Fix current directory anchored paths './'

Author: Mpdreamz

src/Elastic.Markdown/Myst/InlineParsers/DiagnosticLinkInlineParser.cs

@@ -280,7 +280,24 @@ private static void UpdateLinkUrl(LinkInline link, string url, ParserContext con
 		var urlPathPrefix = context.Build.UrlPathPrefix ?? string.Empty;
 
 		if (!url.StartsWith('/') && !string.IsNullOrEmpty(url))
-			url = context.CurrentUrlPath[urlPathPrefix.Length..].TrimEnd('/') + '/' + url;
+		{
+			// eat overall path prefix since its gets appended later
+			var subPrefix = context.CurrentUrlPath.Length >= urlPathPrefix.Length
+				? context.CurrentUrlPath[urlPathPrefix.Length..]
+				: urlPathPrefix;
+
+			var markdownPath = context.MarkdownSourcePath.Name;
+
+			// if the current path is an index e.g /reference/cloud-k8s/
+			// './' current path lookups should be relative to sub-path.
+			// If it's not e.g /reference/cloud-k8s/api-docs/ these links should resolve on folder up.
+			var siblingsGoToCurrent = url.StartsWith("./") && markdownPath == "index.md";
+			if (!siblingsGoToCurrent)
+				subPrefix = subPrefix[..subPrefix.LastIndexOf('/')];
+
+			var combined = '/' + Path.Combine(subPrefix, url).TrimStart('/');
+			url = Path.GetFullPath(combined);
+		}
 
 		if (url.EndsWith(".md"))
 		{

tests/authoring/Inline/RelativeLinks.fs

@@ -2,7 +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
 
-module ``inline elemenents``.``relative links``
+module ``inline elements``.``relative links``
 
 open Xunit
 open authoring
@@ -29,7 +29,12 @@ Through various means $$$including-this-inline-syntax$$$
 [link to parent](../parent.md)
 
 [link to parent](../parent.md#some-header)
+
+[link to sibling](./file2.md)
         """
+        Markdown "deeply/nested/file2.md" """
+# file2.md
+"""
         Markdown "deeply/parent.md" """
 # parent.md
 
@@ -44,6 +49,7 @@ Through various means $$$including-this-inline-syntax$$$
              <p><a href="/#and-anchored">link to root</a></p>
              <p><a href="/deeply/parent">link to parent</a></p>
              <p><a href="/deeply/parent#some-header">link to parent</a></p>
+             <p><a href="/deeply/nested/file2">link to sibling</a></p>
          """
 
     [<Fact>]