♻️ Refactored email localization & template engine

DysonNetwork.Shared/Templating/RazorLightTemplateService.cs

@@ -0,0 +1,108 @@
+using System.Globalization;
+using System.Reflection;
+using RazorLight;
+
+namespace DysonNetwork.Shared.Templating;
+
+public class RazorLightTemplateService : ITemplateService
+{
+    private readonly IRazorLightEngine _engine;
+    private readonly Assembly _assembly;
+    private readonly string _resourceNamespace;
+    private readonly List<string> _availableLocales = new();
+    private readonly object _lock = new();
+
+    public RazorLightTemplateService(Assembly? assembly = null, string? resourceNamespace = null)
+    {
+        _assembly = assembly ?? Assembly.GetEntryAssembly() ?? Assembly.GetCallingAssembly();
+        _resourceNamespace = resourceNamespace ?? "DysonNetwork.Pass.Resources.Templates";
+        
+        DiscoverAvailableLocales();
+        
+        _engine = new RazorLightEngineBuilder()
+            .UseEmbeddedResourcesProject(_assembly, _resourceNamespace)
+            .UseMemoryCachingProvider()
+            .Build();
+    }
+
+    private void DiscoverAvailableLocales()
+    {
+        var resourceNames = _assembly.GetManifestResourceNames();
+        var prefix = $"{_resourceNamespace}.";
+        var suffix = ".cshtml";
+        
+        foreach (var resourceName in resourceNames)
+        {
+            if (resourceName.StartsWith(prefix) && resourceName.EndsWith(suffix))
+            {
+                var locale = ExtractLocaleFromResourceName(resourceName, prefix, suffix);
+                if (!string.IsNullOrEmpty(locale) && !_availableLocales.Contains(locale))
+                {
+                    _availableLocales.Add(locale);
+                }
+            }
+        }
+    }
+
+    private string? ExtractLocaleFromResourceName(string resourceName, string prefix, string suffix)
+    {
+        // Resource name format: Namespace.Locale.TemplateName.cshtml
+        // We need to extract the locale part
+        var contentPart = resourceName.Substring(prefix.Length, resourceName.Length - prefix.Length - suffix.Length);
+        
+        // Split by dot to get locale (first part before template name)
+        var parts = contentPart.Split('.');
+        if (parts.Length >= 2)
+        {
+            // First part is locale (e.g., "en", "zh-hans")
+            return parts[0];
+        }
+        
+        return null;
+    }
+
+    public async Task<string> RenderAsync(string templateName, object model, string? locale = null)
+    {
+        locale ??= CultureInfo.CurrentUICulture.Name;
+
+        var templateKey = $"{locale}.{templateName}";
+
+        try
+        {
+            return await _engine.CompileRenderAsync(templateKey, model);
+        }
+        catch (TemplateNotFoundException)
+        {
+            // Fallback: try all available locales
+            foreach (var availableLocale in _availableLocales)
+            {
+                if (availableLocale.Equals(locale, StringComparison.OrdinalIgnoreCase))
+                    continue;
+
+                var fallbackKey = $"{availableLocale}.{templateName}";
+                try
+                {
+                    return await _engine.CompileRenderAsync(fallbackKey, model);
+                }
+                catch (TemplateNotFoundException)
+                {
+                    // Continue to next locale
+                }
+            }
+
+            return $"[Template not found: {templateName}]";
+        }
+    }
+
+    public async Task<string> RenderWithLayoutAsync(string templateName, string layoutName, object model, string? locale = null)
+    {
+        // RazorLight handles layouts via @Layout directive in the template
+        // This method is provided for API consistency
+        return await RenderAsync(templateName, model, locale);
+    }
+
+    public IReadOnlyList<string> GetAvailableLocales()
+    {
+        return _availableLocales.AsReadOnly();
+    }
+}