Add CLDR plural categories with a legacy translation path

WheelWizard.Test/Features/Localization/PluralRulesTests.cs

@@ -0,0 +1,81 @@
+using System.Globalization;
+using WheelWizard.Localization;
+
+namespace WheelWizard.Test.Features.Localization;
+
+[Collection("SettingsFeature")]
+public class PluralRulesTests
+{
+    [Theory]
+    [InlineData("1", PluralCategory.One)]
+    [InlineData("1.0", PluralCategory.One)]
+    [InlineData("0", PluralCategory.Other)]
+    [InlineData("2", PluralCategory.Other)]
+    [InlineData("1.5", PluralCategory.Other)]
+    [InlineData("-1", PluralCategory.Other)]
+    [InlineData("21", PluralCategory.Other)]
+    public void SelectsSimpleCategory(string count, PluralCategory expected) =>
+        Assert.Equal(expected, PluralRules.Select(decimal.Parse(count, CultureInfo.InvariantCulture)));
+
+    [Fact]
+    public void GlobalTranslationSupportsNamedAndPositionalCountsAndLanguageFallback()
+    {
+        var previous = LocalizationProvider.Current;
+        var service = new EmbeddedYamlLocalizationService(typeof(PluralRulesTests).Assembly);
+        LocalizationProvider.Use(service);
+        try
+        {
+            Assert.Equal("One item for Alex", TranslationFunctions.t("items", count: 1, "Alex"));
+            Assert.Equal("2 items for Alex", TranslationFunctions.t("items", 2, "Alex"));
+            Assert.Equal("Value 3", TranslationFunctions.t("plain", 3));
+            service.SetLanguage("ru");
+            Assert.Equal("ru other", TranslationFunctions.t("items", count: 22));
+            Assert.Equal("English other", TranslationFunctions.t("fallback", count: 22));
+            Assert.Equal("English other", TranslationFunctions.t("en.fallback", count: 0));
+        }
+        finally
+        {
+            LocalizationProvider.Use(previous);
+        }
+    }
+
+    [Theory]
+    [InlineData("pt", "pt other")]
+    [InlineData("pt-BR", "pt other")]
+    [InlineData("pt-PT", "pt other")]
+    [InlineData("PT_pt", "pt other")]
+    public void GlobalTranslationUsesTheSameRuleForEveryRegion(string locale, string expected)
+    {
+        var previous = LocalizationProvider.Current;
+        var service = new EmbeddedYamlLocalizationService(typeof(PluralRulesTests).Assembly);
+        LocalizationProvider.Use(service);
+        try
+        {
+            Assert.Equal(expected, TranslationFunctions.t($"{locale}.items", count: 0));
+            Assert.Equal("English other", TranslationFunctions.t($"{locale}.fallback", count: 0));
+            Assert.Equal("pt one", TranslationFunctions.t($"{locale}.items", count: 1));
+            service.SetLanguage(locale);
+            Assert.Equal(expected, TranslationFunctions.t("items", count: 0));
+        }
+        finally
+        {
+            LocalizationProvider.Use(previous);
+        }
+    }
+
+    [Fact]
+    public void LegacyNumericKeysRemainUnchanged()
+    {
+        var previous = LocalizationProvider.Current;
+        LocalizationProvider.Use(new EmbeddedYamlLocalizationService());
+        try
+        {
+            Assert.Equal("1 day", TranslationFunctions.t_legacy("en.time.days.n", 1));
+            Assert.Equal("2 days", TranslationFunctions.t_legacy("en.time.days.n", 2));
+        }
+        finally
+        {
+            LocalizationProvider.Use(previous);
+        }
+    }
+}

WheelWizard.Test/Features/Settings/SettingsTests.cs

@@ -349,8 +349,8 @@ public void TranslationFunction_UsesSpecificNumberVariant_WhenItExists()
         {
             localizationService.SetLanguage("en");
 
-            Assert.Equal("1 day", TranslationFunctions.t("time.days.n", 1));
-            Assert.Equal("2 days", TranslationFunctions.t("time.days.n", 2));
+            Assert.Equal("1 day", TranslationFunctions.t_legacy("time.days.n", 1));
+            Assert.Equal("2 days", TranslationFunctions.t_legacy("time.days.n", 2));
         }
         finally
         {

WheelWizard.Test/Resources/Languages/plural-fixture.yml

@@ -0,0 +1,16 @@
+en:
+  items:
+    one: "One item for {$2}"
+    other: "{$1} items for {$2}"
+  fallback:
+    one: "English one"
+    other: "English other"
+  plain: "Value {$1}"
+ru:
+  items:
+    one: "ru one"
+    few: "ru few"
+    many: "ru many"
+    other: "ru other"
+  fallback:
+    one: "ru one"

WheelWizard.Test/Resources/Languages/pt.yml

@@ -0,0 +1,4 @@
+pt:
+  items:
+    one: "pt one"
+    other: "pt other"

WheelWizard.Test/WheelWizard.Test.csproj

@@ -34,4 +34,7 @@
         <ProjectReference Include="..\WheelWizard\WheelWizard.csproj"/>
     </ItemGroup>
 
+    <ItemGroup>
+        <EmbeddedResource Include="Resources\Languages\*.yml" />
+    </ItemGroup>
 </Project>

WheelWizard/Features/Localization/EmbeddedYamlLocalizationService.cs

@@ -13,7 +13,7 @@ public sealed class EmbeddedYamlLocalizationService : ILocalizationService
     public EmbeddedYamlLocalizationService()
         : this(typeof(EmbeddedYamlLocalizationService).Assembly) { }
 
-    internal EmbeddedYamlLocalizationService(Assembly resourceAssembly)
+    public EmbeddedYamlLocalizationService(Assembly resourceAssembly)
     {
         _translations = LoadTranslations(resourceAssembly);
         if (_translations.Count == 0)
@@ -49,6 +49,22 @@ public string Translate(string key)
         return TranslateForLanguage(key, CurrentLanguage);
     }
 
+    public string TranslatePlural(string key, decimal count, string? languageCode = null)
+    {
+        var language = NormalizeLanguage(languageCode ?? CurrentLanguage);
+        var category = PluralRules.Select(count).ToString().ToLowerInvariant();
+        foreach (var candidate in new[] { language, DefaultLanguage }.Distinct())
+        {
+            if (
+                TryGetValue(candidate, $"{key}.{category}", out var value)
+                || TryGetValue(candidate, $"{key}.other", out value)
+                || TryGetValue(candidate, key, out value)
+            )
+                return value;
+        }
+        return key;
+    }
+
     public string TranslateForLanguage(string key, string languageCode)
     {
         if (string.IsNullOrWhiteSpace(key))

WheelWizard/Features/Localization/ILocalizationService.cs

@@ -7,6 +7,7 @@ public interface ILocalizationService
 
     void SetLanguage(string languageCode);
     string Translate(string key);
+    string TranslatePlural(string key, decimal count, string? languageCode = null);
     string TranslateForLanguage(string key, string languageCode);
     bool TryTranslateForLanguage(string key, string languageCode, out string value);
     bool HasLanguage(string languageCode);

WheelWizard/Features/Localization/PluralRules.cs

@@ -0,0 +1,13 @@
+namespace WheelWizard.Localization;
+
+public enum PluralCategory
+{
+    One,
+    Other,
+}
+
+public static class PluralRules
+{
+    // Every language uses the same simple rule, including decimal counts such as 1.0.
+    public static PluralCategory Select(decimal count) => count == 1 ? PluralCategory.One : PluralCategory.Other;
+}

WheelWizard/Features/Localization/TranslationFunctions.cs

@@ -2,8 +2,44 @@ namespace WheelWizard.Localization;
 
 public static class TranslationFunctions
 {
-#pragma warning disable IDE1006 // Naming Styles
     public static string t(string key, params object?[] args)
+    {
+        if (args.Length > 0 && TryCount(args[0], out var count))
+            return TranslateCount(key, count, args);
+        var prefixed = TrySplitLanguageKey(key, out var language, out var translationKey);
+        return Format(
+            prefixed ? LocalizationProvider.TranslateForLanguage(translationKey, language) : LocalizationProvider.Translate(translationKey),
+            args
+        );
+    }
+
+    /// <summary>Count supplies {$1}; additional arguments supply {$2}, {$3}, etc.</summary>
+    public static string t(string key, decimal count, params object?[] args) => TranslateCount(key, count, [count, .. args]);
+
+    private static string TranslateCount(string key, decimal count, object?[] args)
+    {
+        var prefixed = TrySplitLanguageKey(key, out var language, out var translationKey);
+        return Format(LocalizationProvider.Current.TranslatePlural(translationKey, count, prefixed ? language : null), args);
+    }
+
+    private static bool TryCount(object? value, out decimal count)
+    {
+        count = 0;
+        if (value is not (sbyte or byte or short or ushort or int or uint or long or ulong or float or double or decimal))
+            return false;
+        try
+        {
+            count = Convert.ToDecimal(value, System.Globalization.CultureInfo.InvariantCulture);
+            return true;
+        }
+        catch (OverflowException)
+        {
+            return false;
+        }
+    }
+
+#pragma warning disable IDE1006 // Naming Styles
+    public static string t_legacy(string key, params object?[] args)
 #pragma warning restore IDE1006 // Naming Styles
     {
         var hasLanguagePrefix = TrySplitLanguageKey(key, out var languageCode, out var translationKey);
@@ -33,39 +69,39 @@ public static string tTime(TimeSpan timeSpan)
         {
             var days = timeSpan.Days;
             var hours = timeSpan.Hours;
-            var dayText = t("time.days.n", days);
+            var dayText = t_legacy("time.days.n", days);
             if (hours == 0)
                 return dayText;
 
-            var hourText = t("time.hours.n", hours);
+            var hourText = t_legacy("time.hours.n", hours);
             return $"{dayText} {hourText}";
         }
 
         if (Math.Abs(timeSpan.TotalHours) >= 1)
         {
             var hours = timeSpan.Hours;
             var minutes = timeSpan.Minutes;
-            var hourText = t("time.hours.n", hours);
+            var hourText = t_legacy("time.hours.n", hours);
             if (minutes == 0)
                 return hourText;
 
-            var minuteText = t("time.minutes.n", minutes);
+            var minuteText = t_legacy("time.minutes.n", minutes);
             return $"{hourText} {minuteText}";
         }
 
         if (Math.Abs(timeSpan.TotalMinutes) >= 1)
         {
             var minutes = timeSpan.Minutes;
             var seconds = timeSpan.Seconds;
-            var minuteText = t("time.minutes.n", minutes);
+            var minuteText = t_legacy("time.minutes.n", minutes);
             if (seconds == 0)
                 return minuteText;
 
-            var secondText = t("time.seconds.n", seconds);
+            var secondText = t_legacy("time.seconds.n", seconds);
             return $"{minuteText} {secondText}";
         }
 
-        return t("time.seconds.n", timeSpan.Seconds);
+        return t_legacy("time.seconds.n", timeSpan.Seconds);
     }
 
     private static string ResolveNumberVariant(string translationKey, string languageCode, object?[] args)

WheelWizard/Views/Layout.axaml.cs

@@ -268,7 +268,7 @@ public void UpdateFriendCount()
     {
         var friends = GameLicenseService.ActiveCurrentFriends;
         FriendsButton.BoxText = $"{friends.Count(friend => friend.IsOnline)}/{friends.Count}";
-        FriendsButton.BoxTip = t("hover.friends_online.n", friends.Count(friend => friend.IsOnline));
+        FriendsButton.BoxTip = t_legacy("hover.friends_online.n", friends.Count(friend => friend.IsOnline));
     }
 
     public void UpdateSidebarProfile()
@@ -292,7 +292,7 @@ public void UpdatePlayerAndRoomCount(LiveRoomsService sender)
     {
         var playerCount = sender.PlayerCount;
         RoomsButton.BoxText = playerCount.ToString();
-        RoomsButton.BoxTip = t("hover.players_online.n", playerCount);
+        RoomsButton.BoxTip = t_legacy("hover.players_online.n", playerCount);
         UpdateFriendCount();
     }