Warn of images outside to current toc scope when using image directive too (#1077)

Author: Mpdreamz

src/Elastic.Markdown/Diagnostics/ProcessorDiagnosticExtensions.cs

@@ -122,41 +122,30 @@ public static void EmitWarning(this DiagnosticsCollector collector, IFileInfo fi
 		collector.Channel.Write(d);
 	}
 
-	public static void EmitError(this IBlockExtension block, string message, Exception? e = null)
-	{
-		if (block.SkipValidation)
-			return;
+	public static void EmitError(this IBlockExtension block, string message, Exception? e = null) => EmitDiagnostic(block, Severity.Error, message, e);
 
-		var d = new Diagnostic
-		{
-			Severity = Severity.Error,
-			File = block.CurrentFile.FullName,
-			Line = block.Line + 1,
-			Column = block.Column,
-			Length = block.OpeningLength + 5,
-			Message = CreateExceptionMessage(message, e),
-		};
-		block.Build.Collector.Channel.Write(d);
-	}
+	public static void EmitWarning(this IBlockExtension block, string message) => EmitDiagnostic(block, Severity.Warning, message);
 
+	public static void EmitHint(this IBlockExtension block, string message) => EmitDiagnostic(block, Severity.Hint, message);
 
-	public static void EmitWarning(this IBlockExtension block, string message)
+	private static void EmitDiagnostic(IBlockExtension block, Severity severity, string message, Exception? e = null)
 	{
 		if (block.SkipValidation)
 			return;
 
 		var d = new Diagnostic
 		{
-			Severity = Severity.Warning,
+			Severity = severity,
 			File = block.CurrentFile.FullName,
 			Line = block.Line + 1,
 			Column = block.Column,
-			Length = block.OpeningLength + 4,
-			Message = message
+			Length = block.OpeningLength + 5,
+			Message = CreateExceptionMessage(message, e),
 		};
 		block.Build.Collector.Channel.Write(d);
 	}
 
+
 	private static void LinkDiagnostic(InlineProcessor processor, Severity severity, Inline inline, int length, string message, Exception? e = null)
 	{
 		var line = inline.Line + 1;

src/Elastic.Markdown/Myst/Directives/ImageBlock.cs

@@ -3,6 +3,7 @@
 // See the LICENSE file in the project root for more information
 
 using Elastic.Markdown.Diagnostics;
+using Elastic.Markdown.IO;
 
 namespace Elastic.Markdown.Myst.Directives;
 
@@ -101,10 +102,17 @@ private void ExtractImageUrl(ParserContext context)
 
 		ImageUrl = imageUrl;
 		var imagePath = Path.Combine(includeFrom, imageUrl.TrimStart('/'));
-		if (context.Build.ReadFileSystem.File.Exists(imagePath))
+		var file = context.Build.ReadFileSystem.FileInfo.New(imagePath);
+		if (file.Exists)
 			Found = true;
 		else
 			this.EmitError($"`{imageUrl}` does not exist. resolved to `{imagePath}");
+
+		if (context.DocumentationFileLookup(context.MarkdownSourcePath) is MarkdownFile currentMarkdown)
+		{
+			if (!file.Directory!.FullName.StartsWith(currentMarkdown.ScopeDirectory.FullName + Path.DirectorySeparatorChar))
+				this.EmitHint($"Image '{imageUrl}' is referenced out of table of contents scope '{currentMarkdown.ScopeDirectory}'.");
+		}
 	}
 }