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// -------------------------------------------------------------------------
// 以下のURLから拝借
// https://msdn.microsoft.com/ja-jp/library/hh925567(v=vs.110).aspx
// -------------------------------------------------------------------------
namespace ShowInstalledDotNetPatches
{
    using System;

    using Microsoft.Win32;

    /// <summary>
    /// インストールされている .NET Framework の更新プログラムを出力します。
    /// </summary>
    internal static class Program
    {
        /// <summary>
        /// アプリケーションエントリポイント
        /// </summary>
        private static void Main()
        {
            using (var baseKey = RegistryKey.OpenBaseKey(RegistryHive.LocalMachine, RegistryView.Registry32).OpenSubKey(@"SOFTWARE\Microsoft\Updates"))
            {
                if (baseKey == null)
                {
                    return;
                }

                foreach (var baseKeyName in baseKey.GetSubKeyNames())
                {
                    if (baseKeyName.Contains(".NET Framework") || baseKeyName.StartsWith("KB") || baseKeyName.Contains(".NETFramework"))
                    {
                        using (var updateKey = baseKey.OpenSubKey(baseKeyName))
                        {
                            if (updateKey == null)
                            {
                                continue;
                            }

                            var name = (string)updateKey.GetValue("PackageName", string.Empty);
                            Console.WriteLine(baseKeyName + "  " + name);
                            foreach (var kbKeyName in updateKey.GetSubKeyNames())
                            {
                                using (var kbKey = updateKey.OpenSubKey(kbKeyName))
                                {
                                    if (kbKey == null)
                                    {
                                        continue;
                                    }

                                    name = (string)kbKey.GetValue("PackageName", string.Empty);
                                    Console.WriteLine("  " + kbKeyName + "  " + name);

                                    if (kbKey.SubKeyCount > 0)
                                    {
                                        foreach (var sbKeyName in kbKey.GetSubKeyNames())
                                        {
                                            using (var sbSubKey = kbKey.OpenSubKey(sbKeyName))
                                            {
                                                name = (string)sbSubKey.GetValue("PackageName", string.Empty);
                                                if (name == string.Empty)
                                                {
                                                    name = (string)sbSubKey.GetValue("Description", string.Empty);
                                                }

                                                Console.WriteLine("    " + sbKeyName + "  " + name);
                                            }
                                        }
                                    }
                                }
                            }
                        }
                    }
                }
            }

            Console.WriteLine("Press any key to exit...");
            Console.ReadLine();
        }
    }
}