From ce7adf847d0ae8e03bc5586ad0a54f6c24dc7c9e Mon Sep 17 00:00:00 2001
From: Saswata Mukherjee <saswataminsta@yahoo.com>
Date: Mon, 28 Jun 2021 16:16:59 +0530
Subject: [PATCH] Fix i18n section links (#52)

* Fix i18n section links

Signed-off-by: Saswata Mukherjee <saswataminsta@yahoo.com>

* Implement suggestions

Signed-off-by: Saswata Mukherjee <saswataminsta@yahoo.com>
---
 pkg/mdformatter/linktransformer/link.go      | 15 +++++++++----
 pkg/mdformatter/linktransformer/link_test.go | 22 ++++++++++++++++++++
 2 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/pkg/mdformatter/linktransformer/link.go b/pkg/mdformatter/linktransformer/link.go
index b25ad21..5fa029a 100644
--- a/pkg/mdformatter/linktransformer/link.go
+++ b/pkg/mdformatter/linktransformer/link.go
@@ -387,17 +387,24 @@ func (l localLinksCache) addRelLinks(localLink string) error {
 
 func toHeaderID(header []byte) string {
 	var id []byte
+	// Remove punctuation from header except '-' or '#'.
+	// '\p{L}\p{N}\p{M}' is the unicode equivalent of '\w', https://www.regular-expressions.info/unicode.html.
+	punctuation := regexp.MustCompile(`[^\p{L}\p{N}\p{M}-# ]`)
+	header = punctuation.ReplaceAll(header, []byte(""))
+	headerText := bytes.TrimLeft(bytes.ToLower(header), "#")
+	// If header is just punctuation it comes up empty, so it cannot be linked.
+	if len(headerText) <= 1 {
+		return ""
+	}
 
-	for _, h := range bytes.TrimLeft(bytes.ToLower(header), "#")[1:] {
-		if (h >= 97 && h <= 122) || (h >= 48 && h <= 57) {
-			id = append(id, h)
-		}
+	for _, h := range headerText[1:] {
 		switch h {
 		case '{':
 			return string(id)
 		case ' ', '-':
 			id = append(id, '-')
 		default:
+			id = append(id, h)
 		}
 	}
 	return string(id)
diff --git a/pkg/mdformatter/linktransformer/link_test.go b/pkg/mdformatter/linktransformer/link_test.go
index 4e33a1f..d1d9a49 100644
--- a/pkg/mdformatter/linktransformer/link_test.go
+++ b/pkg/mdformatter/linktransformer/link_test.go
@@ -203,6 +203,28 @@ func TestValidator_TransformDestination(t *testing.T) {
 		testutil.Equals(t, 0, len(diff), diff.String())
 	})
 
+	t.Run("check valid local links in diff language", func(t *testing.T) {
+		testFile := filepath.Join(tmpDir, "repo", "docs", "test", "valid-local-links-diff-lang.md")
+		testutil.Ok(t, ioutil.WriteFile(testFile, []byte(`# Twój wkład w dokumentację
+
+[1](#twój-wkład-w-dokumentację)
+
+## Hugo का उपयोग करते हुए स्थानीय रूप से साइट चलाना
+
+[2](#hugo-का-उपयोग-करते-हुए-स्थानीय-रूप-से-साइट-चलाना)
+`), os.ModePerm))
+
+		diff, err := mdformatter.IsFormatted(context.TODO(), logger, []string{testFile})
+		testutil.Ok(t, err)
+		testutil.Equals(t, 0, len(diff), diff.String())
+
+		diff, err = mdformatter.IsFormatted(context.TODO(), logger, []string{testFile}, mdformatter.WithLinkTransformer(
+			MustNewValidator(logger, []byte(""), anchorDir),
+		))
+		testutil.Ok(t, err)
+		testutil.Equals(t, 0, len(diff), diff.String())
+	})
+
 	t.Run("check invalid local links", func(t *testing.T) {
 		testFile := filepath.Join(tmpDir, "repo", "docs", "test", "invalid-local-links.md")
 		filePath := "/repo/docs/test/invalid-local-links.md"