Fix root directory logic for tilde links

docs-verifier/src/MarkdownLinksVerifier/LinkValidator/LinkValidatorCreator.cs

@@ -6,26 +6,30 @@ internal static class LinkValidatorCreator
 {
     private static readonly OnlineLinkValidator s_onlineValidator = new();
     private static readonly MailtoLinkValidator s_mailtoValidator = new();
-    private static readonly Dictionary<string, LocalLinkValidator> s_localValidatorDictionary = new();
+    private static readonly Dictionary<(string BaseDirectory, string DocfxConfigurationDirectory), LocalLinkValidator> s_localValidatorDictionary = new();
 
-    internal static ILinkValidator Create(LinkClassification classification, string baseDirectory)
+    internal static ILinkValidator Create(
+        LinkClassification classification,
+        string baseDirectory,
+        string docfxConfigurationDirectory)
         => classification switch
         {
             LinkClassification.Online => s_onlineValidator,
-            LinkClassification.Local => GetLocalLinkValidator(baseDirectory),
+            LinkClassification.Local => GetLocalLinkValidator(baseDirectory, docfxConfigurationDirectory),
             LinkClassification.Mailto => s_mailtoValidator,
             _ => throw new ArgumentException($"Invalid {nameof(classification)}.", nameof(classification))
         };
 
-    private static LocalLinkValidator GetLocalLinkValidator(string baseDirectory)
+    private static LocalLinkValidator GetLocalLinkValidator(string baseDirectory, string docfxConfigurationDirectory)
     {
-        if (s_localValidatorDictionary.TryGetValue(baseDirectory, out LocalLinkValidator? cachedValidator))
+        var key = (baseDirectory, docfxConfigurationDirectory);
+        if (s_localValidatorDictionary.TryGetValue(key, out LocalLinkValidator? cachedValidator))
         {
             return cachedValidator;
         }
 
-        var validator = new LocalLinkValidator(baseDirectory);
-        s_localValidatorDictionary.Add(baseDirectory, validator);
+        var validator = new LocalLinkValidator(baseDirectory, docfxConfigurationDirectory);
+        s_localValidatorDictionary.Add(key, validator);
         return validator;
     }
 }

docs-verifier/src/MarkdownLinksVerifier/LinkValidator/LocalLinkValidator.cs

@@ -10,6 +10,7 @@ namespace MarkdownLinksVerifier.LinkValidator;
 internal class LocalLinkValidator : ILinkValidator
 {
     private readonly string _baseDirectory;
+    private readonly string _docfxConfigurationDirectory;
     private static readonly MarkdownPipeline s_pipeline = new MarkdownPipelineBuilder().UseAutoIdentifiers(AutoIdentifierOptions.GitHub).Build(); // TODO: Is AutoIdentifierOptions.GitHub the correct value to use?
 
     // https://github.com/dotnet/docfx/blob/64fa7e4ed1c1f416e672f2aee2307fd98a21383e/src/Microsoft.DocAsCode.Dfm/Rules/DfmIncludeBlockRule.cs#L44
@@ -20,7 +21,11 @@ internal class LocalLinkValidator : ILinkValidator
         new(@"^\[!INCLUDE\s*\-?\s*\[((?:\[[^\]]*\]|[^\[\]]|\](?=[^\[]*\]))*)\]\(\s*<?([^)]*?)>?(?:\s+(['""])([\s\S]*?)\3)?\s*\)\]", RegexOptions.Compiled | RegexOptions.IgnoreCase | RegexOptions.Multiline, TimeSpan.FromSeconds(10));
 
 
-    public LocalLinkValidator(string baseDirectory) => _baseDirectory = baseDirectory;
+    public LocalLinkValidator(string baseDirectory, string docfxConfigurationDirectory)
+    {
+        _baseDirectory = baseDirectory;
+        _docfxConfigurationDirectory = docfxConfigurationDirectory;
+    }
 
     public ValidationResult Validate(string link, string filePath)
     {
@@ -40,7 +45,7 @@ public ValidationResult Validate(string link, string filePath)
         }
 
         link = link.Replace("%20", " ", StringComparison.Ordinal);
-        link = AdjustLinkPath(link, _baseDirectory);
+        link = AdjustLinkPath(link, _baseDirectory, _docfxConfigurationDirectory);
 
         string? headingIdWithoutHash = null;
         int lastIndex = link.LastIndexOf('#');
@@ -84,13 +89,19 @@ public ValidationResult Validate(string link, string filePath)
         }
     }
 
-    private static string AdjustLinkPath(string link, string baseDirectory)
+    private static string AdjustLinkPath(
+        string link,
+        string baseDirectory,
+        string docfxConfigurationDirectory)
     {
         string relativeTo = baseDirectory;
-        if (link.StartsWith('/') || link.StartsWith("~/", StringComparison.Ordinal))
+        if (link.StartsWith("~/", StringComparison.Ordinal))
+        {
+            link = link[1..];
+            relativeTo = docfxConfigurationDirectory;
+        }
+        else if (link.StartsWith('/'))
         {
-            // The leading slash doesn't matter whether it exists or not.
-            // Only the ~ is problematic and we want to remove it.
             link = link[1..];
             // Links that start with / are relative to the repository root.
             // TODO: Does it work locally (e.g. in VS Code)? Consider a warning for it.
@@ -100,7 +111,7 @@ private static string AdjustLinkPath(string link, string baseDirectory)
         return Path.GetFullPath(Path.Join(relativeTo, link));
     }
 
-    private static bool IsHeadingValid(string path, string headingIdWithoutHash)
+    private bool IsHeadingValid(string path, string headingIdWithoutHash)
     {
         if (headingIdWithoutHash.StartsWith("tab/", StringComparison.Ordinal))
         {
@@ -159,10 +170,10 @@ static bool IsValidHtml(string tag, string headingIdWithoutHash)
         }
     }
 
-    private static IEnumerable<string> GetIncludes(string fileContents, string baseDirectory)
+    private IEnumerable<string> GetIncludes(string fileContents, string baseDirectory)
     {
         return s_inlineIncludeRegex
             .Matches(fileContents)
-            .Select(m => AdjustLinkPath(m.Groups[2].Value, baseDirectory));
+            .Select(m => AdjustLinkPath(m.Groups[2].Value, baseDirectory, _docfxConfigurationDirectory));
     }
 }

docs-verifier/src/MarkdownLinksVerifier/MarkdownFilesAnalyzer.cs

@@ -36,14 +36,18 @@ public static async Task<List<LinkError>> GetResultsAsync(
 
             string? directory = Path.GetDirectoryName(file) ??
                 throw new InvalidOperationException($"Cannot get directory for '{file}'.");
+            string docfxConfigurationDirectory = FindDocfxConfigurationDirectory(directory, rootDirectory);
 
             MarkdownDocument document = Markdown.Parse(await File.ReadAllTextAsync(file), s_pipeline);
             foreach (LinkInline link in
                 document.Descendants<LinkInline>().Where(link => link.Url is not null))
             {
                 string url = link.Url!;
                 LinkClassification classification = Classifier.Classify(url);
-                ILinkValidator validator = LinkValidatorCreator.Create(classification, directory);
+                ILinkValidator validator = LinkValidatorCreator.Create(
+                    classification,
+                    directory,
+                    docfxConfigurationDirectory);
                 if (!IsLinkExcluded(config, url) && validator.Validate(url, file) is { State: not ValidationState.Valid, AbsolutePathWithoutHeading: var absolutePath })
                 {
                     result.Add(new LinkError(
@@ -63,5 +67,27 @@ static bool IsLinkExcluded(MarkdownLinksVerifierConfiguration? config, string ur
 
             return config.IsLinkExcluded(url);
         }
+
+        static string FindDocfxConfigurationDirectory(string fileDirectory, string rootDirectory)
+        {
+            string fullRootDirectory = Path.GetFullPath(rootDirectory);
+            DirectoryInfo? directory = new(Path.GetFullPath(fileDirectory));
+            while (directory is not null)
+            {
+                if (File.Exists(Path.Combine(directory.FullName, "docfx.json")))
+                {
+                    return directory.FullName;
+                }
+
+                if (Path.GetRelativePath(fullRootDirectory, directory.FullName) == ".")
+                {
+                    break;
+                }
+
+                directory = directory.Parent;
+            }
+
+            return fullRootDirectory;
+        }
     }
 }

docs-verifier/tests/MarkdownLinksVerifier/LinkValidatorTests/LocalLinkValidatorTests.cs

@@ -42,6 +42,25 @@ public async Task TestSimpleCase_FileDoesNotExist()
         Assert.Equal(expected, result, s_linkErrorComparer);
     }
 
+    [Fact]
+    public async Task TestTildeLinkIsRelativeToNearestDocfxConfiguration()
+    {
+        using var workspace = new Workspace
+        {
+            Files =
+            {
+                { "/docs/docfx.json", "{}" },
+                { "/docs/content/page.md", "[target](~/content/target.md)" },
+                { "/docs/content/target.md", "Target" }
+            }
+        };
+
+        await workspace.InitializeAsync();
+        List<LinkError> result = await GetResultsAsync();
+
+        Assert.Empty(result);
+    }
+
     [Fact]
     public async Task TestExcludedDirectoriesAreNotAnalyzed()
     {