Add support for yaml metadata in markdown

Author: InfinityGhost

OpenTabletDriver.Web/Controllers/TabletsController.cs

@@ -1,11 +1,9 @@
-using System.IO;
-using System.Net.Http;
-using System.Runtime.Versioning;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Html;
 using Microsoft.AspNetCore.Mvc;
 using OpenTabletDriver.Web.Core.Services;
 using OpenTabletDriver.Web.Models;
+using OpenTabletDriver.Web.Utilities;
 
 namespace OpenTabletDriver.Web.Controllers
 {
@@ -22,8 +20,8 @@ public TabletsController(ITabletService tabletService)
         public async Task<IActionResult> Index(string search = null)
         {
             var markdown = await tabletService.GetMarkdownRaw();
-            string html = Markdown.ToHtml(markdown);
-            string patchedHtml = html.Replace(
+            var html = Markdown.ToHtml(markdown);
+            var patchedHtml = html.Replace(
                 "<table>",
                 "<table id=\"tablets\" class=\"table table-hover\">"
             );

OpenTabletDriver.Web/Controllers/WikiController.cs

@@ -1,8 +1,9 @@
-using System.Text.RegularExpressions;
+using System;
 using System.Threading.Tasks;
-using Microsoft.AspNetCore.Html;
 using Microsoft.AspNetCore.Mvc;
+using Microsoft.Extensions.Caching.Memory;
 using OpenTabletDriver.Web.Core.Services;
+using OpenTabletDriver.Web.Models;
 
 #nullable enable
 
@@ -11,10 +12,12 @@ namespace OpenTabletDriver.Web.Controllers
     public class WikiController : Controller
     {
         private readonly IMarkdownSource _markdownSource;
+        private readonly IMemoryCache _memoryCache;
 
-        public WikiController(IMarkdownSource markdownSource)
+        public WikiController(IMarkdownSource markdownSource, IMemoryCache memoryCache)
         {
             _markdownSource = markdownSource;
+            _memoryCache = memoryCache;
         }
 
         [ResponseCache(Duration = 300)]
@@ -27,22 +30,17 @@ public IActionResult Index()
         [Route("/Wiki/{category}/{page}")]
         public async Task<IActionResult> Wiki(string category, string page)
         {
-            var markdown = await _markdownSource.GetPage(category, page);
-            return markdown == null ? View($"{category}/{page}") : View("WikiMarkdownPage", Format(markdown));
-        }
+            var route = $"{category}/{page}";
+            var model = await _memoryCache.GetOrCreateAsync(route, entry => GenerateMarkdownWikiPage(entry, category, page));
 
-        private static readonly Regex HeaderRegex = new Regex("(?<=.?\n)<h3", RegexOptions.Compiled);
+            return model == null ? View(route) : View("WikiMarkdownPage", model);
+        }
 
-        private IHtmlContent Format(string markdown)
+        private async Task<MarkdownViewModel?> GenerateMarkdownWikiPage(ICacheEntry entry, string category, string page)
         {
-            var html = Markdown.ToHtml(markdown);
-
-            var formatted = HeaderRegex.Replace(html, "<hr><h3")
-                .Replace("<h3", "<h3 class=\"wiki-nav-item pb-2\"")
-                .Replace("<table>", "<table class=\"table table-hover ms-3\">")
-                .Replace("<p>", "<p class=\"ms-3\">");
-
-            return new HtmlString(formatted);
+            entry.AbsoluteExpiration = DateTimeOffset.MaxValue;
+            var markdown = await _markdownSource.GetPage(category, page);
+            return markdown != null ? new MarkdownViewModel(markdown) : null;
         }
     }
 }

OpenTabletDriver.Web/Models/MarkdownViewModel.cs

@@ -0,0 +1,63 @@
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Text.RegularExpressions;
+using Markdig;
+using Markdig.Extensions.Yaml;
+using Markdig.Renderers;
+using Markdig.Syntax;
+using Microsoft.AspNetCore.Html;
+using YamlDotNet.Serialization;
+
+namespace OpenTabletDriver.Web.Models
+{
+    public class MarkdownViewModel
+    {
+        public MarkdownViewModel(string markdown)
+        {
+            var pipeline = new MarkdownPipelineBuilder()
+                .UseYamlFrontMatter()
+                .UseAdvancedExtensions()
+                .Build();
+
+            using (var sw = new StringWriter())
+            {
+                var renderer = new HtmlRenderer(sw);
+                pipeline.Setup(renderer);
+
+                var document = Markdown.Parse(markdown, pipeline);
+
+                var yamlBlock = document.Descendants<YamlFrontMatterBlock>().FirstOrDefault();
+                if (yamlBlock != null)
+                {
+                    var startIndex = yamlBlock.Span.Start + 4;
+                    var length = yamlBlock.Span.Length - 8;
+                    var yaml = markdown.Substring(startIndex, length);
+
+                    Metadata = new Deserializer().Deserialize<Dictionary<string, object>>(yaml);
+                }
+
+                renderer.Render(document);
+                Content = GetHtmlContent(sw);
+            }
+        }
+
+        public IDictionary<string, object> Metadata { get; }
+        public IHtmlContent Content { get; }
+
+        private static readonly Regex HeaderRegex = new Regex("(?<=.?\n)<h3", RegexOptions.Compiled);
+
+        private IHtmlContent GetHtmlContent(StringWriter sw)
+        {
+            sw.Flush();
+            var html = sw.ToString()!;
+
+            var formattedHtml = HeaderRegex.Replace(html, "<hr><h3")
+                .Replace("<h3", "<h3 class=\"wiki-nav-item pb-2\"")
+                .Replace("<table>", "<table class=\"table table-hover ms-3\">")
+                .Replace("<p>", "<p class=\"ms-3\">");
+
+            return new HtmlString(formattedHtml);
+        }
+    }
+}

OpenTabletDriver.Web/OpenTabletDriver.Web.csproj

@@ -11,6 +11,7 @@
 
   <ItemGroup Label="NuGet Packages">
     <PackageReference Include="Markdig" Version="0.25.0" />
+    <PackageReference Include="YamlDotNet" Version="11.2.1" />
     <PackageReference Include="Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation" Version="5.0.8" />
   </ItemGroup>
 

OpenTabletDriver.Web/Markdown.cs renamed to OpenTabletDriver.Web/Utilities/Markdown.cs

@@ -1,9 +1,7 @@
-using System.Reflection.Metadata;
 using Markdig;
 using Microsoft.AspNetCore.Html;
-using Microsoft.AspNetCore.Mvc.Rendering;
 
-namespace OpenTabletDriver.Web
+namespace OpenTabletDriver.Web.Utilities
 {
     public class Markdown
     {

OpenTabletDriver.Web/Views/Wiki/WikiMarkdownPage.cshtml

@@ -1,7 +1,7 @@
-@model Microsoft.AspNetCore.Html.IHtmlContent
+@model MarkdownViewModel
 
 @{
-    ViewBag.Title = "Wiki";
+    ViewBag.Title = Model!.Metadata["title"];
 }
 
-@Model
+@Model.Content