add deleted message in preview

lib/src/channel_preview.dart

@@ -33,14 +33,18 @@ class ChannelPreview extends StatelessWidget {
         mainAxisAlignment: MainAxisAlignment.center,
         crossAxisAlignment: CrossAxisAlignment.end,
         children: <Widget>[
-          _buildDate(context, channel.lastMessageAt),
+          _buildDate(context),
         ],
       ),
     );
   }
 
-  Text _buildDate(BuildContext context, DateTime lastMessageAt) {
-    lastMessageAt = lastMessageAt.toLocal();
+  Widget _buildDate(BuildContext context) {
+    return StreamBuilder<DateTime>(
+      stream: channel.lastMessageAtStream,
+      initialData: channel.lastMessageAt,
+      builder: (context, snapshot) {
+        final lastMessageAt = snapshot.data.toLocal();
 
         String stringDate;
         final now = DateTime.now();
@@ -60,12 +64,14 @@ class ChannelPreview extends StatelessWidget {
           stringDate,
           style: Theme.of(context).textTheme.caption,
         );
+      },
+    );
   }
 
   Widget _buildSubtitle() {
     return StreamBuilder<List<User>>(
         stream: channel.state.typingEventsStream,
-        initialData: [],
+        initialData: channel.state.typingEvents,
         builder: (context, snapshot) {
           final typings = snapshot.data;
           final opacity = channel.state.unreadCount > .0 ? 1.0 : 0.5;
@@ -76,12 +82,20 @@ class ChannelPreview extends StatelessWidget {
   }
 
   Widget _buildLastMessage(BuildContext context, double opacity) {
-    final lastMessage =
-        channel.state.messages.isNotEmpty ? channel.state.messages.last : null;
+    return StreamBuilder<List<Message>>(
+      stream: channel.state.messagesStream,
+      initialData: channel.state.messages,
+      builder: (context, snapshot) {
+        final messages = snapshot.data;
+        final lastMessage = messages.isNotEmpty ? messages.last : null;
         if (lastMessage == null) {
           return SizedBox();
         }
 
+        String text;
+        if (lastMessage.type == 'deleted') {
+          text = 'This message was deleted.';
+        } else {
           final prefix = lastMessage.attachments
               .map((e) {
                 if (e.type == 'image') {
@@ -94,14 +108,19 @@ class ChannelPreview extends StatelessWidget {
               .where((e) => e != null)
               .join(' ');
 
+          text = '$prefix ${lastMessage.text ?? ''}';
+        }
+
         return Text(
-      '$prefix ${lastMessage.text ?? ''}',
+          text,
           maxLines: 1,
           overflow: TextOverflow.ellipsis,
           style: Theme.of(context).textTheme.caption.copyWith(
                 color: Colors.black.withOpacity(opacity),
               ),
         );
+      },
+    );
   }
 
   Text _buildTypings(List<User> typings, BuildContext context, double opacity) {