Sitefinity Language Redirect

Global.asax.cs

protected void Session_Start(object sender, EventArgs e)
{
    // Honor the accept-language-header sent by the user's browser and redirect them to the
    // desired language version of the site (if it is available).

    ResourcesConfig config = Config.Get<ResourcesConfig>();

    if (!config.Multilingual)
    {
        return;
    }

    try
    {
        RedirectByLanguage(config);
    }
    catch (Exception ex)
    {
        // Don't let redirection errors cause visible exceptions.
        // Simply log them and move on.
        Log.Write(ex, ConfigurationPolicy.ErrorLog);
    }
}

/// <summary>
/// Redirects a user according to their browser-configured language preferences.
/// </summary>
private void RedirectByLanguage(ResourcesConfig config)
{
    // Do this only if the request is for the domain root

    string currentRequestPath = System.Web.HttpContext.Current.Request.Path;
    if (!currentRequestPath.Equals("/", StringComparison.InvariantCultureIgnoreCase))
    {
        return;
    }

    // Abort if there is no accept-language header (search engines etc.)

    string acceptLanguageHeader = Request.ServerVariables["HTTP_ACCEPT_LANGUAGE"];

    if (String.IsNullOrWhiteSpace(acceptLanguageHeader))
    {
        return;
    }

    // Get the default language of the site            
    string defaultLanguage = config.DefaultCulture.Culture;

    // Abort if the accept-language header contains the default language as the first entry.
    if (acceptLanguageHeader.StartsWith(defaultLanguage, StringComparison.InvariantCultureIgnoreCase))
    {
        return;
    }

    // Do we have any language in our configured languages that matches any of the accept-language header values?

    string targetLang = null;
    string[] acceptLangs = acceptLanguageHeader.Split(new[] { ",", ";" }, StringSplitOptions.RemoveEmptyEntries);
    int i = 0;

    do // Loop through all the browser-configured languages ...
    {
        string langKey = acceptLangs[i].Substring(0, 2);

        if (!langKey.Equals("q=", StringComparison.InvariantCultureIgnoreCase))
        {
            // ... and try to match them to one of the languages of our site
            if (config.Cultures.Values.Any(culture => langKey.Equals(culture.Culture, StringComparison.InvariantCultureIgnoreCase)))
            {
                targetLang = langKey;
            }
        }

        i += 1;
    } while (String.IsNullOrEmpty(targetLang) && i < acceptLangs.Length);

    if (!String.IsNullOrEmpty(targetLang))
    {
        Response.Redirect(String.Format("~/{0}", targetLang)); // This assumes that the URL localization strategy is "subfolders"!
    }
}