using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using Microsoft.Win32;

namespace Foundations
{
    public static class DotNetVersionCheck
    {
        // ".NET Framework 4.5.1"
        public const int RequiredVersion = 378675;
        
        public static Dictionary<int, string> ReleaseNumberToFramework = new Dictionary<int, string>()
        {
            { 378389, @".NET Framework 4.5" },
            { 378675, @".NET Framework 4.5.1" },
            { 378758, @".NET Framework 4.5.1" },
            { 379893, @".NET Framework 4.5.2" },
            
            // On windows 10:
            { 393295, @".NET Framework 4.6" },
            { 394254, @".NET Framework 4.6.1" },
            { 394802, @".NET Framework 4.6.2" },

            // On other OS versions:
            { 393297, @".NET Framework 4.6" },
            { 394271, @".NET Framework 4.6.1" },
            { 394806, @".NET Framework 4.6.2" },
        };

        public static bool CheckDotNetVersion()
        {
            // Look up the .NET version.  See https://msdn.microsoft.com/en-us/library/hh925568#net_a
            bool pass = false;
            try
            {
                var regkey = "SOFTWARE\\Microsoft\\NET Framework Setup\\NDP\\v4\\Full\\";
                using (RegistryKey ndpKey = RegistryKey
                    .OpenBaseKey(RegistryHive.LocalMachine, RegistryView.Registry32)
                    .OpenSubKey(regkey))
                {
                    int releaseKey = Convert.ToInt32(ndpKey.GetValue("Release"));

                    // Must be at least 4.5.1
                    pass = releaseKey >= RequiredVersion;
                }
            }
            finally
            {
                if (!pass)
                {
                    string versionString = ReleaseNumberToFramework[RequiredVersion];
                    MessageBox.Show(String.Format("You must install the {0} or later to continue.", versionString),
                                    "Exiting...");
                }
            }

            return pass;
        }
    }
}