add: Scan unused and not existed image command.

YaeBlog.Core/Services/EssayScanService.cs

@@ -1,4 +1,5 @@
 using System.Collections.Concurrent;
+using System.Text.RegularExpressions;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 using YaeBlog.Core.Abstractions;
@@ -9,7 +10,7 @@ using YamlDotNet.Serialization;
 
 namespace YaeBlog.Core.Services;
 
-public class EssayScanService(
+public partial class EssayScanService(
     ISerializer yamlSerializer,
     IDeserializer yamlDeserializer,
     IOptions<BlogOptions> blogOptions,
@@ -96,6 +97,79 @@ public class EssayScanService(
         return contents;
     }
 
+    public async Task<ImageScanResult> ScanImages()
+    {
+        BlogContents contents = await ScanContents();
+        ValidateDirectory(_blogOptions.Root, out DirectoryInfo drafts, out DirectoryInfo posts);
+
+        List<FileInfo> unusedFiles = [];
+        List<FileInfo> notFoundFiles = [];
+
+        ImageScanResult draftResult = await ScanUnusedImagesInternal(contents.Drafts, drafts);
+        ImageScanResult postResult = await ScanUnusedImagesInternal(contents.Posts, posts);
+
+        unusedFiles.AddRange(draftResult.UnusedImages);
+        notFoundFiles.AddRange(draftResult.NotFoundImages);
+        unusedFiles.AddRange(postResult.UnusedImages);
+        notFoundFiles.AddRange(postResult.NotFoundImages);
+
+        return new ImageScanResult(unusedFiles, notFoundFiles);
+    }
+
+    private Task<ImageScanResult> ScanUnusedImagesInternal(IEnumerable<BlogContent> contents,
+        DirectoryInfo root)
+    {
+        Regex imageRegex = ImageRegex();
+        ConcurrentBag<FileInfo> unusedImage = [];
+        ConcurrentBag<FileInfo> notFoundImage = [];
+
+        Parallel.ForEach(contents, content =>
+        {
+            MatchCollection result = imageRegex.Matches(content.FileContent);
+            DirectoryInfo imageDirectory = new(Path.Combine(root.FullName, content.FileName));
+
+            Dictionary<string, bool> usedDictionary;
+
+            if (imageDirectory.Exists)
+            {
+                usedDictionary = (from file in imageDirectory.EnumerateFiles()
+                    select new KeyValuePair<string, bool>(file.FullName, false)).ToDictionary();
+            }
+            else
+            {
+                usedDictionary = [];
+            }
+
+            foreach (Match match in result)
+            {
+                string imageName = match.Groups[1].Value;
+
+                FileInfo usedFile = imageName.Contains(content.FileName)
+                    ? new FileInfo(Path.Combine(root.FullName, imageName))
+                    : new FileInfo(Path.Combine(root.FullName, content.FileName, imageName));
+
+                if (usedDictionary.TryGetValue(usedFile.FullName, out _))
+                {
+                    usedDictionary[usedFile.FullName] = true;
+                }
+                else
+                {
+                    notFoundImage.Add(usedFile);
+                }
+            }
+
+            foreach (KeyValuePair<string, bool> pair in usedDictionary.Where(p => !p.Value))
+            {
+                unusedImage.Add(new FileInfo(pair.Key));
+            }
+        });
+
+        return Task.FromResult(new ImageScanResult(unusedImage.ToList(), notFoundImage.ToList()));
+    }
+
+    [GeneratedRegex(@"\!\[.*?\]\((.*?)\)")]
+    private static partial Regex ImageRegex();
+
     private void ValidateDirectory(string root, out DirectoryInfo drafts, out DirectoryInfo posts)
     {
         root = Path.Combine(Environment.CurrentDirectory, root);