Refactor template engine handling and improve comments

- Updated `JsonDocumentExtensions.cs` for comment clarity.
- Enhanced null checks and error handling in `PdfService.cs` for template engine and time zone management.
- Allowed nullable model parameters in `HandlebarsTemplateEngine.cs`, `RazorTemplateEngine.cs`, and `ScribanTemplateEngine.cs`.
- Updated `ITemplateEngine.cs` interface for consistency with nullable model parameters.
- Renamed constant in `ScribanTemplateEngine.cs` for improved clarity.

Author: marcominerva

src/PdfSmith.BusinessLayer/Extensions/JsonDocumentExtensions.cs

@@ -27,7 +27,7 @@ public static class JsonDocumentExtensions
             return element.EnumerateArray().Select(e => ConvertValue(e, timeZoneInfo)).ToList();
         }
 
-        // For all other cases (including Null), delegate to ConvertValue which handles them properly
+        // For all other cases (including Null), delegate to ConvertValue which handles them properly.
         return ConvertValue(element, timeZoneInfo);
     }
 

src/PdfSmith.BusinessLayer/Services/PdfService.cs

@@ -16,47 +16,39 @@ public class PdfService(IServiceProvider serviceProvider, IPdfGenerator pdfGener
 {
     public async Task<Result<StreamFileContent>> GeneratePdfAsync(PdfGenerationRequest request, CancellationToken cancellationToken)
     {
-        string? content;
+        var templateEngine = serviceProvider.GetKeyedService<ITemplateEngine>(request.TemplateEngine!.ToLowerInvariant().Trim());
 
-        if (request.Model is not null)
+        if (templateEngine is null)
         {
-            var templateEngine = serviceProvider.GetKeyedService<ITemplateEngine>(request.TemplateEngine!.ToLowerInvariant().Trim());
-
-            if (templateEngine is null)
-            {
-                return Result.Fail(FailureReasons.ClientError, "Unable to render the template", $"The template engine '{request.TemplateEngine}' has not been registered");
-            }
+            return Result.Fail(FailureReasons.ClientError, "Unable to render the template", $"The template engine '{request.TemplateEngine}' has not been registered");
+        }
 
-            var timeZoneInfo = timeZoneService.GetTimeZone();
+        var timeZoneInfo = timeZoneService.GetTimeZone();
 
-            if (timeZoneInfo is null)
+        if (timeZoneInfo is null)
+        {
+            var timeZoneId = timeZoneService.GetTimeZoneHeaderValue();
+            if (timeZoneId is not null)
             {
-                var timeZoneId = timeZoneService.GetTimeZoneHeaderValue();
-                if (timeZoneId is not null)
-                {
-                    // If timeZoneInfo is null, but timeZoneId has a value, it means that the time zone specified in the header is invalid.
-                    return Result.Fail(FailureReasons.ClientError, "Unable to find the time zone", $"The time zone '{timeZoneId}' is invalid or is not available on the system");
-                }
+                // If timeZoneInfo is null, but timeZoneId has a value, it means that the time zone specified in the header is invalid.
+                return Result.Fail(FailureReasons.ClientError, "Unable to find the time zone", $"The time zone '{timeZoneId}' is invalid or is not available on the system");
             }
+        }
 
-            try
-            {
-                var model = request.Model.ToExpandoObject(timeZoneInfo);
+        string? content;
+        try
+        {
+            var model = request.Model?.ToExpandoObject(timeZoneInfo);
 
-                cancellationToken.ThrowIfCancellationRequested();
+            cancellationToken.ThrowIfCancellationRequested();
 
-                content = await templateEngine.RenderAsync(request.Template, model, CultureInfo.CurrentCulture, cancellationToken);
+            content = await templateEngine.RenderAsync(request.Template, model, CultureInfo.CurrentCulture, cancellationToken);
 
-                cancellationToken.ThrowIfCancellationRequested();
-            }
-            catch (TemplateEngineException ex)
-            {
-                return Result.Fail(FailureReasons.ClientError, "Unable to render the template", ex.Message);
-            }
+            cancellationToken.ThrowIfCancellationRequested();
         }
-        else
+        catch (TemplateEngineException ex)
         {
-            content = request.Template;
+            return Result.Fail(FailureReasons.ClientError, "Unable to render the template", ex.Message);
         }
 
         var output = await pdfGenerator.CreateAsync(content, request.Options, cancellationToken);

src/PdfSmith.BusinessLayer/Templating/HandlebarsTemplateEngine.cs

@@ -10,7 +10,7 @@ public class HandlebarsTemplateEngine(TimeZoneTimeProvider timeZoneTimeProvider)
 {
     private readonly Lazy<IHandlebars> handlebarsInstance = new(() => CreateHandlebarsInstance(timeZoneTimeProvider));
 
-    public Task<string> RenderAsync(string template, object model, CultureInfo culture, CancellationToken cancellationToken = default)
+    public Task<string> RenderAsync(string template, object? model, CultureInfo culture, CancellationToken cancellationToken = default)
     {
         try
         {

src/PdfSmith.BusinessLayer/Templating/Interfaces/ITemplateEngine.cs

@@ -4,5 +4,5 @@ namespace PdfSmith.BusinessLayer.Templating.Interfaces;
 
 public interface ITemplateEngine
 {
-    Task<string> RenderAsync(string template, object model, CultureInfo culture, CancellationToken cancellationToken = default);
+    Task<string> RenderAsync(string template, object? model, CultureInfo culture, CancellationToken cancellationToken = default);
 }

src/PdfSmith.BusinessLayer/Templating/RazorTemplateEngine.cs

@@ -9,7 +9,7 @@ namespace PdfSmith.BusinessLayer.Templating;
 
 public partial class RazorTemplateEngine(IRazorLightEngine engine) : ITemplateEngine
 {
-    public async Task<string> RenderAsync(string template, object model, CultureInfo culture, CancellationToken cancellationToken = default)
+    public async Task<string> RenderAsync(string template, object? model, CultureInfo culture, CancellationToken cancellationToken = default)
     {
         try
         {
@@ -20,9 +20,7 @@ public async Task<string> RenderAsync(string template, object model, CultureInfo
                 @using System
                 @using System.Collections.Generic
                 @using System.Linq
-
                 @inject PdfSmith.BusinessLayer.Services.TimeZoneTimeProvider timeZoneTimeProvider
-
                 {sanitizedTemplate}
                 """;
 

src/PdfSmith.BusinessLayer/Templating/ScribanTemplateEngine.cs

@@ -10,9 +10,9 @@ namespace PdfSmith.BusinessLayer.Templating;
 
 public partial class ScribanTemplateEngine(TimeZoneTimeProvider timeZoneTimeProvider) : ITemplateEngine
 {
-    private const string DateTimeZonePlaceholder = "date_time_zone";
+    private const string DateTimeZonePlaceholder = "datetime_withzone";
 
-    public async Task<string> RenderAsync(string text, object model, CultureInfo culture, CancellationToken cancellationToken = default)
+    public async Task<string> RenderAsync(string text, object? model, CultureInfo culture, CancellationToken cancellationToken = default)
     {
         var sanitizedText = DateNowRegex.Replace(text, DateTimeZonePlaceholder);