Refactor TOC generation to use level count instead of max level

Replaces the use of a fixed max TOC level with a level count parameter in TOC generation methods and logic. This change improves flexibility by allowing the number of heading levels included in the TOC to be specified, rather than a maximum heading level value.

modules/docs/src/Volo.Docs.Web/Pages/Documents/Project/Index.cshtml.cs

@@ -101,7 +101,7 @@ namespace Volo.Docs.Pages.Documents.Project
         public DocumentNavigationsDto DocumentNavigationsDto { get; private set; }
 
         private const int MaxDescriptionMetaTagLength = 200;
-        private const int MaxTocLevel = 3;
+        private const int TocLevelCount = 2;
         private readonly IDocumentAppService _documentAppService;
         private readonly IDocumentToHtmlConverterFactory _documentToHtmlConverterFactory;
         private readonly IProjectAppService _projectAppService;
@@ -544,7 +544,7 @@ namespace Volo.Docs.Pages.Documents.Project
 
                     if (Document != null && !Document.Content.IsNullOrEmpty())
                     {
-                        TocItems = _tocGeneratorService.GenerateTocItems(Document.Content, MaxTocLevel);
+                        TocItems = _tocGeneratorService.GenerateTocItems(Document.Content, TocLevelCount);
                     }
 
                     await ConvertDocumentContentToHtmlAsync();

modules/docs/src/Volo.Docs.Web/TableOfContents/ITocGeneratorService.cs

@@ -7,9 +7,9 @@ public interface ITocGeneratorService : IApplicationService
 {
     List<TocHeading> GenerateTocHeadings(string markdownContent);
     
-    List<TocItem> GenerateTocItems(List<TocHeading> tocHeadings, int topLevel, int maxLevel);
+    List<TocItem> GenerateTocItems(List<TocHeading> tocHeadings, int topLevel, int levelCount);
     
     int GetTopLevel(List<TocHeading> tocHeadings);
     
-    List<TocItem> GenerateTocItems(string markdownContent, int maxLevel, int? topLevel = null);
+    List<TocItem> GenerateTocItems(string markdownContent, int levelCount, int? topLevel = null);
 }

modules/docs/src/Volo.Docs.Web/TableOfContents/TocGeneratorService.cs

@@ -32,8 +32,10 @@ public class TocGeneratorService : ITocGeneratorService, ITransientDependency
             .ToList();
     }
 
-    public virtual List<TocItem> GenerateTocItems(List<TocHeading> tocHeadings, int topLevel, int maxLevel)
+    public virtual List<TocItem> GenerateTocItems(List<TocHeading> tocHeadings, int topLevel, int levelCount)
     {
+        var maxLevel = GetMaxLevel(tocHeadings, topLevel, levelCount);
+
         var filteredHeadings = tocHeadings
             .Where(heading => heading.Level >= topLevel && heading.Level <= maxLevel)
             .ToList();
@@ -47,7 +49,7 @@ public class TocGeneratorService : ITocGeneratorService, ITransientDependency
             .FirstOrDefault(level => headings.Count(h => h.Level == level) > 1, MinHeadingLevel);
     }
 
-    public virtual List<TocItem> GenerateTocItems(string markdownContent, int maxLevel, int? topLevel = null)
+    public virtual List<TocItem> GenerateTocItems(string markdownContent, int levelCount, int? topLevel = null)
     {
         var headings = GenerateTocHeadings(markdownContent);
         if (headings.Count == 0)
@@ -56,7 +58,7 @@ public class TocGeneratorService : ITocGeneratorService, ITransientDependency
         }
 
         var resolvedTopLevel = topLevel ?? GetTopLevel(headings);
-        return GenerateTocItems(headings, resolvedTopLevel, maxLevel);
+        return GenerateTocItems(headings, resolvedTopLevel, levelCount);
     }
 
     protected virtual MarkdownPipeline CreateMarkdownPipeline()
@@ -180,6 +182,16 @@ public class TocGeneratorService : ITocGeneratorService, ITransientDependency
         }
     }
 
+    protected virtual int GetMaxLevel(List<TocHeading> tocHeadings, int topLevel, int levelCount)
+    {
+        return tocHeadings.Where(h => h.Level >= topLevel)
+            .Select(h => h.Level)
+            .Distinct()
+            .OrderBy(level => level)
+            .Skip(levelCount - 1)
+            .FirstOrDefault(topLevel);
+    }
+
     protected virtual bool HasExactCount<T>(IEnumerable<T> enumerable, int count)
     {
         var itemCount = 0;