feat: 添加内容热重载指令 (#4)

Reviewed-on: #4

YaeBlog.Core/Services/EssayScanService.cs

@@ -1,20 +1,104 @@
 using System.Collections.Concurrent;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
+using YaeBlog.Core.Abstractions;
 using YaeBlog.Core.Exceptions;
 using YaeBlog.Core.Models;
+using YamlDotNet.Core;
+using YamlDotNet.Serialization;
 
 namespace YaeBlog.Core.Services;
 
 public class EssayScanService(
+    ISerializer yamlSerializer,
+    IDeserializer yamlDeserializer,
     IOptions<BlogOptions> blogOptions,
-    ILogger<EssayContentService> logger)
+    ILogger<EssayScanService> logger) : IEssayScanService
 {
     private readonly BlogOptions _blogOptions = blogOptions.Value;
 
-    public async Task<List<BlogContent>> ScanAsync()
+    public async Task<BlogContents> ScanContents()
     {
-        string root = Path.Combine(Environment.CurrentDirectory, _blogOptions.Root);
+        ValidateDirectory(_blogOptions.Root, out DirectoryInfo drafts, out DirectoryInfo posts);
+
+        return new BlogContents(
+            await ScanContentsInternal(drafts),
+            await ScanContentsInternal(posts));
+    }
+
+    public async Task SaveBlogContent(BlogContent content, bool isDraft = true)
+    {
+        ValidateDirectory(_blogOptions.Root, out DirectoryInfo drafts, out DirectoryInfo posts);
+
+        FileInfo targetFile = isDraft
+            ? new FileInfo(Path.Combine(drafts.FullName, content.FileName + ".md"))
+            : new FileInfo(Path.Combine(posts.FullName, content.FileName + ".md"));
+
+        if (targetFile.Exists)
+        {
+            logger.LogWarning("Blog {} exists, overriding.", targetFile.Name);
+        }
+
+        await using StreamWriter writer = targetFile.CreateText();
+
+        await writer.WriteAsync("---\n");
+        await writer.WriteAsync(yamlSerializer.Serialize(content.Metadata));
+        await writer.WriteAsync("---\n");
+        await writer.WriteAsync("<!--more-->\n");
+    }
+
+    private async Task<ConcurrentBag<BlogContent>> ScanContentsInternal(DirectoryInfo directory)
+    {
+        IEnumerable<FileInfo> markdownFiles = from file in directory.EnumerateFiles()
+            where file.Extension == ".md"
+            select file;
+
+        ConcurrentBag<(string, string)> fileContents = [];
+
+        await Parallel.ForEachAsync(markdownFiles, async (file, token) =>
+        {
+            using StreamReader reader = file.OpenText();
+            fileContents.Add((file.Name, await reader.ReadToEndAsync(token)));
+        });
+
+        ConcurrentBag<BlogContent> contents = [];
+
+        await Task.Run(() =>
+        {
+            foreach ((string filename, string content) in fileContents)
+            {
+                int endPos = content.IndexOf("---", 4, StringComparison.Ordinal);
+                if (!content.StartsWith("---") || endPos is -1 or 0)
+                {
+                    logger.LogWarning("Failed to parse metadata from {}, skipped.", filename);
+                    return;
+                }
+
+                string metadataString = content[4..endPos];
+
+                try
+                {
+                    MarkdownMetadata metadata = yamlDeserializer.Deserialize<MarkdownMetadata>(metadataString);
+                    logger.LogDebug("Scan metadata title: '{}' for {}.", metadata.Title, filename);
+
+                    contents.Add(new BlogContent
+                    {
+                        FileName = filename[..^3], Metadata = metadata, FileContent = content[(endPos + 3)..]
+                    });
+                }
+                catch (YamlException e)
+                {
+                    logger.LogWarning("Failed to parser metadata from {} due to {}, skipping", filename, e);
+                }
+            }
+        });
+
+        return contents;
+    }
+
+    private void ValidateDirectory(string root, out DirectoryInfo drafts, out DirectoryInfo posts)
+    {
+        root = Path.Combine(Environment.CurrentDirectory, root);
         DirectoryInfo rootDirectory = new(root);
 
         if (!rootDirectory.Exists)
@@ -22,36 +106,17 @@ public class EssayScanService(
             throw new BlogFileException($"'{root}' is not a directory.");
         }
 
-        List<FileInfo> markdownFiles = [];
-
-        await Task.Run(() =>
+        if (rootDirectory.EnumerateDirectories().All(dir => dir.Name != "drafts"))
         {
-            foreach (FileInfo fileInfo in rootDirectory.EnumerateFiles())
-            {
-                if (fileInfo.Extension != ".md")
-                {
-                    continue;
-                }
+            throw new BlogFileException($"'{root}/drafts' not exists.");
+        }
 
-                logger.LogDebug("Scan markdown file: {}.", fileInfo.Name);
-                markdownFiles.Add(fileInfo);
-            }
-        });
-
-        ConcurrentBag<BlogContent> contents = [];
-
-        await Parallel.ForEachAsync(markdownFiles, async (info, token) =>
+        if (rootDirectory.EnumerateDirectories().All(dir => dir.Name != "posts"))
         {
-            StreamReader reader = new(info.OpenRead());
+            throw new BlogFileException($"'{root}/posts' not exists.");
+        }
 
-            BlogContent content = new()
-            {
-                FileName = info.Name.Split('.')[0], FileContent = await reader.ReadToEndAsync(token)
-            };
-
-            contents.Add(content);
-        });
-
-        return contents.ToList();
+        drafts = new DirectoryInfo(Path.Combine(root, "drafts"));
+        posts = new DirectoryInfo(Path.Combine(root, "posts"));
     }
 }