Creating a BrowserLanguageCriteria for Visitor groups.

[VisitorGroupCriterion(
    Category = "Technical Criteria",
    Description = "Match Browser language with specified value",
    DisplayName = "Browser language")]
public class BrowserLanguageCriterion : CriterionBase<BrowserLanguageModel>
{
    private string _browserlang;
    //matches the browserlanguage with the criterion set language.
    public override bool IsMatch(System.Security.Principal.IPrincipal principal, 

System.Web.HttpContextBase httpContext)
    {
        return ((String.IsNullOrEmpty(base.Model.BrowserLanguage) ? true : 

        StringMatchHelper.IsMatch(_browserlang, base.Model.BrowserLanguage, 

        base.Model.BrowserLanguageMatchType)));             
    }

    public override void Subscribe(ICriterionEvents criterionEvents)
    {
        base.Subscribe(criterionEvents);
        criterionEvents.StartRequest += criterionEvents_StartRequest;
    }

    private void criterionEvents_StartRequest(object sender, CriterionEventArgs e)
    {
        //Get the browserlanguage
        string browserLanguage = e.HttpContext.Request.UserLanguages[0];
        Thread.CurrentThread.CurrentCulture = 

        System.Globalization.CultureInfo.CreateSpecificCulture(browserLanguage);
        _browserlang = Thread.CurrentThread.CurrentCulture.EnglishName;
    }

    public override void Unsubscribe(ICriterionEvents criterionEvents)
    {
        criterionEvents.StartRequest -= criterionEvents_StartRequest;
        base.Unsubscribe(criterionEvents);
    }
}

using EPiServer.Personalization.VisitorGroups;
using EPiServer.Data;
using System.Threading;
using System.Globalization;
using EPiServer.Web.Mvc.VisitorGroups;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Web.Mvc;
using System;

namespace EPiServer.Classes
{
    public class BrowserLanguageModel : CriterionModelBase
    {
        private MatchStringType _browserLanguageMatchType;
    
        [DojoWidget(SelectionFactoryType = typeof(EnumSelectionFactory), 

             AdditionalOptions = "{ selectOnClick: true }")]
        public MatchStringType BrowserLanguageMatchType
        {
            get
            {
                return this._browserLanguageMatchType;
            }
            set
            {
                this._browserLanguageMatchType = value;
            }
        }
        [Required]
        [DojoWidget(SelectionFactoryType = typeof(LanguageFactory))]
        public string BrowserLanguage { get; set; }

        public override ICriterionModel Copy()
        {
            return base.ShallowCopy();
        }
    }

    [VisitorGroupCriterion(
        Category = "Technical Criteria",
        Description = "Match Browser language with specified value",
        DisplayName = "Browser language")]
    public class BrowserLanguageCriterion : CriterionBase<BrowserLanguageModel>
    {
        private string _browserlang;
        //matches the browserlanguage with the criterion set language.
        public override bool IsMatch(System.Security.Principal.IPrincipal principal, 

        System.Web.HttpContextBase httpContext)
        {
            return ((String.IsNullOrEmpty(base.Model.BrowserLanguage) ? true : 

            StringMatchHelper.IsMatch(_browserlang, base.Model.BrowserLanguage, 

            base.Model.BrowserLanguageMatchType)));             
        }
        public override void Subscribe(ICriterionEvents criterionEvents)
        {
            base.Subscribe(criterionEvents);
            criterionEvents.StartRequest += criterionEvents_StartRequest;
        }
        private void criterionEvents_StartRequest(object sender, CriterionEventArgs e)
        {
            //Get the browserlanguage
            string browserLanguage = e.HttpContext.Request.UserLanguages[0];
            Thread.CurrentThread.CurrentCulture = 

            System.Globalization.CultureInfo.CreateSpecificCulture(browserLanguage);
            _browserlang = Thread.CurrentThread.CurrentCulture.EnglishName;
        }
        public override void Unsubscribe(ICriterionEvents criterionEvents)
        {
            criterionEvents.StartRequest -= criterionEvents_StartRequest;
            base.Unsubscribe(criterionEvents);
        }
    }
    public class LanguageFactory : ISelectionFactory
    {
        public IEnumerable<SelectListItem> GetSelectListItems(Type property)
        {
            //For each culture availible
            foreach(CultureInfo ci in CultureInfo.GetCultures(CultureTypes.AllCultures)) {
                yield return new SelectListItem() { Text = ci.EnglishName, Value = ci.EnglishName };
            }  
        }
    }
}