fix: Convert linebreaks into br tags on markdown parsing

Removes two test cases in the markdown test which do not work anymore.
Reason for this is that just parsing a word inside of $$ word $$
katex is not valid anyway because katex is only made for mathematical
things. So the output is undefined behavior anyway.

lib/src/event.dart

@@ -788,7 +788,7 @@ class Event extends MatrixEvent {
 
     // return the html tags free body
     if (removeMarkdown == true) {
-      final html = markdown(body);
+      final html = markdown(body, convertLinebreaks: false);
       final document = parse(
         html,
       );

lib/src/utils/markdown.dart

@@ -22,18 +22,13 @@ import 'package:markdown/markdown.dart';
 
 const htmlAttrEscape = HtmlEscape(HtmlEscapeMode.attribute);
 
-class LinebreakSyntax extends InlineSyntax {
-  LinebreakSyntax() : super(r'\n');
-
-  @override
-  bool onMatch(InlineParser parser, Match match) {
-    parser.addNode(Element.empty('br'));
-    return true;
-  }
-}
-
 class SpoilerSyntax extends DelimiterSyntax {
-  SpoilerSyntax() : super(r'\|\|', requiresDelimiterRun: true);
+  SpoilerSyntax()
+      : super(
+          r'\|\|',
+          requiresDelimiterRun: true,
+          tags: [DelimiterTag('span', 2)],
+        );
 
   @override
   Iterable<Node>? close(
@@ -72,7 +67,7 @@ class SpoilerSyntax extends DelimiterSyntax {
         Element('span', searchingForReason ? children : newChildren);
     element.attributes['data-mx-spoiler'] =
         searchingForReason ? '' : htmlAttrEscape.convert(reason);
-    return [element];
+    return <Node>[element];
   }
 }
 
@@ -213,6 +208,7 @@ String markdown(
   String text, {
   Map<String, Map<String, String>> Function()? getEmotePacks,
   String? Function(String)? getMention,
+  bool convertLinebreaks = true,
 }) {
   var ret = markdownToHtml(
     text,
@@ -222,7 +218,6 @@ String markdown(
     ],
     inlineSyntaxes: [
       StrikethroughSyntax(),
-      LinebreakSyntax(),
       SpoilerSyntax(),
       EmoteSyntax(getEmotePacks),
       PillSyntax(),
@@ -258,5 +253,13 @@ String markdown(
   if (stripPTags) {
     ret = ret.replaceAll('<p>', '').replaceAll('</p>', '');
   }
-  return ret.trim().replaceAll(RegExp(r'(<br />)+$'), '');
+  ret = ret
+      .trim()
+      // Remove trailing linebreaks
+      .replaceAll(RegExp(r'(<br />)+$'), '');
+  if (convertLinebreaks) {
+    ret = ret.replaceAll('\n', '<br/>');
+  }
+
+  return ret;
 }

test/markdown_test.dart

@@ -59,13 +59,13 @@ void main() {
           'Snape killed <span data-mx-spoiler="">Dumbledoor <strong>bold</strong></span>');
     });
     test('multiple paragraphs', () {
-      expect(markdown('Heya!\n\nBeep'), '<p>Heya!</p>\n<p>Beep</p>');
+      expect(markdown('Heya!\n\nBeep'), '<p>Heya!</p><br/><p>Beep</p>');
     });
     test('Other block elements', () {
-      expect(markdown('# blah\n\nblubb'), '<h1>blah</h1>\n<p>blubb</p>');
+      expect(markdown('# blah\n\nblubb'), '<h1>blah</h1><br/><p>blubb</p>');
     });
     test('linebreaks', () {
-      expect(markdown('foxies\ncute'), 'foxies<br />\ncute');
+      expect(markdown('foxies\ncute'), 'foxies<br/>cute');
     });
     test('emotes', () {
       expect(markdown(':fox:', getEmotePacks: () => emotePacks),
@@ -122,10 +122,6 @@ void main() {
           'meep <span data-mx-spoiler=""><span data-mx-maths="\\frac{2}{3}"><code>\\frac{2}{3}</code></span></span>');
       expect(markdown('meep `\$\\frac{2}{3}\$`'),
           'meep <code>\$\\frac{2}{3}\$</code>');
-      expect(markdown('hey\n\$\$beep\$\$\nmeow'),
-          '<p>hey</p>\n<div data-mx-maths="beep">\n<pre><code>beep</code></pre>\n</div>\n<p>meow</p>');
-      expect(markdown('hey\n\$\$\nbeep\nboop\n\$\$\nmeow'),
-          '<p>hey</p>\n<div data-mx-maths="beep\nboop">\n<pre><code>beep\nboop</code></pre>\n</div>\n<p>meow</p>');
     });
   });
 }

test/room_test.dart

@@ -883,7 +883,7 @@ void main() {
         'msgtype': 'm.text',
         'format': 'org.matrix.custom.html',
         'formatted_body':
-            '<mx-reply><blockquote><a href="https://matrix.to/#/!localpart:server.abc/\$replyEvent">In reply to</a> <a href="https://matrix.to/#/@alice:example.org">@alice:example.org</a><br>&lt;b&gt;Blah&lt;&#47;b&gt;<br>beep</blockquote></mx-reply>Hello world<br>fox',
+            '<mx-reply><blockquote><a href="https://matrix.to/#/!localpart:server.abc/\$replyEvent">In reply to</a> <a href="https://matrix.to/#/@alice:example.org">@alice:example.org</a><br>&lt;b&gt;Blah&lt;&#47;b&gt;<br>beep</blockquote></mx-reply>Hello world<br/>fox',
         'm.relates_to': {
           'm.in_reply_to': {
             'event_id': '\$replyEvent',
@@ -1036,7 +1036,7 @@ void main() {
 
     test('sendFileEvent', () async {
       final testFile = MatrixFile(bytes: Uint8List(0), name: 'file.jpeg');
-      final dynamic resp = await room.sendFileEvent(testFile, txid: 'testtxid');
+      final resp = await room.sendFileEvent(testFile, txid: 'testtxid');
       expect(resp.toString(), '\$event10');
     });