feat: add sendAudioEvent and isVoiceMessage method to msc extensions

lib/msc_extensions/extension_audio_events/audio_events.dart

@@ -0,0 +1,41 @@
+import 'package:matrix/matrix.dart';
+
+extension AudioEventExtension on Event {
+  /// returns if the event is a voice message
+  bool get isVoiceMessage =>
+      content['org.matrix.msc2516.voice'] is Map<String, Object?> ||
+      content['org.matrix.msc3245.voice'] is Map<String, Object?>;
+}
+
+extension AudioEventRoomExtension on Room {
+  /// Sends an audio file with appropriate info to this room. Returns the event
+  /// ID generated by the server for this event.
+  Future<String?> sendAudioEvent(
+    MatrixAudioFile audioFile, {
+    Event? replyTo,
+    bool isVoiceMessage = false,
+    int? durationInMs,
+    List<int>? waveform,
+    Map<String, dynamic>? otherFileInfo,
+  }) {
+    final extraContent = <String, Map<String, Object?>>{};
+    if (durationInMs != null) {
+      otherFileInfo ??= {};
+      otherFileInfo['duration'] = durationInMs;
+    }
+    if (otherFileInfo != null) extraContent['info'] = otherFileInfo;
+    if (isVoiceMessage) {
+      // No content, this is only used to identify if the event is a voice message.
+      extraContent['org.matrix.msc3245.voice'] = <String, Object?>{};
+    }
+    extraContent['org.matrix.msc1767.audio'] = <String, Object?>{
+      'duration': durationInMs,
+      'waveform': waveform,
+    };
+    return sendFileEvent(
+      audioFile,
+      inReplyTo: replyTo,
+      extraContent: extraContent,
+    );
+  }
+}