Lidarr/src/NzbDrone.Windows/EnvironmentInfo/DotNetPlatformInfo.cs

using System;
using Microsoft.Win32;
using NzbDrone.Common.EnvironmentInfo;

namespace NzbDrone.Windows.EnvironmentInfo
{
    public class DotNetPlatformInfo : PlatformInfo
    {
        public DotNetPlatformInfo()
        {
            var version = GetFrameworkVersion();
            Environment.SetEnvironmentVariable("RUNTIME_VERSION", version.ToString());
            Version = version;
        }

        public override Version Version { get; }

        private static Version GetFrameworkVersion()
        {
            const string subkey = @"SOFTWARE\Microsoft\NET Framework Setup\NDP\v4\Full\";
            using (var ndpKey = RegistryKey.OpenBaseKey(RegistryHive.LocalMachine, RegistryView.Registry32).OpenSubKey(subkey))
            {
                if (ndpKey == null)
                {
                    return new Version(4, 0);
                }

                var releaseKey = (int)ndpKey.GetValue("Release");

                if (releaseKey >= 394802)
                {
                    return new Version(4, 6, 2);
                }
                if (releaseKey >= 394254)
                {
                    return new Version(4, 6, 1);
                }
                if (releaseKey >= 393295)
                {
                    return new Version(4, 6);
                }
                if (releaseKey >= 379893)
                {
                    return new Version(4, 5, 2);
                }
                if (releaseKey >= 378675)
                {
                    return new Version(4, 5, 1);
                }
                if (releaseKey >= 378389)
                {
                    return new Version(4, 5);
                }

                return new Version(4, 0);
            }
        }
    }
}