYSTEM_INFO
        {
            public ushort wProcessorArchitecture;
            public ushort wReserved;
            public uint dwPageSize;
            public IntPtr lpMinimumApplicationAddress;
            public IntPtr lpMaximumApplicationAddress;
            public UIntPtr dwActiveProcessorMask;
            public uint dwNumberOfProcessors;
            public uint dwProcessorType;
            public uint dwAllocationGranularity;
            public ushort wProcessorLevel;
            public ushort wProcessorRevision;
        };

        [DllImport("kernel32.dll")]
        internal static extern void GetNativeSystemInfo(ref SYSTEM_INFO lpSystemInfo);

        [DllImport("kernel32.dll")]
        internal static extern void GetSystemInfo(ref SYSTEM_INFO lpSystemInfo);

        public static Platform GetPlatform()
        {
            SYSTEM_INFO sysInfo = new SYSTEM_INFO();

            if (System.Environment.OSVersion.Version.Major > 5 ||
          (System.Environment.OSVersion.Version.Major == 5 && System.Environment.OSVersion.Version.Minor >= 1))
            {
                GetNativeSystemInfo(ref sysInfo);
            }
            else
            {
                GetSystemInfo(ref sysInfo);
            }

            switch (sysInfo.wProcessorArchitecture)
            {
                case PROCESSOR_ARCHITECTURE_IA64:
                case PROCESSOR_ARCHITECTURE_AMD64:
                    return Platform.X64;

                case PROCESSOR_ARCHITECTURE_INTEL:
                    return Platform.X86;

                default:
                    return Platform.Unknown;
            }
        }
    }
}