add: 图片处理器

YaeBlog.Core/Processors/ImagePostRenderProcessor.cs

@@ -0,0 +1,94 @@
+using AngleSharp;
+using AngleSharp.Dom;
+using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Http.HttpResults;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
+using YaeBlog.Core.Abstractions;
+using YaeBlog.Core.Builder;
+using YaeBlog.Core.Extensions;
+using YaeBlog.Core.Models;
+
+namespace YaeBlog.Core.Processors;
+
+public class ImagePostRenderProcessor(ILogger<ImagePostRenderProcessor> logger,
+    IOptions<BlogOptions> options)
+    : IPostRenderProcessor
+{
+    private static readonly IConfiguration s_configuration = Configuration.Default;
+
+    private readonly BlogOptions _options = options.Value;
+
+    public async Task<BlogEssay> ProcessAsync(BlogEssay essay)
+    {
+        BrowsingContext context = new(s_configuration);
+        IDocument html = await context.OpenAsync(
+            req => req.Content(essay.HtmlContent));
+
+        IEnumerable<IElement> imageElements = from node in html.All
+            where node.LocalName == "img"
+            select node;
+
+        foreach (IElement element in imageElements)
+        {
+            IAttr? attr = element.Attributes.GetNamedItem("src");
+            if (attr is not null)
+            {
+                logger.LogDebug("Found image link: '{}'", attr.Value);
+                attr.Value = GenerateImageLink(attr.Value, essay.FileName);
+            }
+            element.ClassList.Add("essay-image");
+        }
+        return essay.WithNewHtmlContent(html.DocumentElement.OuterHtml);
+    }
+
+    public string Name => "ImagePostRenderProcessor";
+
+    public static void AddImageApiEndpoint(BlogApplicationBuilder builder)
+    {
+        builder.ConfigureWebApplication((application) =>
+        {
+            application.MapGet("/api/files/{*filename}", ImageHandler);
+        });
+    }
+
+    private static Results<FileStreamHttpResult, NotFound> ImageHandler(string filename)
+    {
+        string contentType = "image/png";
+        if (filename.EndsWith("jpg") || filename.EndsWith("jpeg"))
+        {
+            contentType = "image/jpeg";
+        }
+
+        if (!Path.Exists(filename))
+        {
+            return TypedResults.NotFound();
+        }
+
+        Stream imageStream = File.OpenRead(filename);
+        return TypedResults.Stream(imageStream, contentType);
+    }
+
+    private string GenerateImageLink(string filename, string essayFilename)
+    {
+        if (!filename.Contains(essayFilename))
+        {
+            filename = Path.Combine(essayFilename, filename);
+        }
+
+        filename = Path.Combine(_options.Root, filename);
+
+        if (!Path.Exists(filename))
+        {
+            logger.LogWarning("Failed to found image: {}.", filename);
+            return _options.BannerImage;
+        }
+
+        string imageLink = "api/files/" + filename;
+        logger.LogDebug("Generate image link '{}' for image file '{}'.",
+            imageLink, filename);
+
+        return imageLink;
+    }
+}