From 0e290efb22f09cea0f630d51f890bf19c08b26fb Mon Sep 17 00:00:00 2001
From: Gregory Danielson <gregory.danielson3@gmail.com>
Date: Sun, 17 Sep 2023 17:26:44 -0500
Subject: [PATCH] fix: Correctly detect frontmatter to avoid mangling document

The previous format would incorrectly capture:
- A single horizontal rule at the top of the file
- Three literal dashes with arbitrary content after them.
This was detected as a frontmatter, and an extra HR would be inserted after as a result.

The new format requires that there are two sets of triple dashes on their own lines, where the first is the first text in the document.
---
 lib/insert.js | 2 +-
 package.json  | 1 +
 test/test.js  | 5 +++++
 3 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/lib/insert.js b/lib/insert.js
index 67f76ed..9b4382e 100644
--- a/lib/insert.js
+++ b/lib/insert.js
@@ -28,7 +28,7 @@ module.exports = function insert(str, options) {
   if (m) newlines = m[0];
 
   // does the file have front-matter?
-  if (/^---/.test(str)) {
+  if (/^---\n.*\n---\n/.test(str)) {
     // extract it temporarily so the syntax
     // doesn't get mistaken for a heading
     obj = utils.matter(str);
diff --git a/package.json b/package.json
index 25d988d..90a06c4 100644
--- a/package.json
+++ b/package.json
@@ -14,6 +14,7 @@
     "David Mohl (https://dvcrn.github.io)",
     "Federico Soave (https://github.com/Feder1co5oave)",
     "Gary Green (https://github.com/garygreen)",
+    "Gregory Danielson III (https://gregdan3.dev)",
     "Jon Schlinkert (http://twitter.com/jonschlinkert)",
     "Josh Duff (https://tehshrike.github.io)",
     "Matt Ellis (http://sticklebackplastic.com)",
diff --git a/test/test.js b/test/test.js
index e93e41b..055e804 100644
--- a/test/test.js
+++ b/test/test.js
@@ -426,4 +426,9 @@ describe('toc.insert', function() {
     assert.equal(strip(toc.insert(str, { linkify: true })), read('test/expected/insert.md'));
     assert.equal(strip(toc.insert(str, { linkify: false })), read('test/expected/insert-no-links.md'));
   });
+
+  it('should not mangle a file with an initial horizontal rule', function() {
+    assert.equal(toc.insert('---\nExample\n'),  '---\nExample\n');
+  })
+
 });