Add support for "previous" and "next" document navigation

Introduced navigation indices for Markdown files, enabling seamless transitions between "previous" and "next" documents. Updated views and models to reflect these changes, improving navigation usability.

Author: Mpdreamz

src/Elastic.Markdown/IO/DocumentationSet.cs

@@ -2,6 +2,7 @@
 // Elasticsearch B.V licenses this file to you under the Apache 2.0 License.
 // See the LICENSE file in the project root for more information
 
+using System.Collections.Frozen;
 using System.IO.Abstractions;
 using Elastic.Markdown.Diagnostics;
 using Elastic.Markdown.IO.Configuration;
@@ -56,17 +57,24 @@ public DocumentationSet(BuildContext context)
 
 		LastWrite = Files.Max(f => f.SourceFile.LastWriteTimeUtc);
 
-		FlatMappedFiles = Files.ToDictionary(file => file.RelativePath, file => file);
+		FlatMappedFiles = Files.ToDictionary(file => file.RelativePath, file => file).ToFrozenDictionary();
+
 		var folderFiles = Files
 			.GroupBy(file => file.RelativeFolder)
 			.ToDictionary(g => g.Key, g => g.ToArray());
 
-		Tree = new DocumentationGroup(Configuration.TableOfContents, FlatMappedFiles, folderFiles)
+		var fileIndex = 0;
+		Tree = new DocumentationGroup(Configuration.TableOfContents, FlatMappedFiles, folderFiles, ref fileIndex)
 		{
 			Parent = null
 		};
+
+		MarkdownFiles = Files.OfType<MarkdownFile>().ToDictionary(i => i.NavigationIndex, i => i).ToFrozenDictionary();
+
 	}
 
+	public FrozenDictionary<int, MarkdownFile> MarkdownFiles { get; }
+
 	public MarkdownFile? GetMarkdownFile(IFileInfo sourceFile)
 	{
 		var relativePath = Path.GetRelativePath(SourcePath.FullName, sourceFile.FullName);
@@ -104,9 +112,9 @@ private DocumentationFile CreateMarkDownFile(IFileInfo file, BuildContext contex
 
 	public DocumentationGroup Tree { get; }
 
-	public List<DocumentationFile> Files { get; }
+	public IReadOnlyCollection<DocumentationFile> Files { get; }
 
-	public Dictionary<string, DocumentationFile> FlatMappedFiles { get; }
+	public FrozenDictionary<string, DocumentationFile> FlatMappedFiles { get; }
 
 	public void ClearOutputDirectory()
 	{

src/Elastic.Markdown/IO/MarkdownFile.cs

@@ -61,8 +61,15 @@ public string? NavigationTitle
 	public string FileName { get; }
 	public string Url => $"{UrlPathPrefix}/{RelativePath.Replace(".md", ".html")}";
 
+	public int NavigationIndex
+	{
+		get { return _navigationIndex; }
+		set { _navigationIndex = value; }
+	}
+
 	private bool _instructionsParsed;
 	private DocumentationGroup? _parent;
+	private int _navigationIndex;
 
 	public MarkdownFile[] YieldParents()
 	{

src/Elastic.Markdown/IO/Navigation/DocumentationGroup.cs

@@ -36,12 +36,13 @@ public DocumentationGroup(
 		IReadOnlyCollection<ITocItem> toc,
 		IDictionary<string, DocumentationFile> lookup,
 		IDictionary<string, DocumentationFile[]> folderLookup,
+		ref int fileIndex,
 		int depth = 0,
 		MarkdownFile? index = null
 	)
 	{
 		Depth = depth;
-		Index = ProcessTocItems(index, toc, lookup, folderLookup, depth, out var groups, out var files, out var navigationItems);
+		Index = ProcessTocItems(index, toc, lookup, folderLookup, depth, ref fileIndex, out var groups, out var files, out var navigationItems);
 
 		GroupsInOrder = groups;
 		FilesInOrder = files;
@@ -59,6 +60,7 @@ public DocumentationGroup(
 		IDictionary<string, DocumentationFile> lookup,
 		IDictionary<string, DocumentationFile[]> folderLookup,
 		int depth,
+		ref int fileIndex,
 		out List<DocumentationGroup> groups,
 		out List<MarkdownFile> files,
 		out List<INavigationItem> navigationItems)
@@ -75,10 +77,11 @@ public DocumentationGroup(
 					continue;
 
 				md.Parent = this;
+				md.NavigationIndex = ++fileIndex;
 
 				if (file.Children.Count > 0 && d is MarkdownFile virtualIndex)
 				{
-					var group = new DocumentationGroup(file.Children, lookup, folderLookup, depth + 1, virtualIndex)
+					var group = new DocumentationGroup(file.Children, lookup, folderLookup, ref fileIndex, depth + 1, virtualIndex)
 					{
 						Parent = this
 					};
@@ -108,7 +111,7 @@ public DocumentationGroup(
 						.ToArray();
 				}
 
-				var group = new DocumentationGroup(children, lookup, folderLookup, depth + 1)
+				var group = new DocumentationGroup(children, lookup, folderLookup, ref fileIndex, depth + 1)
 				{
 					Parent = this
 				};

src/Elastic.Markdown/IO/State/LinkReference.cs

@@ -24,8 +24,7 @@ public record LinkReference
 	public static LinkReference Create(DocumentationSet set)
 	{
 		var crossLinks = set.Context.Collector.CrossLinks.ToHashSet().ToArray();
-		var links = set.FlatMappedFiles.Values
-			.OfType<MarkdownFile>()
+		var links = set.MarkdownFiles.Values
 			.Select(m => m.RelativePath).ToArray();
 		return new LinkReference
 		{

src/Elastic.Markdown/Slices/HtmlWriter.cs

@@ -45,7 +45,8 @@ public async Task<string> RenderLayout(MarkdownFile markdown, Cancel ctx = defau
 		await DocumentationSet.Tree.Resolve(ctx);
 		var navigationHtml = await RenderNavigation(markdown, ctx);
 
-		var previous = DocumentationSet;
+		var previous = DocumentationSet.MarkdownFiles.GetValueOrDefault(markdown.NavigationIndex -1);
+		var next = DocumentationSet.MarkdownFiles.GetValueOrDefault(markdown.NavigationIndex +1);
 
 		var remote = DocumentationSet.Context.Git.RepositoryName;
 		var branch = DocumentationSet.Context.Git.Branch;
@@ -59,6 +60,8 @@ public async Task<string> RenderLayout(MarkdownFile markdown, Cancel ctx = defau
 			PageTocItems = markdown.TableOfContents.Values.ToList(),
 			Tree = DocumentationSet.Tree,
 			CurrentDocument = markdown,
+			PreviousDocument = previous,
+			NextDocument = next,
 			NavigationHtml = navigationHtml,
 			UrlPathPrefix = markdown.UrlPathPrefix,
 			Applies = markdown.YamlFrontMatter?.AppliesTo,

src/Elastic.Markdown/Slices/Index.cshtml

@@ -7,6 +7,8 @@
 		PageTocItems = Model.PageTocItems,
 		Tree = Model.Tree,
 		CurrentDocument = Model.CurrentDocument,
+		Previous = Model.PreviousDocument,
+		Next = Model.NextDocument,
 		NavigationHtml = Model.NavigationHtml,
 		UrlPathPrefix = Model.UrlPathPrefix,
 		GithubEditUrl = Model.GithubEditUrl

src/Elastic.Markdown/Slices/_Layout.cshtml

@@ -64,15 +64,30 @@
 					<span>Back to top</span>
 				</button>
 				<div class="navigation flex print:hidden">
+					@if (Model.Previous != null)
+					{
+					<div class="navigation-previous">
+						<i class="i-lucide chevron-left"></i>
+						<a href="@Model.Previous.Url">
+							<div class="page-info">
+								<span>Previous</span>
+								<div class="title">@Model.Previous.NavigationTitle</div>
+							</div>
+						</a>
+					</div>
+					}
+					@if (Model.Next != null)
+					{
 					<div class="navigation-next">
-						<a href="elastic/index.html">
+						<a href="@Model.Next.Url">
 							<div class="page-info">
 								<span>Next</span>
-								<div class="title">Elastic content</div>
+								<div class="title">@Model.Next.NavigationTitle</div>
 							</div>
 							<i class="i-lucide chevron-right"></i>
 						</a>
 					</div>
+					}
 				</div>
 			</div>
 		</div>

src/Elastic.Markdown/Slices/_ViewModels.cs

@@ -14,6 +14,8 @@ public class IndexViewModel
 	public required DocumentationGroup Tree { get; init; }
 	public required IReadOnlyCollection<PageTocItem> PageTocItems { get; init; }
 	public required MarkdownFile CurrentDocument { get; init; }
+	public required MarkdownFile? PreviousDocument { get; init; }
+	public required MarkdownFile? NextDocument { get; init; }
 	public required string NavigationHtml { get; init; }
 	public required string? UrlPathPrefix { get; init; }
 	public required string? GithubEditUrl { get; init; }
@@ -26,6 +28,8 @@ public class LayoutViewModel
 	public required IReadOnlyCollection<PageTocItem> PageTocItems { get; init; }
 	public required DocumentationGroup Tree { get; init; }
 	public required MarkdownFile CurrentDocument { get; init; }
+	public required MarkdownFile? Previous { get; init; }
+	public required MarkdownFile? Next { get; init; }
 	public required string NavigationHtml { get; set; }
 	public required string? UrlPathPrefix { get; set; }
 	public required string? GithubEditUrl { get; set; }