add: 元数据提取

YaeBlog.Core/Builder/BlogApplicationBuilder.cs

@@ -5,6 +5,7 @@ using Microsoft.Extensions.Diagnostics.Metrics;
 using Microsoft.Extensions.Hosting;
 using Microsoft.Extensions.Logging;
 using YaeBlog.Core.Extensions;
+using YamlDotNet.Serialization;
 
 namespace YaeBlog.Core.Builder;
 
@@ -12,12 +13,15 @@ public sealed class BlogApplicationBuilder : IHostApplicationBuilder
 {
     private readonly HostApplicationBuilder _hostApplicationBuilder;
 
-    public MarkdownPipelineBuilder MarkdigPipelineBuilder { get; set; }
+    public MarkdownPipelineBuilder MarkdigPipelineBuilder { get; }
+
+    public DeserializerBuilder YamlDeserializerBuilder { get; }
 
     internal BlogApplicationBuilder(BlogApplicationOptions options)
     {
         ConfigurationManager configuration = new();
         MarkdigPipelineBuilder = new MarkdownPipelineBuilder();
+        YamlDeserializerBuilder = new DeserializerBuilder();
 
         _hostApplicationBuilder = new HostApplicationBuilder(new HostApplicationBuilderSettings
         {

YaeBlog.Core/Extensions/BlogApplicationExtension.cs

@@ -4,6 +4,8 @@ using Microsoft.Extensions.DependencyInjection;
 using YaeBlog.Core.Builder;
 using YaeBlog.Core.Models;
 using YaeBlog.Core.Services;
+using YamlDotNet.Serialization;
+using YamlDotNet.Serialization.NamingConventions;
 
 namespace YaeBlog.Core.Extensions;
 
@@ -19,11 +21,17 @@ internal static class BlogApplicationExtension
         builder.Services.Configure<BlogOptions>(
             builder.Configuration.GetSection(BlogOptions.OptionName));
 
+        builder.YamlDeserializerBuilder.WithNamingConvention(CamelCaseNamingConvention.Instance);
+        builder.YamlDeserializerBuilder.IgnoreUnmatchedProperties();
+
+        builder.Services.AddSingleton<MarkdownPipeline>(
+            _ => builder.MarkdigPipelineBuilder.Build());
+        builder.Services.AddSingleton<IDeserializer>(
+            _ => builder.YamlDeserializerBuilder.Build());
+
         builder.Services.AddHostedService<BlogHostedService>();
         builder.Services.AddSingleton<EssayScanService>();
         builder.Services.AddSingleton<RendererService>();
-        builder.Services.AddSingleton<MarkdownPipeline>(
-            _ => builder.MarkdigPipelineBuilder.Build());
         builder.Services.AddSingleton<EssayContentService>();
 
         return builder;

YaeBlog.Core/Models/BlogContent.cs

@@ -4,5 +4,5 @@ public class BlogContent
 {
     public required string FileName { get; init; }
 
-    public required string FileContent { get; init; }
+    public required string FileContent { get; set; }
 }

YaeBlog.Core/Models/BlogEssay.cs

@@ -6,5 +6,12 @@ public class BlogEssay
 
     public required DateTime PublishTime { get; init; }
 
+    public List<string> Tags { get; } = [];
+
     public required string HtmlContent { get; init; }
+
+    public override string ToString()
+    {
+        return $"{Title}-{PublishTime}";
+    }
 }

YaeBlog.Core/Models/MarkdownMetadata.cs

@@ -0,0 +1,10 @@
+namespace YaeBlog.Core.Models;
+
+public class MarkdownMetadata
+{
+    public string? Title { get; set; }
+
+    public DateTime? Date { get; set; }
+
+    public List<string> Tags { get; set; } = [];
+}

YaeBlog.Core/Services/RendererService.cs

@@ -1,14 +1,15 @@
-using System.Collections.Concurrent;
-using Markdig;
+using Markdig;
 using Microsoft.Extensions.Logging;
 using YaeBlog.Core.Exceptions;
 using YaeBlog.Core.Models;
+using YamlDotNet.Serialization;
 
 namespace YaeBlog.Core.Services;
 
 public class RendererService(ILogger<RendererService> logger,
     EssayScanService essayScanService,
     MarkdownPipeline markdownPipeline,
+    IDeserializer yamlDeserializer,
     EssayContentService essayContentService)
 {
     public async Task RenderAsync()
@@ -17,19 +18,56 @@ public class RendererService(ILogger<RendererService> logger,
 
         Parallel.ForEach(contents, content =>
         {
-            logger.LogDebug("Render markdown file {}.", content.FileName);
+            MarkdownMetadata? metadata = TryParseMetadata(content);
+
             BlogEssay essay = new()
             {
-                Title = content.FileName,
-                PublishTime = DateTime.Now,
+                Title = metadata?.Title ?? content.FileName,
+                PublishTime = metadata?.Date ?? DateTime.Now,
                 HtmlContent = Markdown.ToHtml(content.FileContent, markdownPipeline)
             };
+            if (metadata is not null)
+            {
+                essay.Tags.AddRange(essay.Tags);
+            }
 
             if (!essayContentService.TryAdd(essay.Title, essay))
             {
                 throw new BlogFileException(
                     $"There are two essays with the same name: '{content.FileName}'.");
             }
+            logger.LogDebug("Render markdown file {}.", essay);
+            logger.LogDebug("{}", essay.HtmlContent);
         });
     }
+
+    private MarkdownMetadata? TryParseMetadata(BlogContent content)
+    {
+        string fileContent = content.FileContent.Trim();
+
+        if (!fileContent.StartsWith("---"))
+        {
+            return null;
+        }
+
+        // 移除起始的---
+        fileContent = fileContent[3..];
+
+        int lastPos = fileContent.IndexOf("---", StringComparison.Ordinal);
+        if (lastPos is -1 or 0)
+        {
+            return null;
+        }
+
+        string yamlContent = fileContent[..lastPos];
+        MarkdownMetadata metadata = yamlDeserializer.Deserialize<MarkdownMetadata>(yamlContent);
+        logger.LogDebug("Title: {}, Publish Date: {}.",
+            metadata.Title, metadata.Date);
+
+        // 返回去掉元数据之后的文本
+        lastPos += 3;
+        content.FileContent = fileContent[lastPos..];
+
+        return null;
+    }
 }

YaeBlog.Core/YaeBlog.Core.csproj

@@ -15,6 +15,7 @@
     <PackageReference Include="Markdig" Version="0.34.0" />
     <PackageReference Include="Microsoft.AspNetCore.Components.Web" Version="8.0.0" />
     <PackageReference Include="Microsoft.Extensions.Hosting" Version="8.0.0" />
+    <PackageReference Include="YamlDotNet" Version="13.7.1" />
   </ItemGroup>
 
   <ItemGroup>