From 7b56de11ee789d61a507bbe6d7c43df6b79bbb69 Mon Sep 17 00:00:00 2001
From: Alan Mantoux <alan.mantoux@gmail.com>
Date: Tue, 21 Nov 2023 16:00:16 +0100
Subject: [PATCH] Fix HTML encoder for tangled inline tags

---
 packages/parchment/lib/src/codecs/html.dart   | 12 +++++-
 packages/parchment/test/codecs/html_test.dart | 42 +++++++++++++++++++
 2 files changed, 53 insertions(+), 1 deletion(-)

diff --git a/packages/parchment/lib/src/codecs/html.dart b/packages/parchment/lib/src/codecs/html.dart
index edb0e18d..9f3907e8 100644
--- a/packages/parchment/lib/src/codecs/html.dart
+++ b/packages/parchment/lib/src/codecs/html.dart
@@ -273,12 +273,22 @@ class _ParchmentHtmlEncoder extends Converter<ParchmentDocument, String> {
     // Closing tags effectively adds the opening tag at the appropriate position
     // AND adds the closing tag
     final attributesToRemove = <_HtmlInlineTag>{};
-    for (final attr in openInlineTags) {
+    for (var i = 0; i < openInlineTags.length; i++) {
+      final attr = openInlineTags[i];
       if (!inlineAttributes.contains(attr.attribute)) {
+        // remove any tag that was opened later as they must be closed
+        for (var j = 0; j <= i; j++) {
+          final prevAttr = openInlineTags[j];
+          if (prevAttr.openingPosition > attr.openingPosition) {
+            _writeTag(buffer, prevAttr);
+            attributesToRemove.add(prevAttr);
+          }
+        }
         _writeTag(buffer, attr);
         attributesToRemove.add(attr);
       }
     }
+
     for (final attr in attributesToRemove) {
       openInlineTags.remove(attr);
     }
diff --git a/packages/parchment/test/codecs/html_test.dart b/packages/parchment/test/codecs/html_test.dart
index f3cf4e1d..dd09632f 100644
--- a/packages/parchment/test/codecs/html_test.dart
+++ b/packages/parchment/test/codecs/html_test.dart
@@ -101,6 +101,27 @@ void main() {
             '<u><a href="https://wikipedia.org">Something </a><em>in the way</em> mmmm...</u>');
       });
 
+      test('tangled inline tags', () {
+        final doc = ParchmentDocument.fromJson([
+          {'insert': 'AAA'},
+          {
+            'insert': 'BB',
+            'attributes': {'b': true}
+          },
+          {
+            'insert': 'B',
+            'attributes': {'b': true, 's': true}
+          },
+          {
+            'insert': 'CCC',
+            'attributes': {'s': true}
+          },
+          {'insert': '\n'}
+        ]);
+        expect(codec.encode(doc),
+            'AAA<strong>BB<del>B</del></strong><del>CCC</del>');
+      });
+
       test('html escaping', () {
         final doc = ParchmentDocument.fromJson([
           {
@@ -1204,6 +1225,27 @@ void main() {
         expect(codec.decode(html).toDelta(), doc.toDelta());
       });
 
+      test('tangled inline tags', () {
+        final html = 'AAA<strong>BB<del>B</del></strong><del>CCC</del>';
+        final doc = ParchmentDocument.fromJson([
+          {'insert': 'AAA'},
+          {
+            'insert': 'BB',
+            'attributes': {'b': true}
+          },
+          {
+            'insert': 'B',
+            'attributes': {'b': true, 's': true}
+          },
+          {
+            'insert': 'CCC',
+            'attributes': {'s': true}
+          },
+          {'insert': '\n'}
+        ]);
+        expect(codec.decode(html).toDelta(), doc.toDelta());
+      });
+
       test('embedded inline attributes text', () {
         final html =
             '<p><u><a href="https://wikipedia.org">Something </a><em>in the way</em> mmmm...</u></p>';