Add validation to locale setting, remove hard-coded resource options. Closes #4818

Author: comintern

Rubberduck.Core/Settings/GeneralSettings.cs

@@ -4,6 +4,7 @@
 using System.Linq;
 using System.Xml.Serialization;
 using Rubberduck.Common;
+using Rubberduck.Resources;
 
 namespace Rubberduck.Settings
 {
@@ -26,7 +27,20 @@ public interface IGeneralSettings
     [XmlType(AnonymousType = true)]
     public class GeneralSettings : IGeneralSettings, IEquatable<GeneralSettings>
     {
-        public DisplayLanguageSetting Language { get; set; }
+        private DisplayLanguageSetting _language = new DisplayLanguageSetting(Locales.DefaultCulture.Name);
+
+        public DisplayLanguageSetting Language
+        {
+            get => _language;
+            set
+            {
+                if (Locales.AvailableCultures.Exists(culture => culture.Name.Equals(value.Code, StringComparison.OrdinalIgnoreCase)))
+                {
+                    _language = value;
+                }
+            }
+        }
+
         public bool CanShowSplash { get; set; }
         public bool CanCheckVersion { get; set; }
         public bool CompileBeforeParse { get; set; }

Rubberduck.Core/UI/Settings/GeneralSettingsViewModel.cs

@@ -44,15 +44,10 @@ public GeneralSettingsViewModel(
             _messageBox = messageBox;
             _vbeSettings = vbeSettings;
             _experimentalFeatureTypes = experimentalTypesProvider.ExperimentalTypes;
-            Languages = new ObservableCollection<DisplayLanguageSetting>(
-                new[]
-                {
-                    new DisplayLanguageSetting("en-US"),
-                    new DisplayLanguageSetting("fr-CA"),
-                    new DisplayLanguageSetting("de-DE"),
-                    new DisplayLanguageSetting("es-ES"),
-                    new DisplayLanguageSetting("cs-CZ")
-                });
+
+            Languages = new ObservableCollection<DisplayLanguageSetting>(Locales.AvailableCultures
+                .OrderBy(locale => locale.NativeName)
+                .Select(locale => new DisplayLanguageSetting(locale.Name)));
 
             LogLevels = new ObservableCollection<MinimumLogLevel>(
                 LogLevelHelper.LogLevels.Select(l => new MinimumLogLevel(l.Ordinal, l.Name)));
@@ -296,7 +291,8 @@ protected override void TransferSettingsToView(Rubberduck.Settings.GeneralSettin
 
         private void TransferSettingsToView(IGeneralSettings general, IHotkeySettings hottkey)
         {
-            SelectedLanguage = Languages.First(l => l.Code == general.Language.Code);
+            SelectedLanguage = Languages.FirstOrDefault(culture => culture.Code == general.Language.Code);
+
             Hotkeys = hottkey == null
                 ? new ObservableCollection<HotkeySetting>()
                 : new ObservableCollection<HotkeySetting>(hottkey.Settings);

Rubberduck.Resources/Locales.cs

@@ -0,0 +1,46 @@
+using System.Collections.Generic;
+using System.Globalization;
+using System.Linq;
+using System.Reflection;
+using System.Resources;
+
+namespace Rubberduck.Resources
+{
+    public static class Locales
+    {
+        private static List<CultureInfo> _cultures;
+
+        public static CultureInfo DefaultCulture => CultureInfo.GetCultureInfo("en-US");
+
+        //Adapted from https://stackoverflow.com/a/32161480/4088852
+        public static List<CultureInfo> AvailableCultures
+        {
+            get
+            {
+                if (!(_cultures is null))
+                {
+                    return _cultures;
+                }
+
+                _cultures = new List<CultureInfo> { DefaultCulture };
+                var resources = new ResourceManager("Rubberduck.Resources.RubberduckUI", Assembly.GetAssembly(typeof(Locales)));
+                foreach (var culture in CultureInfo.GetCultures(CultureTypes.AllCultures).Where(locale => !locale.Equals(CultureInfo.InvariantCulture)))
+                {
+                    try
+                    {
+                        if (!(resources.GetResourceSet(culture, true, false) is null))
+                        {
+                            _cultures.Add(culture);
+                        }
+                    }
+                    catch (CultureNotFoundException)
+                    {
+                        // Ignored.
+                    }
+                }
+
+                return _cultures;
+            }
+        }
+    }
+}