add: 渲染前处理器和渲染后处理器

YaeBlog.Core/Services/RendererService.cs

@@ -1,6 +1,8 @@
-using System.Diagnostics;
+using System.Collections.Concurrent;
+using System.Diagnostics;
 using Markdig;
 using Microsoft.Extensions.Logging;
+using YaeBlog.Core.Abstractions;
 using YaeBlog.Core.Exceptions;
 using YaeBlog.Core.Models;
 using YamlDotNet.Core;
@@ -16,18 +18,23 @@ public class RendererService(ILogger<RendererService> logger,
 {
     private readonly Stopwatch _stopwatch = new();
 
+    private readonly List<IPreRenderProcessor> _preRenderProcessors = [];
+
+    private readonly List<IPostRenderProcessor> _postRenderProcessors = [];
+
     public async Task RenderAsync()
     {
         _stopwatch.Start();
         logger.LogInformation("Render essays start.");
 
         List<BlogContent> contents = await essayScanService.ScanAsync();
+        IEnumerable<BlogContent> preProcessedContents =
+            PreProcess(contents);
 
         List<BlogEssay> essays = [];
-
         await Task.Run(() =>
         {
-            foreach (BlogContent content in contents)
+            foreach (BlogContent content in preProcessedContents)
             {
                 MarkdownMetadata? metadata = TryParseMetadata(content);
                 BlogEssay essay = new()
@@ -46,6 +53,7 @@ public class RendererService(ILogger<RendererService> logger,
             }
         });
 
+        ConcurrentBag<BlogEssay> postProcessEssays = [];
         Parallel.ForEach(essays, essay =>
         {
 
@@ -58,19 +66,79 @@ public class RendererService(ILogger<RendererService> logger,
             };
             newEssay.Tags.AddRange(essay.Tags);
 
-            if (!essayContentService.TryAdd(newEssay.FileName, newEssay))
-            {
-                throw new BlogFileException(
-                    $"There are two essays with the same name: '{newEssay.FileName}'.");
-            }
+            postProcessEssays.Add(newEssay);
             logger.LogDebug("Render markdown file {}.", newEssay);
         });
 
+        PostProcess(postProcessEssays);
+
         _stopwatch.Stop();
         logger.LogInformation("Render finished, consuming {} s.",
             _stopwatch.Elapsed.ToString("s\\.fff"));
     }
 
+    public void AddPreRenderProcessor(IPreRenderProcessor processor)
+    {
+        bool exist = _preRenderProcessors.Any(p => p.Name == processor.Name);
+
+        if (exist)
+        {
+            throw new InvalidOperationException("There exists one pre-render processor " +
+                                                $"with the same name: {processor.Name}.");
+        }
+
+        _preRenderProcessors.Add(processor);
+    }
+
+    public void AddPostRenderProcessor(IPostRenderProcessor processor)
+    {
+        bool exist = _postRenderProcessors.Any(p => p.Name == processor.Name);
+
+        if (exist)
+        {
+            throw new InvalidCastException("There exists one post-render processor " +
+                                           $"with the same name: {processor.Name}.");
+        }
+
+        _postRenderProcessors.Add(processor);
+    }
+
+    private IEnumerable<BlogContent> PreProcess(IEnumerable<BlogContent> contents)
+    {
+        ConcurrentBag<BlogContent> processedContents = [];
+
+        Parallel.ForEach(contents, content =>
+        {
+            foreach (IPreRenderProcessor processor in _preRenderProcessors)
+            {
+                content = processor.Process(content);
+            }
+
+            processedContents.Add(content);
+        });
+
+        return processedContents;
+    }
+
+    private void PostProcess(IEnumerable<BlogEssay> essays)
+    {
+        Parallel.ForEach(essays, essay =>
+        {
+            foreach (IPostRenderProcessor processor in _postRenderProcessors)
+            {
+                essay = processor.Process(essay);
+            }
+
+            if (!essayContentService.TryAdd(essay.FileName, essay))
+            {
+                throw new BlogFileException(
+                    $"There are two essays with the same name: '{essay.FileName}'.");
+            }
+
+            logger.LogDebug("Post-Process essay: {}.", essay);
+        });
+    }
+
     private MarkdownMetadata? TryParseMetadata(BlogContent content)
     {
         string fileContent = content.FileContent.Trim();