fix(blog): add missing TemplateService impl

OliverBooth.Blog/Services/TemplateService.cs

@@ -0,0 +1,70 @@
+using System.Buffers.Binary;
+using Microsoft.EntityFrameworkCore;
+using OliverBooth.Blog.Data;
+using OliverBooth.Common.Formatting;
+using OliverBooth.Common.Markdown;
+using OliverBooth.Common.Services;
+using SmartFormat;
+using SmartFormat.Extensions;
+
+namespace OliverBooth.Blog.Services;
+
+/// <summary>
+///     Represents a service that renders MediaWiki-style templates.
+/// </summary>
+internal sealed class TemplateService : ITemplateService
+{
+    private static readonly Random Random = new();
+    private readonly IDbContextFactory<BlogContext> _webContextFactory;
+    private readonly SmartFormatter _formatter;
+
+    /// <summary>
+    ///     Initializes a new instance of the <see cref="TemplateService" /> class.
+    /// </summary>
+    /// <param name="serviceProvider">The <see cref="IServiceProvider" />.</param>
+    /// <param name="webContextFactory">The <see cref="BlogContext" /> factory.</param>
+    public TemplateService(IServiceProvider serviceProvider, IDbContextFactory<BlogContext> webContextFactory)
+    {
+        _formatter = Smart.CreateDefaultSmartFormat();
+        _formatter.AddExtensions(new DefaultSource());
+        _formatter.AddExtensions(new ReflectionSource());
+        _formatter.AddExtensions(new DateFormatter());
+        _formatter.AddExtensions(new MarkdownFormatter(serviceProvider));
+
+        _webContextFactory = webContextFactory;
+    }
+
+    /// <inheritdoc />
+    public string RenderTemplate(TemplateInline templateInline)
+    {
+        if (templateInline is null) throw new ArgumentNullException(nameof(templateInline));
+
+        using BlogContext webContext = _webContextFactory.CreateDbContext();
+        Template? template = webContext.Templates.Find(templateInline.Name);
+        if (template is null)
+        {
+            return $"{{{{{templateInline.Name}}}}}";
+        }
+
+        Span<byte> randomBytes = stackalloc byte[20];
+        Random.NextBytes(randomBytes);
+
+        var formatted = new
+        {
+            templateInline.ArgumentList,
+            templateInline.ArgumentString,
+            templateInline.Params,
+            RandomInt = BinaryPrimitives.ReadInt32LittleEndian(randomBytes[..4]),
+            RandomGuid = new Guid(randomBytes[4..]).ToString("N"),
+        };
+
+        try
+        {
+            return _formatter.Format(template.FormatString, formatted);
+        }
+        catch
+        {
+            return $"{{{{{templateInline.Name}|{templateInline.ArgumentString}}}}}";
+        }
+    }
+}