AboutTools

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.Win32;

public static class AboutTools {
    public static string NiceWindowsVersion(this OperatingSystem os) {
        switch(os.Platform) {
            case PlatformID.Win32Windows:
                switch(os.Version.Minor) {
                    case 0:
                        return "Windows 95";
                    case 10:
                        if(os.Version.Revision.ToString() == "2222A")
                            return "Windows 98 SE";
                        else
                            return "Windows 98";
                    case 90:
                        return "Windows ME";
                }
                break;
            case PlatformID.Win32NT:
                switch(os.Version.Major) {
                    case 3:
                        return "Windows NT 3.51";
                    case 4:
                        return "Windows NT 4.0";
                    case 5:
                        switch(os.Version.Minor) {
                            case 0:
                                return "Windows 2000";
                            case 1:
                                return "Windows XP";
                            case 2:
                                return "Windows 2003 Server";
                        }
                        break;
                    case 6:
                        switch(os.Version.Minor) {
                            case 0:
                                return "Windows Vista / 2008 Server";
                            case 1:
                                return "Windows 7";
                        }
                        break;
                }
                break;
        }

        return os.VersionString;
    }

    public static DateTime CompilationTime(this Version v) {
        return new DateTime(v.Build * TimeSpan.TicksPerDay + v.Revision * TimeSpan.TicksPerSecond * 2).AddYears(1999).AddDays(-1);
    }

    public static List<NetFrameworkVersion> FrameworkVersions() {
        List<NetFrameworkVersion> versions = new List<NetFrameworkVersion>();
        RegistryKey oldComponentsKey = Registry.LocalMachine.OpenSubKey(@"Software\Microsoft\Active Setup\Installed Components\{78705f0d-e8db-4b2d-8193-982bdda15ecd}\");
        if(oldComponentsKey == null)
            oldComponentsKey = Registry.LocalMachine.OpenSubKey(@"HKLM\Software\Microsoft\Active Setup\Installed Components\{FDC11A6F-17D1-48f9-9EA3-9051954BAA24}\");
        if(oldComponentsKey != null)
            versions.AddRange(oldComponentsKey.SubKeys((n,k) =>
                new NetFrameworkVersion() {
                    GlobalVersion = "v1.0",
                    FullVersion = (string)k.GetValue("Version"),
                    ServicePack = GetOldComponentServicePack(k)
                }).ToList());


        RegistryKey componentsKey = Registry.LocalMachine.OpenSubKey(@"SOFTWARE\Microsoft\Net Framework Setup\NDP\");
        versions.AddRange(componentsKey.SubKeys((n,k) =>
            new NetFrameworkVersion {
                GlobalVersion = n,
                FullVersion = (string)k.GetValue("Version"),
                ServicePack = (int?)k.GetValue("SP")
            }).ToList());
        return versions;
    }

    private static int? GetOldComponentServicePack(RegistryKey k) {
        string[] e = ((string)k.GetValue("Version")).Split(',');
        int sp;
        if(int.TryParse(e.LastOrDefault(),out sp))
            return sp;
        else
            return null;
    }

    public static IEnumerable<T> SubKeys<T>(this RegistryKey key,Func<string,RegistryKey,T> func) {
        string[] keyNames = key.GetSubKeyNames();
        foreach(var keyName in keyNames) {
            using(var k = key.OpenSubKey(keyName))
                yield return func(keyName,k);
        }
    }

    public class NetFrameworkVersion {
        public string GlobalVersion { get; internal set; }
        public string FullVersion { get; internal set; }
        public int? ServicePack { get; internal set; }

        public override string ToString() {
            return GlobalVersion + (ServicePack != null ? " SP" + ServicePack : "");
        }
    }

}