fix: Introduce a TextMessage widget that doesn't render HTML

Messages that don't have the format set to `org.matrix.custom.html` shouldn't be interpreted as HTML. This achieves that by adding a simpler TextMessage widget that renders messages as plain text.

TextMessage was created by copying relevant parts of HtmlMessage, so there's definitely potential for deduplicating.

lib/pages/chat/events/message_content.dart

@@ -22,6 +22,7 @@ import 'html_message.dart';
 import 'image_bubble.dart';
 import 'map_bubble.dart';
 import 'message_download_content.dart';
+import 'text_message.dart';
 
 class MessageContent extends StatelessWidget {
   final Event event;
@@ -255,43 +256,56 @@ class MessageContent extends StatelessWidget {
                 },
               );
             }
-            var html = AppConfig.renderHtml && event.isRichMessage
+            var messageContent = AppConfig.renderHtml && event.isRichMessage
                 ? event.formattedText
                 : event.body;
             if (event.messageType == MessageTypes.Emote) {
-              html = '* $html';
+              messageContent = '* $messageContent';
             }
 
             final bigEmotes = event.onlyEmotes &&
                 event.numberEmotes > 0 &&
                 event.numberEmotes <= 3;
+            final textFontSize = AppConfig.fontSizeFactor *
+                AppConfig.messageFontSize *
+                (bigEmotes ? 5 : 1);
+            final linkStyle = TextStyle(
+              color: linkColor,
+              fontSize: AppConfig.fontSizeFactor * AppConfig.messageFontSize,
+              decoration: TextDecoration.underline,
+              decorationColor: linkColor,
+            );
+
             return Padding(
               padding: const EdgeInsets.symmetric(
                 horizontal: 16,
                 vertical: 8,
               ),
-              child: HtmlMessage(
-                html: html,
-                textColor: textColor,
-                room: event.room,
-                fontSize: AppConfig.fontSizeFactor *
-                    AppConfig.messageFontSize *
-                    (bigEmotes ? 5 : 1),
-                limitHeight: !selected,
-                linkStyle: TextStyle(
-                  color: linkColor,
-                  fontSize:
-                      AppConfig.fontSizeFactor * AppConfig.messageFontSize,
-                  decoration: TextDecoration.underline,
-                  decorationColor: linkColor,
-                ),
-                onOpen: (url) => UrlLauncher(context, url.url).launchUrl(),
-                eventId: event.eventId,
-                checkboxCheckedEvents: event.aggregatedEvents(
-                  timeline,
-                  EventCheckboxRoomExtension.relationshipType,
-                ),
-              ),
+              child: AppConfig.renderHtml && event.isRichMessage
+                  ? HtmlMessage(
+                      html: messageContent,
+                      textColor: textColor,
+                      room: event.room,
+                      fontSize: textFontSize,
+                      limitHeight: !selected,
+                      linkStyle: linkStyle,
+                      onOpen: (url) =>
+                          UrlLauncher(context, url.url).launchUrl(),
+                      eventId: event.eventId,
+                      checkboxCheckedEvents: event.aggregatedEvents(
+                        timeline,
+                        EventCheckboxRoomExtension.relationshipType,
+                      ),
+                    )
+                  : TextMessage(
+                      text: messageContent,
+                      fontSize: textFontSize,
+                      textColor: textColor,
+                      limitHeight: !selected,
+                      linkStyle: linkStyle,
+                      onOpen: (url) =>
+                          UrlLauncher(context, url.url).launchUrl(),
+                    ),
             );
         }
       case EventTypes.CallInvite:

lib/pages/chat/events/text_message.dart

@@ -0,0 +1,40 @@
+import 'package:flutter/material.dart';
+
+import 'package:flutter_linkify/flutter_linkify.dart';
+
+class TextMessage extends StatelessWidget {
+  final String text;
+  final Color textColor;
+  final double fontSize;
+  final TextStyle linkStyle;
+  final void Function(LinkableElement) onOpen;
+  final bool limitHeight;
+
+  const TextMessage({
+    super.key,
+    required this.text,
+    required this.fontSize,
+    required this.linkStyle,
+    required this.onOpen,
+    this.textColor = Colors.black,
+    this.limitHeight = true,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    return Text.rich(
+      LinkifySpan(
+        text: text,
+        options: const LinkifyOptions(humanize: false),
+        linkStyle: linkStyle,
+        onOpen: onOpen,
+      ),
+      style: TextStyle(
+        fontSize: fontSize,
+        color: textColor,
+      ),
+      maxLines: limitHeight ? 64 : null,
+      overflow: TextOverflow.fade,
+    );
+  }
+}